Skull

1
Skull

• Usually consists of 22 bones, all of which
  (except the lower jaw) are firmly interlocked
  along lines called sutures.
• Cranium 8 bones
• Facial skeleton 13 bones lower jaw
• Lower jaw bone is called the mandible, and is the
  only movable bone.

2
Cranium

• Functions
• Encloses and protects the brain
• Provides attachments for muscles that make
  chewing and head movement possible
• Has air-filled, mucous-membrane-lined (??), sinus
  cavities

3
Cranial Bones

1. Frontal bone
2. Parietal bones (2)
3. Occipital bone
4. Temporal bones (2)
5. Sphenoid bone
6. Ethmoid bone

4
Cranial Bones, continued..

• Frontal bone
• Anterior portion of skull above the eyes
• Houses 2 frontal sinuses, one above each eye near
  the midline
• Parietal bones
• One on each side of the skull just behind the
  frontal bone
• Form bulging sides and roof of cranium
• Fused at midline (sagittal suture) and to frontal
  bone (coronal suture)

5
Cranial Bones, continued..

• Occipital bone
• Joins the parietal bones (lambdoidal suture)
• Forms back of skull and base of cranium
• Foramen magnum opening at bottom of occipital
  bone for nerve processes to connect to spinal
  cord
• Occipital condyles rounded processes on each
  side of foramen magnum that articulate with 1st
  vertebra

6
Cranial Bones, continued..

• Temporal bones
• On each side of the skull
• Joins parietal bone (squamosal suture)
• Form parts of sides and base of cranium
• External auditory meatus (???)
• Mandibular fossae depressions in the temporal
  bone that articulate with condyles (???) of the
  mandible

7
Cranial Bones, continued..

• Temporal bones, continued.
• Below each external auditory meatus
• Mastoid process rounded attachment for certain
  neck muscles
• Styloid process long, pointed anchor for
  muscles associated with tongue and pharynx
• Zygomatic process
• Projects anteriorly (???) from temporal bone,
  joins the zygomatic bone (cheek bone), and
  helps form prominence of the cheek

8
Cranial Bones, continued..

• Sphenoid bone
• Wedged between several other bones in anterior
  portion of cranium
• Has a central portion and 2 wing-like structures
  that extend laterally (???)
• Helps form base of cranium, sides of skull, and
  sides of orbits (eye sockets)
• Midline of sphenoid bone has a depression (sella
  turcica) that houses pituitary gland
• Contains 2 sphenoidal sinuses

9
Cranial Bones, continued..

• Ethmoid bone
• Located in front of sphenoid bone
• Consists of 2 masses, one on each side of nasal
  cavity
• Masses joined by thin cribriform plates (???)
• Cribriform plates form part of nasal cavity roof.
• Crista galli triangular process between
  cribriform plates
• Perpendicular plate
• projects downward from cribriform plates
• helps form nasal septum

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Cranial Bones, continued..

• Ethmoid bone, continued..
• Superior nasal concha and middle nasal concha -
  project inward from lateral portions of ethmoid
  bone toward perpendicular plate
• Lateral portions of ethmoid bone contain small
  air spaces (ethmoidal sinuses)

11
Facial Skeleton

• Maxillae (2)
• Form the upper jaw
• Portions comprise the anterior (???) roof of the
  mouth (hard palate), the floors of the orbits
  (???), and the sides and floor of the nasal
  cavity.
• Contain sockets of the upper teeth
• Maxillary sinuses
• Inside the maxillae, lateral (???) to nasal
  cavity
• The largest of the sinuses

12
Facial Bones, continued.

• Maxillae, continued.
• Palatine processes fuse midline (???) to form
  anterior section of hard palate
• Teeth are found in cavities in the alveolar
  arch (aka dental arch) formed by the alveolar
  processes projecting downward from the inferior
  (???) border of the maxillae.

13
Facial Bones, continued.

• Palatine bones
• Behind the maxillae
• Horizontal portions form posterior (???) section
  of hard palate and floor of nasal cavity
• Perpendicular portions help form lateral (???)
  walls of nasal cavity

14
Facial Bones, continued..

• Zygomatic bones (???)
• Also help form lateral walls and floors of the
  orbits
• Each bone has a temporal process that connects
  to the zygomatic process (forming the zygomatic
  arch).
• Lacrimal bones
• Thin, scale-like structure in medial wall (??) of
  each orbit between ethmoid bone and maxilla

15
Facial Bones, continued..

• Nasal bones
• Long, thin, and nearly rectangular
• Lie side by side and fused at midline to form
  bridge of nose
• Vomer bone
• Thin and flat
• Along midline in nasal cavity
• Joins perpendicular plate of ethmoid bone
  posteriorly (???) to form nasal septum

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Facial Bones, continued..

• Inferior nasal conchae
• Fragile, scroll-shaped bones attached to lateral
  walls (???) of nasal cavity
• Support mucous membranes in nasal cavity
• Mandible (???)
• Upward projection at ends
• Posterior mandibular condyle articulates with
  mandibular fossae on _______ bone
• Anterior coronoid process provides attachments
  for muscles for chewing
• Alveolar arch curved, superior (???) border
  that contains sockets for lower teeth