Ch. 5 Skeletal Tissues Human Anatomy B. Classification of bones 1. Bone types by structure a. Compact dense, smooth appearance b. Spongy a.k.a. cancellous, needlelike cells & much open space 2. Types by shape/size a. Long = longer than wide, uniquely shaped articular ends 1) ex: femur, humerus b. Short = as broad as long, cube-like or boxy 1) ex: carpals, tarsals c. Flat = broad, thin, flat & often curved surface 1) ex: some of skull, scapula, ribs d. Irregular = variety of shapes, sizes; found in groups 1) ex: vertebrae, facial bones, patella I. The Skeletal System ( skeletos = Greek: dried up) A. Bone physiology 1. Support a. aid shape, alignment, position of parts 2. Protection a. esp. brain, heart, lungs, spinal cord 3. Movement a. site of muscle attachment b. work together to move body parts 4. Mineral storage a. reservoir for calcium, phosphorous, etc. 5. Hematopoiesis a. blood cell formation w/in red marrow C. Anatomy of long bones 1. Diaphysis a. hollow cylindrical main shaft b. made of compact bone c. strong support 2. Periosteum a. fibrous membrane around all of bone except cartilage 1) held on by perforating (Sharpey s) fibers b. site of attachment for muscles & tendons
3. Epiphysis a.k.a. growth plate a. bulb-shaped ends of bone 1) joins to diaphysis at epiphyseal plate where growth occurs a) becomes epiphyseal line when bone is done growing b. made of spongy bone enclosed by thin layer of compact c. form joints, attachment for muscles 4. Articular cartilage a. on outer surface of epiphysis b. made of hyaline cartilage c. reduces friction, cushions joints 5. Medullary cavity (a.k.a. yellow marrow cavity) a. hollow space inside diaphysis b. in adult bodies, filled with yellow marrow 1) fat-rich connective tissue c. in infants, forms blood cells 1) red marrow also located here d. lined with endosteum 6. Bone markings a. bumps, holes, ridges on surface b. two categories 1) processes raised areas a) form joints or sites of attachment for muscles, tendons, ligaments b) ex. Tuberosity, process, condyle 2) depressions indentations or holes a) form joints or passageways for nerves, blood vessels b) ex: groove, fissure, foramen, notch
D. Microscopic Bone Anatomy 1. Compact bone Named for Clopton Havers, English anatomist, 17th cent. a. made of osteons 1) a.k.a. Haversian systems 2) components a) Lamellae concentric matrix cylinders b) Lacunae fluid-filled cavities w/ osteocytes (mature cells) c) Canaliculi tiny canals connecting lacunae to nutrients d) Haversian (central) canal w/ blood & lymph vessels, nerves e) Perforating (Volkmann s) canals path to communicate from outside to bone interior, 2. Cancellous bone a. a.k.a. spongy bone b. composed of trabeculae 1) needle-like spicules holding bone cells 2) arranged to allow stress & weight bearing c. lack osteons d. diffuse O2, nutrients from compact bones
E. Types of bone cells Osteo - bone 1. Osteoblasts = secrete materials to form new bone cells & matrix 2. Osteocytes = mature, non-dividing osteoblasts surrounded by matrix, located in lacunae 3. Osteoclasts = actively erode bone minerals a. allows continuous change & remodeling F. Bone Formation, Growth & Remodeling 1. Osteogenesis formation of bony tissue 2. Ossification a. bones are sculpted into adult shapes, changing size, shape & density b. 2 forms, depending on tissue type 1) Endochondral ossification from cartilage a) ex: forming arm & leg bones 2) Intramembranous ossification within a connective tissue membrane a) ex: at fontanels between flat bones of skull 3. Bone remodeling continual process a. due to calcium levels in blood & pull of gravity b. aided by osteoclasts & hormones c. helps bones maintain proper proportions & strength d. may also occur in response to disease or fractures G. Bone marrow (a.k.a. myeloid tissue) 1. specialized soft connective tissue 2. in medullary cavities of some long bones & in spaces of some spongy bone 3. two forms during life a. Red marrow 1) infant/children = found in most bones 2) adults = found in ribs, vertebral bodies, ends of humerus, pelvis & femur 3) forms red blood cells
b. Yellow marrow 1) red marrow becomes saturated w/ fat cells as we age (done by about 21 yrs.) 2) no blood cell formation a) if blood supply is decreased for a time, can change back 1) ex: prolonged anemia due to disease, radiation, chemical exposure
II. The Skeleton A. Axial skeleton 1. longitudinal axis of body 2. 80 bones in 3 major parts a. skull, vertebral column, thoracic cage 3. Skull a. Cranium 1) encloses, protects brain 2) its bones join by sutures a) interlocking, immovable joints 3) 8 bones a) Frontal forehead, top part of eye sockets b) Parietal (2) top & sides c) Temporal (2) on sides near ears, helps form cheekbones d) Occipital most posterior, w/ opening for brain & spinal cord to connect e) Sphenoid parts of cranial cavity floor, eye sockets & sinuses f) Ethmoid roof of nasal cavity & medial walls of eye sockets b. Facial bones 1) forms lower face 2) bones join by sutures (except mandible) 3) 14 bones a) Maxillae (2) upper jaw, house top teeth b) Palatine (2) back of hard palate c) Zygomatic (2) cheekbones, lateral walls of eye sockets d) Lacrimal (2) in medial walls of eye socket e) Nasal (2) bridge of nose f) Vomer (1) median line of nasal cavity g) Inferior nasal conchae (2) - project into nasal cavity h) Mandible (1) lower jaw; only freely moving skull bone
4. Bones associated with skull a. Hyoid 1) only bone w/out joints to other bones 2) mid-neck, about 2 cm above larynx 3) movable base of tongue & neck muscle attachment b. Auditory Ossicles 1) bones in middle ear 2) vibrate to pass soundwaves to inner ear 3) three per ear a) Malleus (hammer) b) Incus (anvil) c) Stapes (stirrup)
Cranium 1 = frontal 2 = parietal 3 = temporal 4 = ethmoid 5 = sphenoid Not pictured: ~occipital ~palatine ~inf. nasal conchae ~hyoid ~auditory ossicles Face 6 = maxilla 7 = mandible 8 = nasal 9 = zygomatic 10 = lacrimal 11 = vomer 5. Vertebral Column a. between skull & pelvis b. houses, protects spinal cord c. 33 vertebrae - 24 individual, 9 fused 1) Cervical vertebrae (7) neck a) C1 = atlas Different shapes & functions than other b) C2 = axis cervical vertebrae 2) Thoracic vertebrae (12) chest 3) Lumbar vertebrae (5) lower back 4) Sacrum (5 fused) between upper hip bones 5) Coccyx (3-5 fused) tail bone
d. Vertebra anatomy 1) body weight-bearing portion 2) vertebral arch created by joining processes & their connections a) lamina joins transverse & spinous processes b) pedicle joins transverse process to body 3) vertebral foramen opening for spinal cord 4) transverse processes extensions to sides 5) spinous process extension to surface of back 6) articular processes form joints w/ other vertebrae Vertebral Column: 12 = cervical vertebrae 13 = thoracic vertebrae 14 = lumbar vertebrae 15 = sacrum 16 = coccyx 5. Thoracic Cage (a.k.a. bony thorax) a. protects heart, lungs, major blood vessels b. includes thoracic vertebrae on dorsal side c. Sternum (a.k.a. breastbone) 1) joins 1st 7 pairs ribs 2) 3 fused bones a) manubrium top b) body shaft c) xiphoid process bottom tip
d. Ribs 1) surround lungs, heart 2) attach to sternum w/ costal cartilage 3) twelve pairs a) True ribs 1st 7 pairs; attach directly to sternum b) False ribs next 3 pairs; attach as a unit to sternum c) Floating ribs last 2 pairs; do not attach to sternum B. Appendicular skeleton 1. body s appendages & their attachment sites 2. 126 bonesin 4 major parts a. pectoral girdles, arms, pelvic girdles, legs 3. Pectoral (shoulder) girdles a. Clavicle (2) collar bones b. Scapula (2) shoulder blades, rest on rib surfaces 1) body w/ angled spine 2) acromion process joins humerus 3) coracoid process anchors arm muscles 4) glenoid cavity joins humerus Sternum: 17 = manubrium 18 = body 19 = xiphoid process Rib Cage: 20 = true ribs 21 = false ribs 22 = floating ribs
4. Arms (2) upper limbs # s indicate amount of a. Humerus upper arm bone bones per arm b. Radius forearm bone on thumb side c. Ulna forearm bone on pinkie side d. Carpals (8) wrist; part of hand 1) hamate, pisiform, triquetrum, lunate, trapezium, trapezoid, scaphoid, capitate e. Metacarpals (5) palm; part of hand 1) numbered 1-5 from thumb to pinkie f. Phalanges (14) fingers; parts of hand 1) 3 per digit, except thumb 2) proximal, middle & distal 5. Pelvic girdle 2 coxal bones (a.k.a. hip bones) a. each coxal bone has 3 fused sections 1) Ilium large, superior portion 2) Ischium most inferior portion 3) Pubis most anterior portion a) join by cartilaginous pubic symphysis 4) all are fused at the acetabulum on lateral sides a) also forms socket for femur 5) two regions a) false pelvis superior part, from ilium to ilium b) true pelvis internal opening between bones Pectoral Girdle: 23 = scapula 24 = clavicle Arm: 25 = humerus 26 = radius (bigger @ thumb) 27 = ulna Hand: 28 = carpals 29 = metacarpals 30 = phalanges
31 = Pelvic Girdle 32 = Ilium 33 = Ischium 34 = Pubis 6. Legs (2) lower limbs # s indicate amount of bones per leg; foot a. Femur thigh; upper leg bones are numbered like hands were b. Patella knee cap 1) sesamoid bone in patellar ligament in front of knee joint c. Tibia shinbone of lower leg 1) medial & larger d. Fibula lower leg; forms lateral side of ankle 1) lateral & thinner e. Tarsals (7) heel & ankle; parts of foot 1) calcaneus (heel), talus (medial side of ankle), navicular, cuboid, 3 cuneiforms (lateral, intermediate & medial) f. Metatarsals (5) sole/instep; parts of foot g. Phalanges (14) toes; parts of foot Leg: 35 = Femur 36 = Patella 37 = Tibia 38 = Fibula Foot: 39 = Tarsals 40 = Calcaneus 41 = Metatarsals 42 = Phalanges