Chapter 7: The Skeleton
Part A
The Axial Skeleton
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Consists of 80 bones
Three major regions
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Skull
Vertebral column
Thoracic cage
The Axial Skeleton
Skull
Thoracic cage
(ribs and
sternum)
Vertebral
column
Sacrum
Cranium
Facial bones
Clavicle
Scapula
Sternum
Rib
Humerus
Vertebra
Radius
Ulna
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
(a) Anterior view
Tarsals
Metatarsals
Phalanges
Figure 7.1a
The Skull
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Two sets of bones
1.
Cranial bones
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2.
Enclose the brain in the cranial cavity
Gives attachment sites for head and neck muscles
Facial bones
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Framework of face
Contains cavities for the special sense organs of sight, taste, and
smell
Provides openings for the passage of air and food
Secures the teeth
Anchors the facial muscles of expression, which we use to show
emotion
Bones of cranium (cranial vault)
Coronal
suture
Squamous
suture
Lambdoid
suture
Facial
bones
(a) Cranial and facial divisions of the skull
Figure 7.2a
Cranial Bones
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Occipital bone
Parietal bones (2)
Frontal bone
Temporal bones (2)
Ethmoid bone
Sphenoid bone
Remember:
Old P-People From T-Texas Eat Spiders
Frontal bone
Parietal bone
Nasal bone
Sphenoid bone
(greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Zygomatic bone
Ethmoid
bone
Maxilla
Mandible
(a) Anterior view
Vomer
Mandibular symphysis
Figure 7.4a
Parietal Bones and Major Associated
Sutures
 Superior and lateral aspects of cranial vault
 Four sutures mark the articulations of parietal
bones with frontal, occipital, and temporal bones:
1.
2.
3.
4.
Coronal suture—between parietal bones and frontal bone
Sagittal suture—between right and left parietal bones
Lambdoid suture—between parietal bones and occipital
bone
Squamous (squamosal) sutures—between parietal and
temporal bones on each side of skull
Coronal suture
Parietal bone
Frontal bone
Sphenoid bone
(greater wing)
Ethmoid bone
Temporal bone
Lacrimal bone
Lambdoid
suture
Squamous
suture
Occipital
bone
Zygomatic
process
Occipitomastoid
suture
Nasal bone
Zygomatic
bone
Maxilla
Mandible
(a) External anatomy of the right side of the skull
Figure 7.5a
Occipital Bone
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Most of skull’s posterior wall and posterior cranial fossa
Contains the foramen magnum “large hole” through
which the brain connects with the spinal cord
Articulates at the occipital condyles with 1st vertebra
Sites of attachment for the many neck and back muscles
Sagittal suture
Parietal
bone
Sutural
bone
Lambdoid
suture
Occipital bone
Occipitomastoid
suture
(b) Posterior view
Figure 7.4b
Maxilla
Palatine bone
Zygomatic bone
Temporal bone
(zygomatic process)
Intermaxillary suture
Median palatine suture
Maxilla
Sphenoid bone
(greater wing)
Vomer
Temporal bone
Parietal bone
Foramen magnum
(a) Inferior view of the skull (mandible removed)
Figure 7.6a
Temporal Bones
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Inferolateral aspects of skull and parts of cranial floor
Contains the zygomatic process, external acoustic meatus,
the styloid process, and the mastoid process
Articulates with the mandible
at the TMJ
Sphenoid Bone
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Complex, butterfly-shaped bone
Keystone bone
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Articulates with all other cranial bones
Three pairs of processes
Contains the sella turcica and the
hypophyseal fossa that surround the
pituitary gland
Ethmoid Bone
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Deepest skull bone
Superior part of nasal septum, roof of nasal cavities
Contributes to medial wall of orbits
Contains the superior and middle nasal conchae
Contains the crista galli (rooster’s comb)
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The attachment site for the outermost covering of the brain
Figure 7.10
Sutural Bones
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Tiny irregularly shaped bones that appear within sutures
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http://www.sciencekids.co.nz/videos/humanbody/skullbon
es.html
Sagittal suture
Parietal
bone
Sutural
bone
Lambdoid
suture
Occipital bone
Occipitomastoid
suture
(b) Posterior view
Figure 7.4b
Facial Bones (14 Total)
Unpaired Bones:
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Mandible
Vomer
Paired Bones:
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Maxillary bones (2)
Zygomatic bones (2)
Nasal bones (2)
Lacrimal bones (2)
Palatine bones (2)
Inferior nasal Conchae (2)
Virgil Can Not Make My Pet Zebra Laugh!
Mandible
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Lower jaw
Largest, strongest bone of face
Articulates at the temporomandibular joint (TMJ): only
freely movable joint in skull
Temporomandibular
joint
Ramus
of
mandible
Mandibular
angle
Body of mandible
(a) Mandible, right lateral view
Figure 7.11a
Maxillary Bones
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
Medially fused to form upper jaw and central portion of
facial skeleton
Keystone bone of the facial bones: all facial bones except
the mandible articulate with it
Zygomatic Bones
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Cheekbones
Inferolateral margins of orbits
Articulates with 3 separate
zygomatic processes
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Frontal zygomatic process
Maxillary zygomatic process
Temporal zygomatic process
Nasal Bones and Lacrimal Bones
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Nasal bones
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Form bridge of nose
Attach to the cartilage that forms most of the skeleton of the
nose
Lacrimal bones
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In medial walls of orbits
Forms part of the canal that drains tears into the nasal cavity
Lacrimation = crying/tear production
Frontal bone
Parietal bone
Nasal bone
Sphenoid bone
(greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Zygomatic bone
Ethmoid
bone
Maxilla
Mandible
(a) Anterior view
Vomer
Mandibular symphysis
Figure 7.4a
Palatine Bones and Vomer

Palatine bones
 Posterior one-third of
hard palate
 Posterolateral walls of
the nasal cavity
 Small part of the orbits

Vomer
 Plow shaped
 Lower part of nasal
septum
Maxilla
Palatine bone
Zygomatic bone
Temporal bone
(zygomatic process)
Intermaxillary suture
Median palatine suture
Maxilla
Sphenoid bone
(greater wing)
Vomer
Temporal bone
Parietal bone
Foramen magnum
(a) Inferior view of the skull (mandible removed)
Figure 7.6a
Orbits
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Encase eyes and lacrimal glands
Sites of attachment for eye muscles
Formed by parts of seven bones
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Frontal bones
Zygomatic
Sphenoid bones
Palatine
Ethmoid
Lacrimal
Maxilla
Friendly Zebras Speed Past Elderly Lions Mating
Roof of orbit
• Lesser wing of
sphenoid bone
• Orbital plate of
frontal bone
Lateral wall of orbit
• Zygomatic process
of frontal bone
• Greater wing of
sphenoid bone
• Orbital surface of
zygomatic bone
Medial wall
• Sphenoid body
• Orbital plate
of ethmoid bone
• Lacrimal bone
Nasal bone
Floor of orbit
Zygomatic bone
• Orbital surface of
maxillary bone
• Zygomatic bone
(b) Contribution of each of the seven bones forming the right orbit
Figure 7.13a
Nasal Cavity
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Roof, lateral walls, and floor formed by parts of four
bones
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Ethmoid
Palatine bones
Maxillary bones
Inferior nasal conchae
Nasal septum of bone and hyaline cartilage
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Ethmoid
Vomer
Anterior septal cartilage
Frontal sinus
Ethmoid
bone
Nasal bone
Sphenoid
bone
Palatine bone
(perpendicular plate)
Maxillary bone
(palatine process)
Palatine bone
(horizontal plate)
(a) Bones forming the left lateral wall of the nasal cavity
(nasal septum removed)
Figure 7.14a
Paranasal Sinuses
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Mucosa-lined, air-filled spaces
Lighten the skull
Enhance resonance of voice
Found in frontal, sphenoid, ethmoid, and maxillary bones
Frontal
sinus
Ethmoidal
air cells
(sinus)
Sphenoid
sinus
Maxillary
sinus
(a) Anterior aspect
Frontal
sinus
Ethmoidal
air cells
Sphenoid
sinus
Maxillary
sinus
(b) Medial aspect
Figure 7.15
Hyoid Bone
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Not a bone of the skull
Does not articulate directly with another bone
Site of attachment for muscles of swallowing and speech
Developmental Aspects of the Skull
At birth, the newborn’s skull not fully developed and sutures
have not yet fused
• Allows for head compression during birth
• Allows for brain growth in the infant
Unossified regions are covered with fibrous membranes called
fontanelles “little fountains”
Anterior fontanelle is present until 1-1/2 –2 years of age
Homeostatic Imbalance of the Skull
The Cleft Lip and Palate
Caused by right and left halves of the palate failing to fuse medially
Leads to difficulties feeding/nursing
Risk for aspiration (inhalation) pneumonia
Review Slides