1. 7
The Axial Skeleton

2. 7-3 The Facial Bones of the Skull
The Mandible
Foramina of the mandible
Mental foramina
For sensory nerves of lips and chin
Mandibular foramen
Entrance to the mandibular canal
For blood vessels and nerves of lower teeth

3. 7-3 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

4. 7-3 The Facial Bones of the Skull
The Hyoid Bone
Marks of the hyoid bone
Body of the hyoid
Attaches muscles of larynx, tongue, and pharynx

5. 7-3 The Facial Bones of the Skull
The Hyoid Bone
Marks of the hyoid bone
Greater horns (greater cornua)
Support larynx
Attach muscles of the tongue
Lesser horns (lesser cornua)
Attach stylohyoid ligaments
Support hyoid and larynx

6. Figure 7-12b The Mandible and Hyoid Bone
Articular surface
Alveolar
process
Condylar process
Coronoid process
Mandibular foramen
Mylohyoid line
Depression for submandibular
salivary gland
A medial view of the right mandible 6

7. Figure 7-12c The Mandible and Hyoid Bone
Greater horn
Lesser horn
Body
An anterior view of the hyoid bone 7

8. 7-4 The Orbital and Nasal Complexes
The Eye Sockets (Orbits)
Frontal bone (roof)
Maxilla (floor)
Maxillary, lacrimal, and ethmoid bones (orbital rim and medial wall)
Sphenoid and palatine bones

9. Figure 7-13 The Orbital Complex
FRONTAL
BONE
Supra-orbital
notch
SPHENOID
Optic canal
ETHMOID
Superior
orbital
fissure
LACRIMAL
BONE
Lacrimal
sulcus
Inferior orbital
fissure
Nasolacrimal
canal
ZYGOMATIC
BONE
PALATINE
BONE
Infra-orbital
groove
Infra-orbital
foramen
MAXILLA 9

10. Figure 7-13 The Orbital Complex
Supra-orbital notch
FRONTAL BONE
SPHENOID
Optic canal
Superior orbital
fissure
ETHMOID
Nasolacrimal canal
Inferior orbital
fissure
Infra-orbital
groove
ZYGOMATIC BONE
MAXILLA
Infra-orbital
foramen 10

11. 7-4 The Orbital and Nasal Complexes
Bones of the Nasal Cavities and Paranasal Sinuses Make Up the Nasal Complex
Frontal bone, sphenoid, and ethmoid
Superior wall of nasal cavities
Maxillae, lacrimal bones, ethmoid, and inferior nasal conchae
Lateral walls of nasal cavities
Maxillae and nasal bones
Bridge of nose

12. Figure 7-14a The Nasal Complex
FRONTAL BONE
Frontal sinuses
Sphenoidal
sinuses
ETHMOID
NASAL BONE
SPHENOID
PALATINE BONE
(bony palate)
Superior
Nasal
conchae
of ethmoid
MAXILLA
(bony palate)
Middle
INFERIOR
NASAL
CONCHA
A sagittal section through the skull,
with the nasal septum removed to
show major features of the wall of
the right nasal cavity. The
sphenoidal sinuses are visible. 12

13. Figure 7-14b The Nasal Complex
FRONTAL
BONE
Cranial cavity
Frontal sinus
Right orbit
Ethmoidal air cell
Superior
nasal concha
Perpendicular
plate of ethmoid
Middle nasal
concha
Maxillary
sinus
ZYGOMATIC
BONE
INFERIOR NASAL
CONCHA
VOMER
MAXILLA
(bony palate)
Tongue
MANDIBLE
A frontal section through the
ethmoidal air cells and maxillary
sinuses, part of the paranasal sinuses. 13

14. 7-4 The Orbital and Nasal Complexes
Paranasal Sinuses
Air-filled chambers connected to the nasal cavities
Lighten skull bones
Provide mucous epithelium (flushes nasal cavities)

15. 7-5 Fontanelles The Infant Skull Grows rapidly
Is large compared to the body
Has many ossification centers

16. 7-5 Fontanelles The Infant Skull Fusion is not complete at birth
Two frontal bones
Four occipital bones
Several sphenoidal and temporal elements

17. 7-5 Fontanelles Fontanelles
Are areas of fibrous connective tissue (soft spots)
Cover unfused sutures in the infant skull
Allow the skull to flex during birth

18. 7-5 Fontanelles Anterior Fontanelle Occipital Fontanelle
Frontal, sagittal, and coronal sutures
Occipital Fontanelle
Lambdoid and sagittal sutures
Sphenoidal Fontanelles
Squamous and coronal sutures
Mastoid Fontanelles
Squamous and lambdoid sutures

19. Figure 7-15a The Skull of an Infant
Coronal
suture
FRONTAL
BONE
PARIETAL
BONE
Sphenoidal
fontanelle
NASAL BONE
Squamous suture
Lambdoid suture
MAXILLA
OCCIPITAL BONE
SPHENOID
MANDIBLE
TEMPORAL
BONE
Mastoid
fontanelle
Lateral view 19

20. Figure 7-15b The Skull of an Infant
PARIETAL
BONE
FRONTAL
BONE
Lambdoid
suture
Coronal
suture
Sagittal suture
Frontal suture
Anterior
fontanelle
OCCIPITAL
BONE
FRONTAL
BONE
PARIETAL
BONE
Occipital
fontanelle
Superior view 20

21. 7-6 The Vertebral Column The Vertebral Column (Spine)
Protects the spinal cord
Supports the head and body
26 bones
24 vertebrae, the sacrum, and the coccyx

22. Figure 7-16 The Vertebral Column
Spinal Curves
Vertebral Regions
Primary curves develop
before birth, and secondary
curves after birth.
Regions are defined
by anatomical
characteristics of
individual vertebrae.
The cervical curve, a
secondary curve, develops as
the infant learns to balance the
weight of the head on the
vertebrae of the neck.
Cervical
(7 vertebrae)
The thoracic curve, a
primary curve,
accommodates the
thoracic organs.
Thoracic
(12 vertebrae)
The lumbar curve, a
secondary curve, balances
the weight of the trunk over
the lower limbs; it develops
with the ability to stand.
Lumbar
(5 vertebrae)
The sacral curve, a
primary curve,
accommodates the
abdominopelvic organs.
Sacral
Coccygeal 22

23. 7-6 The Vertebral Column Vertebrae The neck The upper 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

24. 7-6 The Vertebral Column The Sacrum and Coccyx
The fifth lumbar vertebra articulates with the sacrum
The sacrum articulates with the coccyx

25. 7-6 The Vertebral Column Four Spinal Curves Cervical curve
Thoracic curve
Lumbar curve
Sacral curve

26. 7-6 The Vertebral Column Thoracic and Sacral Curves
Are called primary curves (present during fetal development)
Or accommodation curves (accommodate internal organs)
Lumbar and Cervical Curves
Are called secondary curves (appear after birth)
Or compensation curves (shift body weight for upright posture)

27. Figure 7-17a Abnormal Curvatures of the Spine
Kyphosis 27

28. Figure 7-17b Abnormal Curvatures of the Spine
Lordosis 28

29. Figure 7-17c Abnormal Curvatures of the Spine
Scoliosis 29

30. 7-6 The Vertebral Column Vertebral Anatomy
The vertebral body (centrum)
Transfers weight along the spine
The vertebral arch
Posterior margin of vertebral foramen
The articular processes
Lateral projections between laminae and pedicles

31. Figure 7-18a Vertebral Anatomy
Articular processes
Vertebral arch
Vertebral body
The major components of
a typical vertebra 31

32. 7-6 The Vertebral Column Vertebral Anatomy The vertebral arch Pedicles
Walls of the vertebral arch
Laminae
Roof of the vertebral arch

33. 7-6 The Vertebral Column Vertebral Anatomy The vertebral arch
Spinous process
Projection where vertebral laminae fuse
Transverse process
Projection where laminae join pedicles

34. 7-6 The Vertebral Column Vertebral Anatomy The articular processes
Superior articular process
Inferior articular process
Have articular facets on articular faces

35. Figure 7-18b Vertebral Anatomy
Superior articular
process
Pedicle
Transverse
process
Vertebral body
Spinous
process
Inferior articular
facet
Arrow passing
through vertebral
foramen
Inferior articular
process
A lateral and slightly inferior
view of a vertebra 35

36. Figure 7-18c Vertebral Anatomy
Spinous
process
Superior
articular
process
Inferior
articular
process
Transverse
process
Pedicle
Inferior
articular
facet
Vertebral
foramen
Vertebral
body
An inferior view of a
vertebra 36

37. 7-6 The Vertebral Column Vertebral Foramina Intervertebral foramina
Gaps between pedicles of adjacent vertebrae
For nerve connections to spinal cord
Vertebral canal
Formed by vertebral foramina
Encloses the spinal cord

38. 7-6 The Vertebral Column Intervertebral Discs
Are pads of fibrocartilage
Separate the vertebral bodies
Absorb shocks

39. Figure 7-18d Vertebral Anatomy
Superior articular facets
Superior articular process
Lamina of
vertebral arch
Spinous process
Intervertebral
disc
Transverse process
Vertebral body
Inferior
articular
process
An posterior view
of three articulated
vertebrae 39

40. Figure 7-18e Vertebral Anatomy
Superior articular facets
Lamina of
vertebral arch
Intervertebral
foramen
Intervertebral
disc
Spinous process
Transverse process
Vertebral body
Inferior
articular
facet
Arrow passing
through vertebral
canal
A lateral and sectional view
of three articulated
vertebrae 40

41. 7-7 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

42. 7-7 Vertebral Regions Regions of the Vertebral Column Cervical (C)
Thoracic (T)
Lumbar (L)
Sacral (S)
Coccygeal (Co)

43. 7-7 Vertebral Regions The Cervical Vertebrae
Small body (support only head)
Large vertebral foramen (largest part of spinal cord)
Concave superior surface
Slope posterior to anterior
C1 (atlas) has no spinous process
All others have short spinous processes
Tip of each spinous process is notched (bifid)

44. Figure 7-19a The Cervical Vertebrae
Spinous
process of
vertebra
prominens C7
A lateral view of the
cervical vertebrae,
C1–C7 44

45. Figure 7-19b The Cervical Vertebrae
Vertebral
arch
Spinous process
Lamina
Vertebral
foramen
Superior articular
process
Pedicle
Vertebral body
Transverse
process
Superior
articular
facet
Transverse
foramen
Costal process
A superior view of a representative
cervical vertebra showing
characteristics of C3–C6. Notice the
typical features listed in Table 7–2. 45

46. Figure 7-19c The Cervical Vertebrae
Superior articular
process
Transverse process
Inferior articular
process
Spinous process
Bifid tip of
spinous process
Location of
transverse
foramen
Inferior articular
facet
Vertebral
body
A lateral view of the same vertebra
as in b. 46

47. 7-7 Vertebral Regions The Cervical Vertebrae Transverse processes
Are fused to costal processes
Which encircle transverse foramina (protect arteries and veins)
Atlas (C1)
Articulates with occipital condyles of skull
Has no body or spinous process
Has a large, round foramen within anterior and posterior arches

48. 7-7 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

49. Figure 7-19d The Cervical Vertebrae
Dens of
axis
Anterior
arch
Transverse
ligament
Atlas (C1)
Posterior
arch
Axis (C2)
The atlas (C1) and axis (C2). 49

50. 7-7 Vertebral Regions The Cervical Vertebrae Vertebra prominens (C7)
Transitions to thoracic vertebrae
Has a long spinous process with a broad tubercle
Has large transverse processes
Ligamentum nuchae (elastic ligament) extends from C7 to skull

51. 7-7 Vertebral Regions Thoracic Vertebrae (T1–T12)
Have heart-shaped bodies
Larger bodies than in C1–C7
Smaller vertebral foramen than in C1–C7
Long, slender spinous processes
Dorsolateral surfaces of body have costal facets
Which articulate with heads of ribs

52. 7-7 Vertebral Regions Thoracic Vertebrae (T1–T12) T1–T10
Have transverse costal facets
On thick transverse processes for rib articulation
Ribs at T1–T10
Contact costal and transverse costal facets
T1–T8 articulate with two pairs of ribs
At superior and inferior costal facets
T9–T11 articulate with one pair of ribs
T10–T12 transition to lumbar vertebrae

53. Figure 7-20a The Thoracic Vertebrae
Intervertebral
foramen T4 T5 T6
Thoracic
vertebrae
(T1–T12) T7 T8 T9
T10
T11
T12
A lateral view of the thoracic region of
the vertebral column. The vertebra
prominems (C7) resembles T1, but lacks
facets for rib articulation. Vertebra T12
resembles the first lumbar vertebra (L1)
but has a facet for rib articulation. 53

54. Figure 7-20b The Thoracic Vertebrae
Spinous
process
Transverse
process
Lamina
Transverse
costal facet
Superior
articular
facet
Vertebral
foramen
Superior
costal facet
Vertebral
body
Thoracic vertebra, superior view. 54

55. Figure 7-20c The Thoracic Vertebrae
Superior
articular facet
Superior costal facet
for head of superior rib
Transverse costal
facet for tubercle
of superior rib
Transverse
process
Vertebral
body
Spinous
process
Inferior costal facet
for head of inferior rib
Thoracic vertebra, lateral view. 55

56. 7-7 Vertebral Regions Lumbar Vertebrae (L1–L5) Largest vertebrae
Oval-shaped bodies
Thicker bodies than T1–T12
No costal or transverse costal facets
Triangular vertebral foramen
Superior articular processes
Face up and in
Inferior articular processes
Face down and out

57. 7-7 Vertebral Regions Lumbar Vertebrae (L1–L5) Transverse processes
Slender
Project dorsolaterally
Spinous process
Short, heavy
For attachment of lower back muscles

58. Figure 7-21a The Lumbar Vertebrae
Sacrum
Coccyx
A lateral view of the lumbar
vertebrae and sacrum 58

59. Figure 7-21b The Lumbar Vertebrae
Superior articular
process
Pedicle
Transverse process
Vertebral
body
Spinous
process
Inferior articular process
Inferior articular facet
A lateral view of a typical lumbar vertebra 59

60. Figure 7-21c The Lumbar Vertebrae
Spinous process
Superior articular facet
Lamina
Superior articular
process
Transverse
process
Transverse process
Vertebral
foramen
Pedicle
Vertebral
body
A superior view of the same
vertebra shown in part b 60

61. 7-7 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

62. 7-7 Vertebral Regions The Sacrum The adult sacrum
Consists of five fused sacral vertebrae
Fuses between puberty and ages 25–30
Leaving transverse lines
Sacral canal
Replaces the vertebral canal

63. 7-7 Vertebral Regions The Sacrum Sacral cornua Horn shaped
Formed by laminae of the fifth sacral vertebra
Which do not meet at midline
Sacral hiatus
Opening at the inferior end of the sacral canal
Formed by ridges of sacral cornua
Covered by connective tissues

64. 7-7 Vertebral Regions The Sacrum Median sacral crest
Fused spinous processes
Four pairs of sacral foramina open to either side
Lateral sacral crest
Fused transverse processes
Attach to muscles of lower back and hip

65. 7-7 Vertebral Regions The Sacrum Auricular surface Sacral tuberosity
Thick, flattened area
Articulates with pelvic girdle (forming sacroiliac joint)
Sacral tuberosity
Rough area
Attaches ligaments of the sacroiliac joint

66. 7-7 Vertebral Regions The Sacrum Base Ala Sacral promontory Apex
The broad superior surface
Ala
Wings at either side of the base
To attach muscles
Sacral promontory
At the center of the base
Apex
The narrow inferior portion
Articulates with the coccyx

67. 7-7 Vertebral Regions The Coccyx
Attaches ligaments and a constricting muscle of the anus
Mature coccyx
Consists of three to five fused coccygeal vertebrae
First two coccygeal vertebrae
Have transverse processes
Have unfused vertebral arches
Coccygeal cornua
Formed by laminae of first coccygeal vertebra

68. Figure 7-22a The Sacrum and Coccyx
Articular
process
Entrance to
sacral canal
Sacral
tuberosity
Lateral
sacral crest
Median
sacral crest
Sacral
hiatus
Sacral cornu
Coccygeal cornu
A posterior view 68

69. Figure 7-22b The Sacrum and Coccyx
Sacral
promontory
Auricular
surface
Lateral
sacral crest
Median
sacral crest
Sacral cornu
Sacral curve
Coccygeal cornu
Coccyx
A lateral view from the right side 69

70. Figure 7-22c The Sacrum and Coccyx
Base
Sacral
promontory
Ala
Ala
Sacral
foramina
Transverse
lines
Apex
Coccyx
An anterior view 70

71. 7-8 The Thoracic Cage The Thoracic Cage The Rib Cage
The skeleton of the chest
Supports the thoracic cavity
Consists of:
Thoracic vertebrae
Ribs
Sternum (breastbone)
The Rib Cage
Formed of ribs and sternum

72. Figure 7-23a The Thoracic Cage
Jugular notch T1
Clavicular articulation 1
Manubrium 2 3
Sternum
Body
True ribs
(ribs 1–7) 4
Xiphoid
process 5
Costal
cartilages 10
T11 6
T12 11 7
Vertebrochondral
ribs
(ribs 8–10) 12 8 9
False ribs
(ribs 8–12)
Floating ribs
(ribs 11–12)
An anterior view, showing the
costal cartilages and the sternum 72

73. Figure 7-23b The Thoracic Cage1 T1 1 2 T2 2 3 3 T3 4 T4 4 5 T5 5
True ribs
(ribs 1–7) 6 T6 6 7 T7 7 8 T8 8 T9 9 9
T10 10
T11 10
False ribs
(ribs 8–12) 11
T12 11 12 12 L1
A posterior view, showing the
articulations of the ribs and vertebrae 73

74. 7-8 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 and the upper limbs

75. thoracic cavity is similar to the movement of a
Figure 7-24c The Ribs
Sternum
Ribs
The effect of rib
movement on the
thoracic cavity is similar
to the movement of a
bucket handle. Elevation
of curved ribs increases
the volume of the
thoracic cavity. 75

76. 7-8 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

77. 7-8 The Thoracic Cage Ribs 1–7 (True Ribs) Vertebrosternal ribs
Connected to the sternum by costal cartilages

78. 7-8 The Thoracic Cage 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

79. Figure 7-23a The Thoracic Cage
Jugular notch T1
Clavicular articulation 1
Manubrium 2 3
Sternum
Body
True ribs
(ribs 1–7) 4
Xiphoid
process 5
Costal
cartilages 10
T11 6
T12 11 7
Vertebrochondral
ribs
(ribs 8–10) 12 8 9
False ribs
(ribs 8–12)
Floating ribs
(ribs 11–12)
An anterior view, showing the
costal cartilages and the sternum 79

80. 7-8 The Thoracic Cage Structures of the Ribs The head (capitulum)
At the vertebral end of the rib
Has superior and inferior articular facets
The neck
The short area between the head and the tubercle

81. 7-8 The Thoracic Cage Structures of the Ribs The tubercle (tuberculum)
A small dorsal elevation
Has an auricular facet that contacts the facet of its thoracic vertebra (at T1–T10 only)
The tubular body (shaft)
Attaches muscles of the pectoral girdle and trunk
Attaches to the intercostal muscles that move the ribs

82. A superior view of the details of rib
Figure 7-24a The Ribs
Transverse
costal
facet
Tubercle
of rib
Angle
Neck
Vertebral
end
Demifacet
Head
(capitulum)
A superior view of the details of rib
structure and the articulations between
the ribs and thoracic vertebrae. 82

83. A posterior view of the head of a
Figure 7-24b The Ribs
Head
Neck
Attachment to
costal cartilage
(sternal end)
Articular facets
Tubercle
Body
Angle
Costal groove
A posterior view of the head of a
representative rib from the right side (ribs 2–9). 83

84. 7-8 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

85. 7-8 The Thoracic Cage Manubrium The superior portion of sternum
Broad, triangular shape
Articulates with clavicles (collarbones)
Articulates with cartilages of first rib pair
Has a jugular notch, a shallow indentation between clavicular articulations

86. 7-8 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

87. Figure 7-23a The Thoracic Cage
Jugular notch T1
Clavicular articulation 1
Manubrium 2 3
Sternum
Body
True ribs
(ribs 1–7) 4
Xiphoid
process 5
Costal
cartilages 10
T11 6
T12 11 7
Vertebrochondral
ribs
(ribs 8–10) 12 8 9
False ribs
(ribs 8–12)
Floating ribs
(ribs 11–12)
An anterior view, showing the
costal cartilages and the sternum 87

88. 7-8 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