Lab 5

1
Lab 5

• Axial Skeleton - Skull

2
The Skull

• 22 bones joined together by sutures
• Cranial bones surround cranial cavity
• 8 bones in contact with meninges
• calvaria (skullcap) forms roof walls
• Facial bones support teeth form nasal cavity
  orbit
• 14 bones with no direct contact with brain or
  meninges
• attachment of facial jaw muscles

3
Frontal Bone

• Forms forehead and part of the roof of the
  cranium
• Forms roof of the orbit
• Supraorbital ridges and foramina

4
Parietal Bone

• Forms cranial roof and part of its lateral walls
• Bordered by 4 sutures
• coronal, sagittal, lambdoid and squamous
• Marked by temporal lines of temporalis muscle

Temporal lines
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Temporal Bone

• Forms lateral wall part of floor of cranial
  cavity
• squamous part
• zygomatic process
• mandibular fossa TMJ
• tympanic part
• external auditory meatus
• styloid process for muscle attachment
• mastoid part
• mastoid process
• mastoiditis from ear infection

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Temporal Bone
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Petrous Portion of Temporal Bone

• Forms part of cranial floor
• separates middle from posterior cranial fossa
• Houses middle and inner ear cavities
• receptors for hearing and sense of balance
• internal auditory meatus is opening for CN VII
  (vestibulocochlear nerve)

8
Occipital Bone

• Rear much of base of skull
• Foramen magnum holds spinal cord
• Skull rests on atlas at occipital condyles
• External occipital protuberance for nuchal
  ligament
• Nuchal lines mark neck muscles

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Occipital Bone
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Sphenoid Bone

• Lesser wing

• Greater wing

• Body of sphenoid

• Medial and lateral pterygoid processes

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Sphenoid Bone

• Body of the sphenoid
• sella turcica contains deep pit (hypophyseal
  fossa)
• houses pituitary gland
• Lesser wing
• optic foramen contains optic nerve ophthalmic
  a.
• Greater wing -- 3 foramina
• foramen rotundum ovale for trigeminal nerve
• foramen spinosum for meningeal artery

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Sphenoid Bone

• Sphenoid sinus

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Ethmoid Bone

• Found between the orbital cavities
• Forms lateral walls and roof of nasal cavity
• Cribriform plate crista galli
• Ethmoid air cells form ethmoid sinus
• Perpendicular plate forms part of nasal septum
• Concha or turbinates on lateral wall

14
Ethmoid Bone

• Superior middle concha

• Perpendicular plate of nasal septum

15
Maxillary Bones

• Forms upper jaw
• alveolar processes are bony pointsbetween teeth
• alveolar sockets hold teeth
• Forms inferomedial wall of orbit
• infraorbital foramen
• Forms anterior 2/3sof hard palate
• incisive foramen
• cleft palate

16
The Maxilla
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Palatine Bones

• L-shaped bone
• Posterior 1/3 of the hard palate
• Part of lateral nasal wall
• Part of the orbital floor

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Zygomatic Bones

• Forms angles of the cheekbones and part of
  lateral orbital wall
• Zygomatic arch is formed from temporal process of
  zygomatic bone and zygomatic process of temporal
  bone

19
Lacrimal Bones

• Form part of medial wall of each orbit
• Lacrimal fossa houses lacrimal sac in life
• tears collect in lacrimal sac and drain into
  nasal cavity

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Nasal Bones

• Forms bridge of nose and supports cartilages of
  nose
• Often fractured by blow to the nose

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Inferior Nasal Conchae

• A separate bone
• Not part of ethmoid like the superior middle
  concha

22
Vomer

• Inferior half of the nasal septum
• Supports cartilage of nasal septum

23
Mandible

• Only bone of the skull that can move
• jaw joint formed between mandibular fossaof
  temporal bone condyloid process
• Holds the lower teeth
• Attachment of muscles of mastication
• temporalis muscle onto coronoid process
• masseter muscle onto angle of mandible
• Mandibular foramen
• Mental foramen

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Ramus, Angle and Body of Mandible
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Last But Not Least, What are the Seven Bones that
make up the orbit?

• Frontal Bone
• Sphenoid Bone
• Zygomatic Bone
• Maxilla Bone
• Palatine Bone
• Lacrimal Bone
• Ethmoid Bone
• Remember Some Pretty Fine Zebras Make Lunch
  Everyday!

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The Skull in Infancy Childhood

• Spaces between unfused skull bones called
  fontanels
• filled with fibrous membrane
• allow shifting of bones during birth growth of
  brain in infancy
• fuse by 2 years of age
• 2 frontal bones fuse by age six
• metopic suture
• Skull reaches adult size by 8 or 9 causing heads
  of children to be larger in proportion to trunk