Unit 5 Skeletal System Nov 21 10:24 PM I. Functions A. Support: > internal framework, structure, anchors & supports soft tissue organs B. Protection: > protects vital organs C. Movement: > provides attach point for muscles > bones & muscles act as levers D. Storage: > fat, calcium, and phosphorus E. Blood Cell Formation: (hematopoiesis) > occurs in spongy bone within red marrow cavities Nov 21 10:43 AM 1
II. Division of Skeletal System A. Axial Skeleton (blue) skull, ribs, spine protects organs B. Appendicular Skeleton (pink) limbs & attachments aids in movement Nov 21 10:00 PM III. Classification of Bones A. Compact Bone: very dense & smooth appearance long diaphysis (shaft) **All bones have external layer of compact with spongy bone internally B. Spongy Bone: small porous pieces of bone a lot of open spaces (epiphysis) 2
Nov 22 7:01 AM IV. Shapes of Bones A. Long Bones: longer than wide shaft with heads on both ends mostly compact B. Short Bones: cube like mostly spongy C. Flat Bones: thin, flat, curved 2 layers compact around spongy D. Irregular Bones: varieties of shapes don't fit other categories Nov 21 10:14 PM 3
Nov 21 10:15 PM Nov 20 7:54 AM 4
V. Bone Gross Anatomy (long bone) A. Diaphysis shaft of the bone, mostly compact bone > Periosteum: fibrous connective tissue covers bone > Medullary Cavity: space inside Diaphysis adults: yellow marrow (fat) infants: red marrow (Hematopoiesis) B. Epiphyses: ends of long bones (heads), mostly spongy bone > Articular cartilage: hyaline cartilage covers end of Epiphyses absorbs shock & reduces friction > Epiphyseal plate: (growth plate) hyaline cartilage line across epiphyses > Epiphyseal line: compact bone line across epiphyses signifies bone done growing Nov 19 12:06 PM 5
VI. Bone Microscopic Anatomy A. Cell Types: 1. Osteocytes: mature bone cells found in cavities «connected by gap junctions 2. Osteoblasts: bone forming cells «will convert into osteocyte 3. Osteoclasts: bone destroying cells VI. Bone Microscopic Anatomy cont'd B. Haversian Systems / Osteon: complex, consisting of a central canal & matrix rings with mature bone cells > Lacunae: tiny cavities in which mature bone cells are found > Lamellae: calcified matrix rings lacunae found in between rings in compact bone: rings of lamellae around central canal > Central Canals: run lengthwise through bone carry blood vessels & nerves > Canaliculi: tiny canals that connect lacunae together & to central canal > Perforating (Volkmann's) Canals: canals that run at 90 degree angles through the compact bone Nov 27 10:33 AM 6
Dec 1 8:12 AM Nov 19 12:12 PM 7
Dec 3 8:49 AM VII. Bone Formation, Growth, and Remodeling A. Formation (Ossification / Osteogenesis) & Growth: 1. Embryonic Development: skeleton composed of fibrous membranes & hyaline cartilage ossification begins ~6 7 weeks in development «Intramembraneous Ossification» skull flat bones & clavicles form from fibrous membranes «Endochondral Ossification» other bones form from hyaline cartilage Endochondral Ossification 8
VII. Bone Formation, Growth, and Remodeling cont'd Endochonral Ossification Steps: a. Bone Collar forms b. Cavitation of the hyaline cartilage (Primary Ossification Center) > Chondrocytes hypertrophy > Surrounding matrix calcifies > Chondrocytes die (nutrient diffusion inhibited) > Matrix begins to deteriorate Bone collar stabilizes c. Cavities are invaded with blood vessels, red marrow, osteoblasts, osteoclasts (known as the periosteal bud) > Spongy bone development begins (by osteoblasts) d. Medullary cavity forms & Diaphysis elongates > Osteoclasts form medullary cavity > Diaphysis elongates due to: epiphyseal cartilage dividing & ossification "chases" cartilage formation along length of diaphysis (will discuss this in our next section) e. Ossification of Epiphyses (Secondary Ossification Center) > Similar to primary ossification (no medullary cavity) > Hyaline cartilage remaining when secondary ossification is complete: Articular Cartilage Epiphyseal Plates Nov 27 10:58 AM 9
VII. Bone Formation, Growth, and Remodeling cont'd 2. Growth (early adults) > Epiphyseal plates are site of long bone growth > Steps are as follows: new cartilage is formed on external face of articular cartilage & on epiphyseal plate surface that is farthest away from medullary cavity old cartilage on internal face of articular cartilage & side of epiphyseal plate closest to medullary cavity is broken down and replaced by bony matrix process controlled by growth hormones & ends when epiphyseal plate is converted to bone «usually occurring at the end of puberty Bone Growth > growth plate maintains constant thickness: > rate of cartilage growth balanced by replacement of bony tissue Dec 2 12:06 AM 10
Bone Growth Dec 4 9:26 PM VII. Bone Formation, Growth, and Remodeling cont'd B. Bone Remodeling (throughout life) bones are remodeled in response to: 1. Calcium levels in blood If calcium levels get too low «PTH (parathyroid hormone) released» Activates osteoclasts Bone broken down to release Ca + into blood If calcium levels are too high «PTH release decreases» Inhibit osteoclast activity «Osteoblasts are activated...deposit Ca+ into bone matrix as hard salts «Calcitonin plays minimal role in humans 2. Pull of gravity and muscle stress a. Bones become thicker and form larger projections to increase strength in areas where muscles attach «Osteoblasts lay down new matrix forming new bone where stress of muscle pulls b. Bones of inactive people atrophy & lose mass if not subjected to stress «Osteoclasts break down bone due to lack of stress from muscles Dec 4 7:40 AM 11
Kevin_Ware Dec 5 8:43 PM VIII. Bone Fractures and Repair A. Types: > Simple (closed): clean break, no skin penetration > Compound (open): break, penetrates through skin > Comminuted: many fragments > Compression: crushed, osteoporosis > Depressed: pressed inward, skull > Impacted: broken ends pressed into each other > Spiral: excessive twisting > Greenstick: incomplete break, child 12
Dec 5 8:08 PM VIII. Bone Fractures and Repair cont'd B. Treatment: 1. Reduction the realignment of bone ends «closed reduction «open reduction 2. Immobilization cast or splint C. Repair Process: 1. Hematoma is formed: «blood filled swelling 2. Fibrocartilage Callus forms: «New capillaries formed (granulation tissue) «Repair tissue that contains cartilage matrix, bony matrix, & collagen fibers 3. Bony Callus forms: «Spongy bone replaces fibrocartilage 4. Remodeling: «Stress on bone causes remodeling at fractured site Dec 7 4:03 PM 13
Dec 5 8:17 PM IX. Axial Skeleton Skull, Vertebral Column, Thoracic Cage A. Skull: formed by two sets of bones 1. Cranium consists of 8 bones «frontal «parietal «temporal (zygomatic process, mastoid, styloid processes) «occipital «ethmoid «sphenoid 2. Facial: «maxillae «zygomatic «mandible* «nasal «lacrimal «vomer «palatine «inferior nasal conchae hyoid bone 14
Dec 8 7:23 PM IX. Axial Skeleton cont'd B. Vertebral Column (spine): consists of 26 irregular bones 1. Cervical vertebrae: (C1 C7) found in " " region Atlas 1 st vertebra (articulates with the skull), allows head to nod Axis 2 nd vertebra, allows rotation of atlas (& head) 2. Thoracic vertebrae: (T1 T12) larger than the cervical, articulate with ribs 3. Lumbar vertebrae: (L1 L5) main weight bearing vertebrae 4. Sacrum: fusion of 5 vertebrae articulates with hip bones forms sacroiliac joints 5. Coccyx: fusion of 3 vertebrae (tailbone) *intervertebral disk made of flexible fibrocartilage 15
Dec 8 6:46 PM Dec 8 7:26 PM 16
Dec 8 7:13 PM IX. Axial Skeleton cont'd C. Thoracic Cage 1. Sternum: fusion of manubrium, body, xiphoid process articulates with first 7 pairs of ribs 2. True ribs: first 7 pairs 3. False ribs: next 5 pairs share articulation point floating ribs last 2 pairs that are not connected to the sternum at all 17
X. Appendicular Skeleton A. Pectoral Girdle: allows for great 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 3 bones in the hip socket hip socket called acetabulum «ilium «ischuim «pubis articulates with sacrum "sit down" bone, most inferior most anterior bone X. Appendicular Skeleton cont'd C. Bones of the upper limbs: 1. Humerus shoulder to elbow 2. Radius thumb side of forearm 3. Ulna pinky side of forearm 4. Hand carpals, metacarpals, phalanges D. Bones of the lower limbs: 1. Femur greater & lesser trochanters 2. Tibia (shin) medial malleolus 3. Fibula lateral malleolus 4. Patella kneecap 5. Foot talus, calcaneous, tarsals, metatarsals, phalanges 18