anatomy axial skeleton VAN.ppt

1. BONES, PART 1: THE AXIAL SKELETON PART 1

2. THE SKELETON • Consists of • Bones, cartilage, joints, and ligaments • Composed of 206 named bones grouped into two divisions • Axial skeleton (80 bones) • Appendicular skeleton (126 bones)

4. THE AXIAL SKELETON Figure 7.1b

5. BONE MARKINGS • Projections that provide attachment for muscles and ligaments • Projections that help form joints • Depressions and openings for passage of nerves and blood vessels

6. THE SKULL • Formed by cranial and facial bones Figure 7.2a

7. THE CRANIUM • The cranium serves to • Enclose brain • Provide attachment sites for some head and neck muscles

8. THE FACE • Facial bones serve to • Form framework of the face • Form cavities for the sense organs of sight, taste, and smell • Provide openings for the passage of air and food • Hold the teeth in place • Anchor muscles of the face

9. OVERVIEW OF SKULL GEOGRAPHY • Facial bones form anterior aspect • Cranium is divided into cranial vault and the base • Internally, prominent bony ridges divide skull into distinct fossae

10. OVERVIEW OF SKULL GEOGRAPHY • The skull contains smaller cavities • Middle and inner ear cavities – in lateral aspect of cranial base • Nasal cavity – lies in and posterior to the nose • Orbits – house the eyeballs • Air-filled sinuses – occur in several bones around the nasal cavity

11. OVERVIEW OF SKULL GEOGRAPHY • The skull contains approximately 85 named openings • Foramina, canals, and fissures • Provide openings for important structures • Spinal cord • Blood vessels serving the brain • 12 pairs of cranial nerves

12. CRANIAL BONES • Formed from eight large bones • Paired bones include • Temporal bones • Parietal bones • Unpaired bones include • Frontal bone • Occipital bone • Sphenoid bone • Ethmoid bone

13. FRONTAL BONES • Forms the forehead and roofs of the orbits • Forms superciliary arches • Internally, it contributes to the anterior cranial fossa • Contains frontal sinuses

14. PARIETAL BONES AND SUTURES • Parietal bones form superior and lateral parts of skull • Four sutures of the cranium • Coronal suture – runs in the coronal plane • Located where parietal bones meet the frontal bone • Squamous suture – occurs where each parietal bone meets a temporal bone inferiorly

15. PARIETAL BONES AND SUTURES • Sutures of the cranium (continued) • Sagittal suture – occurs where right and left parietal bones meet superiorly • Lambdoid suture – occurs where the parietal bones meet the occipital bone posteriorly

16. SUTURAL BONES • Small bones that occur within sutures • Irregular in shape, size, and location • Not all people have sutural bones

17. THE SKULL – POSTERIOR VIEW Figure 7.2b

18. OCCIPITAL BONE • Forms the posterior portion of the cranium and cranial base • Articulates with the temporal bones and parietal bones • Forms the posterior cranial fossa • Foramen magnum located at its base

19. OCCIPITAL BONE • Features and structures • Occipital condyles • Hypoglossal foramen • External occipital protuberance • Superior nuchal lines • Inferior nuchal lines

20. INFERIOR ASPECT OF THE SKULL Figure 7.4a

21. TEMPORAL BONES • Lie inferior to parietal bones • Form the inferolateral portion of the skull • Term “temporal” • Comes from Latin word for time • Specific regions of temporal bone • Squamous, temporal, petrous, and mastoid regions

22. LATERAL ASPECT OF THE SKULL Figure 7.3a

23. THE TEMPORAL BONE Figure 7.5

25. THE SPHENOID BONE • Spans the width of the cranial floor • Resembles a butterfly or bat • Consists of a body and three pairs of processes • Contains five important openings

26. THE SPHENOID BONE Figure 7.6a

27. THE SPHENOID BONE Figure 7.6b

28. THE ETHMOID BONE • Lies between nasal and sphenoid bones • Forms most of the medial bony region between the nasal cavity and orbits

29. THE ETHMOID BONE Figure 7.7

30. BONES OF THE SKULL Table 7.1 (1 of 2)

31. FACIAL BONES • Unpaired bones • Mandible and vomer • Paired bones • Maxillae • Zygomatic bones • Nasal bones • Lacrimal bones • Palatine bones • Inferior nasal conchae

32. MANDIBLE • The lower jawbone is the largest and strongest facial bone • Composed of two main parts • Horizontal body • Two upright rami

33. MANDIBLE Figure 7.8a

34. MAXILLARY BONES • Articulate with all other facial bones except the mandible • Contain maxillary sinuses – largest paranasal sinuses • Forms part of the inferior orbital fissure

35. MAXILLARY BONES Figure 7.8b

36. MAXILLARY BONES Figure 7.4a

37. OTHER BONES OF THE FACE • Zygomatic bones • Form lateral wall of orbits • Nasal bones • Form bridge of nose • Lacrimal bones • Located in the medial orbital walls • Palatine bones • Complete the posterior part of the hard palate

38. OTHER BONES OF THE FACE • Vomer • Forms the inferior part of the nasal septum • Inferior nasal conchae • Thin, curved bones that project medially form the lateral walls of the nasal cavity

39. FACIAL BONES Table 7.1 (2 of 2)

42. SPECIAL PARTS OF THE SKULL • Orbits • Nasal cavity • Paranasal sinuses • Hyoid bone

43. NASAL CAVITY Figure 7.9a

44. NASAL SEPTUM Figure 7.9b

45. ORBITS Figure 7.10b

46. PARANASAL SINUSES • Air-filled sinuses are located within • Frontal bone • Ethmoid bone • Sphenoid bone • Maxillary bones • Lined with mucous membrane • Serve to lighten the skull

47. PARANASAL SINUSES Figure 7.11a, b

49. THE HYOID BONE • Lies inferior to the mandible • The only bone with no direct articulation with any other bone • Acts as a movable base for the tongue Figure 7.12

50. THE VERTEBRAL COLUMN • Formed from 26 bones in the adult • Transmits weight of trunk to the lower limbs • Surrounds and protects the spinal cord

51. THE VERTEBRAL COLUMN • Serves as attachment sites for muscles of the neck and back • Held in place by ligaments • Anterior and posterior longitudinal ligaments • Ligamentum flavum

52. THE VERTEBRAL COLUMN Figure 7.13

53. INTERVERTEBRAL DISCS • Cushion-like pads between vertebrae • Act as shock absorbers • Compose about 25% of height of vertebral column • Composed of • Nucleus pulposus and annulus fibrosis

54. INTERVERTEBRAL DISCS • Nucleus pulposus • The gelatinous inner sphere of intervertebral disc • Enables spine to absorb compressive stresses

55. INTERVERTEBRAL DISCS • Annulus fibrosis • An outer collar of ligaments and fibrocartilage • Contains the nucleus pulposus • Functions to bind vertebrae together, resist tension on the spine, and absorb compressive forces

56. LIGAMENTS AND INTERVERTEBRAL DISCS Figure 7.14a

57. HERNIATED DISC • May be caused by trauma to the spine • Aging is also a contributing factor • Nucleus pulposes loses cushioning properties • Anulus fibrosis weakens Figure 7.14c

58. REGIONS AND NORMAL CURVATURES • Vertebral column is about 70 cm (28 inches) • Vertebral column is divided into five major regions • Cervical vertebrae • 7 vertebrae of the neck region • Thoracic vertebrae • 12 vertebrae of the thoracic region

59. REGIONS AND NORMAL CURVATURES • Vertebral column is divided into five major regions (continued) • Lumbar vertebrae • 5 vertebrae of the lower back • Sacrum • Inferior to lumbar vertebrae • Articulates with coxal bones • Coccyx • Most inferior region of the vertebral column

60. REGIONS AND NORMAL CURVATURES • Four distinct curvatures give vertebral column an S-shape • Cervical and lumbar curvature • Are concave posteriorly • Thoracic and sacral curvatures • Are convex posteriorly • Curvatures increase the resilience of the spine

61. REGIONS AND NORMAL CURVATURES Figure 7.13 PLAY Spine (vertical)

62. GENERAL STRUCTURE OF VERTEBRAE PLAY Spine (horizontal) Figure 7.15

64. REGIONS VERTEBRAL CHARACTERISTICS • Specific regions of the spine perform specific functions • Types of movement that occur between vertebrae • Flexion and extension • Lateral flexion • Rotation in the long axis

65. CERVICAL VERTEBRAE • Seven cervical vertebrae (C1 – C7) – smallest and lightest vertebrae • C3 – C7 are typical cervical vertebrae • Body is wider laterally • Spinous processes are short and bifid (except C7) • Vertebral foramen are large and triangular • Transverse processes contain transverse foramina • Superior articular facets face superoposteriorly

66. CERVICAL VERTEBRAE Table 7.2a

67. CERVICAL VERTEBRAE Figure 7.17a

68. THE ATLAS • C1 is termed the atlas • Lacks a body and spinous process • Supports the skull • Superior articular facets receive the occipital condyles • Allows flexion and extension of neck • Nodding the head “yes”

69. THE ATLAS Figure 7.16a

70. THE ATLAS Figure 7.16b

71. THE AXIS • Has a body and spinous process • Dens (odontoid process) projects superiorly • Formed from fusion of the body of the atlas with the axis • Acts as a pivot for rotation of the atlas and skull • Participates in rotating the head from side to side

72. THE AXIS Figure 7.16c

74. THORACIC VERTEBRAE (T1 – T12) • All articulate with ribs • Have heart-shaped bodies from the superior view • Each side of the body of T1 – T10 bears demifacts for articulation with ribs • T1 has a full facet for the first rib • T10 – T12 only have a single facet

76. THORACIC VERTEBRAE • Spinous processes are long and point inferiorly • Vertebral foramen are circular • Transverse processes articulate with tubercles of ribs • Superior articular facets point posteriorly • Inferior articular processes point anteriorly • Allows rotation and prevents flexion and extension Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

77. LUMBAR VERTEBRAE (L1 – L5) • Bodies are thick and robust • Transverse processes are thin and tapered • Spinous processes are thick, blunt, and point posteriorly • Vertebral foramina are triangular • Superior and inferior articular facets directly medially • Allows flexion and extension – rotation prevented Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

80. SACRUM (S1 – S5) • Shapes the posterior wall of pelvis • Formed from 5 fused vertebrae • Superior surface articulates with L5 • Inferiorly articulates with coccyx • Sacral promontory • Where the first sacral vertebrae bulges into pelvic cavity • Center of gravity is 1 cm posterior to sacral promontory Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

81. SACRUM • Sacral foramina • Ventral foramina • Passage for ventral rami of sacral spinal nerves • Dorsal foramina • Passage for dorsal rami of sacral spinal nerves Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

85. BONY THORAX • Forms the framework of the chest • Components of the bony thorax • Thoracic vertebrae – posteriorly • Ribs – laterally • Sternum and costal cartilage – anteriorly • Protects thoracic organs • Supports shoulder girdle and upper limbs • Provides attachment sites for muscles Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

88. STERNUM • Formed from three sections • Manubrium – superior section • Articulates with medial end of clavicles • Body – bulk of sternum • Sides are notched at articulations for costal cartilage of ribs 2–7 • Xiphoid process – inferior end of sternum • Ossifies around age 40 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

89. STERNUM • Anatomical landmarks • Jugular notch • Central indentation at superior border of the manubrium • Sternal angle • A horizontal ridge where the manubrium joins the body Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

90. RIBS • All ribs attach to vertebral column posteriorly • True ribs - superior seven pairs of ribs • Attach to sternum by costal cartilage • False ribs – inferior five pairs of ribs • Ribs 11–12 are known as floating ribs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

93. DISORDERS OF THE AXIAL SKELETON • Abnormal spinal curvatures • Scoliosis – an abnormal lateral curvature • Kyphosis – an exaggerated thoracic curvature • Lordosis – an accentuated lumbar curvature – “swayback” • Stenosis of the lumbar spine • A narrowing of the vertebral canal Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

94. THE AXIAL SKELETON THROUGHOUT LIFE • Membrane bones begin to ossify in second month of development • Bone tissue grows outward from ossification centers • Fontanels • Unossified remnants of membranes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

97. THE AXIAL SKELETON THROUGHOUT LIFE • Many bones of the face and skull form by intramembranous ossification • Endochondral bones of the skull • Occipital bone • Sphenoid • Ethmoid bones • Parts of the temporal bone Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

98. THE AXIAL SKELETON THROUGHOUT LIFE • Curvatures of the vertebral column • Primary curvatures – thoracic and sacral curvatures • An infant's spine is C-shaped at birth • Secondary curvatures – cervical and lumbar curvatures • Develop when a baby begins to walk • Redistributes weight of the upper body over the lower limbs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

99. THE AXIAL SKELETON THROUGHOUT LIFE • Aging of the axial skeleton • Water content of the intervertebral discs decreases • By age 55, loss of a few centimeters in height is common • Thorax becomes more rigid • Bones lose mass with age Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

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