1. Chapter 7: The Axial Skeleton

2. Human Skeleton Human Skeleton = 206 Bones Axial Skeleton:
-longitudinal axis
-80 bones
Appendicular Skeleton:
-limbs
-126 bones

3. The Axial Skeleton
Figure 7–1a

4. Axial Skeleton

5. Appendicular Skeleton

6. Axial Skeleton Function
Support and protect organs in dorsal and ventral body cavities
Provide surface area for muscle attachment:
Adjust position of head, neck, & trunk
Perform respiratory movements
Stabilize appendicular skeleton

7. Bones of the Axial Skeleton
The skull: 22 bones
8 cranial bones:
form the braincase or cranium
14 facial bones:
protect and support entrances to digestive and respiratory tracts
Skull bones interconnect at immovable joints called sutures
Dense fibrous CT

8. Skull: 22 Bones

9. Cranial Bones Enclose the cranial cavity Which contains the brain:
and its fluids, blood vessels, nerves, and membranes

10. The Facial Bones Superficial facial bones: Deep facial bones:
for muscle attachment
Maxillary, Lacrimal, Nasal, Zygomatic, and Mandible
Deep facial bones:
separate the oral and nasal cavities
form the nasal septum
Palatine bones, Inferior nasal conchae, and Vomer

11. The Maxillary Bones
The largest facial bones
Figure 7–10a

12. Functions of the Maxillary Bones
Support upper teeth
Form inferior orbital rim
Form lateral margins of external nares
Form upper jaw and hard palate
Contain maxillary sinuses (largest sinuses)

13. The Palatine Bones
Figure 7–10b,c

14. Functions of the Palatine Bones
Form the posterior portion of the hard palate
Contribute to the floors of the orbits

15. The structures and functions of the nasal complex.

16. The Small Bones of the Face
Figure 7–11

17. Functions of the Nasal Bones
Support the bridge of the nose
Connect to cartilages of the distal part of the nose (external nares)
Vomer
Forms the inferior portion of the bony nasal septum
Inferior Nasal Conchae
To create air turbulence in the nasal cavity
To increase the epithelial surface area
To warm and humidify inhaled air

18. The Mandible Forms the lower jaw
Figure 7–12a,b

19. The Hyoid Bone Function: Supports the larynx
Attaches muscles of the larynx, pharynx, and tongue
Figure 7–12c

20. 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

21. Skull Four major sutures: Lambdoid: Corona: Sagittal: Squamous:
- separates occipital bone from parietal bones
Corona:
- separates frontal bone from parietal bones
Sagittal:
- separates parietal bones
Squamous:
- (2) separates temporal bone from parietal bone

22. Sutures
The immovable joints of the skull
Figure 7–3a, b

23. Sutures
Figure 7–3c

24. Sutures
Figure 7–3d, e

25. The Orbital Complex
Portions of 7 cranial and facial bones
Figure 7–13

26. The Orbital Complex Forms the eye sockets (orbits):
frontal bone (roof)
maxillary bone (floor)
maxillary, lacrimal and ethmoid bones (orbital rim and medial wall)
sphenoid and palatine bones

27. The Nasal Complex Bones of the nasal cavities and paranasal sinuses
Figure 7–14

28. The Nasal Complex: Sinuses
air filled chambers inside flat bones
Function:
Reduce weight of bone
House mucus membranes that moisten and clean incoming air
Found in:
Sphenoid, ethmoid, frontal, palatine, and maxillary bones

29. The differences between the skulls of infants, children, and adults.

30. Skull Development
Intramembranous ossification from many centers of ossification
During development:
brain grows more rapidly than cranial bones
Growing skull bones are held together by bands of fibrous CT to provide flexibility
Expansion of brain, compression for birth
Large intersections of CT between the bones = fontalels (“soft spots”)
Persist until age 5
Around age 5:
Brain stops growing in size, solid sutures form between cranial bones

31. The Infant Skull Fusion is not complete at birth: Fontanels
2 frontal bones
4 occipital bones
several sphenoid and temporal elements
Fontanels
Are areas of fibrous connective tissue (soft spots)
Cover unfused sutures in the infant skull
Allow the skull to flex during birth

32. The 4 Fontanels Anterior fontanel: Occipital fontanel:
frontal, sagittal, and coronal sutures
Occipital fontanel:
lambdoid and sagittal sutures
Sphenoidal fontanels:
squamous and coronal sutures
Mastoid fontanel:
squamous and lambdoid sutures

33. Infant Skull

34. Skull Development Abnormalities
Craniostenosis:
Premature closure of frontanels,
Without surgery, the brain is crushed
Microcephaly:
- Brain fails to enlarge
- Cranium remains small

35. Craniostenosis
Microcephaly

36. In which bone is the foramen magnum located?
sphenoid
occipital bone
ethmoid
parietal bone

37. Tomás suffers a blow to the skull that fractures the right superior lateral surface of his cranium. Which bone is fractured?
frontal bone
right temporal bone
right parietal bone
ethmoid

38. Which bone contains the depression called the sella turcica
Which bone contains the depression called the sella turcica? What is located in this depression?
sphenoid bone; pituitary gland
ethmoid; olfactory epithelium
temporal bone; inner ear
lacrimal bone; tear apparatus

39. The vertebral regions, the curvatures of the vertebral column, and their functions.

40. The Vertebral Column: 26 Bones
The spine or vertebral column:
protects the spinal cord
supports the head and body
7 cervical vertebrae (C1-C7)
12 Thoracic vertebrae (T1-T12)
5 Lumbar vertebrae (L1-L5)
1 Sacrum (5 fused)
1 Coccyx (3-5 fused)

41. Regions and Curves of the Vertebral Column
26 bones:
24 vertebrae, the sacrum, and coccyx
Vertebral column is not straight
4 curves bring the weight of the body in line with the central axis
Figure 7–16

42. The Vertebrae
Figure 7–20a

43. Comparing Vertebrae

44. Characteristics of the Sacrum and Coccyx
is curved, more in males than in females
protects reproductive, urinary, and digestive organs
The coccyx:
attaches ligaments and a constricting muscle of the anus

45. 4 Curvatures of the Vertebral Column
Cervical curve
Thoracic curve
Lumbar curve
Sacral curve

46. Primary Curves Thoracic and sacral curves:
are called primary curves (present during fetal development)
or accommodation curves (accommodate internal organs)

47. Secondary Curves Lumbar and cervical curves:
are called secondary curves (appear after birth in first year of life)
or compensation curves (shift body weight for upright posture)
Necessary for bipedalism
Cervical: holds head up
Lumbar: standing

48. Abnormalities in Curvature
Kyphosis:
- exaggerated thoracic curvature
Lordosis:
- exaggerated lumber curvature
Scoliosis:
- abnormal lateral curvature

49. Construction of Column
Vertebral body: stacking
transfers weight along the spine
Intervertebral disc:
Spacing between bodies (not C1 and C2)
Annulus Fibrosus: Outside
Fibrocartilage
Nucleus pulposus: Inside
Gel (cushion)
Absorbs Shock
Loss of water from discs = shrinking height

50. Construction of Column
Elastic ligaments:
link bodies for alignment
Intervertebral foramen:
holes formed by spacing from discs, allow spinal nerves to exit column
Vertebral arch:
Bone attached to vertebral body, with body it forms vertebral foramen
Vertebral Foramen:
Hole for spinal cord
Vertebral Canal:
Bony canal for spinal cord
Formed by stacking of vertebral foramen

51. Structure of a Vertebra
Figure 7–17a,b

52. The Vertebral Canal
Figure 7–17d,e

53. Spina bifida
Vertebral arch fails to develop correctly at 3 weeks (fetus) and the spinal cord is unprotected or even exposed
4/1000 births show some degree
Due to lack of folic acid

54. Why does the vertebral column of an adult have fewer vertebrae than that of a newborn?
Vertebrae are absorbed as adult stature is reached.
Newborns require more support in the cervical region.
The sacrum and coccyx fuse post-puberty.
Vertebrae are formed that later become ribs.

55. What is the importance of the secondary curves of the spine?
balances weight of head
balances weight on lower limbs
allows walking
provides greater flexibility

56. superior articular processes pedicles transverse processes
When you run your finger along a person’s spine, what part of the vertebrae are you feeling just beneath the skin?
superior articular processes
pedicles
transverse processes
spinous processes

57. Joe suffered a hairline fracture at the base of the dens
Joe suffered a hairline fracture at the base of the dens. Which bone is fractured, and where is it located?
second cervical vertebra; posterior neck
first cervical vertebra; posterior neck
occipital bone; posterior base of skull
sacrum; posterior pelvis

58. thoracic lumbar sacral cervical
Examining a human vertebra, you notice that, in addition to the large foramen for the spinal cord, two smaller foramina are on either side of the bone in the region of the transverse processes. From which region of the vertebral column is this vertebra?
thoracic
lumbar
sacral
cervical

59. Why are the bodies of the lumbar vertebrae so large?
They develop first and therefore have longer to grow.
To provide more flexibility.
To distribute weight over a larger area.
To provide greater protection to the lumbar spinal nerves.

60. The significance of articulations between ribs, thoracic vertebrae, and sternum.

61. The Thoracic Cage The skeleton of the chest: Consists of:
supports the thoracic cavity
Consists of:
24 Ribs
1 sternum (breastbone)

62. The Sternum The sternum: a flat bone
in the midline of the thoracic wall

63. The Rib Cage
Formed of ribs and sternum
Figure 7–22a

64. Articulations of Ribs and Vertebrae
Figure 7–22b

65. 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

66. The Ribs
Figure 7–23

67. Functions of Ribs Ribs: Rib movements (breathing): are flexible
are mobile
can absorb shock
Rib movements (breathing):
affect width and depth of thoracic cage
changing its volume

68. Ribs Ribs (costae): Ribs are divided into 3 types:
are 12 pairs of long, curved, flat bones
extending from the thoracic vertebrae
Ribs are divided into 3 types:
1. 7 pairs of true ribs:
Separate cartilage to attach to sternum
2. 3 pairs of false ribs:
Common shared cartilage to attach to sternum
3. 2 pairs of floating ribs:
- no cartilage, no attachment to sternum

69. KEY CONCEPT The axial skeleton: Vertebrae:
protects the brain, spinal cord, and visceral organs of the chest
Vertebrae:
conduct body weight to the lower limbs
Lower vertebrae are larger and stronger:
because they bear more weight

70. How could you distinguish between true ribs and false ribs?
True ribs attach directly to the sternum by their own costal cartilage.
True ribs are entirely bony.
False ribs are not part of the thoracic cage.
True ribs are attached only to the sternum.

71. Improper administration of cardiopulmonary resuscitation (CPR) can result in a fracture of which bone(s)?
cervical vertebra and ribs
thoracic vertebra and ribs
sternum and thoracic vertebra
sternum and ribs

72. What are the main differences between vertebrosternal and vertebrochondral ribs?
Vertebrosternal ribs attach to the sternum.
Vertebrochondral ribs attach to costal cartilage.
Vertebrosternal ribs increase in curvature and length from
All of the above are true.