1. Chapter 6 Lecture Slides
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2. Functions of the Skeletal System
Support
Protection
Attachment sites for skeletal muscles
Blood cell production
Mineral storage 2

3. Bone Structure Bones are composed of a number of tissues
Bone tissue is the bulk of each bone
There are four basic types of bone based on shape
Long bones
Short bones
Flat bones
Irregular bones 3

4. Structure of a long bone
Epiphysis
Articular cartilage
Diaphysis
Medullary cavity
Endosteum
Epiphyseal disk
Periosteum 4

5. Spongy bone Interior of small bones, skull bones, and epiphyses
Consists of trabeculae and spaces filled with red bone marrow
Reduces bone weight without reducing strength 5

6. Compact bone Wall of diaphysis and surface of diaphysis
Tightly packed tissue with no spaces
Strong and gives supportive strength 6

7. Microscopic structure
Bone cells lie inside lacunae
Compact bone
Osteons
Osteonic canals
Lamellae
Foramen
Canaliculi
Spongy bone
Lack osteons
Receive nutrients by diffusion through canaliculi 7

8. 8

9. Bone Formation
Ossification is the process of bone formation during the 6th or 7th week of embryonic life
Two types of bone formation
Intramembranous ossification
Endochondral ossification 9

10. 10

11. For both types of bone formation
Primitive connective tissue cells become osteoblasts
Osteoblasts deposit bone matrix around them
Once trapped in matrix, osteoblasts become osteocytes 11

12. Intramembranous ossification
Forms most skull bones
Steps involved
Connective tissue membranes form at sites of future intramembranous bones
Some cells become osteoblasts
Osteoblasts deposit spongy bone beginning at center of bone
Osteoblasts form layer of compact bone atop the spongy bone 12

13. To produce the correct bone shape
Use osteoclasts to remove bone matrix
Use osteoblasts to reform new bone matrix 13

14. Endochondral ossification
Forms most bones of the body
Example: long bones
Steps involved
Bones are preformed in hyaline cartilage 14

15. Primary ossification center forms in center of cartilage
Periosteal osteoblasts form a compact bone collar around primary ossification center
Cartilage in the primary center calcifies and chondrocytes die 15

16. Osteoblasts form spongy bone at the primary ossification center
Blood vessels and nerves penetrate the center, bring osteoblasts with them
Osteoblasts form spongy bone at the primary ossification center 16

17. Secondary ossification center forms in the epiphyses
Osteoclasts remove the spongy bone and form the medullary cavity 17

18. Bone continues to grow
At the end of the process, the epiphyseal disk separates the epiphyses from the diaphysis 18

19. Continued growth in length takes place at the epiphyseal disk
Continued growth in diameter due to formation of compact bone beneath the periosteum
Continued growth in length takes place at the epiphyseal disk
Cartilage grows on the epiphyseal side
Cartilage is converted into bone on the diaphysis side 20

20. Osteoblasts and osteoclasts continually reshape the bone as it grows
Bone growth in length continues until age 25
Epiphyseal disk is completely replaced by bone
Epiphyseal line is all that remains 21

21. Homeostasis of bone
Bone is continually remodeled due to activity of osteoclasts and osteoblasts
Remodeling can be affected by
Physical activity
Dietary calcium intake
Age 22

22. Divisions of the Skeleton
Skeleton is divided into two divisions
Axial skeleton
Bones along the longitudinal axis of the body
Appendicular skeleton
Pectoral girdle and upper extremities
Pelvic girdle and lower extremities

24. Axial Skeleton Skull Divided into two segments Bones joined by sutures
Cranium
Facial bones
Bones joined by sutures
Immovable joints

25. Several bones possess paranasal sinuses

26. Cranium Frontal bone Parietal bones Occipital bones Temporal bones
Anterior part of cranium
Parietal bones
Sides and roof of cranium
Occipital bones
Posterior portion and floor of cranium
Temporal bones
Inferior to parietal bones on each side of the cranium
Temporomandibular joint

27. Sphenoid bone Ethmoid bone
Forms part of cranium floor, lateral posterior portions of eye orbits, lateral portions of cranium anterior to temporal bones
Ethmoid bone
Anterior portion of cranium, including medial surface of eye orbit and roof of nasal cavity
Nasal conchae

32. Facial bones Maxillae Palatine bones
Form upper jaw, anterior portion of hard palate, part of lateral walls of nasal cavity, floors of eye orbits
Maxillary sinus
Palatine bones
Form posterior portion of hard palate, lateral wall of nasal cavity

33. Zygomatic bones Lacrimal bones Nasal bones Cheek bones
Also form floor and lateral wall of each eye orbit
Lacrimal bones
Medial surfaces of eye orbits
Nasal bones
Form bridge of nose

34. Inferior nasal conchae
Vomer
In midline of nasal cavity
Forms nasal septum with the ethmoid bone
Inferior nasal conchae
Attached to lateral walls of nasal cavity
Mandible
Lower jawbone
Only movable skull bone

39. Hyoid bone Found in anterior portion of neck, inferior to mandible
Does not articulate with any other bones
Used as attachment site for tongue muscles

40. The infant skull Newborn skull is incompletely developed
Possess fontanels
Non-ossified areas
Allow for flexibility during birth and growth afterwards

42. Vertebral column Extends from skull to pelvis
Flexible and sturdy longitudinal support for trunk
Formed by 24 movable vertebrae, a sacrum, and a coccyx
Possess intervertebral discs
Shock absorbers
Possess four distinct curvatures

44. Structure of a vertebra
All vertebrae have common features
Neural arch
Vertebral foramen
Spinous process
Transverse process
Superior and inferior articulating process
Intervertebral foramina

45. Cervical vertebrae
Support neck
Possess unique transverse foramen

46. Atlas: cervical vertebra 1
Articulate occipital condyles of occipital bone
Supports head

47. Axis: cervical vertebra 2
Possesses the odontoid process
Serves as a pivot point for axis

48. Thoracic vertebrae
Larger vertebra with longer spinous process then cervical vertebrae
Ribs articulate on the transverse processes and bodies

49. Lumbar vertebrae
Heavy, thick bodies to support greater stress and weight
Larger processes for attachment of back muscles

50. Sacrum Coccyx Five fused sacral bones
Forms posterior wall of pelvic girdle
Coccyx
Tailbone
Three to five fused rudimentary vertebrae

52. Thoracic cage Composed of Functions Thoracic vertebrae Ribs
Costal cartilages
Sternum
Functions
Protection of internal organs
Support of upper body

54. Ribs Attached to thoracic vertebrae True ribs (#1-7)
Attached to sternum directly by costal cartilages
False ribs (#8-10)
Attach to costal cartilage of superior ribs
Floating ribs (#11-12)
Do not attach anteriorly, no costal cartilages

55. Sternum Flat, elongated bone in the anterior midline of thoracic cage
Composed of three fused bones
Manubrium
Body
Xiphoid process

56. Appendicular Skeleton
Consists of
Pelvic girdle and upper extremity
Pelvic girdle and lower extremity
Composed of 126 individual bones

57. Pectoral girdle Composed of Clavicle Two clavicles Two scapula
Articulates with sternum and scapula

58. Scapula Located on each side of vertebral column
Held in place by muscles to allow free shoulder movement

59. Upper extremity Humerus
Articulates with scapula at the shoulder and ulna and radius at the elbow

60. Ulna Radius Medial bone in forearm
Bone does not move with hand rotation
Radius
Lateral bone in the forearm
Bone that rotates when the hand is rotated

61. Carpals Metacarpals Phalanges Wrist bones
Bones of the palm of the hand
Phalanges
Bones of the fingers

62. Pelvic girdle Consists of Forms a rigid, bony pelvis Two coxal bones
Sacrum
Forms a rigid, bony pelvis

63. The pelvic girdles of males and females have several structural differences

65. Coxal bones Formed by three fused bones Attachment site for the legs
Ilium
Ischium
Pubis
Attachment site for the legs
Symphysis pubis

66. Lower extremity Femur Patella Thigh bone
Largest and strongest bone in the body
Patella
Kneecap
Sesamoid bone in tendon that extends anterior to knee

67. Tibia Fibula Shinbone Larger of the lower leg bones Bears body weight
Slender, lateral bone in lower leg

68. Tarsals Metatarsals Phalanges Ankle bones Bones of the instep
Toe bones

70. Articulations An articulation is a joint or junction between two bones
Joints allow for varying degrees of movement
Three categories of joints
Immovable
Slightly movable
Freely movable

71. Immovable joints (synarthrosis)
Bones are tightly joined and separated by thin fibrous connective tissue
No movement at the joint
Example: sutures

72. Slightly movable joints (amphiarthrosis)
Bones separated by layer of cartilage or fibrous connective tissue
Limited flexibility
Example: joints between vertebrae

73. Freely movable joints (diarthrosis)
Joints are freely movable
Structurally more complex
Several types of freely movable joints

74. Gliding joints Condyloid joints
Involve sliding of bones across each other
Example: carpal and tarsal bones
Condyloid joints
Allow movement from side to side and back and forth
Example: between carpals and bones of forearm

75. Hinge joints Allow movement in one direction only
Example: knee and elbow joints

76. Saddle joints Pivot joints Ends of each bone are saddle shaped
Movement is side to side and back and forth
Example: joint between trapezium and metacarpal of thumb
Pivot joints
Allow rotational movement
Example: atlas on the axis

77. Ball-and-Socket joints
A rounded head of one bone fits into a concavity on another bone
Movement may be rotational or in any plane
Example: hip and shoulder joint

78. Movements at freely movable joints
Movement is caused by contraction of muscles that span the joint
Movement depends upon joint type and location of muscle(s) involved

79. Disorders of the Skeletal System
Common disorders can be characterized as
Disorders of bones
Disorders of joints
Orthopedics
Branch of medicine that specializes in treating skeletal disease and abnormalities

80. Disorders of Bones Fractures: broken bones Complete Incomplete
Compound
Simple
Greenstick
Comminuted
Impacted

81. Osteomyelitis Osteoporosis
Inflammation of bone and bone marrow due to bacterial infection
Osteoporosis
Weakening of bone due to loss of calcium salts
Common in older people, especially postmenopausal women
Caused by inactivity and decrease in hormone production

82. Rickets Childhood disease Due to deficiency of calcium salts in bones
Dietary deficiency in calcium or Vitamin D
Children have a bowlegged appearance

83. Disorders of Joints Arthritis Rheumatoid arthritis Osteoarthritis
Characterized by inflammation, swelling, and pain
Rheumatoid arthritis
Most painful and crippling type
Result is ossification of joint, making it immovable
Auto-immune dissorder
Osteoarthritis
Most common type
Loss of articular cartilage makes movement restricted and painful

84. Bursitis Dislocation Herniated disk Inflammation of bursa
Displacement of bones forming the joint
Herniated disk
Intervertebral disc protrudes out beyond vertebrae
Caused by excessive pressure
May apply pressure to nerves

85. Spinal curvatures Sprain Kyphosis (hunchback) Lordosis (swayback)
Excessive thoracic curvature
Lordosis (swayback)
Excessive lumbar curvature
Scoliosis
Abnormal lateral curvature
Sprain
Tearing or stretching of ligaments and tendons without dislocation