Download Skull

The Skull
Seatwork: Which bone is known
as the Keystone of the facial
skeleton?
The Maxillae
aka Maxillary Bones
All facial bones except
the mandible articulate
with the maxillae
The Skull
The skull is made up of 22 bones;
Including:
• 8 cranial bones
• 13 facial bones
• The mandible
• Infant Skull
– Incompletely developed
– Separated by fibrous membranes called
FONTANELS (aka soft spots)
Cranium: (aka Braincase)
1. Houses brain
2. Encloses & protects the brain, provides
attachments for muscles, and contains
air-filled sinuses that reduce its weight
3. Features of the frontal bone (behind
forehead):
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Supraorbital foramina (notch) above the orbital
cavity; where blood vessels & nerves pass to
forehead tissues
2 frontal sinuses
Cranium cont’d
4. Parietal bones—lie at sides of cranium
posterior to the frontal bone. Join at sagittal
suture. They meet the frontal bone along the
coronal suture.
5. Occipital bone—lie at back & base of cranium.
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Lambdoidal suture (between the parietal & occipital)
Foramen magnum (where spinal cord passes through)
Occipital condyles (articulate with the 1st vertebra)
Cranium cont’d
6. Temporal bones—at sides of cranium (lower area
where ear openings are found)
– Squamosal suture (between temporal & parietal bone)
– External auditory/acoustic meatus (ear canal in
temporal bone)
– Mandibular fossae (articulate with mandible)
– Mastoid process (attaches to neck muscles; a spongy
bone that projects from the temporal)
– Styloid process (anchors muscles, tongue & pharynx)
– Zygomatic process (projects anteriorly and joins with
the temporal process of the zygomatic bone to help
form the cheek)
Cranium cont’d
7. Sphenoid bone—winged bone at anterior
floor of cranium
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Sella turcica —saddle shaped depression that
houses pituitary gland
Sphenoid sinuses
Cranium cont’d
8. Ethmoid bone—in front of sphenoid
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Cribiform plates (hold it together)
Perpendicular plate (goes downward into nasal
cavity & forms nasal septum)
Superior & middle nasal conchae —coils/folds of
bone that project inward into nasal cavity
Ethmoidal sinuses
Crista galli —projects into cranial cavity; upward
attachment for membranes around the brain
Note: the inferior nasal conchae—considered part of
facial skeleton; they increase surface area in the
nasal cavity
Figure 7.7 The Ethmoid bone (anterior
view)
FACIAL SKELETON
1. The 13 immovable facial bones & the
moveable mandible bone of the lower
jaw form the face; they provide
attachments for muscles of mastication &
expression (total number of facial bones
= 14)
Facial Skeleton cont’d
2. The maxillae (maxillary bones) form:
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The upper jaw
Hard palate
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Floor of the orbits
Sides of the nasal cavity
House the upper teeth
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Formed anteriorly by the fusing of the palatine processes &
posteriorly by the palatine bones)
Alveolar process –inferior part of each maxillary bone
projects downward, holds upper teeth)
Maxillary sinuses (largest sinuses in skull)
Facial Skeleton Cont’d
3. Palatine bones: L-shaped bones located
behind maxillae; form the floor of the nasal
cavity & posterior part of hard palate
4. Zygomatic bones: make up cheekbones; join
with the temporal bones to form the zygomatic
arches
5. Lacrimal bones: form part of the medial walls
of the orbits
6. Nasal bones: form bridge of nose
Facial Skeleton Cont’d
7. Vomer bone: makes up lower part of nasal
septum
8. Inferior nasal conchae: fragile scroll shaped
bones that support mucous membranes within
the nasal cavity
9. Mandible (aka lower jawbone): supports lower
teeth
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Includes mandibular condyle
Coronoid process (anterior projection of mandible)
Alveolar arch
Bones forming left lateral wall of nasal cavity (nasal septum removed)
The end