The axial skeleton consists of the skull, vertebrae, ribs, sternum, sacrum, and coccyx. It is involved in support and protection more than movement. The skull has 29 bones including the frontal, parietal, temporal, occipital, maxilla, zygomatic, nasal, and mandible. The vertebrae are divided into 7 cervical, 12 thoracic, and 5 lumbar. The ribs articulate with the thoracic vertebrae. The sternum consists of the manubrium, gladiolus, and xiphoid process. The sacrum fuses five elements and the coccyx is variable.

1. The axial Skeleton

2. THE AXIAL SKELETON
CONSISTS OF:
• Skull
• Vertebrae
• Ribs
• Sternum
• Sacrum
• Coccyx
The axial skeleton is harder to
puzzle out than the appendicular,
because it’s involved in support and
protection more than movement.
More memorization is required.

3. SKULL
• skull = cranium + mandible
• cranium = cranial vault +
face + basicranium
• A vault without a face or
basicranium is called a
calvarium.
• The splanchnocranium is
another name for the face.

4. Skull
• 29 bones and 32 teeth.
• Most joints are immovable,
the exceptions being those
with the mandible and
vertebral column.
• The boundaries between the
bones of the vault are
marked by the cranial
sutures.

5. THE CRANIAL VAULT
• Frontal (anterior)
• Parietal (lateral)
• Temporal (lateral)
• Occipital (posterior)
• The parietal and temporal
are paired (they have a left
and a right). The frontal
and occipital are unpaired
(there’s one of each).

6. Sutures
• The coronal suture is parallel
to the coronal plane and
forms the posterior border of
the frontal.
• The sagittal suture is along
the sagittal plane.
• The squamosal suture is
between the temporal and the
parietal.
• The lambdoid suture is
posterior and forms the
superior border of the
occipital.

7. Frontal
• Forehead
• Orbits (anterior and
inferior)
• Supraorbital torus (brow
ridge)
• Coronal suture (posterior)
• Zygomatic process (lateral)
• Billowed internal surface
• Frontal crest (internal)

8. Parietal
• Deeply curved.
• Grooves for middle
meningeal vessels on the
inside. They go back and up.
The deepest is the most
anterior. It is parallel to the
coronal suture.
• coronal suture to anterior
• Sagittal suture medially
• Squamosal suture to inferior
• Lambdoid suture posterior

9. TEMPORAL
• External auditory meatus (ear
canal)
• Squamosal suture superiorly
• Lambdoid suture posteriorly
• Zygomatic process to anterior
• Mastoid process w/ digastric
groove to posterior
• External auditory meatus in
between mastoid and zygomatic
• Petrous process medially and
internally

10. Occipital
• The back of the head.
• External occipital
protuberance (posterior)
• Lambdoid suture (anterior)
• Articulates with first
cervical vertebrae at
occipital condyles
• Foramen magnum (“big
hole”) for spinal cord
(inferior)

11. Major bones of the
Face
• Frontal
• Nasal
• Zygomatic
• Maxilla

12. zygomatic
• Cheekbone
• Articulates with frontal
(superiorly), maxilla
(medially), and temporal
(posteriorly)
• Contributes to orbits
superiorly and medially

13. Maxilla
• Upper jaw
• Articulates with frontal
(superiorly) and zygomatic
(laterally/posteriorly)
• Dentition (teeth) inferiorly
• Maxillary sinus internally

14. Major bones of the
basicranium
• Occipital (posterior)
• Temporal (lateral)
• Sphenoid (midline)

15. Sphenoid
• Highly complex bone
• Contributes to vault,
basicranium, and posterior
portion of the eye orbit
• Often recovered in
fragmentary state, usually in
connection with another
cranial bone
• To remember its anatomical
orientation, think of it
resembling bat, butterfly, or
owl

16. Mandible
• Lower jaw
• One of two movable joints
in the skull
• Articulates with the
temporal’s glenoid fossa
• Ramus
• Condylar process and
coronoid process

17. Vertebrae
• 24 vertebrae: 7 cervical, 12
thoracic, 5 lumbar
• Cervical vertebrae are
located in the neck
• Thoracic are located in the
chest
• Lumbar are located in the
lower back
• Ribs articulate with the
thoracic vertebrae.

18. Ribs
• 24 ribs (12 pairs)
• Ribs 1, 2, 3-10, and 11-12
are distinguishable with
practice
• Ribs articulate posteriorly
and medially with one or
two thoracic vertebrae
• Articulate anteriorly and
medially with 1) the sternum
2) costal cartilage that
attaches to the sternum or 3)
nothing.

19. STERNUM
• The breastbone
• Three sections: the
manubrium, the gladiolus
(or body), and the xiphoid
process.
• Can have a naturally
occurring hole in it that is
possible to mistake for a
gunshot wound

20. Sacrum + Coccyx
• Sacrum is the posterior,
medial-most part of the
pelvis
• Sacrum follows a vertebral
pattern and ossifies from five
elements
• coccyx = tailbone. Very
variable. Not always
recovered. Sometimes fused
to sacrum.