1. Chapter 7: The Skeleton
Part A

2. The Axial Skeleton Consists of 80 bones Three major regions Skull
Vertebral column
Thoracic cage

3. The Axial Skeleton Cranium Skull Facial bones Clavicle Thoracic cage
(ribs and
sternum)
Scapula
Sternum
Rib
Humerus
Vertebra
Vertebral
column
Radius
Ulna
Sacrum
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
Tarsals
Metatarsals
(a) Anterior view
Phalanges
Figure 7.1a

4. The Skull Two sets of bones Cranial bones Facial bones
Enclose the brain in the cranial cavity
Gives attachment sites for head and neck muscles
Facial bones
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

5. Bones of cranium (cranial vault)
Coronal
suture
Squamous
suture
Lambdoid
suture
Facial
bones
(a) Cranial and facial divisions of the skull
Figure 7.2a

6. Cranial Bones Occipital bone Parietal bones (2) Frontal bone
Temporal bones (2)
Ethmoid bone
Sphenoid bone
Remember:
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7. Frontal bone Parietal bone Nasal bone Sphenoid bone (greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Ethmoid
bone
Zygomatic bone
Maxilla
Mandible
Vomer
(a) Anterior view
Mandibular symphysis
Figure 7.4a

8. 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:
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

9. (a) External anatomy of the right side of the skull
Coronal suture
Frontal bone
Sphenoid bone
(greater wing)
Parietal bone
Ethmoid bone
Temporal bone
Lacrimal bone
Lambdoid
suture
Squamous
suture
Nasal bone
Occipital
bone
Zygomatic
bone
Zygomatic
process
Maxilla
Occipitomastoid
suture
Mandible
(a) External anatomy of the right side of the skull
Figure 7.5a

10. Occipital Bone
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

11. Sagittal suture Parietal bone Sutural bone Lambdoid suture
Occipital bone
Occipitomastoid
suture
(b) Posterior view
Figure 7.4b

12. Intermaxillary suture Palatine bone Median palatine suture
Zygomatic bone
Sphenoid bone
(greater wing)
Temporal bone
(zygomatic process)
Vomer
Temporal bone
Parietal bone
Foramen magnum
(a) Inferior view of the skull (mandible removed)
Figure 7.6a

13. Temporal Bones
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

14. Sphenoid Bone Complex, butterfly-shaped bone Keystone bone
Articulates with all other cranial bones
Three pairs of processes
Contains the sella turcica and the hypophyseal fossa that surround the pituitary gland

15. Ethmoid Bone 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)
The attachment site for the outermost covering of the brain

16. Figure 7.10

17. Sutural Bones Tiny irregularly shaped bones that appear within sutures
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18. Sagittal suture Parietal bone Sutural bone Lambdoid suture
Occipital bone
Occipitomastoid
suture
(b) Posterior view
Figure 7.4b

19. Facial Bones (14 Total) Unpaired Bones: Mandible Vomer Paired Bones:
Maxillary bones (2)
Zygomatic bones (2)
Nasal bones (2)
Lacrimal bones (2)
Palatine bones (2)
Inferior nasal Conchae (2)
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20. Mandible Lower jaw Largest, strongest bone of face
Articulates at the temporomandibular joint (TMJ): only freely movable joint in skull

21. (a) Mandible, right lateral view
Temporomandibular
joint
Ramus of
mandible
Mandibular
angle
Body of mandible
(a) Mandible, right lateral view
Figure 7.11a

22. Maxillary Bones
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

23. Zygomatic Bones Cheekbones Inferolateral margins of orbits
Articulates with 3 separate zygomatic processes
Frontal zygomatic process
Maxillary zygomatic process
Temporal zygomatic process

24. Nasal Bones and Lacrimal Bones
Form bridge of nose
Attach to the cartilage that forms most of the skeleton of the nose
Lacrimal bones
In medial walls of orbits
Forms part of the canal that drains tears into the nasal cavity
Lacrimation = crying/tear production

25. Frontal bone Parietal bone Nasal bone Sphenoid bone (greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Ethmoid
bone
Zygomatic bone
Maxilla
Mandible
Vomer
(a) Anterior view
Mandibular symphysis
Figure 7.4a

26. Palatine Bones and Vomer
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

27. Intermaxillary suture Palatine bone Median palatine suture
Zygomatic bone
Sphenoid bone
(greater wing)
Temporal bone
(zygomatic process)
Vomer
Temporal bone
Parietal bone
Foramen magnum
(a) Inferior view of the skull (mandible removed)
Figure 7.6a

28. Orbits Encase eyes and lacrimal glands
Sites of attachment for eye muscles
Formed by parts of seven bones
Frontal bones
Zygomatic
Sphenoid bones
Palatine
Ethmoid
Lacrimal
Maxilla
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29. • Lesser wing of sphenoid bone
Roof of orbit
• Lesser wing of sphenoid bone
• Orbital plate of frontal bone
Medial wall
• Sphenoid body
Lateral wall of orbit
• Orbital plate of ethmoid bone
• Zygomatic process of frontal bone
• Greater wing of sphenoid bone
• Lacrimal bone
• Orbital surface of zygomatic 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

30. Nasal Cavity
Roof, lateral walls, and floor formed by parts of four bones
Ethmoid
Palatine bones
Maxillary bones
Inferior nasal conchae
Nasal septum of bone and hyaline cartilage
Vomer
Anterior septal cartilage

31. (perpendicular plate) Palatine bone (horizontal plate)
Frontal sinus
Ethmoid
bone
Nasal bone
Maxillary bone
(palatine process)
Sphenoid
bone
Palatine bone
(perpendicular plate)
Palatine bone
(horizontal plate)
(a) Bones forming the left lateral wall of the nasal cavity
(nasal septum removed)
Figure 7.14a

32. Paranasal Sinuses Mucosa-lined, air-filled spaces Lighten the skull
Enhance resonance of voice
Found in frontal, sphenoid, ethmoid, and maxillary bones

33. Frontal sinus Frontal sinus Ethmoidal air cells (sinus) Ethmoidal
Sphenoid
sinus
Sphenoid
sinus
Maxillary
sinus
Maxillary
sinus
(a) Anterior aspect
(b) Medial aspect
Figure 7.15

34. Hyoid Bone Not a bone of the skull
Does not articulate directly with another bone
Site of attachment for muscles of swallowing and speech

35. 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

37. 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

38. Review Slides