UNIT 5 THE SKELETAL SYSTEM

Transcription

1 UNIT 5 THE SKELETAL SYSTEM Nov 20 12:02 PM I. Functions A. Support: Internal framework, Structure, Anchors & Supports soft tissue/organs B. Protection: Protects vital organs C. Movement: Provide attach point for muscle Bones & Muscle acts as levers D. Storage: Fat, Calcium & Phospholipids E. Blood Cell Formation: hematopoiesis Occurs in spongy bone within red marrow cavities 1

2 II. Division of Skeletal System A. Axial Skeleton: blue Skull, Ribs & Spine Protects Organs B. Appendicular Skeleton: pink Limbs & Attachments Aids in Movement III. Classification of Bones A. Compact Bone: Very dense & smooth appearance Long Diaphysis shaft B. Spongy Bone: Small porous pieces of bone A lot of open spaces Epiphysis 2

3 IV. Shapes of Bones A. Long Bones: Longer than wide Shaft with heads on ends Mostly Compact B. Short Bones: Cube like Mostly Spongy C. Flat Bones: Thin, Flat, Curved Two layers Compact around Spongy D. Irregular Bones: Varieties of shapes Don't fit other categories Nov 20 12:21 PM 3

4 V. Bones: Gross Anatomy long bone A. Diaphysis: Shaft of Bone, Mostly Compact Bone > Periosteum: Fibrous connective tissue Covers bone > Medullary Cavity : Space in Diaphysis Adults: Yellow Marrow fat Infants: Red Marrow Hematopoiesis B. Epiphyses: Ends of Bone, Mostly Spongy Bone > Articular Cartilage : Hyaline Cartilage Covers end of Epiphyses Absorbs Shock & Reduces Friction > Epiphyseal Line : Compact bone line across Epiphyses Signifies bone done growing (Growth Plate) > Epiphyseal Plate : Hyaline Cartilage line across Epiphyses Site of Longitudinal Bone Growth Jan 4 7:47 AM 4

5 VI. Bones: Microscopic Anatomy A. Cell Types: 1. Osteoblasts: Bone forming cells Lay down New Matrix 2. Osteoclasts: Bone destroying cells Break down current Matrix 3. Osteocytes: Mature bone cells Found in bone matrix cavities Jan 4 7:57 AM 5

6 VI. Bones: Microscopic Anatomy Cont. B. Haversian Systems: Complex of central canal & matrix rings with mature bone cells > Lacunae: Tiny cavities where bone cells found Form rings > Lamellae: Ring or circle of lacunae > Central Canal: Canals that run lengthwise through bone Carry blood vessels & nerves > Canaliculi: Canals that connect central canal to the osteocytes > Volkmann's perforating Canals: Canals that run at 90 0 angles through compact bone Jan 4 7:57 AM 6

7 Dec 4 12:42 PM VII. Bone Formation, Growth & Remodeling A. Formation Osteogenesis & Growth: 1. Embryonic Development : > Skeleton is composed of fibrous membranes & hyaline cartilage. > At about 6 weeks, Ossification begins > Intramembranous ossification Flat bones form from fibrous membranes > Endochondral Ossification Other bones form from hyaline cartilage 7

8 Endochondral Ossification Steps a. formation of a bone collar b. cavitation of the hyaline cartilage c. the cavities are invaded with blood vessels, red marrow, osteoblasts, osteoclasts. Spongy bone development also begins at this stage. d. formation of the medullary cavity and continue ossification of the shaft e. ossification of the epiphyses with exception of the hyaline cartilage forming the articular cartilage surface and epiphyseal plates. Nov 27 4:31 PM 2. Growth : > Epiphyseal plates are the site of long bone growth > Steps are as follows... New cartilage formed on external face of articular cartilage & on epiphyseal plate surface that is farthest away from the medullary cavity Old Cartilage on internal side of articular cartilage & epiphyseal plate is broken down and replaced by bony matrix Process controlled by growth hormones & ends when epiphyseal plate is converted to bone» Usually occuring at end of puberty Jan 6 7:42 AM 8

9 B. Bone Remodeling: > Bones are remodeled in response to Calcium Levels in the Blood > If Ca + levels fall too much... PTH parathyroid hormone released and activates osteoclasts Bone broken down to release Ca + into blood > If Ca + levels rise too much... Osteoblasts are activated Deposit Ca + into bone matrix as hard salts 2. Pull of Gravity & Muscle Stress > Bones become thicker & form large projections to increase strength in areas where muscles attach. Osteoblasts lay down new matrix forming new bone where the stress of muscle pulls. > Bones of inactive people atrophy & lose mass if not subjected to stress Osteoclasts break down bone due to lack of stress from muscles Nov 27 4:34 PM VIII. Bone Fracture & Repair A. Types: 1. Simple Closed : > clean break, no skin penetration 2. Compound open : > break, penetrates through skin 3. Comminuted: > many fragments 4. Compression: > crushed, osteoporosis 5. Depressed: > pressed inward, skull 6. Impacted: > broken ends pressed into each other 7. Spiral: > excessive twisting 8. Greenstick: > incomplete break, child 9

10 Dec 2 9:14 AM VIII. Bone Fracture & Repair B. Treatment: 1. Reduction: The realignment of bone ends. Closed: Open: 2. Immobilization: Cast or Splint C. Repair Process: 1. Hematoma is formed: > blood filled swelling 2. Fibrocartilage Callus forms: > repair tissue that contains cartilage matrix, bony matrix, and collagen fibers. > new capillaries also formed 3. Bony Callus forms: > spongy bone replaces fibrocartilage 4. Remodeling: > stress on bone causes remodeling at fractured site 10

11 Nov 27 4:36 PM IX. Axial Skeleton Skull, Vertebral Column & Thoracic Cage A. Skull: formed by two sets of bones 1. Cranium: consists of eight bones > frontal > parietal > temporal zygomatic, mastoid, styloid processes > occipital 2. Facial: > maxillae > zygomatic > nasal > mandible > hyoid bone 11

12 IX. Axial Skeleton cont. B. Vertebral Column spine : consists of 26 irregular bones 1. Cervical: C1 C7 > vertebrae found in " " region. Atlas: 1st vertebra, allows to nod head Axis: 2nd vertebra, allows rotation of atlas head 2. Thoracic: T1 T12 > larger than cervical, articulate with ribs. 3. Lumbar: L1 L5 > main weight bearing vertebrae 4. Sacrum: fusion of 5 vertebrae > articulates with hip bones > forms sacroilliac joints 5. Coccyx: fusion of 3 vertebrae > referred to as the tailbone * intervertebral disk: made of flexible fibrocartilage IX. Axial Skeleton cont. C. Thoracic Cage 1. Sternum: fusion of manubrium, body, xiphoid process > Articulates the first 7 pair of ribs 2. True Ribs: first 7 pairs 3. False Ribs: next 5 pairs > share articulation point 4. Floating Ribs: last 2 pairs > not connected to sternum 12

13 X. Appendicular Skeleton A. Pectoral Girdle: allows flexibility/ movement of arms. 1. Clavicle: Collar bone 2. Scapula: Shoulder blade B. Pelvic Girdle: Weight bearing / protection Formed by 2 Coxal hip bones Each formed by fusion of three bones in the hip. Hip socket called acetabulum 1. Ilium 2. Ischium 3. Pubis X. Appendicular Skeleton Cont. C. Bones of Upper Limbs: 1. Humerus: shoulder to elbow 2. Radius: thumb side of forearm 3. Ulna: pinky side of forearm 4. Hands: carpals, metacarpals, phalanges D. Bones of Lower Limbs: 1. Femur: greater & lesser trochanter 2. Tibia: medial malleolus 3. Fibula: lateral malleolus 4. Patella: knee cap 5. Foot: talus, calcaneus, tarsals, metatarsals, phalanges 13

14 XI. Joints articulations Joints are classified in 2 ways... A. Functional: 1. Synarthroses: immovable joints 2. Amphiarthroses: slightly moveable joints 3. Diarthroses: freely moveable joints B. Structural: 1. Fibrous: sutures of the skull bound tightly together by fibrous conn. tissue 2. Cartilaginous: bone ends are connected by cartilage Ex. Pubic symphysis & Intervertebral disks XI. Joints articulations 3. Synovial > Bone ends separated by joint cavity > Contains synovial fluid > Features... Articular Cartilage Fibrous Articular Capsule «lined with synovial membrane Joint Cavity filled w/ synovial fluid Reinforcing ligaments Types of synovial joints a. plane joint carpals b. hinge joint elbow c. pivot joint radius d. condyloid joint between metacarpals & phalanges e. saddle joint between carpals & metacarpals f. ball and socket joint shoulder or hip *these are classified as nonaxial uniaxial biaxial multiaxial 14

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17 Attachments Pectoral_girdles en.svg