1. 7
The Axial Skeleton

2. Repition…. Repition…. Repition…. Repition…. Repition….

3. I. The Skeleton A. Bones, cartilage, joints, and ligaments
1. joints - also called articulations
B. 206 named bones grouped into two divisions
1. Axial skeleton (80 bones)
► skull, vertebral column, and thoracic cage
2. Appendicular skeleton (126 bones)
► upper and lower limbs

4. II. The Cranium (Skull)
A. The cranium is formed by cranial and facial bones
1. enclose and protect the brain
2. provide attachment sites for muscles of the head and neck
B. Facial bones
1. Form framework of the face
2. Form cavities for sense organs of sight, taste, and smell
3. Provide openings for passage of air and food
4. Hold the teeth in place
5. Anchor muscles of the face

6. C. Internally bony ridges divide skull into distinct fossae (surfaces)
1. anterior
2. middle
3. posterior
D. Brain sits within the cranial fossae
1.brain occupies cranial cavity

7. Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
Superior view of the cranial fossae 7

8. E. The skull contains smaller cavities
1. middle & inner ear cavities—in lateral aspect of cranial base
2. nasal cavity—lies in and posterior to the nose
3. orbits—house the eyeballs
4. sinuses — air-filled spaces in bones around the nasal cavity

9. Sinuses of the cranium 9

10. F. The skull contains approximately 85 named openings
1. foramina, canals, and fissures
2. provide openings for important structures
a. spinal cord
b. blood vessels serving the brain
c. 12 pairs of cranial nerves

11. IV. Cranial Bones A. Formed from eight large bones 1. paired bones
a. temporal bones
b. parietal bones
2. unpaired bones
a. frontal bone
b. occipital bone
c. sphenoid bone
d. ethmoid bone

12. V. Sutures A. Four sutures of the cranium
1. coronal suture - runs in the coronal plane
2. squamous suture - parietal bone meets temporal bone
3. sagittal suture - where right and left parietal bones
4. lambdoid suture – parietal bones meet the occipital bone

13. Cranium

14. right side of the skull Coronal suture Frontal bone Sphenoid bone
Parietal bone
Sphenoid bone
Squamous suture
Ethmoid bone
Lambdoid suture
Lacrimal bone
Lacrimal fossa
Occipital bone
Nasal bone
Temporal bone
Zygomatic process
Zygomatic bone
Maxilla
External acoustic meatus
Mastoid process
Styloid process
Mandible
Condylar process
Mental foramen
Mandibular notch
Mandibular ramus
Coronoid process
Mandibular angle 14

15. right side of the skull 15

16. Superior orbital fissure
Frontal bone
Parietal bone
Supraorbital foramen
Nasal bone
Sphenoid bone
Superior orbital fissure
Temporal bone
Optic canal
Ethmoid bone
Inferior orbital fissure
Lacrimal bone
Ethmoid bone
Zygomatic bone
Infraorbital foramen
Maxilla
Vomer
Mandible
Mental foramen 16

17. Ethmoid bone 17

18. External occipital protuberance
Parietal bone
Sagittal suture
Lambdoid suture
Occipital bone
Superior nuchal line
External occipital protuberance
Inferior nuchal line
Occipital
condyle 18

19. 19

20. Maxilla
Hard palate
Palatine bone
Infraorbital foramen
Maxilla
Zygomatic bone
Sphenoid bone
Vomer
zygomatic process
External acoustic meatus
Styloid process
Mastoid process
Temporal bone
Jugular foramen
Occipital condyle
Occipital bone
External occipital protuberance
Foramen magnum
Inferior view of the skull (mandible removed) 20

21. Inferior view of the skull (mandible removed)21

22. External acoustic meatus Zygomatic process Mastoid process
Styloid process 22

23. Optic canal
Lesser wing
Foramen rotundum
Greater wing
Foramen ovale
Sella turcica
Foramen
spinosum
Body of sphenoid
Superior view 23

24. Cribriform plate with cribriform foramina
Crista galli
Cribriform plate with cribriform foramina 24

25. The Holes in the Head Optic foramen Foramen rotundum Foramen ovale
Foramen spinosum
Foramen lacerum
Internal acoustic meatus
Jugular foramen
Hypoglossal canal
Foramen magnum ▲

26. Internal acoustic meatus
Crista galli
View
Ethmoid bone
Cribriform plate
Frontal bone
Lesser wing
Optic canal
Sphenoid
Greater wing
Foramen rotundum
sella turcica
Foramen ovale
Foramen spinosum
Foramen lacerum
Temporal bone
Internal acoustic meatus
Jugular foramen
Hypoglossal canal
Parietal bone
Occipital bone
Foramen magnum
Superior view of the skull, calvaria removed 26

27. Superior view of the skull, calvaria removed27

28. The Sphenoid Bone Optic canal Lesser wing Foramen rotundum
Greater wing
Foramen ovale
Sella turcica
Foramen
spinosum
Body of sphenoid
Superior view 28

29. 29 Parietal bone Coronal suture Frontal bone Sphenoid bone
Squamous suture
Temporal bone
Crista galli
Lambdoid suture
Nasal bone
Occipital bone
Ethmoid bone
Vomer
External occipital protuberance
Maxilla
Internal acoustic meatus
Mandible
Mandibular foramen
Palatine bone
Midsagittal section showing the internal anatomy of the left half of skull 29

30. Midsagittal section showing the internal anatomy of the left half of skull30

31. Mandible Temporomandibular joint Coronoid process Mandibular notch
Condylar process
Mandibular foramen
Ramus of mandible
Mental foramen
Mandibular angle
Body of mandible
Mandible, right lateral view 31

32. Mandible
Mandible, right lateral view 32

33. Figure 7-15a Paranasal sinuses.
Frontal sinus
Ethmoidal air cells (sinus)
Sphenoidal sinus
Maxillary sinus
Anterior aspect 33

34. Hyoid Bone

35. Figure The hyoid bone.
Greater horn
Lesser horn
Body 35

36. XIII. Thoracic Cage 36 Jugular notch Clavicular notch Manubrium
Sternal angle
Body
Sternum
True ribs (17)
Xiphoid process
False ribs (812)
Costal cartilage
L1 Vertebra
Floating ribs (11, 12) 36

37. XIII. Thoracic Cage
L1 Vertebra 37

38. Vertebral Column

39. The Vertebral Column A. In the adult, is formed from 26 bones
B. Transmits weight of trunk to the lower limbs
C. Surrounds and protects the spinal cord 39

40. Regions and Normal Curvatures
A. The vertebral column has five major regions
► 7 cervical vertebrae of the neck region
► 12 thoracic vertebrae
► 5 lumbar vertebrae
► Sacrum - five fused bones
► Coccyx - inferior to sacrum 40

41. 41 C1 Cervical curvature (concave) 7 vertebrae, C1  C72 3
Cervical curvature
(concave) 4
7 vertebrae, C1  C7 5 6 7 T1
Spinous process 2 3
Transverse processes 4 5
Thoracic curvature 6
(convex)
12 vertebrae, T1  T12 7 8 9
Intervertebral discs 10 11
Intervertebral foramen 12 L1 2
Lumbar curvature 3
(concave)
5 vertebrae, L1  L5 4 5
Sacral curvature
(convex)
5 fused vertebrae sacrum
Coccyx
4 fused vertebrae
Anterior view
Right lateral view 41

42. Regions and Normal Curvatures
A. Curvatures of the spine
1. Cervical and lumbar curvatures
► Concave posteriorly
2. Thoracic and sacral curvatures
► Convex posteriority
kyphosis – exagerated curvature in thoracic region (humpback)
lordosis – exaggerated curvature in the lumbar region
scoliosis – S-shaped curvature of the whole vertebral column 42

43. Supraspinous ligament Anterior longitudinal ligament
Intervertebral disc
Supraspinous ligament
Anterior longitudinal ligament
Transverse process
Sectioned spinous process
Intervertebral foramen
Posterior longitudinal ligament
Ligamentum flavum
Anulus fibrosus
Interspinous ligament
Nucleus pulposus
Inferior articular process
Sectioned body of vertebra
Median section of three vertebrae, illustrating the composition of the discs and the ligaments 43

44. Posterior longitudinal ligament
Anterior longitudinal ligament
Body of a vertebra
Intervertebral disc
Anterior view of part of the spinal column 44

45. Intervertebral Discs A. Are cushion-like pads between vertebrae
1. Nucleus pulposus
a. gelatinous inner sphere
b. absorbs compressive stresses
2. Anulus fibrosus
a. outer rings formed of ligament
b. inner rings formed of fibrocartilage
c. contains the nucleus pulposus 45

46. Vertebrae

47. Superior articular process and facet
Posterior
Vertebral arch
Lamina
Spinous process
Transverse process
Superior articular process and facet
Vertebral foramen
Pedicle
Body
Anterior 47

48. Posterior
Anterior 48

49. Cervical Vertebrae A. Cervical 1. C1 (atlas) no body, no spine
2. C2 (axis) bifid spine, dens (head)
3. C3-6 bifid spine
4. C7 non-bifid spine, first bulge in lower neck
5. transverse foramen (vessel+nerve)
6. bodies get larger in descending fashion 49

50. 50

51. Transverse ligament of atlas
Dens of axis
Transverse ligament of atlas
C1 (atlas)
C2 (axis) C3
Inferior articular process
Bifid spinous process
Transverse processes
C7 (vertebra prominens)
Cervical vertebrae 51

52. C1 – The Atlas C1 Posterior Posterior tubercle Posterior arch
Transverse foramen
Lateral masses
Superior articular facet
Anterior arch
Anterior tubercle
Superior view of atlas (C1) 52

53. C1 – Axis Posterior C2 Spinous process Inferior articular process
Lamina
Pedicle
Superior articular facet
Transverse process
Dens
Body
Superior view of axis (C2) 53

54. Thoracic Vertebrae A. Thoracic
1. long, inferior-directed spinous processes
2. transverse processes are long and heavy
3. T1 superior whole facet : inferior demifacet
4. T2-8 two demifacets; superior large / inferior small
5. T9 single superior demifacet
6. T10-12 whole facet for individual rib articulation 54

55. 55

56. Lumbar Vertebrae A. Lumbar 1. all have largest, thickest bodies
2. spinous processes are oblong and heavy 56

57. 57

58. Superior articular process
Body
Transverse process
Intervertebral
disc
Inferior articular process
Spinous process
Lumbar vertebrae 58

59. The Sacrum

60. Sacral promontory
Body
Sacral canal
Facet of superior articular process
Ala
Body of first sacral vertebra
Auricular surface
Median sacral crest
Lateral sacral crest
Transverse ridges (sites of vertebral fusion)
Posterior sacral foramina
Anterior sacral foramina
Apex
Sacral hiatus
Coccyx
Coccyx
Anterior view
Posterior view 60

61. Coccyx A. Is the “tailbone” B. Formed from 3–5 fused vertebrae
C. Offers only slight support to pelvic organs 61

62. The Thoracic Cage A. Forms the bony framework of the chest
B. Components
1. thoracic vertebrae—posteriorly
2. ribs - laterally
3. sternum and costal cartilage - anteriorly
C. Protects thoracic organs
D. Supports shoulder girdle and upper limbs
E. Provides attachment sites for many muscles of the back

63. Ribs A. All ribs attach to vertebral column posteriorly
1. true ribs—superior seven pairs of ribs
► Attach to sternum by costal cartilage
2. false ribs—inferior five pairs of ribs
3. floating ribs – ribs 11 and 12

64. 64 Jugular notch Clavicular notch Manubrium Sternal angle Body Sternum
Xiphisternal joint
True ribs (17)
Xiphoid process
False ribs (812)
Intercostal spaces
Costal cartilage
L1 Vertebra
Floating ribs (11, 12)
Costal margin
Skeleton of the thoracic cage, anterior view 64

65. Superior costal facet (for head of rib) Angle of rib
Body of vertebra
Head of rib
Intervertebral disc
Neck of rib
Tubercle of rib
Shaft
Sternum
Cross- section of rib
Costal cartilage
Vertebral and sternal articulations of a typical true rib 65

66. Articular facet on tubercle of rib Spinous process
Figure 7.25c Ribs.
Articular facet on tubercle of rib
Spinous process
Shaft
Transverse costal facet (for tubercle of rib)
Ligaments
Neck of rib
Body of thoracic vertebra
Head of rib
Superior view of the articulation between a rib and a thoracic vertebra 66

67. Sternum A. Formed from three sections 1. Manubrium—superior section
► clavicular notches articulate with medial end of clavicles
2. Body—bulk of sternum
► sides are notched at joints for costal cartilage of ribs 2–7
3. Xiphoid process—inferior end of sternum
► ossifies around age 40

68. 68 Jugular notch Clavicular notch Manubrium Body Sternum
True ribs (17)
Xiphoid process
False ribs (812)
Intercostal spaces
Costal cartilage
L1 Vertebra
Floating ribs (11, 12)
Costal margin
Skeleton of the thoracic cage, anterior view 68

69. Fetal Skeleton A. Fontanelles 1. unossified remnants of membranes
2. soft spots in infant cranium

70. Fontanelles Frontal suture Frontal bone Anterior fontanelle
Ossification center
Parietal bone
Posterior fontanelle
Occipital bone
Superior view 70

71. Infant Cranium Frontal bone Parietal bone Sphenoidal fontanelle
Ossification center
Posterior fontanelle
Mastoid fontanelle
Temporal bone
(squamous part)
Occipital bone
Lateral view 71