THE SKULL

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THE SKULL

• 2 Divisions
• Cranium
• Face

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• Most complex bony structure
• 22 bones in all
• Mostly flat bones, but not all!

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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)

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Functions of Cranial Bones

• Enclose and protect the brain
• Attachment sites for head and neck muscles

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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

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

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THE CRANIUM (8)

• 1 frontal bone
• 2 parietal bones
• 2 temporal bones
• 1 occipital bone
• 1 sphenoid bone
• 1 ethmoid bone

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THE FRONTAL BONE
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Parietal Bones Form most of the superior and
lateral aspects of the skull
Figure 7.3a
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Parietal Bones

• Curved, rectangular bones forming majority of the
  cranium
• All four major sutures articulate with this bone

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Look up the 4 major sutures of the skull
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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

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Occipital Bone and Its Major Markings

• Forms most of skulls posterior wall and base
• Major markings include the posterior cranial
  fossa, foramen magnum, occipital condyles, and
  the hypoglossal canal

Figure 7.2b
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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

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Temporal Bones
Figure 7.5
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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

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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

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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

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Maxillary Bone
Figure 7.8b