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The Skeletal System. Divisions of the Skeletal System The human skeletal system is divided into two major divisions  Axial Skeleton  Appendicular skeleton.

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Presentation on theme: "The Skeletal System. Divisions of the Skeletal System The human skeletal system is divided into two major divisions  Axial Skeleton  Appendicular skeleton."— Presentation transcript:

1 The Skeletal System

2 Divisions of the Skeletal System The human skeletal system is divided into two major divisions  Axial Skeleton  Appendicular skeleton

3 Axial Skeleton  The axial skeleton contains the bones of the head, neck, and torso (80 bones total)

4 appendicular skeleton  The appendicular skeleton contains the bones of the upper and lower extremities (126 bones total)

5 Human Skeleton  The human skeleton has a total of 206 bones in all

6 Bones Functions:  Support  Protection  Movement  Storage  Blood cell formation

7 Bones Function- Support  Form the internal framework that supports and anchors all soft organs

8 Bones Function- Protection  Bones protect soft body organs  Ex. Skull protects brain

9 Bones Function- Movement  Skeletal Muscles attach to bones by tendons  Bones are used as levers to move body

10 Bones Functions-storage  Fat is stored in internal cavities of bones

11 Bones Functions-storage  Store minerals  Most important—Calcium and phosphorus

12 Bones Functions-storage  Calcium in its ion form (Ca 2+ ) must always be present in blood  for nervous system to transmit messages  For muscles to contract  For blood to clot  Bones are a storage place for Calcium

13 Bones Functions-storage  Blood cell formation  Hematopoiesis (formation of blood cells) occurs in the cavities of bone marrow

14 Bones Classification of bones  2 basic types of bone types  Compact Bone  Spongy Bone

15 Bones Compact Bone  Dense  Looks smooth

16 Bones Spongy Bone  Small needle-like pieces of bone  Lots of open space

17

18 Shapes of Bones Long Bones Short Bones Irregular Bones

19 Bones Long Bones  Longer than they are wide  Usually have a shaft with heads at both ends  Mostly compact bones  most bones of limbs

20 Bones Short Bones  Generally cube-shaped  Mostly spongy bone  Ex. Patella (knee cap), bones of wrist and ankle

21 Flat Bones Thin, flattened, usually curved Two thick layers of compact bone sandwiching a layer of spongy bone Bones of skull, ribs, sternum

22 Irregular Bones Don’t fit other categories Ex. Vertebrate, hip bone

23 Structure of a long bone Diaphysis-  Shaft  Makes up most of the bone’s length  Composed of compact bone  Covered and protected by periosteum

24 Structure of a long bone Cavity of shaft  In infants- this area forms blood cells  Red marrow  In adults primarily filled with yellow marrow (adipose)  Called yellow marrow cavity or medullary cavity  Red marrow is confined to spongy bone

25 Structure of a long bone Epiphyses- the ends of the long bone  Epiphyseal line  Thin line spanning the epiphysis

26 Structure of a long bone Epiphyseal plate  Plate of hyaline cartilage  Causes the lengthwise growth of a long bone  By end of puberty the plate is completely replaced by bone

27 Structure of Long Bone Surfaces of bones aren’t smooth  Bumps, holes, and ridges Bone markings  Reveal where muscles, tendons, and ligaments were attached  Reveal where blood vessels and nerves passed

28 Structure of Long Bone Bone markings  Projections or processes-  Grow out from the bone surface  Depressions or cavities  Indentations in the bone

29 Structure of a long Microscopic anatomy  Compact bone:  To the naked eye looks very dense  With microscope we see a much different picture!

30 Structure of a long Microscopic anatomy  Compact bone  Passageways carrying nerves and blood vessels  Provides living bone with nutrients and route for waste disposal

31 Structure of Long Bone Osteocytes  The mature bone cells  Found in cavities of the bone matrix called lacunae ( a very tough matrix)

32 Structure of Long Bone Osteocytes  Lacunae arranged in concentric circles called lamellae  Lacunae arranged around central (Haversian) canals

33 Structure of Long Bone Perforating (Volkmann’s) canals  Run into the compact bone at right angles to the shaft  Let the inside of bone communicate with outside

34 Bone Formation, Growth, and Remodeling Embryo’s skeleton  Primarily hyaline cartilage Young child  Most of cartilage has been replaced by bone  Remains in isolated areas  Bridge of nose  Parts of ribs  joints

35 Bone Formation, Growth, and Remodeling Most bones develop using hyaline cartilage structures as their “models” Ossification- the formation of bone

36 Bone Formation, Growth, and Remodeling Ossification  2 major stages  1. hylane cartilage model is completely covered with bone by bone forming cells called osteoblasts

37 Bone Formation, Growth, and Remodeling Ossification  Step Two:  Hyaline cartilage model is digested away  Opens up a medullary cavity within newly formed bone

38 Bone Formation, Growth, and Remodeling By birth  Most hyaline cartilage models have been converted to bone  Excepts two reasons  Articular cartilages –cover bone ends  Epiphyseal plates

39 Bone Formation, Growth, and Remodeling Articular cartilages  Persist for life  Reduce friction at the joint surfaces

40 Bone Formation, Growth, and Remodeling How is the articular cartilage injured?  Trauma- twisting, sport injury  Certain diseases  Gradually over time

41 Bone Formation, Growth, and Remodeling When there is significant loss of the articular cartilage, the knee is considered to have “arthritis”.

42 Bone Formation, Growth, and Remodeling Epiphyseal plates  Provide for longitudinal growth of long bones during childhood  New cartilage is formed on external surface  Old cartilage is broken down and replaced by bony matrix

43 Bone Formation, Growth, and Remodeling Epiphyseal plates  Growth controlled by hormones  Ends during adolescence, when the epiphyseal plates are completely converted to bone

44 Bone Formation, Growth, and Remodeling How do bones widen? –called Appositional Growth  Osteoblasts in the periosteum add bone to the external face  Osteoclasts in the endosteum remove bone from inner wall

45 What happens when long bone growth ends?

46 Bone Formation, Growth, and Remodeling Bone Remodeling  Bones continually remodeled in response to 2 factors:  1. calcium levels in the blood  2. the pull of gravity and muscles on the skeleton

47 Bone Formation, Growth, and Remodeling Bone Remodeling  When blood calcium levels are low  Parathyroid hormone (PTH) is released into blood  PTH activates osteoclasts (bone destroying cells) to break down bone matrix and release calcium

48 Bone Formation, Growth, and Remodeling Bone Remodeling  When blood calcium levels are too high (hypercalcemia)  Calcium is deposited in bone matrix as hard calcium salts

49 Bone Formation, Growth, and Remodeling Bone Remodeling  Essential for bones to:  retain normal proportions  Strengthen as body increases size and weight

50 Bone Formation, Growth, and Remodeling Bone Remodeling  Bedridden or physically inactive people tend to lose bone mass and atrophy  Because they aren’t subjected to stress

51 Bone Formation, Growth, and Remodeling Rickets  Disease of children in which bones fail to calcify  Bones soften and definite bowing of weight-bearing bones of legs occurs

52 Bone Formation, Growth, and Remodeling Rickets—  Called osteomalacia in adults  Causes  Usually due to lack of calcium in diet  Or lack of vitamin D Is needed to absorb calcium

53 Divisions of the Skeletal System Axial

54 Bones of the Axial Skeleton Bones of the axial skeleton are divided into four major groups 1) Bones of the Skull 2) Hyoid Bone 3) Bones of the Spinal Column 4) Sternum and Ribs

55 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones (8 total) form the cranium which surrounds the brain

56 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones  1) Frontal Bone (1 bone) Anterior Portion of Cranium (Forehead) Forms Anterior Cranial Floor Forms the Roofs of Orbits (Eye Sockets)

57 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones  2) Parietal Bone (2 bones) Forms Superior Portion of Cranium

58 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones  3) Temporal Bone (2 bones) Forms Lateral Portion of Cranium & Lateral Cranial Floor

59 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones  4) Occipital Bone (1 bone) Forms Posterior Portion of Cranium & Posterior Cranial Floor

60 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones  5) Sphenoid Bone (1 bone) Forms central portion of cranial floor Known as the “keystone of the cranium” because the sphenoid bone anchors all the other cranial bones

61 Bones of the Axial Skeleton Bones of the Skull (28 total)  Cranial Bones  6) Ethmoid Bone (1 bone) Complex, irregularly shaped bone found between the nasal and the sphenoid bones

62 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  1) Nasal Bone (2 bones) Forms the bridge of the nose

63 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  2) Maxillary bone (2 Bones) Upper jawbone that forms the central portion of the face Forms the floor of the orbits and the anterior portion of the hard palate

64 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  3) Zygomatic Bone (2 Bones) Forms the cheekbones and the lateral walls of the orbits

65 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  4) Mandible Bone (1 Bone) Lower jawbone Largest and strongest bone of the face

66 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  5) Lacrimal Bone (2 Bones) Forms the medial walls of the orbits Bones are paper thin

67 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  6) Palatine Bone (2 Bones) Forms posterior portion of the hard palate and forms the lateral and posterior walls of the nasal cavity

68 Bones of the Axial Skeleton Bones of the Skull (28 total)  Facial Bones  8) Vomer Bone (1 Bone) Forms the lower portion of the nasal septum

69 Bones of the Axial Skeleton Bones of the Skull (28 total)  Bones of the Ear  Three tiny bones located in the middle ear 1) Malleus (2 Bones) 2) Incus (2 Bones) 3) Stapes (2 Bones)

70 Bones of the Axial Skeleton Bones of the Skull (28 total)  Bones of the Ear  Smallest bones in the body  Carry sound vibrations to inner ear  Amplifies sound about 7x

71 Bones of the Axial Skeleton Hyoid Bone (1 total)  The hyoid bone is a U shaped bone found in the neck between the mandible and the larynx  It is the only bone in the body which does not form a joint with another bone (held in place by ligaments and muscles)

72 Bones of the Axial Skeleton Hyoid Bone (1 total)  Function:  Supports the base of the tongue

73 Bones of the Axial Skeleton Vertebral Column –Spine  26 irregular bones connected by ligaments  Flexible, curved structure

74 Bones of the Axial Skeleton Vertebral Column –Spine  Running through the central cavity of vertebral column is the delicate spinal cord  Spine preserves and protects spinal cord

75 Bones of the Axial Skeleton Vertebral Column –Spine  Single vertebrae are separated by pads of flexible fibrocartilage called intervertebral discs  They cushion the vertebrae and absorb shock

76 Bones of the Axial Skeleton Vertebral Column –Spine  Young Person  Discs have high water content ( 90%)  Discs are spongy and compressible

77 Bones of the Axial Skeleton Vertebral Column –Spine  Aging  The water content of disc decreases  Drying of discs and weakening of ligaments predisposes older people to herniated discs (slipped disc) if slipped disc presses on spinal cord- major pain

78 Bones of the Axial Skeleton Vertebral Column –Spine  The spine has 2 curvatures  1. Primary Curvature  2. Secondary Curvature

79 Bones of the Axial Skeleton Vertebral Column –Spine  Primary Curvature-  curvature in the thoracic and sacral regions  Called primary because it is there when we are born

80 Bones of the Axial Skeleton Vertebral Column –Spine  Secondary Curvature-  Cervical curvature- develops when baby begins to lifts its head  Lumbar curvature- develops when baby begins to walk

81 Bones of the Axial Skeleton Several types of abnormal spinal curvature 1. Scoliosis-

82 Bones of the Axial Skeleton Several types of abnormal spinal curvature 2. lordosis-

83 Bones of the Axial Skeleton Several types of abnormal spinal curvature 2. lordosis-

84 Several types of abnormal spinal curvature 3. kyphosis-

85

86

87 Bones of the vertebral column (backbone)

88 Bones of the Axial Skeleton Bones of the Spinal Column (26 total)  1) Cervical Vertebrae (7 Bones) Top seven vertebrae of the spinal column The atlas (to bear )is the first cervical vertebrae The axis is the second cervical vertebrae

89 Bones of the Axial Skeleton Bones of the Spinal Column (26 total)  1) Cervical Vertebrae (7 Bones)

90 Bones of the Axial Skeleton Bones of the Spinal Column (26 total)  2) Thoracic Vertebrae (12 Bones) Middle 12 vertebrae of the spinal column

91 Bones of the Axial Skeleton Bones of the Spinal Column (26 total)  3) Lumbar Vertebrae (5 Bones) Bottom five vertebrae of the spinal column

92 Bones of the Axial Skeleton Bones of the Spinal Column (26 total)  4) Sacrum (5 Bones Fused Into 1 Bone) Five separate vertebrae that fuse into 1 bone after the bones mature

93 Bones of the Axial Skeleton Bones of the Spinal Column (26 total)  5) Coccyx (4 or 5 Bones Fused Into 1 Bone) Tailbone; consists of separate vertebrae that have fused together

94

95 Bones of the Axial Skeleton Sternum and Ribs (25 total)  Sternum (1 Bone)  “Breastbone”

96 Bones of the Axial Skeleton Ribs  You have two types of ribs 1. True Ribs 2. False Ribs

97 Bones of the Axial Skeleton Sternum and Ribs (25 total)  Ribs (12 pairs = 24 Ribs)  True Ribs (First 7 pairs) Ribs attach directly to the sternum by costal cartilage

98 Bones of the Axial Skeleton Ribs  False Ribs (Bottom 5 pairs) Rib pairs 8, 9, & 10 attach indirectly to the sternum by the costal cartilage of rib pair #7 Rib pairs 11 & 12 are called floating ribs because they do not attach to the sternum at all

99 Bones of the Axial Skeleton  All ribs attach to a thoracic vertebrae posteriorly

100 Bones of the Axial Skeleton Bones of the Upper Extremities  The sternum, ribs, and vertebral column create the thorax

101 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Clavicle (2 Bones)  Collarbone

102 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Scapula (2 Bones)  Shoulder Blade

103 Bones of the Appendicular Skeleton Bones of the Upper Extremities  The scapula and clavicle together make up the shoulder girdle

104 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Humerus (2 Bones)  Long bone of the upper arm

105 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Radius (2 Bones)  Ulna (2 Bones)  The radius and ulna are bones of the forearm  The radius is on the thumb side and the ulna is on the little finger side

106 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Carpals (16 Bones; 8 in Each Hand)  Bones of the wrist

107 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Metacarpals (10 Bones, 5 in Each Hand)  Bones in the palm of the hand

108 Bones of the Appendicular Skeleton Bones of the Upper Extremities  Phalanges (28 Bones, 14 in Each Hand)  Bones of the fingers (3 in each finger and 2 in the thumb)

109 Bones of the Appendicular Skeleton Bones of the Lower Extremities (Label bones in your notes !)

110 Skeletal Differences in Men & Women Male Female

111 Skeletal Differences in Men & Women

112 Bones of the Appendicular Skeleton Bones of the Lower Extremities  Femur Bone Thigh bone  Longest, largest, and strongest bone in the body

113 Bones of the Appendicular Skeleton Bones of the Lower Extremities  Patella (2 Bones)  Kneecap

114 Bones of the Appendicular Skeleton Bones of the Lower Extremities  Tibia  Fibula  The tibia and fibula are the bones of the lower leg  Tibia “shin bone” is larger, medial, and more superficial than the fibula

115 Bones of the Appendicular Skeleton Bones of the Lower Extremities  Tarsal Bones (14 Bones, 7 in Each Foot)  Bones that form the heel and the posterior portion of the foot

116 Bones of the Appendicular Skeleton Bones of the Lower Extremities  Metatarsals (10 Bones, 5 in each foot)  Bones that form the long portion of the foot

117 Bones of the Appendicular Skeleton Bones of the Lower Extremities  Phalanges (28 Bones, 14 in each foot)  Bones of the toes (3 in each toe except big toe; big toe has 2 bones)


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