the skull

THE SKULL

2 Divisions

Cranium

Face

• Most complex bony structure

• 22 bones in all

• Mostly flat bones, but not all!

Cranial Bones: 8

• Friday Find and describe:

• 1. frontal bone

• 2. occipital bone

• 3. sphenoid bone

• 4. ethmoid bone

• 5. parietal bones (2)

• 6. temporal bones (2)

Functions of Cranial Bones

• Enclose and protect the brain

• Attachment sites for head and neck muscles

Functions of Facial Bones

• 1. form framework of face

• 2. contain cavities for special sense organs

• 3. openings for food/air passage

• 4. secure the teeth

• 5. anchor the facial muscles of expression

• ALL BONES OF THE SKULL ARE FIRMLY LOCKED IN PLACE BY JOINTS CALLED SUTURES

• Four major sutures

THE CRANIUM (8)

1 frontal bone

2 parietal bones

2 temporal bones

1 occipital bone

1 sphenoid bone

1 ethmoid bone

THE FRONTAL BONE

Parietal Bones: Form most of the superior and

lateral aspects of the skull

Figure 7.3a

Parietal Bones

• Curved, rectangular bones forming majority of the cranium

• All four major sutures articulate with this bone

Look up the 4 major sutures of the skull

Parietal Bones and Major Associated Sutures

• Four sutures mark the articulations of the parietal bones – Coronal suture – articulation between

parietal bones and frontal bone anteriorly– Sagittal suture – where right and left parietal

bones meet superiorly– Lambdoid suture – where parietal bones

meet the occipital bone posteriorly– Squamosal or squamous suture – where

parietal and temporal bones meet

Occipital Bone and Its Major Markings

• Forms most of skull’s posterior wall and base

• Major markings include the posterior cranial fossa, foramen magnum, occipital condyles, and the hypoglossal canal

Figure 7.2b

Temporal Bones

• Lateral sides of the skull

• Zygomatic process connects with zygomatic arch

• External auditory meatus (external ear)

• Styloid process muscle attachment for tongue and neck

• Mastoid process neck muscles

Temporal Bones

Figure 7.5

Sphenoid Bone

• Spans width of middle cranial fossa

• Articulates with all other cranial bones

• Three parts greater wing, lesser wing and pterygoid processes

• Sella turcica enclosure for pituitary gland

Ethmoid Bone

• Complex shape

• Nasal cavity and orbital cavity

• Cribriform plate roof of the nasal cavity

• Crista galli- outermost covering of the brain cover connects here

Maxillary Bones

• Medially fused bones that make up the upper jaw and the central portion of the facial skeleton

• Facial keystone bones that articulate with all other facial bones except the mandible

• Their major markings include palatine, frontal, and zygomatic processes, the alveolar margins, inferior orbital fissure, and the maxillary sinuses

Maxillary Bone

Figure 7.8b