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Introduction to the Skeletal System Structure, function, and classification of bones.

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Presentation on theme: "Introduction to the Skeletal System Structure, function, and classification of bones."— Presentation transcript:

1 Introduction to the Skeletal System Structure, function, and classification of bones

2 Skeletal System Interconnected system of bones ligaments and tendons Provide support and protection for body Composed of 206 bones

3 Functions of Skeletal System 1)Support – provides solid axis for muscles to act against, creating motion. 2)Protection- bones such as skull provide barrier of protection from external forces 3)Hematopoiesis- production of red blood cells

4 Types of Bones Bones are divisible into 5 class.  Long  Short  Flat  Irregular  Sesamoid

5 Long Bones Found in the limbs Each bone is made of a body (diaphysis) and two extremities (epiphyses) Wall consists of dense tissue Central canal called medullary canal is filled with marrow

6 Short Bones Found in skeleton where strength, compactness, and limited movement are desired 2 main examples  Tarsus  Carpus

7 Flat Bones Used in spots where protection or muscular attachment is desired Main locations are skull and scapula

8 Irregular Bones Bones which don’t fit into other categories due to irregular shapes Examples: vertebrae;sphenoid; hyoid

9 Sesamoid (Round) Bones Usually small and round. Embedded within tendons adjacent to joints. Example: patella (knee cap)

10 Bone Formation and Fractures

11 Fetal Skeleton Begins as mainly cartilage Calcifies in utero At birth, fontanels remain

12 Ossification Bone production process gives bone extreme tensile and compressional strength Several things contribute to strength

13 Factors which contribute to bone growth Nutrition Exposure to sunlight Hormonal Secretion Physical Exercise

14 Nutrition Mainly calcium consumption Increased blood calcium triggers release of calcitonin Causes uptake of calcium by osteoblasts (bone builders)

15 Nutrition (contd) Decrease in calcium triggers release of Parathyroid hormone Triggers osteoclasts to break down bone, releasing calcium into blood

16 Exposure to Sunlight UV light on the skin causes Vitamin D production Promotes proper absorption of calcium in the SI

17 Hormonal Secretion Human growth hormone Somatotropin Both hormones stimulate activity in the epiphyseal plate

18 Physical Activity Increase in physical exertion on bone tissue actually increases bone density and strength

19 Bone maintenance Osteoblasts- constantly producing new bone tissue Osteoclasts – clean out old bone tissue  Causes holes or tunnels in bone which osteoblasts then fill in with calcium and phosphate compounds

20 Fractures

21 Simple Fracture Also called closed fracture Bone breaks cleanly, and does not penetrate skin. Little chance of infection

22 Compound Fracture Bone breaks completely Bone ends protrude through skin Major chance of serious bone infection

23 Comminuted Fracture Bone breaks into many fragments Common in elderly

24 Compression Fracture Bone is crushed Common in porous bones Especially common in vertebrae of osteoporosis patients

25 Depression fracture Broken bones are forced inward Common in skull fractures

26 Impacted Fracture Broken bone ends are forced into each other Common in falls (ie. From ladder) where person attempts to break their fall

27 Spiral Fracture Occurs from excessive twisting force on bone Common in sports injuries

28 Greenstick Fracture Bone breaks incompletely Common in children due to more collagen in bones

29 Repairing Fractures Closed reduction = bones are eased back into alignment and “reset” Open reduction = bones are surgically reset using screws or wires After either, a cast is usually applied to immobilize the bone; healing begins

30 Internal Bone Repair 1)Hematoma forms from ruptured blood vessels. 2)After new capillaries form, fibrocartillage callus “splints” broken bone using cartilage and bony matrix. 3)Osteoblasts migrate to area, forming bone “patch” over break. Fibrocartilage is replaced by bony callus.

31 The Axial Skeleton

32 Divisions of the Skeletal System Skeletal system is divided into two main division Skeletal system is divided into two main division  Axial – central skeleton that protects and supports vital organs  Appendicular – skeleton of the extremities

33 Axial Skeleton Composed of skull and vertabrae Composed of skull and vertabrae Mainly flat and irregular bones Mainly flat and irregular bones Serve to protect organs such as brain, heart, and lungs Serve to protect organs such as brain, heart, and lungs Also helps to support body along central axis (backbone) Also helps to support body along central axis (backbone)

34 Parts of the axial skeleton Skull – protects brain Skull – protects brain Vertebrae – protect spinal chord ;also serves to keep skeleton upright Vertebrae – protect spinal chord ;also serves to keep skeleton upright Ribs – protect lungs and heart ; gives intercostal muscles a hard surface to move against for breathing Ribs – protect lungs and heart ; gives intercostal muscles a hard surface to move against for breathing

35 Divisions of the skull Skull is divided into 2 sets of bones Skull is divided into 2 sets of bones  Cranium – collection of 8 bones which hold and protect brain  Facial bones – 14 bones that make up the face; all but 2 are paired

36 Cranium Frontal Bone – makes up forehead, eyebrows, and superior section of eye orbital Frontal Bone – makes up forehead, eyebrows, and superior section of eye orbital Parietal Bone – form most of the superior and lateral walls of cranium Parietal Bone – form most of the superior and lateral walls of cranium Temporal bones – lie inferior to parietal bones Temporal bones – lie inferior to parietal bones Occipital bone – forms back and floor of cranium; foramen magnum (large hole) allows spinal chord to meet brain Occipital bone – forms back and floor of cranium; foramen magnum (large hole) allows spinal chord to meet brain

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38 Facial Bones Mandible- lower jaw bone Mandible- lower jaw bone Maxillary bones (maxillae) fuse together to form upper jaw Maxillary bones (maxillae) fuse together to form upper jaw Palatine processes – directly posterior to maxillae; forms rear of hard palate Palatine processes – directly posterior to maxillae; forms rear of hard palate

39 Facial Bones Contd. Zygomatic bones – cheekbones Zygomatic bones – cheekbones Lacrimal bones – inferior section of orbital bones; provides passageway for tears Lacrimal bones – inferior section of orbital bones; provides passageway for tears Ethmoid bone- forms roof of nasal cavity Ethmoid bone- forms roof of nasal cavity

40 More Facial Bones Nasal bones- form bridge of nose Nasal bones- form bridge of nose Vomer – divides nasal cavity in half Vomer – divides nasal cavity in half Inferior conchae- thin curved bones which project from interior of nasal cavity Inferior conchae- thin curved bones which project from interior of nasal cavity

41 Axial Skeleton Intervertebral Discs Spinal curvatures Bony Thorax

42 Intervertebral Discs Pads of cartilage between each vertebrae Pads of cartilage between each vertebrae Provide cushioning; reduce shock Provide cushioning; reduce shock High water content High water content As you age, water content lowers, drying discs As you age, water content lowers, drying discs Can cause herniated (slipped) disc; where disc protrudes from spine Can cause herniated (slipped) disc; where disc protrudes from spine

43 Bony Thorax Made of bones which connect and protect heart and lungs Made of bones which connect and protect heart and lungs Ribs, Costal Cartilage, and Sternum Ribs, Costal Cartilage, and Sternum

44 Ribs 12 pairs of ribs, each connects to a thoracic vertebrae 12 pairs of ribs, each connects to a thoracic vertebrae First 7 pairs = true ribs; attach directly to sternum First 7 pairs = true ribs; attach directly to sternum Last 5 pairs = false ribs; indirect or no attachment; last two are floating (no sternal attachment) Last 5 pairs = false ribs; indirect or no attachment; last two are floating (no sternal attachment)

45 Sternum Fusion of three bones Fusion of three bones 1) Manubrium (top) 1) Manubrium (top) 2) Body (middle) 2) Body (middle) 3) Xiphoid Process (bottom) 3) Xiphoid Process (bottom) Location for rib attachment Location for rib attachment Surrounded by costal cartilage Surrounded by costal cartilage

46 Sternal Puncture Process by which marrow is removed from sternum Process by which marrow is removed from sternum Good location because of proximity to body surface Good location because of proximity to body surface

47 The Spinal Column

48 Intro Supports body Supports body Connects skull to pelvis Connects skull to pelvis Sends weight down to pelvis, where it is transmitted through the legs Sends weight down to pelvis, where it is transmitted through the legs Surrounds and protects spinal cord Surrounds and protects spinal cord 26 total bones 26 total bones

49 Divisions of the Spinal Column 4 main divisions 4 main divisions  1) Cervical curvature  2)Thoracic curvature  3)Lumbar curvature  4)Pelvic Sacrum Sacrum Thorax Thorax

50 Cervical curvature Begins where skull meets spine Begins where skull meets spine Composed of 7 vertebrae Composed of 7 vertebrae Labeled C1-C7, starting at skull Labeled C1-C7, starting at skull First two vertebrae (C1 and C2)are different First two vertebrae (C1 and C2)are different

51 C1 and C2 Perform different jobs than other vertebrae Perform different jobs than other vertebrae C1 (atlas) has depressions that accept the occipital codyles (“yes nod”) C1 (atlas) has depressions that accept the occipital codyles (“yes nod”) C2 (axis) acts as pivot point for skull (“no” head shake) C2 (axis) acts as pivot point for skull (“no” head shake)

52 Thoracic Curvature 12 bones 12 bones T1-T12 T1-T12 Costal demifacet – point of attachment of ribs Costal demifacet – point of attachment of ribs

53 Lumbar Vertebrae 5 vertebrae 5 vertebrae (L1-L5) (L1-L5) Sturdiest because under the most stress Sturdiest because under the most stress

54 Sacrum 1 bone composed of 5 fused vertebrae 1 bone composed of 5 fused vertebrae “wing-like” alae connect laterally with hip bones (forms sacroiliac joints) “wing-like” alae connect laterally with hip bones (forms sacroiliac joints) Makes up posterior wall of pelvis Makes up posterior wall of pelvis

55 Coccyx 1 bone formed by fusion of 3 vertebrae 1 bone formed by fusion of 3 vertebrae Tailbone Tailbone Thought to be left over from when our ancestors had tails Thought to be left over from when our ancestors had tails

56 Spinal Curvatures Scoliosis- lateral curvature Scoliosis- lateral curvature Lordosis- Apex towards anterior (ie. Lumbar curvature) Lordosis- Apex towards anterior (ie. Lumbar curvature) Kyphosis- Apex towards posterior (Osteoporosis patients) Kyphosis- Apex towards posterior (Osteoporosis patients)

57 Appendicular Skeleton Pelvic Girdle

58 Pelvis Juncture point for axial skeleton and lower body Holds internal organs Distributes weight down legs 3 fused bones Obturator foramen- large hole through which nerves and muscles pass

59 Bones of the Pelvis Ilium Ischium Pubis Become fused into “pelvis” at puberty

60 Ilium Makes up top of hip (iliac crest) Lateral portions of the pelvis Contains hip socket

61 Features of the Ilium Iliac crest – rounded projection on superior surface; makes up “hip” Acetabulum- joint between femure and pelvis Width from crest to crest = false pelvis Width of actual inlet = true pelvis

62 Ischium Inferior portion of pelvis Ischial Tuberosity – point of muscle attachment; “sit bones”

63 Pubis Anterior portion of pelvis Joined medially by pubic symphysis

64 Leg bones

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67 Hands and Feet

68 Appendicular Skeleton Superior Extremities

69 Shoulder Girdle Also called pectoral girdle Also called pectoral girdle Composed of only two bones Composed of only two bones  Clavicle  Scapula

70 Clavicle Collar bone Collar bone Double-curved Double-curved Attaches medially to manubrium of sternum Attaches medially to manubrium of sternum Attaches laterally to scapula Attaches laterally to scapula Acts as a brace, keeping arm away from thorax Acts as a brace, keeping arm away from thorax Also prevents shoulder dislocation Also prevents shoulder dislocation

71 Scapula Shoulder Blade Shoulder Blade Main function is attachment of shoulder Main function is attachment of shoulder Major point of muscle attachment for movement of arms Major point of muscle attachment for movement of arms Weakly attached to thorax, so moves easily Weakly attached to thorax, so moves easily

72 Major Processes of the Scapulae 1)Acromion – extends from spine of scapulae 1)Acromion – extends from spine of scapulae  Point of attachment of clavicle 2)Coracoid- main site of arm muscle attachment 2)Coracoid- main site of arm muscle attachment

73 Glenoid Cavity Socket of arm joint Socket of arm joint Shallow Shallow Allows for great range of motion Allows for great range of motion Also dislocates easily Also dislocates easily

74 Movement in the Shoulder Girdle Very free moving because Very free moving because  1)Only attaches at one point to axial skeleton  2)Loose attachment of scapula allows it to slide  3)Glenoid cavity very shallow

75 Arm Bones Arms composed of long bones Arms composed of long bones Humerus (upper arm) Humerus (upper arm) Radius and Ulna (forearm) Radius and Ulna (forearm)

76 Humerus Simple long bone Simple long bone Greater and lesser tubercle allow for muscle attachment Greater and lesser tubercle allow for muscle attachment Deltoid tuberosity- place of attachment for deltoid muscle Deltoid tuberosity- place of attachment for deltoid muscle

77 Attachment to the forearm Trochlea articulates against bones of forearm Trochlea articulates against bones of forearm Olecranon fossa shaped like spoon Olecranon fossa shaped like spoon

78 Forearm bones Ulna – pinkie-side of forearm Ulna – pinkie-side of forearm Radius – Thumb side of forearm Radius – Thumb side of forearm

79 Processes of the ulna Olecranon process attaches to humerus at olecranon fossa Olecranon process attaches to humerus at olecranon fossa Allows for articulation between upper and lower arm Allows for articulation between upper and lower arm

80 Hands and Feet

81 Joints

82 Intro Any point where bones meet Also called articulations Every bone (except hyoid) articulates with at least 1 other bone

83 Classifications of Joints Can be classified by mobility, or by the type of tissue which connects the bones

84 Joint classification by Mobility Can be one of three types.  1) Synarthroses – immovable joint  2)amphiarthroses- slightly moveable joint  3)diarthroses- freely movable

85 Classification by connective tissue type Joints are connected by either fibrous, cartilage, or synovial connective tissue. Fibrous is usually synarthroses, Synovial – diarthroses

86 Fibrous Joints Fibrous tissue Example= sutures of the skull Tight fibrous tissue allows for essentially no movement

87 Cartilaginous Joints Cartilage Example= intervertebral joints Can express either type of movement

88 Synovial Joints Bones separated by synovial cavity Empty pocket serves to reduce friction between moving bones Usually located in extremities, where movement is necessary

89 So… What does it mean to be double-jointed? Usually not actually two joint cavities Ligaments are simply less taut than normal, allowing for more flexibility Can be indicative of serious genetic defects

90 Joint Problems Osteoarthritis – general break-down of joints, leading to ossification, and then pain. Rheumatoid Arthritis – autoimmune disease where body attacks its own tissues; cause unknown

91 Features of the Skull

92 Sutures of the cranium Suture – location where flat bones of the cranium meet and fuse Squamous- fuses temporal and parietal Coronal – fuses frontal to parietal Saggital – fuses plates of parietal bones Lambdoid – fuses occipital to parietal

93 Bone markings of the Temporal Bones 1) external auditory meatus – canal which leads to inner ear 2) styloid process – sharp, needlelike projections inferior to the e.a.m.;location of muscle attachment 3) zygomatic process- forms cheek bones;forms large hole which allows jaw muscles to pass through to mandible

94 Temporal bone markings (contd.) 4) mastoid process – posterior and inferior to e.a.m.;location of muscle attachment for muscles of the neck 5) jugular foramen- at junction of occipital and temporal bones; allows jugular vein to pass through from brain 6) carotid canal – anterior to j.f. Allows carotid artery to pass to brain

95 Occipital Condyles Lie lateral to the foramen magnum Rest upon the spinal column Provides point of attachment for skull to spinal column

96 Cribriform Bones Cribriform bones – “holey” bone plates which make up roof of nasal cavity;allow for olfactory sensors to pass from nose to brain

97 Sinuses Empty pocket inside bones which are lines with mucous membranes Paranasal sinus- surrounds nasal cavity Lighten skull, and thought to amplify sounds when speaking

98 Deformations Cleft palate = when palatine bones fail to properly or completely fuse. Leads to inability to nurse, due to failure to form a vacuum.

99 Male vs. Female Skeleton

100 In general Male skeleton is larger, with thicker bones Female bones maintain many characteristics of prepubescent skeleton Male features change at puberty (usually at points of muscular attachment)

101 Skull Male mastoid process more pronounced Superior portion of female orbital (brow ridge) less pronounced Female mandible is pointed, while male is squared

102 Facial Differences Female face wider than male Females have more pointed nose, while males are more blunt Female forehead less sloping Eyebrows positioned higher in females

103 Pelvis Female Pelvis wider and more shallow Male iliac crests more pointed Male pelvis more narrow

104 Sacrum Female sacrum wider and flatter Usually more rounded than male

105 Forensic anthropology Most will say that there is no exact way to determine sex from skeleton (not exact science) Pelvis is probably most reliable feature to analyze, followed by mandible


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