1. 7 The Axial Skeleton C h a p t e r
PowerPoint® Lecture Slides prepared by Jason LaPres
Lone Star College - North Harris
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publishing as Pearson Benjamin Cummings

2. An Introduction to the Axial Skeleton
Structures of Bones
Articulations
Contacts with other bones
Landmarks (Bone Markings; Marks)
Areas of muscle and ligament attachment
Foramina
Openings for nerves and blood vessels
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3. The Axial Skeleton The axial skeleton
Forms the longitudinal axis of the body
Has 80 bones
The skull:
8 cranial bones
14 facial bones
Bones associated with the skull:
6 auditory ossicles
the hyoid bone
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4. The Axial Skeleton The axial skeleton The vertebral column
24 vertebrae (singular = vertebra)
The sacrum
The coccyx
The thoracic cage
24 ribs
The sternum
Peel-Away of Whole Axial Skeleton
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5. The Axial Skeleton Figure 7–1 The Axial Skeleton.
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6. The Axial Skeleton Figure 7–1 The Axial Skeleton.
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7. The Axial Skeleton Functions of the Axial Skeleton
Supports and protects organs in body cavities
Attaches to muscles of
Head, neck, and trunk
Respiration
Appendicular skeleton
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8. The Skull The skull protects The skull contains 22 bones The brain
Entrances to respiratory system
Entrance to digestive system
The skull contains 22 bones
8 cranial bones:
Form the braincase or cranium
14 facial bones:
Protect and support entrances to digestive and respiratory tracts
The Adult Skull
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9. The Skull Figure 7–2 Cranial and Facial Subdivisions of the Skull.
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10. The Skull Cranial Bones Facial Bones Enclose the cranial cavity
Which contains the brain
And its fluids, blood vessels, nerves, and membranes
Facial Bones
Superficial facial bones
For muscle attachment
Deep facial bones
Separate the oral and nasal cavities
Form the nasal septum
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11. The Skull Figure 7–3a The Adult Skull.
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12. The Skull Figure 7–3b The Adult Skull.
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13. The Skull Figure 7–3c The Adult Skull.
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14. The Skull Figure 7–3d The Adult Skull.
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15. The Skull Figure 7–3e The Adult Skull.
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16. The Skull Figure 7–4a The Sectional Anatomy of the Skull.
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17. The Skull Figure 7–4b The Sectional Anatomy of the Skull.
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18. The Skull Superficial Facial Bones Maxillae = maxillary bones Lacrimal
Nasal
Zygomatic
Mandible
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19. The Skull Sinuses Sutures
Cavities that decrease the weight of the skull
Lined with mucous membranes
Protect the entrances of the respiratory system
Sutures
The immovable joints of the skull
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20. The Cranial Bones of the Skull
Occipital bone
Parietal bones
Frontal bone
Temporal bones
Sphenoid
Ethmoid
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21. The Cranial Bones of the Skull
The Occipital Bone
Functions of the occipital bone
Forms the posterior and inferior surfaces of the cranium
Articulations of the occipital bone
Parietal bones
Temporal bones
Sphenoid
First cervical vertebra (atlas)
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22. The Cranial Bones of the Skull
The Occipital Bone
Marks of the occipital bone
Occipital condyles: articulate with neck
Foramina of the occipital bone
Foramen magnum: connects cranial and spinal cavities
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23. The Cranial Bones of the Skull
Figure 7–5a The Occipital and Parietal Bones.
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24. The Cranial Bones of the Skull
The Parietal Bones
Functions of the parietal bones
Forms part of the superior and lateral surfaces of the cranium
Articulations of the parietal bones
Other parietal bone
Occipital bone
Temporal bone
Frontal bone
Sphenoid
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25. The Cranial Bones of the Skull
Figure 7–5b The Occipital and Parietal Bones.
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26. The Cranial Bones of the Skull
The Frontal bone
Functions of the frontal bone
Forms the anterior cranium and upper eye sockets
Contains frontal sinuses
Articulations of the frontal Bone
Parietal bone
Maxilla
Metopic suture
Ethmoid
Lacrimal bone
Zygomatic bone
Sphenoid
Nasal bone
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27. The Cranial Bones of the Skull
The Frontal Bone
Marks of the frontal bone
Frontal sinuses
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28. The Cranial Bones of the Skull
Figure 7–6a The Frontal Bone.
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29. The Cranial Bones of the Skull
Figure 7–6b The Frontal Bone.
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30. The Cranial Bones of the Skull
The Temporal Bones
Functions of the temporal bones
Part of lateral walls of cranium and zygomatic arches
Articulate with mandible
Surround and protect inner ear
Attach muscles of jaws and head
Articulations of the temporal bones
Zygomatic bone
Sphenoid
Parietal bone
Occipital bone
Mandible
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31. The Cranial Bones of the Skull
Marks of the Temporal Bones
Zygomatic process
Articulates with temporal process of zygomatic bone
Forms zygomatic arch (cheekbone)
Mastoid process
For muscle attachment
Contains mastoid air cells connected to middle ear
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32. The Cranial Bones of the Skull
Marks of the Temporal Bones
Styloid process
To attach tendons and ligaments of the hyoid, tongue, and pharynx
Petrous part
Encloses structures of the inner ear
Auditory ossicles
Three tiny bones in tympanic cavity (middle ear)
Transfer sound from tympanic membrane (eardrum) to inner ear
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33. The Cranial Bones of the Skull
Figure 7–7a The Temporal Bones.
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34. The Cranial Bones of the Skull
Figure 7–7b The Temporal Bones.
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35. The Cranial Bones of the Skull
Figure 7–7c The Temporal Bones.
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36. The Cranial Bones of the Skull
The Sphenoid
Functions of the Sphenoid
Part of the floor of the cranium
Unites cranial and facial bones
Strengthens sides of the skull
Contains sphenoidal sinuses
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37. The Cranial Bones of the Skull
Articulations of the Sphenoid
Ethmoid
Frontal bone
Occipital bone
Parietal bone
Temporal bone
Palatine bones
Zygomatic bones
Maxillae
Vomer
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38. The Cranial Bones of the Skull
Marks of the Sphenoid
Sphenoidal sinuses
On either side of the body
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39. The Cranial Bones of the Skull
Figure 7–8a The Sphenoid.
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40. The Cranial Bones of the Skull
Figure 7–8b The Sphenoid.
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41. The Cranial Bones of the Skull
The Ethmoid
Functions of the ethmoid
Forms anteromedial floor of the cranium
Roof of the nasal cavity
Part of the nasal septum and medial orbital wall
Contains ethmoidal air cells (network of sinuses)
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42. The Cranial Bones of the Skull
Articulations of the Ethmoid
Frontal bone
Sphenoid
Nasal bone
Lacrimal bone
Palatine bone
Maxillary bones
Inferior nasal conchae
Vomer
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43. The Cranial Bones of the Skull
Figure 7–9 The Ethmoid.
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44. The Cranial Bones of the Skull
Figure 7–9 The Ethmoid.
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45. The Facial Bones of the Skull
Maxillae (maxillary bones)
Nasal bones
Zygomatic bones
Lacrimal bones
Mandible
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46. The Facial Bones of the Skull
The Maxillae
Functions of the maxillae
Support upper teeth
Form inferior orbital rim
Form lateral margins of external nares
Form upper jaw and hard palate
Contain maxillary sinuses (largest sinuses)
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47. The Facial Bones of the Skull
Articulations of the Maxillae
Frontal bones
Ethmoid
With one another
All other facial bones except the mandible
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48. The Facial Bones of the Skull
Marks of the Maxillae
Orbital rim:protects eye and orbit
Maxillary sinuses: to lighten bone
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49. The Facial Bones of the Skull
Figure 7–10a The Maxillae and Palatine Bones.
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50. The Facial Bones of the Skull
The Nasal Bones
Functions of the nasal bones
Support the bridge of the nose
Connect to cartilages of the distal part of the nose (external nares)
Articulations of the nasal bones
With other nasal bones
Ethmoid
Frontal bones
Maxillae
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51. The Facial Bones of the Skull
The Zygomatic Bones
Functions of the zygomatic bones
Contribute to the rim and lateral wall of the orbit
Form part of the zygomatic arch
Articulations of the zygomatic bones
Sphenoid
Frontal bone
Temporal bones
Maxillae
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52. The Facial Bones of the Skull
Marks of the zygomatic bones
Temporal process
Meets the zygomatic process of the temporal bone
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53. The Facial Bones of the Skull
The Lacrimal Bones
Functions of the lacrimal bones
The smallest facial bones
Form part of the medial wall of the orbit
Articulations of the lacrimal bones
Frontal bone
Maxillae
Ethmoid
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54. The Facial Bones of the Skull
Figure 7–11 The Smaller Bones of the Face.
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55. The Facial Bones of the Skull
The Mandible
Functions of the mandible
Forms the lower jaw
Articulations of the mandible
the temporal bones
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56. The Facial Bones of the Skull
The Hyoid Bone
Functions of the hyoid bone
Supports the larynx
Attaches muscles of the larynx, pharynx, and tongue
Articulations of the hyoid bone
Connects lesser horns to styloid processes of temporal bones
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57. The Facial Bones of the Skull
Figure 7–12a The Mandible and Hyoid Bone.
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58. The Facial Bones of the Skull
Figure 7–12b The Mandible and Hyoid Bone.
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59. The Facial Bones of the Skull
Figure 7–12c The Mandible and Hyoid Bone.
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60. Foramina and Fissures of the Skull
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61. Foramina and Fissures of the Skull
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62. Foramina and Fissures of the Skull
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63. The Orbital Complex Paranasal Sinuses
Air-filled chambers connected to the nasal cavities
Lighten skull bones
Provide mucous epithelium (flushes nasal cavities)
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65. Fontanelles Fontanelles (sometimes spelled fontanels)
Are areas of fibrous connective tissue (soft spots)
Cover unfused sutures in the infant skull
Allow the skull to flex during birth
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66. Fontanelles Figure 7–15a The Skull of an Infant.
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67. Fontanelles Figure 7–15b The Skull of an Infant.
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68. The Vertebral Column The spine or vertebral column
Protects the spinal cord
Supports the head and body
26 bones
24 vertebrae, the sacrum, and the coccyx
The Vertebral Column
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69. The Vertebral Column Figure 7–16 The Vertebral Column.
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70. The Vertebral Column Vertebrae The neck The upper back The lower back
Seven cervical vertebrae
The upper back
12 thoracic vertebrae
Each articulates with one or more pair of ribs
The lower back
Five lumbar vertebrae
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71. The Vertebral Column The Sacrum and Coccyx
The fifth lumbar vertebra articulates with the sacrum
The sacrum articulates with the coccyx
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72. The Vertebral Column Four Curvatures of the Vertebral Column
Cervical curve
Thoracic curve
Lumbar curve
Sacral curve
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73. The Vertebral Column Figure 7–17 Abnormal Curvatures of the Spine.
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74. The Vertebral Column Intervertebral Discs
Are pads of fibrous cartilage
Separate the vertebral bodies
Absorb shocks
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75. The Vertebral Column Figure 7–18 Vertebral Anatomy.
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76. Vertebral Regions Vertebral Regions Vertebrae are numbered
By region, from top (superior) to bottom(inferior)
C1 articulates with skull, L5 with sacrum
Vertebrae of each region
Have characteristics determined by functions
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77. Vertebral Regions Regions of the Vertebral Column Cervical (C)
Thoracic (T)
Lumbar (L)
Sacral (S)
Coccygeal (Co)
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78. Vertebral Regions The Cervical Vertebrae
Small body (support only head)
C1 (atlas) has no spinous process
All others have short spinous processes
tip of each spinous process is notched (bifid)
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79. Vertebral Regions Figure 7–19 The Cervical Vertebrae.
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80. Vertebral Regions Atlas (C1)
Articulates with occipital condyles of skull
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81. Vertebral Regions Figure 7–19 The Cervical Vertebrae.
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82. Vertebral Regions The Cervical Vertebrae Axis (C2) Supports the atlas
Has heavy spinous process
To attach muscles of head and neck
Axis and atlas bodies fuse during development to form the dens
Vertebra prominens (C7)
Transitions to thoracic vertebrae
Has a long spinous process with a broad tubercle
Has large transverse processes
Rotation of Cervical Vertebrae
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83. Vertebral Regions Figure 7–19 The Cervical Vertebrae.
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84. Vertebral Regions Figure 7–19 The Cervical Vertebrae.
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85. Vertebral Regions Thoracic vertebrae (T1–T12) Have heart-shaped bodies
Larger than in C1–C7
Dorsolateral surfaces of body have costal facets:
Which articulate with heads of ribs
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86. Vertebral Regions Figure 7–20a The Thoracic Vertebrae.
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87. Vertebral Regions Figure 7–20b The Thoracic Vertebrae.
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88. Vertebral Regions Figure 7–20c The Thoracic Vertebrae.
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89. Vertebral Regions Lumbar vertebrae (L1–L5) Largest vertebrae
Oval-shaped bodies
Thicker bodies than T1–T12
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90. Vertebral Regions Figure 7–21a The Lumbar Vertebrae.
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91. Vertebral Regions Figure 7–21b The Lumbar Vertebrae.
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92. Vertebral Regions Figure 7–21c The Lumbar Vertebrae.
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93. Vertebral Regions
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94. Vertebral Regions
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95. Vertebral Regions
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96. Vertebral Regions The sacrum Is curved, more in males than in females
Protects reproductive, urinary, and digestive organs
Attaches
The axial skeleton to pelvic girdle of appendicular skeleton
Broad muscles that move the thigh
The adult sacrum
Consists of five fused sacral vertebrae
Fuses between puberty and ages 25–30
Leaving transverse lines
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97. Vertebral Regions The coccyx
Attaches ligaments and a constricting muscle of the anus
Mature coccyx
Consists of three to five fused coccygeal vertebrae
3D Rotation of Sacrum and Coccyx
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98. Vertebral Regions Figure 7–22 The Sacrum and Coccyx.
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99. The Thoracic Cage The skeleton of the chest The Rib Cage
Supports the thoracic cavity
Consists of:
thoracic vertebrae
ribs
sternum (breastbone)
The Rib Cage
Formed of ribs and sternum
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100. The Thoracic Cage Figure 7–23a The Thoracic Cage.
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101. The Thoracic Cage Figure 7–23b The Thoracic Cage.
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102. The Thoracic Cage Functions of the Thoracic Cage
Protects organs of the thoracic cavity
Heart, lungs, and thymus
Attaches muscles
For respiration
Of the vertebral column
Of the pectoral girdle
Of the upper limbs
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103. The Thoracic Cage Ribs Are mobile Can absorb shock Functions of ribs
Rib movements (breathing):
affect width and depth of thoracic cage
changing its volume
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104. The Thoracic Cage Figure 7–24c The Ribs.
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105. The Thoracic Cage Ribs (costae)
Are 12 pairs of long, curved, flat bones
Extending from the thoracic vertebrae
Ribs are divided into two types
True ribs
False ribs
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106. The Thoracic Cage Ribs 1–7 (true ribs) Ribs 8–12 (false ribs)
Vertebrosternal ribs
Connected to the sternum by costal cartilages
Ribs 8–12 (false ribs)
Do not attach directly to the sternum
Vertebrochondral ribs (ribs 8–10)
Fuse together
Merge with cartilage before reaching the sternum
Floating or vertebral ribs (ribs 11–12)
Connect only to the vertebrae and back muscles
Have no connection with the sternum
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107. The Thoracic Cage Figure 7–23 The Thoracic Cage.
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108. The Thoracic Cage Figure 7–24a The Ribs.
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109. The Thoracic Cage Figure 7–24b The Ribs.
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110. The Thoracic Cage The sternum A flat bone
In the midline of the thoracic wall
Three parts of the sternum
The manubrium
The sternal body
The xiphoid process
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111. The Thoracic Cage Manubrium The superior portion of sternum
Broad, triangular shape
Articulates with clavicles (collarbones)
Articulates with cartilages of first rib pair
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112. The Thoracic Cage The sternal body The xiphoid process
Is tongue-shaped
Attaches to the manubrium
Attaches to costal cartilages of ribs 2–7
The xiphoid process
Is the smallest part of the sternum
Attaches to the sternal body
Attaches to diaphragm and rectus abdominis muscles
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113. The Thoracic Cage Figure 7–23 The Thoracic Cage.
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114. The Thoracic Cage Development of the Sternum
The developing sternal body
Consists of four unfused bones
Completes fusion about age 25
Leaving transverse lines
The xiphoid process
Is the last part of sternum to fuse
Can easily be broken away
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