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Chapter
                                                    2
Face

       OUTLINE
           I. Facial Bones
              A. Maxillary Bones
              B. Zygomatic Bones
              C. Lacrimal Bones
              D. Nasal Bones
              E. Inferior Nasal Conchae
               F. Palatine Bones
              G. Vomer
              H. Mandible
          II. Bony Nasal Septum
         III. Nasal Fossae
        IV. Orbit
         V. Eye
        VI. Paranasal Sinuses
       VII. CT Images
              A. Exam 1
                  1. Coronal Images
                  2. Axial Images
              B. Exam 2
                  1. Coronal Images
                  2. Axial Images
       VIII. Review Questions




                                                    67
68    Fundamentals of Sectional Anatomy


FACIAL BONES                                                  Maxillary Bones
Chapter 1 presented the eight cranial bones: the frontal,         The two maxillary bones are the largest immovable
two parietals, occipital, two temporals, sphenoid, and eth-   bones of the face and are solidly united midline inferiorly.
moid. In examining CT images for facial bones you again       They are involved in forming three cavities: the oral, nasal,
encounter some of these same bones as well as the 14          and orbital. The upper teeth are imbedded in the inferior
facial bones themselves. The list of facial bones includes    margin, the alveolar process or alveolar ridge. Figure
the two maxillae, two zygomatic bones, two lacrimal bones,    2-1 demonstrates the maxillary bones from an anterior per-
two nasal bones, two nasal conchae, two palatine bones,       spective, including the frontal processes articulating with
one vomer, and one mandible.                                  the frontal bone. Figure 2-2 shows the inferior horizontal
                                                              portion of the maxillary bone, the palatine process. It forms
                                                              the anterior part of the hard palate, or roof of the mouth.




                Frontal bone                                                                  Parietal bone


               Temporal bone                                                                 Frontal process
                                                                                             of maxillary bone

              Sphenoid bone                                                                   Nasal bone

               Ethmoid bone
                                                                                              Zygomatic bone

               Lacrimal bone
                                                                                            Middle nasal concha
              Superior concha
                                                                                              Maxilla

                Perpendicular plate
                of the ethmoid bone                                                    Inferior nasal concha

                        Vomer bone
                                                                                      Alveolar process of maxillary bone

              Alveolar process of mandible
                                                                                    Mandible


                                                                       Mentum of mandible

Figure 2-1 External frontal view of facial bones
CHAPTER 2    Face    69

Zygomatic Bones                                               Nasal Bones
    The two zygomatic or malar bones form the promi-              The two nasal bones are fused midline and form the
nent part of our “cheek bones” and are seen on Figure 2-1.    bridge of the nose as seen on Figure 2-1.
The zygomatic bones have three points of attachment:
anteriorly with the maxillary bone, superiorly with the       Inferior Nasal Conchae
frontal bone, and posteriorly with the temporal bone.            Also demonstrated on Figure 2-1 are the two inferior nasal
Trauma may cause them to become free-floating, an injury      conchae, or turbinates, which are separate facial bones.
called a “tripod” fracture.
                                                              Palatine Bones
Lacrimal Bones                                                    Forming the posterior part of the hard palate are the
   The two lacrimal bones, also seen on Figure 2-1, are       two palatine bones. On Figure 2-2, they are seen pos-
very tiny bones that help form the medial wall of the         terior to the palatine processes of the maxilla. The palatine
orbits. They are difficult to distinguish on CT images        bones have vertical portions that extend superiorly and are
because of their size.                                        minimally involved in forming the orbit.




                                                                       Palatine
                                                      Hard            processes
                                                     palate           of maxilla

                                 Horizontal
                                    plate                                 Maxilla
                                 of palatine
                                    bone

                                                                               Zygomatic
                                Vomer
                                                                                 arch

                               Temporal                                              Medial
                                 bone                                              pterygoid
                                                                                   lamina of
                                                                                   sphenoid


                                                                                     Lateral
                                                                                   pterygoid
                                                                                   lamina of
                                                                                   sphenoid



                                                                               Parietal
                                                                                bone

                                                                        Foramen
                                             Occipital                  magnum
                                              bone


Figure 2-2 External view of inferior skull
70    Fundamentals of Sectional Anatomy


Vomer                                                                         the mandible from an anterior perspective and Figure 2-4
   The vomer forms the inferior part of the bony nasal                        demonstrates it from a lateral perspective. The lower teeth
septum while the perpendicular plate of the ethmoid bone                      are rooted in the alveolar ridge or process of the mandible.
forms the superior segment. Their relationship is shown on                    The inferior tip of the mandible is the chin or mentum
Figures 2-1 and 2-3.                                                          and is identified on Figures 2-1 and 2-4. Also seen on
                                                                              Figure 2-4 is one of the bilateral condyloid processes of
                                                                              the mandible. These processes articulate with the temper-
Mandible                                                                      omandibular fossae of the temporal bones to form the
  The mandible is the largest facial bone and the only                        temporomandibular joints.
movable bone in the adult skull. Figure 2-1 demonstrates




                                                          Ethmoid
                                                          crista galli
                             Frontal bone                                            Ethmoid
                                                                                 cribriform plate
                                                                                                     Sphenoid
                                                                                                    sella turcica
                                                                                                                    Sphenoid sinus
             Frontal sinus


                                                                                                                        Sphenoid bone
              Nasal bone


                                                          Ethmoid
                                                     perpendicular plate



                                  Septal cartilage

                                                                         Vomer




                                                                                                               Lateral pterygoid
                                                                                                                  process of
                                                                                                                sphenoid bone

                                                                                                           Medial
                                                                                                      pterygoid process
         Palatine process                                                                             of sphenoid bone
            of maxilla
                                                                                               Hamulus

                                                Horizontal plate         Perpendicular plate
                                                of palatine bone          of palatine bone

Figure 2-3 Midsagittal view of bony nasal septum
CHAPTER 2       Face   71




                          Frontal bone
                                                                                         Parietal bone


                                                                                                   Temporal bone
             Sphenoid bone




         Ethmoid bone



         Nasal bone                                                                                      Occipital bone


         Lacrimal bone                                                                             Temporomandibular
                                                                                                   joint
        Zygomatic bone

                                                                                           External auditory
      Condyloid process                                                                    meatus

                Maxilla                                                     Mastoid process of
                                                                            temporal bone
           Alveolar process                                      Styloid process
           of mandible

                                                              Alveolar process of maxillary bone
        Mentum of mandible                         Mandible


Figure 2-4 External lateral view of facial bones
72    Fundamentals of Sectional Anatomy


BONY NASAL SEPTUM                                                       sagittal line drawing of the nasal septum, and you see both
                                                                        the perpendicular plate of the ethmoid bone and the
The nasal septum, the partition separating the two nasal                vomer. When studying coronal CT images, the perpendi-
fossae, is cartilaginous anteriorly and bony posteriorly. The           cular plate of the ethmoid bone is easily differentiated
bony nasal septum is actually composed of two separate                  from the vomer. The separate components of the bony
pieces of bone. Superiorly it is formed by the perpendi-                nasal septum are more difficult to identify on axial CT
cular plate of the ethmoid bone, as pictured from an                    images. Also easily identified on CT coronal images are the
anterior perspective on Figure 2-5. Figure 2-6 places the               cribiform plate, the horizontal superior portion of the
ethmoid bone with respect to the orbits and nasal cavity.               ethmoid bone, and the crista galli, the small superior
The inferior portion of the bony nasal septum is a separate             extension off the cribiform plate. Figures 2-3, 2-5, and 2-6
facial bone, the vomer. Look back at Figure 2-3, a mid-                 show these structures.




                                                            Cribriform plate



                                Crista galli




                                                                                                Left
                               Ethmoidal                                                      lateral
                                air cells                                                      mass




                                 Superior
                                   nasal
                                  concha                                  Middle
                                                                           nasal
                                         Perpendicular
                                                                          concha
                                             plate


                               Figure 2-5 Frontal view of ethmoid bone




                                     Crista galli            Cribriform plate




                                                                                                   Left
                                                                                                 lateral
                                                                                                  mass




                                            Perpendicular
                                                plate

                                Figure 2-6 Ethmoid bone in place
CHAPTER 2       Face      73


NASAL FOSSAE                                                   bone. All are visible on Figure 2-7. The orbit is conical in
                                                               shape, as shown on Figure 2-8, with the widest portion, the
The nasal fossae, cavities found on either side of the nasal
                                                               base, being located anteriorly. When doing coronal CT
septum, are broken into compartments by smaller scroll-
                                                               images, it becomes increasingly smaller as one cuts pos-
like bones called conchae or turbinates. There are three
                                                               teriorly. If someone receives a direct hit in the region of
pairs of conchae or turbinates, the superior, middle, and
                                                               the orbit, the orbit will give in the weakest region, the
inferior. The superior and middle conchae are medial
                                                               floor. This would be termed a “blow-out” fracture.
extensions off the two lateral masses of the ethmoid bone.
The inferior conchae are separate facial bones. The func-
tion of the conchae is to separate the nasal cavity into
smaller compartments. When air is inhaled, it is forced to
travel through the compartments, and is warmed, filtered                                       Frontal
                                                                                                bone
by the cilia, and moistened by the mucous membranes lin-                                                   Sphenoid
ing the nasal cavity. From a coronal perspective, the infe-                                                  bone
                                                                             Palatine
rior and middle conchae are visible on CT images. The                                                           Malar
superior conchae are much smaller and may not always be             Ethmoid                                  (zygomatic)
identifiable. Figure 2-1 labels the conchae.                         bone                                       bone


                                                                       Lacrimal
ORBIT                                                                   bone
There are seven bones involved in forming the orbit. The
roof of the orbit is formed by the horizontal portion of the          Maxilla
frontal bone. The floor is formed by the maxillary bone
along the medial aspect and the zygomatic bone along the
lateral aspect. The medial wall is formed by the ethmoid
and lacrimal bones. The lateral wall is formed by the zygo-
                                                                    Medial                                    Lateral
matic bone and posterolaterally by the sphenoid bone.
Minimally involved is the vertical portion of the palatine     Figure 2-7 The bones of the orbit




                                                                                                               Apex
                                                                                                         (optic foramen)




                                 30


                                                                                                                           Base

                                                                                    37




Figure 2-8 The orbits
74    Fundamentals of Sectional Anatomy


EYE                                                                 ity exiting the back of the eye. The lens of the eye is also
                                                                    visible on sagittal and axial CT images, but should not be
Certain muscles are involved in moving the eye. Those evi-
                                                                    confused with the optic nerve on coronal images, as it is
dent on CT images are the superior, inferior, medial (or
                                                                    not visible. It is transparent and convex, allowing light to
internal), and lateral (or external) rectus muscles. From a
                                                                    reach the retina, but at the same time causing refraction of
coronal perspective you see all four; from an axial per-
                                                                    light. Figure 2-9 demonstrates the medial and lateral rec-
spective you see the medial and lateral muscles; and from
                                                                    tus muscles, optic nerve, retina, and lens while Figure 2-10
a sagittal perspective you see the superior and inferior. The
                                                                    shows three of the four rectus muscles.
retina is the innermost layer in the posterior eye that con-
tains the rods and cones, the nerve cells responsible for
vision. The optic nerve exits through the optic foramen in
the posterior orbit carrying the sensory information                PARANASAL SINUSES
received by the retina. The optic nerve is seen on coronal          The paranasal or accessory nasal sinuses are air-filled
CT images as an area of opacity in the center of the eye.           cavities located in some cranial and facial bones. They
Looking at axial images, it is visible as a linear area of opac-    communicate with the nasal cavity and with each other.



                                                             Lateral rectus muscle




                                                                                               Retina




                           Lens
                                                                                                        Optic
                                                                                                        nerve




                                                        Medial rectus muscle

                           Figure 2-9 Transverse view of the eye




                                     Superior
                                     oblique                                         Superior
                                                                                     rectus




                                     Inferior                         Inferior       Lateral
                                     oblique                          rectus         rectus

                           Figure 2-10 The muscles of the eye
CHAPTER 2   Face    75

Their function is to lighten the head and add resonance to      The sphenoid sinuses are beneath the sella turcica, in the
the voice. They are lined with mucous membranes and with        body of the sphenoid bone. A septum separates the sphe-
pathology can become filled with fluid. Named for the           noid sinus from the ethmoid sinuses and an additional
bones in which they are located, they are the maxillary,        septum exists if there is more than one sphenoid sinus.
frontal, ethmoid, and sphenoid. Only the maxillary              The sphenoid sinuses are located posterior to the ethmoid
sinuses are present at birth. The frontal and sphenoids         sinuses, as drawn on Figure 2-11. The frontal sinuses
form around the age of 6 or 7, and the last to develop,         are the most superior and the maxillary sinuses the most
in the late teens, are the ethmoids. The largest are the        inferior. Coronal CT images demonstrate that the frontal
maxillary sinuses, with one being located in the body of        sinuses are the most anterior and the sphenoid sinuses
each of the two maxillary bones. The frontal sinuses are in     the most posterior. If the orbits are visible on coronal
the vertical portion of the frontal bone. There may be          cuts, the sinuses you are visualizing are probably the eth-
either one or two, with a septum or wall dividing them if       moids rather than sphenoids. Figure 2-12 demonstrates
two exist. Rarely are they symmetric. The many ethmoid          all four paranasal sinuses from a coronal perspective. The
sinuses are located within the two lateral masses of the        sinuses appear translucent on CT images unless pathology
ethmoid bone, found along the medial wall of each orbit.        exists.




                                 Frontal sinus



                                 Ethmoid
                                 air cells



                                Maxillary sinus




                                             Sphenoid sinus

                               Figure 2-11 Lateral view of paranasal sinuses




                                 Frontal
                                 sinuses



                                Ethmoid
                                air cells                                         Sphenoid
                                                                                   sinuses




                                    Maxillary
                                    sinuses




                               Figure 2-12 Frontal view of paranasal sinuses
76   Fundamentals of Sectional Anatomy


CT IMAGES
Exam 1
Coronal Images




                 Frontal
                  bone                                                                                     Frontal
                                                                                                            sinus
          Perpendicular plate
           of ethmoid bone                                                                                 Nasal
                                                                                                           bone
            Frontal process
              of maxillary
                 bone




         Figure 2-13 Although Figure 2-13 is not the first image of this exam, it is anterior enough to demonstrate the
         unusually large but typical asymmetric frontal sinuses.The nasal bones are seen along with the portions of the maxillary
         bones involved in forming the medial walls of the orbits, the frontal processes. Just starting to appear is the perpen-
         dicular plate of the ethmoid bone which forms the superior portion of the bony nasal septum.




               Frontal bone

                                                                                                             Frontal
              Superior orbital                                                                                sinus
                 margin
                                                                                                            Lacrimal
              Perpendicular
                                                                                                             bone
             plate of ethmoid
                   bone


                                                                                                            Alveolar
                                                                                                           process of
                                                                                                            maxillary
                                                                                                              bone




         Figure 2-14 The superior orbital margin, formed by the frontal bone, is evident on Figure 2-14. More of the per-
         pendicular plate of the ethmoid bone has appeared. The lower edge of the maxillary bone, the alveolar process, is
         shown. It is here that the upper teeth attach.The lacrimal bones, which help to make up the medial walls of the orbits,
         are labeled.
CHAPTER 2       Face   77




         Crista galli
                                                                                                        Superior
       Cribiform plate                                                                                   orbital
      of ethmoid bone                                                                                    margin
       Ethmoidal air                                                                                Lateral mass of
           cells                                                                                     ethmoid bone

        Middle nasal                                                                                    Zygoma
          concha
                                                                                                        Maxillary
       Inferior orbital
                                                                                                         sinus
           margin

       Maxillary bone                                                                                    Inferior
                                                                                                          nasal
           Vomer                                                                                         concha

                                                                                                       Mentum of
                                                                                                       mandible




Figure 2-15 Clearly seen on Figure 2-15 is the crista galli extending superiorly from the cribiform plate of the
ethmoid bone. Some of the many ethmoidal air cells, found in the lateral mass of the ethmoid bone, have become
visible. In addition to the lacrimal bones, the lateral masses of the ethmoid bone help form the medial walls of the
orbits. Just starting to appear are the largest of the sinuses, the maxillary sinuses, in the bodies of the maxillary bones.
Figure 2-15 also shows the midpoint of the mandible, the mentum, as well as the inferior and middle conchae or
turbinates. The inferior conchae, separate facial bones, and the superior and middle conchae extending medially from
the lateral masses of the ethmoid bone divide the nasal cavities into compartments. The vomer is seen forming
the inferior part of the bony nasal septum. Notice the role the nasal maxillary bones assume in forming the inferior
orbital margin.




          Cribiform
            plate


          Ethmoid                                                                                 Superior orbital margin
           sinus                                                                                      (frontal bone)

        Lateral mass                                                                                    Crista galli
      of ethmoid bone

       Superior nasal
                                                                                                        Zygomatic
          concha
                                                                                                       (malar) bone
        Middle nasal
          concha                                                                                          Vomer

       Maxillary sinus                                                                                    Inferior
                                                                                                       nasal concha




Figure 2-16 Figure 2-16 demonstrates the cribiform plate of the ethmoid bone along with the crista galli.
The zygomatic or malar bones are prominent and their involvement in forming the lateral walls of the orbits can be
appreciated.
78   Fundamentals of Sectional Anatomy




                                                                                                               Optic
               Superior rectus                                                                                 nerve
                  muscle
                                                                                                              Lateral
                Medial rectus                                                                                 rectus
                  muscle                                                                                      muscle
                Inferior rectus                                                                               Maxillary
                    muscle                                                                                     sinus

                    Vomer




                                                                                                              Mandible




         Figure 2-17 On Figure 2-17, the maxillary sinuses are fully demonstrated, for the most part nonpathologic except
         for a small area of opacity in the lower right maxillary sinus. A small part of the upper mandible is just starting to
         appear. Also seen on this coronal image are the four rectus muscles (superior, inferior, lateral, and medial), along with
         the optic nerve.




              Cribiform plate
                                                                                                            Perpendicular
             of ethmoid bone
                                                                                                               plate of
                                                                                                              ethmoid
             Sphenoid bone
                                                                                                                bone

               Middle nasal                                                                                    Maxillary
                 concha                                                                                         sinus
                                                                                                                Inferior
                 Vomer
                                                                                                                 nasal
                                                                                                                concha




         Figure 2-18 Notice the diminished size of the orbits on Figure 2-18, an indication that the image is posterior.
         The sphenoid bone is seen making up the posterolateral walls of the orbits.
CHAPTER 2     Face   79




                                                                                                  Anterior
            Body of                                                                               clinoid
           sphenoid
             bone
                                                                                                 Sphenoid
                                                                                                   sinus
           Maxillary
            sinus




Figure 2-19 This last coronal image of Exam 1, Figure 2-19, shows the anterior clinoids of the sphenoid bone along
with the sphenoid sinuses, found in the body of the sphenoid bone. Little of the maxillary sinuses remain to be seen
this far posteriorly.




Axial Images




       Frontal
                                                                                                   Frontal
        bone
                                                                                                    sinus


       Compact
        bone


        Diploe




Figure 2-20 This first axial image of Exam 1, Figure 2-20, demonstrates the frontal sinuses within the frontal bone. It
also shows the unique construction of the cranial bones with diploe sandwiched between two layers of compact bone.
80   Fundamentals of Sectional Anatomy




                Roof of orbit
                  formed by
              horizontal portion
               of frontal bone




         Figure 2-21 Figure 2-21 shows how the roof of the orbits is formed by the horizontal portion of the frontal bone.




                                                                                                     Lateral
                                                                                                     mass of
                                                                                                     ethmoid
                                                                                                      bone




         Figure 2-22 On Figure 2-22, the lateral masses of the ethmoid bone are involved in forming the medial walls of
         the orbits.
CHAPTER 2     Face   81




                                                                                                   Nasal bone

                                                                                                 Perpendicular
                                                                                                plate of ethmoid
       Lens of eye                                                                                    bone
      Ethmoidal air                                                                               Medial rectus
          cells                                                                                     muscle

       Optic nerve                                                                               Lateral rectus
                                                                                                    muscle




Figure 2-23 Seen on Figure 2-23 are the small, numerous, ethmoidal air cells found in the lateral masses or
labrynths of the ethmoid bone. Identified are the nasal bones, as well as the perpendicular plate of the ethmoid bone
forming the superior portion of the bony nasal septum. Although faintly visible, you can distinguish the medial and
lateral rectus muscles, optic nerve, and lens of the eye.




           Bony nasal                                                                             Lacrimal
            septum                                                                                 bone
                                                                                                 Ethmoidal
            Zygoma                                                                                air cells

           Sphenoid
             sinus




Figure 2-24 The bony nasal septum separates the two nasal fossae on Figure 2-24. Between the two orbits are
the ethmoidal sinuses. Helping to form the medial walls of the orbits are the two lacrimal bones.The zygoma, involved
in forming the lateral walls of the orbits, is shown.
82   Fundamentals of Sectional Anatomy




                                                                                                        Maxillary
                                                                                                         bone


                    Bony nasal
                     septum
                                                                                                        Zygoma
                     Maxillary
                      sinus

                                                                                                        Sphenoid
                      Nasal                                                                               sinus
                     concha




         Figure 2-25 Appearing for the first time in this series of images on Figure 2-25 are the maxillary sinuses and the
         maxillary bones. Also distinguishable are the sphenoidal sinuses, located in the body of the sphenoid bone beneath
         the sella turcica. On either side of the bony nasal septum are the conchae or turbinates.The prominent zygoma is seen
         in profile.




                                                                                                       Zygoma

                     Maxillary                                                                          Bony
                      sinus                                                                             nasal
                                                                                                       septum



                                                                                                      Sphenoid
                                                                                                        sinus

                                                                                                      Temporal
                      Mastoid                                                                           bone
                      air cells




         Figure 2-26 On Figure 2-26, compare the size of the maxillary sinuses, the largest and the only ones present at
         birth, to the frontal, ethmoidal, and sphenoidal sinuses. In the mastoid region of the temporal bones are the mastoid
         air cells.
CHAPTER 2     Face   83




                                                                                               Maxillary
                                                                                                sinus




Figure 2-27 Figure 2-27 is at a lower level of the maxillary sinuses.




    Palatine processes
       of maxillary
           bone
                                                                                             Palatine
                                                                                              bone


         Mandible




Figure 2-28 Figure 2-28, a thinner interslice gap compared to the previous images, is included because it demon-
strates the hard palate. The hard palate or roof of the mouth is composed of the palatine processes (the horizontal
portion of the maxillary bone) anteriorly and the two palatine bones posteriorly. Both should be united midline.
84   Fundamentals of Sectional Anatomy




             Alveolar process
                of maxillary
                   bone




                                                                                                       Mandible




         Figure 2-29 This last slice of Exam 1, Figure 2-29, shows the mandible, along with the alveolar process of the max-
         illary bones where the teeth insert.
CHAPTER 2     Face   85

Exam 2
Coronal Images




           Frontal                                                                                Nasal bone
            sinus
                                                                                                 Perpendicular
                                                                                                    plate of
      Frontal process
                                                                                                   ethmoid
        of maxillary
                                                                                                     bone
           bone




Figure 2-30 Seen on Figure 2-30 are the frontal sinuses within the frontal bone, the union of the frontal bone
with the frontal processes of the maxillary bones, the nasal bones, and the perpendicular plate of the ethmoid bone.




                                                                                                  Frontal bone

                                                                                                  Crista galli
            Superior
             orbital                                                                            Cribiform plate
             margin
                                                                                                  Lateral mass
            Ethmoidal                                                                              of ethmoid
             sinuses                                                                                  bone

                                                                                                   Maxillary
                                                                                                    bone




Figure 2-31 On Figure 2-31, the lateral masses of the ethmoid bone descending from the cribiform plate form
the medial walls of the orbits. Extending superiorly from the cribiform plate is the crista galli and within the lateral
masses are the ethmoid sinuses.The maxillary bones are just becoming visible.The superior orbital margin is formed
by the frontal bone.
86   Fundamentals of Sectional Anatomy




                                                                                                        Maxillary
                     Cribiform
                                                                                                         bone
                       plate
                                                                                                         Inferior
                      Maxillary                                                                           orbital
                       sinus                                                                             margin




                                                                                                        Alveolar
                                                                                                        process




         Figure 2-32 The inferior orbital margins are shown on Figure 2-32 formed by the maxillary bones medially and
         the two zygomatic bones laterally. The upper teeth are imbedded in the alveolar process of the maxillary bone. Just
         starting to appear are the maxillary sinuses.




                 Superior rectus
                    muscle

                  Lateral rectus                                                                           Optic nerve
                     muscle
                                                                                                       Ethmoidal air sinus
                 Superior nasal
                    concha                                                                             Zygomatic (malar)
                                                                                                            bone
                    Maxillary
                     sinus                                                                                 Middle nasal
                                                                                                             concha

                     Vomer                                                                                Inferior nasal
                                                                                                             concha




         Figure 2-33 On Figure 2-33 the conchae are seen dividing the nasal fossae into compartments. The size of the
         maxillary sinuses is appreciated. The vomer, making up the lower bony nasal septum, is identified as is the zygomatic
         prominence forming the cheeks bilaterally. Lastly, notice the rectus muscles and optic nerve.
CHAPTER 2   Face   87




           Sphenoid
             bone

                                                                                          Superior
            Maxillary
                                                                                           Middle     Conchae
             sinus
                                                                                           Inferior




           Mentum of
           mandible




Figure 2-34 Figure 2-34 has labeled the mentum or midpoint of the chin.




           Sphenoid
             sinus
                                                                                          Middle
                                                                                          concha
           Bony nasal
            septum                                                                       Maxillary
                                                                                          sinus

                                                                                          Inferior
                                                                                          concha




Figure 2-35 On Figure 2-35, the nasal septum separates the two nasal fossae while the conchae divide them into
compartments.
88   Fundamentals of Sectional Anatomy




                      Anterior
                       clinoid
                    of sphenoid
                                                                                                 Sphenoid
                        bone
                                                                                                   sinus




         Figure 2-36 The anterior clinoids of the sphenoid bone are seen on Figure 2-36 along with the sphenoid sinuses
         in the body of the sphenoid bone beneath the sella turcica.




                                                                                                   Sphenoid
                  Medial and                                                                         sinus
                     lateral
                   pterygoid
                 processes of
                   sphenoid




         Figure 2-37 Figure 2-37 shows the sphenoid sinuses as well as the medial and lateral pterygoid processes of the
         sphenoid bone.
CHAPTER 2     Face   89




        Mastoid
        air cells                                                                         Temperomandibular
  Temperomandibular                                                                             joint
        fossa
                                                                                               Condyloid
                                                                                          process of mandible

                                                                                               Mandible




Figure 2-38 Figure 2-38, the last image in this series, is a larger interslice gap compared to the previous images
but is included to demonstrate the condyloid processes of the mandible articulating with the temporomandibular
fossae of the temporal bones comprising the temporomandibular joints.




Axial Images




         Frontal sinus

           Horizontal
            portion of
          frontal bone




            Mastoid
            air cells




Figure 2-39 On Figure 2-39 you see the horizontal portion of the frontal bone forming the roof of the orbits.
The frontal sinuses within the squamous portion of the frontal bone are also identified.
90   Fundamentals of Sectional Anatomy




                                                                                                       Medial wall
                     Lateral                                                                            of orbit
                     wall of
                      orbit
                                                                                                         Anterior
                    Posterior                                                                           clinoid of
                    clinoid of                                                                          sphenoid
                    sphenoid




         Figure 2-40 Figure 2-40 demonstrates the medial and lateral walls of the orbits taking shape. The anterior and
         posterior clinoids of the sphenoid bone are shown.




               Lacrimal bone                                                                              Ethmoid air
                                                                                                             cells
              Lateral mass of
                 ethmoid                                                                                 Perpendicular
                                                                                                        plate of ethmoid
               Lateral rectus
                  muscle
                                                                                                         Medial rectus
                 Sphenoid                                                                                  muscle
                   sinus




                  Mastoid
                  air cells




         Figure 2-41 On Figure 2-41, the ethmoid and sphenoid sinuses are seen. Also identified is the medial wall of the
         orbit, formed by the lateral masses of the ethmoid bone and by the lacrimal bones. Labeled is the perpendicular plate
         of the ethmoid bone forming the superior portion of the bony nasal septum. Notice the medial and lateral rectus
         muscles and the mastoid air cells.
CHAPTER 2    Face   91




              Nasal
              bone                                                                      Lens of
                                                                                          eye
           Ethmoid air
              cells


            Maxillary                                                                   Sphenoid
             sinus                                                                        sinus




Figure 2-42 Three of the four sinuses are seen on Figure 2-42: the maxillary, sphenoid, and ethmoid. All com-
municate with the nasal cavity. Also seen are the lens of the eyes and the nasal bones.




             Nasal
             bone



            Maxillary                                                                    Zygoma
             sinus




            Foramen
            magnum                                                                     Mastoid air
                                                                                         cells




Figure 2-43 Still apparent on Figure 2-43 are the nasal bones but more obvious now is the zygoma.The foramen
magnum is seen along with the mastoid region of the temporal bones containing the mastoid air cells.
92   Fundamentals of Sectional Anatomy




                      Maxillary
                       sinus

                                                                                                       Vomer




         Figure 2-44 Demonstrated on Figure 2-44 is the inferior bony nasal septum formed by the vomer. The fully
         formed maxillary sinuses are also seen.




             Palatine process
              of hard palate




         Figure 2-45 Figure 2-45, the last image shown in this exam, is a bigger interslice gap than the preceding images but
         is included to demonstrate the palatine process of the hard palate.
CHAPTER 2      Face   93


REVIEW QUESTIONS                                             10. Which of the following imaging planes will not
                                                                 demonstrate the lens of the eye?
 1. The superior, middle, and inferior turbinates are part       a. Coronal
    of the lateral masses of the ethmoid bone.                   b. Axial
    a. True                                                      c. Sagittal
    b. False                                                     d. They all will demonstrate the lens of the eye.
 2. Which bone ends up disassociated in a tripod fracture?   11. On which imaging plane would you be able to see all
    a. Frontal                                                   four rectus muscles of the eye?
    b. Zygoma                                                    a. Sagittal
    c. Temporal                                                  b. Coronal
    d. Maxilla                                                   c. Axial
                                                                 d. All would be visible on all imaging planes.
 3. Which bone forms the superior portion of the bony
    nasal septum?                                            12. Which paranasal sinus would appear first on CT
    a. Ethmoid                                                   images of the face done in a coronal plane arranged
    b. Sphenoid                                                  from anterior to posterior?
    c. Vomer                                                     a. Ethmoid
    d. Frontal bone                                              b. Maxillary
                                                                 c. Frontal
 4. What is the function of the conchae or turbinates in
                                                                 d. Sphenoid
    the nasal cavity?
                                                             13. The largest of the paranasal sinuses are the
                                                                 a. frontal.
                                                                 b. ethmoid.
Match the different portions of the orbit with the bones         c. sphenoid.
composing them.                                                  d. maxillary.
     5. Roof                   a. Maxillary, zygoma          14. The first paranasal sinuses to develop are the
                                                                 a. frontal.
     6. Floor                  b. Ethmoid, lacrimal
                                                                 b. ethmoid.
     7. Medial wall            c. Zygoma, sphenoid               c. maxillary.
                                                                 d. sphenoid.
     8. Lateral wall           d. Frontal bone
                                                             15. The function of the paranasal sinuses is
 9. Which part of the orbit is involved in a blowout frac-
    ture?
    a. Roof                                                                                                             .
    b. Lateral wall
    c. Medial wall
    d. Floor
Sectional anatomy

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Sectional anatomy

  • 1. Chapter 2 Face OUTLINE I. Facial Bones A. Maxillary Bones B. Zygomatic Bones C. Lacrimal Bones D. Nasal Bones E. Inferior Nasal Conchae F. Palatine Bones G. Vomer H. Mandible II. Bony Nasal Septum III. Nasal Fossae IV. Orbit V. Eye VI. Paranasal Sinuses VII. CT Images A. Exam 1 1. Coronal Images 2. Axial Images B. Exam 2 1. Coronal Images 2. Axial Images VIII. Review Questions 67
  • 2. 68 Fundamentals of Sectional Anatomy FACIAL BONES Maxillary Bones Chapter 1 presented the eight cranial bones: the frontal, The two maxillary bones are the largest immovable two parietals, occipital, two temporals, sphenoid, and eth- bones of the face and are solidly united midline inferiorly. moid. In examining CT images for facial bones you again They are involved in forming three cavities: the oral, nasal, encounter some of these same bones as well as the 14 and orbital. The upper teeth are imbedded in the inferior facial bones themselves. The list of facial bones includes margin, the alveolar process or alveolar ridge. Figure the two maxillae, two zygomatic bones, two lacrimal bones, 2-1 demonstrates the maxillary bones from an anterior per- two nasal bones, two nasal conchae, two palatine bones, spective, including the frontal processes articulating with one vomer, and one mandible. the frontal bone. Figure 2-2 shows the inferior horizontal portion of the maxillary bone, the palatine process. It forms the anterior part of the hard palate, or roof of the mouth. Frontal bone Parietal bone Temporal bone Frontal process of maxillary bone Sphenoid bone Nasal bone Ethmoid bone Zygomatic bone Lacrimal bone Middle nasal concha Superior concha Maxilla Perpendicular plate of the ethmoid bone Inferior nasal concha Vomer bone Alveolar process of maxillary bone Alveolar process of mandible Mandible Mentum of mandible Figure 2-1 External frontal view of facial bones
  • 3. CHAPTER 2 Face 69 Zygomatic Bones Nasal Bones The two zygomatic or malar bones form the promi- The two nasal bones are fused midline and form the nent part of our “cheek bones” and are seen on Figure 2-1. bridge of the nose as seen on Figure 2-1. The zygomatic bones have three points of attachment: anteriorly with the maxillary bone, superiorly with the Inferior Nasal Conchae frontal bone, and posteriorly with the temporal bone. Also demonstrated on Figure 2-1 are the two inferior nasal Trauma may cause them to become free-floating, an injury conchae, or turbinates, which are separate facial bones. called a “tripod” fracture. Palatine Bones Lacrimal Bones Forming the posterior part of the hard palate are the The two lacrimal bones, also seen on Figure 2-1, are two palatine bones. On Figure 2-2, they are seen pos- very tiny bones that help form the medial wall of the terior to the palatine processes of the maxilla. The palatine orbits. They are difficult to distinguish on CT images bones have vertical portions that extend superiorly and are because of their size. minimally involved in forming the orbit. Palatine Hard processes palate of maxilla Horizontal plate Maxilla of palatine bone Zygomatic Vomer arch Temporal Medial bone pterygoid lamina of sphenoid Lateral pterygoid lamina of sphenoid Parietal bone Foramen Occipital magnum bone Figure 2-2 External view of inferior skull
  • 4. 70 Fundamentals of Sectional Anatomy Vomer the mandible from an anterior perspective and Figure 2-4 The vomer forms the inferior part of the bony nasal demonstrates it from a lateral perspective. The lower teeth septum while the perpendicular plate of the ethmoid bone are rooted in the alveolar ridge or process of the mandible. forms the superior segment. Their relationship is shown on The inferior tip of the mandible is the chin or mentum Figures 2-1 and 2-3. and is identified on Figures 2-1 and 2-4. Also seen on Figure 2-4 is one of the bilateral condyloid processes of the mandible. These processes articulate with the temper- Mandible omandibular fossae of the temporal bones to form the The mandible is the largest facial bone and the only temporomandibular joints. movable bone in the adult skull. Figure 2-1 demonstrates Ethmoid crista galli Frontal bone Ethmoid cribriform plate Sphenoid sella turcica Sphenoid sinus Frontal sinus Sphenoid bone Nasal bone Ethmoid perpendicular plate Septal cartilage Vomer Lateral pterygoid process of sphenoid bone Medial pterygoid process Palatine process of sphenoid bone of maxilla Hamulus Horizontal plate Perpendicular plate of palatine bone of palatine bone Figure 2-3 Midsagittal view of bony nasal septum
  • 5. CHAPTER 2 Face 71 Frontal bone Parietal bone Temporal bone Sphenoid bone Ethmoid bone Nasal bone Occipital bone Lacrimal bone Temporomandibular joint Zygomatic bone External auditory Condyloid process meatus Maxilla Mastoid process of temporal bone Alveolar process Styloid process of mandible Alveolar process of maxillary bone Mentum of mandible Mandible Figure 2-4 External lateral view of facial bones
  • 6. 72 Fundamentals of Sectional Anatomy BONY NASAL SEPTUM sagittal line drawing of the nasal septum, and you see both the perpendicular plate of the ethmoid bone and the The nasal septum, the partition separating the two nasal vomer. When studying coronal CT images, the perpendi- fossae, is cartilaginous anteriorly and bony posteriorly. The cular plate of the ethmoid bone is easily differentiated bony nasal septum is actually composed of two separate from the vomer. The separate components of the bony pieces of bone. Superiorly it is formed by the perpendi- nasal septum are more difficult to identify on axial CT cular plate of the ethmoid bone, as pictured from an images. Also easily identified on CT coronal images are the anterior perspective on Figure 2-5. Figure 2-6 places the cribiform plate, the horizontal superior portion of the ethmoid bone with respect to the orbits and nasal cavity. ethmoid bone, and the crista galli, the small superior The inferior portion of the bony nasal septum is a separate extension off the cribiform plate. Figures 2-3, 2-5, and 2-6 facial bone, the vomer. Look back at Figure 2-3, a mid- show these structures. Cribriform plate Crista galli Left Ethmoidal lateral air cells mass Superior nasal concha Middle nasal Perpendicular concha plate Figure 2-5 Frontal view of ethmoid bone Crista galli Cribriform plate Left lateral mass Perpendicular plate Figure 2-6 Ethmoid bone in place
  • 7. CHAPTER 2 Face 73 NASAL FOSSAE bone. All are visible on Figure 2-7. The orbit is conical in shape, as shown on Figure 2-8, with the widest portion, the The nasal fossae, cavities found on either side of the nasal base, being located anteriorly. When doing coronal CT septum, are broken into compartments by smaller scroll- images, it becomes increasingly smaller as one cuts pos- like bones called conchae or turbinates. There are three teriorly. If someone receives a direct hit in the region of pairs of conchae or turbinates, the superior, middle, and the orbit, the orbit will give in the weakest region, the inferior. The superior and middle conchae are medial floor. This would be termed a “blow-out” fracture. extensions off the two lateral masses of the ethmoid bone. The inferior conchae are separate facial bones. The func- tion of the conchae is to separate the nasal cavity into smaller compartments. When air is inhaled, it is forced to travel through the compartments, and is warmed, filtered Frontal bone by the cilia, and moistened by the mucous membranes lin- Sphenoid ing the nasal cavity. From a coronal perspective, the infe- bone Palatine rior and middle conchae are visible on CT images. The Malar superior conchae are much smaller and may not always be Ethmoid (zygomatic) identifiable. Figure 2-1 labels the conchae. bone bone Lacrimal ORBIT bone There are seven bones involved in forming the orbit. The roof of the orbit is formed by the horizontal portion of the Maxilla frontal bone. The floor is formed by the maxillary bone along the medial aspect and the zygomatic bone along the lateral aspect. The medial wall is formed by the ethmoid and lacrimal bones. The lateral wall is formed by the zygo- Medial Lateral matic bone and posterolaterally by the sphenoid bone. Minimally involved is the vertical portion of the palatine Figure 2-7 The bones of the orbit Apex (optic foramen) 30 Base 37 Figure 2-8 The orbits
  • 8. 74 Fundamentals of Sectional Anatomy EYE ity exiting the back of the eye. The lens of the eye is also visible on sagittal and axial CT images, but should not be Certain muscles are involved in moving the eye. Those evi- confused with the optic nerve on coronal images, as it is dent on CT images are the superior, inferior, medial (or not visible. It is transparent and convex, allowing light to internal), and lateral (or external) rectus muscles. From a reach the retina, but at the same time causing refraction of coronal perspective you see all four; from an axial per- light. Figure 2-9 demonstrates the medial and lateral rec- spective you see the medial and lateral muscles; and from tus muscles, optic nerve, retina, and lens while Figure 2-10 a sagittal perspective you see the superior and inferior. The shows three of the four rectus muscles. retina is the innermost layer in the posterior eye that con- tains the rods and cones, the nerve cells responsible for vision. The optic nerve exits through the optic foramen in the posterior orbit carrying the sensory information PARANASAL SINUSES received by the retina. The optic nerve is seen on coronal The paranasal or accessory nasal sinuses are air-filled CT images as an area of opacity in the center of the eye. cavities located in some cranial and facial bones. They Looking at axial images, it is visible as a linear area of opac- communicate with the nasal cavity and with each other. Lateral rectus muscle Retina Lens Optic nerve Medial rectus muscle Figure 2-9 Transverse view of the eye Superior oblique Superior rectus Inferior Inferior Lateral oblique rectus rectus Figure 2-10 The muscles of the eye
  • 9. CHAPTER 2 Face 75 Their function is to lighten the head and add resonance to The sphenoid sinuses are beneath the sella turcica, in the the voice. They are lined with mucous membranes and with body of the sphenoid bone. A septum separates the sphe- pathology can become filled with fluid. Named for the noid sinus from the ethmoid sinuses and an additional bones in which they are located, they are the maxillary, septum exists if there is more than one sphenoid sinus. frontal, ethmoid, and sphenoid. Only the maxillary The sphenoid sinuses are located posterior to the ethmoid sinuses are present at birth. The frontal and sphenoids sinuses, as drawn on Figure 2-11. The frontal sinuses form around the age of 6 or 7, and the last to develop, are the most superior and the maxillary sinuses the most in the late teens, are the ethmoids. The largest are the inferior. Coronal CT images demonstrate that the frontal maxillary sinuses, with one being located in the body of sinuses are the most anterior and the sphenoid sinuses each of the two maxillary bones. The frontal sinuses are in the most posterior. If the orbits are visible on coronal the vertical portion of the frontal bone. There may be cuts, the sinuses you are visualizing are probably the eth- either one or two, with a septum or wall dividing them if moids rather than sphenoids. Figure 2-12 demonstrates two exist. Rarely are they symmetric. The many ethmoid all four paranasal sinuses from a coronal perspective. The sinuses are located within the two lateral masses of the sinuses appear translucent on CT images unless pathology ethmoid bone, found along the medial wall of each orbit. exists. Frontal sinus Ethmoid air cells Maxillary sinus Sphenoid sinus Figure 2-11 Lateral view of paranasal sinuses Frontal sinuses Ethmoid air cells Sphenoid sinuses Maxillary sinuses Figure 2-12 Frontal view of paranasal sinuses
  • 10. 76 Fundamentals of Sectional Anatomy CT IMAGES Exam 1 Coronal Images Frontal bone Frontal sinus Perpendicular plate of ethmoid bone Nasal bone Frontal process of maxillary bone Figure 2-13 Although Figure 2-13 is not the first image of this exam, it is anterior enough to demonstrate the unusually large but typical asymmetric frontal sinuses.The nasal bones are seen along with the portions of the maxillary bones involved in forming the medial walls of the orbits, the frontal processes. Just starting to appear is the perpen- dicular plate of the ethmoid bone which forms the superior portion of the bony nasal septum. Frontal bone Frontal Superior orbital sinus margin Lacrimal Perpendicular bone plate of ethmoid bone Alveolar process of maxillary bone Figure 2-14 The superior orbital margin, formed by the frontal bone, is evident on Figure 2-14. More of the per- pendicular plate of the ethmoid bone has appeared. The lower edge of the maxillary bone, the alveolar process, is shown. It is here that the upper teeth attach.The lacrimal bones, which help to make up the medial walls of the orbits, are labeled.
  • 11. CHAPTER 2 Face 77 Crista galli Superior Cribiform plate orbital of ethmoid bone margin Ethmoidal air Lateral mass of cells ethmoid bone Middle nasal Zygoma concha Maxillary Inferior orbital sinus margin Maxillary bone Inferior nasal Vomer concha Mentum of mandible Figure 2-15 Clearly seen on Figure 2-15 is the crista galli extending superiorly from the cribiform plate of the ethmoid bone. Some of the many ethmoidal air cells, found in the lateral mass of the ethmoid bone, have become visible. In addition to the lacrimal bones, the lateral masses of the ethmoid bone help form the medial walls of the orbits. Just starting to appear are the largest of the sinuses, the maxillary sinuses, in the bodies of the maxillary bones. Figure 2-15 also shows the midpoint of the mandible, the mentum, as well as the inferior and middle conchae or turbinates. The inferior conchae, separate facial bones, and the superior and middle conchae extending medially from the lateral masses of the ethmoid bone divide the nasal cavities into compartments. The vomer is seen forming the inferior part of the bony nasal septum. Notice the role the nasal maxillary bones assume in forming the inferior orbital margin. Cribiform plate Ethmoid Superior orbital margin sinus (frontal bone) Lateral mass Crista galli of ethmoid bone Superior nasal Zygomatic concha (malar) bone Middle nasal concha Vomer Maxillary sinus Inferior nasal concha Figure 2-16 Figure 2-16 demonstrates the cribiform plate of the ethmoid bone along with the crista galli. The zygomatic or malar bones are prominent and their involvement in forming the lateral walls of the orbits can be appreciated.
  • 12. 78 Fundamentals of Sectional Anatomy Optic Superior rectus nerve muscle Lateral Medial rectus rectus muscle muscle Inferior rectus Maxillary muscle sinus Vomer Mandible Figure 2-17 On Figure 2-17, the maxillary sinuses are fully demonstrated, for the most part nonpathologic except for a small area of opacity in the lower right maxillary sinus. A small part of the upper mandible is just starting to appear. Also seen on this coronal image are the four rectus muscles (superior, inferior, lateral, and medial), along with the optic nerve. Cribiform plate Perpendicular of ethmoid bone plate of ethmoid Sphenoid bone bone Middle nasal Maxillary concha sinus Inferior Vomer nasal concha Figure 2-18 Notice the diminished size of the orbits on Figure 2-18, an indication that the image is posterior. The sphenoid bone is seen making up the posterolateral walls of the orbits.
  • 13. CHAPTER 2 Face 79 Anterior Body of clinoid sphenoid bone Sphenoid sinus Maxillary sinus Figure 2-19 This last coronal image of Exam 1, Figure 2-19, shows the anterior clinoids of the sphenoid bone along with the sphenoid sinuses, found in the body of the sphenoid bone. Little of the maxillary sinuses remain to be seen this far posteriorly. Axial Images Frontal Frontal bone sinus Compact bone Diploe Figure 2-20 This first axial image of Exam 1, Figure 2-20, demonstrates the frontal sinuses within the frontal bone. It also shows the unique construction of the cranial bones with diploe sandwiched between two layers of compact bone.
  • 14. 80 Fundamentals of Sectional Anatomy Roof of orbit formed by horizontal portion of frontal bone Figure 2-21 Figure 2-21 shows how the roof of the orbits is formed by the horizontal portion of the frontal bone. Lateral mass of ethmoid bone Figure 2-22 On Figure 2-22, the lateral masses of the ethmoid bone are involved in forming the medial walls of the orbits.
  • 15. CHAPTER 2 Face 81 Nasal bone Perpendicular plate of ethmoid Lens of eye bone Ethmoidal air Medial rectus cells muscle Optic nerve Lateral rectus muscle Figure 2-23 Seen on Figure 2-23 are the small, numerous, ethmoidal air cells found in the lateral masses or labrynths of the ethmoid bone. Identified are the nasal bones, as well as the perpendicular plate of the ethmoid bone forming the superior portion of the bony nasal septum. Although faintly visible, you can distinguish the medial and lateral rectus muscles, optic nerve, and lens of the eye. Bony nasal Lacrimal septum bone Ethmoidal Zygoma air cells Sphenoid sinus Figure 2-24 The bony nasal septum separates the two nasal fossae on Figure 2-24. Between the two orbits are the ethmoidal sinuses. Helping to form the medial walls of the orbits are the two lacrimal bones.The zygoma, involved in forming the lateral walls of the orbits, is shown.
  • 16. 82 Fundamentals of Sectional Anatomy Maxillary bone Bony nasal septum Zygoma Maxillary sinus Sphenoid Nasal sinus concha Figure 2-25 Appearing for the first time in this series of images on Figure 2-25 are the maxillary sinuses and the maxillary bones. Also distinguishable are the sphenoidal sinuses, located in the body of the sphenoid bone beneath the sella turcica. On either side of the bony nasal septum are the conchae or turbinates.The prominent zygoma is seen in profile. Zygoma Maxillary Bony sinus nasal septum Sphenoid sinus Temporal Mastoid bone air cells Figure 2-26 On Figure 2-26, compare the size of the maxillary sinuses, the largest and the only ones present at birth, to the frontal, ethmoidal, and sphenoidal sinuses. In the mastoid region of the temporal bones are the mastoid air cells.
  • 17. CHAPTER 2 Face 83 Maxillary sinus Figure 2-27 Figure 2-27 is at a lower level of the maxillary sinuses. Palatine processes of maxillary bone Palatine bone Mandible Figure 2-28 Figure 2-28, a thinner interslice gap compared to the previous images, is included because it demon- strates the hard palate. The hard palate or roof of the mouth is composed of the palatine processes (the horizontal portion of the maxillary bone) anteriorly and the two palatine bones posteriorly. Both should be united midline.
  • 18. 84 Fundamentals of Sectional Anatomy Alveolar process of maxillary bone Mandible Figure 2-29 This last slice of Exam 1, Figure 2-29, shows the mandible, along with the alveolar process of the max- illary bones where the teeth insert.
  • 19. CHAPTER 2 Face 85 Exam 2 Coronal Images Frontal Nasal bone sinus Perpendicular plate of Frontal process ethmoid of maxillary bone bone Figure 2-30 Seen on Figure 2-30 are the frontal sinuses within the frontal bone, the union of the frontal bone with the frontal processes of the maxillary bones, the nasal bones, and the perpendicular plate of the ethmoid bone. Frontal bone Crista galli Superior orbital Cribiform plate margin Lateral mass Ethmoidal of ethmoid sinuses bone Maxillary bone Figure 2-31 On Figure 2-31, the lateral masses of the ethmoid bone descending from the cribiform plate form the medial walls of the orbits. Extending superiorly from the cribiform plate is the crista galli and within the lateral masses are the ethmoid sinuses.The maxillary bones are just becoming visible.The superior orbital margin is formed by the frontal bone.
  • 20. 86 Fundamentals of Sectional Anatomy Maxillary Cribiform bone plate Inferior Maxillary orbital sinus margin Alveolar process Figure 2-32 The inferior orbital margins are shown on Figure 2-32 formed by the maxillary bones medially and the two zygomatic bones laterally. The upper teeth are imbedded in the alveolar process of the maxillary bone. Just starting to appear are the maxillary sinuses. Superior rectus muscle Lateral rectus Optic nerve muscle Ethmoidal air sinus Superior nasal concha Zygomatic (malar) bone Maxillary sinus Middle nasal concha Vomer Inferior nasal concha Figure 2-33 On Figure 2-33 the conchae are seen dividing the nasal fossae into compartments. The size of the maxillary sinuses is appreciated. The vomer, making up the lower bony nasal septum, is identified as is the zygomatic prominence forming the cheeks bilaterally. Lastly, notice the rectus muscles and optic nerve.
  • 21. CHAPTER 2 Face 87 Sphenoid bone Superior Maxillary Middle Conchae sinus Inferior Mentum of mandible Figure 2-34 Figure 2-34 has labeled the mentum or midpoint of the chin. Sphenoid sinus Middle concha Bony nasal septum Maxillary sinus Inferior concha Figure 2-35 On Figure 2-35, the nasal septum separates the two nasal fossae while the conchae divide them into compartments.
  • 22. 88 Fundamentals of Sectional Anatomy Anterior clinoid of sphenoid Sphenoid bone sinus Figure 2-36 The anterior clinoids of the sphenoid bone are seen on Figure 2-36 along with the sphenoid sinuses in the body of the sphenoid bone beneath the sella turcica. Sphenoid Medial and sinus lateral pterygoid processes of sphenoid Figure 2-37 Figure 2-37 shows the sphenoid sinuses as well as the medial and lateral pterygoid processes of the sphenoid bone.
  • 23. CHAPTER 2 Face 89 Mastoid air cells Temperomandibular Temperomandibular joint fossa Condyloid process of mandible Mandible Figure 2-38 Figure 2-38, the last image in this series, is a larger interslice gap compared to the previous images but is included to demonstrate the condyloid processes of the mandible articulating with the temporomandibular fossae of the temporal bones comprising the temporomandibular joints. Axial Images Frontal sinus Horizontal portion of frontal bone Mastoid air cells Figure 2-39 On Figure 2-39 you see the horizontal portion of the frontal bone forming the roof of the orbits. The frontal sinuses within the squamous portion of the frontal bone are also identified.
  • 24. 90 Fundamentals of Sectional Anatomy Medial wall Lateral of orbit wall of orbit Anterior Posterior clinoid of clinoid of sphenoid sphenoid Figure 2-40 Figure 2-40 demonstrates the medial and lateral walls of the orbits taking shape. The anterior and posterior clinoids of the sphenoid bone are shown. Lacrimal bone Ethmoid air cells Lateral mass of ethmoid Perpendicular plate of ethmoid Lateral rectus muscle Medial rectus Sphenoid muscle sinus Mastoid air cells Figure 2-41 On Figure 2-41, the ethmoid and sphenoid sinuses are seen. Also identified is the medial wall of the orbit, formed by the lateral masses of the ethmoid bone and by the lacrimal bones. Labeled is the perpendicular plate of the ethmoid bone forming the superior portion of the bony nasal septum. Notice the medial and lateral rectus muscles and the mastoid air cells.
  • 25. CHAPTER 2 Face 91 Nasal bone Lens of eye Ethmoid air cells Maxillary Sphenoid sinus sinus Figure 2-42 Three of the four sinuses are seen on Figure 2-42: the maxillary, sphenoid, and ethmoid. All com- municate with the nasal cavity. Also seen are the lens of the eyes and the nasal bones. Nasal bone Maxillary Zygoma sinus Foramen magnum Mastoid air cells Figure 2-43 Still apparent on Figure 2-43 are the nasal bones but more obvious now is the zygoma.The foramen magnum is seen along with the mastoid region of the temporal bones containing the mastoid air cells.
  • 26. 92 Fundamentals of Sectional Anatomy Maxillary sinus Vomer Figure 2-44 Demonstrated on Figure 2-44 is the inferior bony nasal septum formed by the vomer. The fully formed maxillary sinuses are also seen. Palatine process of hard palate Figure 2-45 Figure 2-45, the last image shown in this exam, is a bigger interslice gap than the preceding images but is included to demonstrate the palatine process of the hard palate.
  • 27. CHAPTER 2 Face 93 REVIEW QUESTIONS 10. Which of the following imaging planes will not demonstrate the lens of the eye? 1. The superior, middle, and inferior turbinates are part a. Coronal of the lateral masses of the ethmoid bone. b. Axial a. True c. Sagittal b. False d. They all will demonstrate the lens of the eye. 2. Which bone ends up disassociated in a tripod fracture? 11. On which imaging plane would you be able to see all a. Frontal four rectus muscles of the eye? b. Zygoma a. Sagittal c. Temporal b. Coronal d. Maxilla c. Axial d. All would be visible on all imaging planes. 3. Which bone forms the superior portion of the bony nasal septum? 12. Which paranasal sinus would appear first on CT a. Ethmoid images of the face done in a coronal plane arranged b. Sphenoid from anterior to posterior? c. Vomer a. Ethmoid d. Frontal bone b. Maxillary c. Frontal 4. What is the function of the conchae or turbinates in d. Sphenoid the nasal cavity? 13. The largest of the paranasal sinuses are the a. frontal. b. ethmoid. Match the different portions of the orbit with the bones c. sphenoid. composing them. d. maxillary. 5. Roof a. Maxillary, zygoma 14. The first paranasal sinuses to develop are the a. frontal. 6. Floor b. Ethmoid, lacrimal b. ethmoid. 7. Medial wall c. Zygoma, sphenoid c. maxillary. d. sphenoid. 8. Lateral wall d. Frontal bone 15. The function of the paranasal sinuses is 9. Which part of the orbit is involved in a blowout frac- ture? a. Roof . b. Lateral wall c. Medial wall d. Floor