3. introduction
The skull is a bony structure that supports the face
and forms a protective cavity for the brain.
• The skull consists of 22 bones.
• It is formed by two sets of bones
1. Cerebral cranium (8 bones)
2. Facial cranium (14 bones)
4. The Cerebral cranium
• Contains and protects the brain
• Provides attachment sites for some head and
neck muscles.
Facial cranium
• Provides a framework for the face, sense organs,
and teeth
• Provides openings for the passage of air and
food
5. Bones of Cerebral cranium
Cranium consists of both paired and non-paired bone
Single bones(4):
• Frontal bone
• Ethmoid bone
• Sphenoid bone
• Occipital bone.
Paired bones (4):
• Temporal bones
• Parietal bones
6.
7. SUTURES OF SKULL
1. CORONAL SUTURE: junction between frontal & parietal bones.
2. SAGITTAL SUTURE: junction between two parietal bones.
3. LAMBDOIDAL SUTURE: junction between parietal bones &
occipital bone.
4. SQUAMOUS SUTURE: junction between parietal & temporal
bones.
The suture is a line formed by the junction of two skull bones.
8.
9. Frontal bone
Major marking:-
• Supra-orbital margin: arch of bone above
the orbital opening
• Superciliary arch: the ridge of bone above
the orbital margin
• Glabella: midline point between the paired
superciliary arches
• supraorbital notch: a notch in the supra-
orbital margin.
10. OCCIPITAL BONE
1. Forms the posterior portion of the cranium and
posterior cranial fossa.
2. Foramen magnum located at its base and
communicates with the vertebral canal.
Major markings:-
• External occipital protuberance :
• Superior nuchal lines: low transverse ridge on the
external surface of the squamous part
• Inferior nuchal lines
• Occipital condyles
11. Parietal Bones
1. Form superior and lateral parts of the skull.
Major markings:-
• Superior temporal line: attachment point
of the temporal fascia.
• Inferior temporal line: attachment point
for the temporal muscle.
12. Temporal Bones
1. Lie inferior to parietal bones.
2. Form the inferolateral portion of the skull.
Major markings:-
• Squamous: (flat portion of the bone that projects superiorly toward
the parietal bone )including its Zygomatic Process
• Tympanic Bone: (External Auditory Cana) around the ear
• Mastoid: (Mastoid Air Cells ) behind the ear
• Petrous Bone: (surrounds the inner ear)
• Styloid Process
15. The Sphenoid Bone
1. Butterfly-shaped bone that forms part of the floor of the anterior,
middle, and posterior cranial fossae.
2. Consists of a central body, greater wings, lesser wings, and
pterygoid processes.
Major Openings:-
• foramina rotundum
• ovale
• spinosum
• optic canals
• superior orbital fissure
16.
17. ETHMOID BONE
1. Lies between the nasal and sphenoid bones
2. Forms most of the medial bony region
between the nasal cavity and orbits, the
ethmoid sinuses.
18. Bones of Facial Cranium
Face consists of both paired and non-paired bone
Single bones (3): include
• mandible
• vomer
• hyoid bone
Paired bones (12): include
• maxilla
• nasal bone
• lacrimal bone
• palatine bone
• zygomatic bone
• inferior nasal concha.
23. Overview of Skull Geography
The cranium is divided into the cranial vault and the base
Internally, prominent bony ridges divide the skull into distinct fossae. The skull contains
smaller cavities
• Middle and inner ear cavities – in the lateral aspect of the cranial base
• Nasal cavity lies in and posterior to the nose
• Orbits – house the eyeballs
• Air-filled sinuses – occur in several bones around the nasal cavity
The skull contains approximately 85 named openings
• Foramina, canals, and fissures
• Provide openings for important structures
• Spinal cord
• Blood vessels serving the brain
• 12 pairs of cranial nerves
24. HYOID BONE
Small & U-shaped bone located between the
mandible and larynx
Made of 5 parts:-
Body: central portion
2 Greater horns: posterior extension from body
2 Lesser horns: small superior extensions from
the body
26. MALLEUS
Two main parts:
Manubrium- adheres to the tympanic
membrane
Head- articulates with the incus.
Also has two processes: one anterior and
one lateral
27. INCUS
3 principal parts:
body
two processes ( short and long).
Head articulates with the head of the
malleus
The end of the long process (lenticular
process) articulates with the head of the
stapes.
Short process attached to the cavity wall.
28. STAPES
looks like a stirrup.
four components:
• footplate,
• two crura (posterior and anterior),
• head.
• The head articulates with the incus.
• footplate covers the oval window.
