chapter 12 - the musculoskeletal system (skeleton) Flashcards
what is the axial skeleton
- bones making up central axis of body (cranium, mandible, sternum, ribs, cervical vertebrae 7, thoracic vertebrae 12, lumbar vertebrae 5, sacrum, coccyx)
- provides support for erect posture, protects CNS and organs
what is the appendicular skeleton
- upper / lower limbs, pectoral / pelvic girdles (clavicle, scapula, humerus, radius, ulna, pelvic girdle, femur, tibia, fibula, patella, carpals, metacarpals, tarsals, metatarsals, phalanges)
- girdles allow for articulation of limbs
describe the macroscopic structure of the bone
diaphysis: main hollow shaft, cylindrical, thick.
- compact bone (provides protection and strength)
- medullary cavity: hollow, contains yellow bone marrow (produces WBC, fat storage site)
- periosteum: dense, white, fibrous covering, protective layer / attachment surface
epiphyses: ‘head’, helps with transmission of weight
- compact bone on outside (covered by articular cartilage)
- cancellous bone on inside (porous, contains red marrow)
describe the microscopic structure of compact bone
- connective tissue: cells separated by matrix (lamella)
- matrix: contains inorganic salts (increases rigidity and strength)
- osteon / Haversian system: make up bone, run parallel (increase strength)
- Haversian canal: centre of osteon, contain blood / lymph capillaries and nerves
- lamellae: concentric / circumferential layers of bony matrix (make up osteon)
- lacunae: spaces in lamellae containing osteocytes (bone cells)
- canaliculi: canals, allow for projections from osteocytes to make contact with adjacent cells (provides materials)
describe the microscopic structure of a spongy bone
- trabeculae: thin, bony plates, not organised in osteons (irregular arrangements), osteons are found in these spaces
- lamellae: not arranged in concentric layers
- nerve / blood vessels: pass through irregular spaces
what are the functions of the skeleton
- supports: body parts, framework, shape
- movement: muscles attach to bones, enabling movement, standing erect, muscles contract -> bones allow movement
- protection: of vital organs
- storage organs: store mineral salts and fats (Ca, P, Na, K)
- blood cell production: red bone marrow produces RBC
what is a short bone
- structure: small, cube shaped
- function: gives strength with reduced movement
- eg: carpals and tarsals
what is a flat bone
- structure: broad flat plates
- function: provide protection, surface area for attachments of muscles
- eg: pelvic blade
what are long bones
- structure: consist of a shaft and enlarged ends
- example: femur, humerus, tibia, metacarpals
what are irregular bones
- structure: those that aren’t long, short or flat
- example: vertebrae, facial bones, mandible
explain growth and repair
- through infancy and adolescence to adulthood bones grow
- in adults: bones are capable of repair
- throughout growth: bones are involved in blood cell formation and storage
what is a joint
- site at which bones come together
what is a fixed / fibrous joint
- function: fixed / immovable, no movement
- structure: held in place by fibrous connective tissue
- example: sutures of the skull, teeth in their sockets
what is a slightly moveable / cartilaginous joint
- function: allows slight movement
- structure: held in place by fibrocartilage
- example: symphysis pubis, vertebrae, ribs + sternum
what is a freely moveable / synovial joint
- function: movement is only limited due to ligaments, tendons and adjoining bones
- structure: held together by articular cartilage
- example: shoulder, elbow, wrist, fingers, hip, knee, ankle, toes
- types: ball and socket, gliding, hinge, pivot, saddle and condyloid
what are the factors that keep articular cartilage / surfaces in contact with each other
- way bones come together at joint (ball and socket)
- strength of joint ligaments (hip joint)
- tension provided by muscles around the joint
describe the different movements possible at a joint
- flexion: bending, decreases angle between the articulating bones
- extension: straightening, increases angle between articulating bones
- abduction: movement away from body
- adduction: movement towards body
- rotation: movement of bone along its axis
what is a ball and socket joint
- spherical head of one bone fits into the cup like cavity of another
- movement: most mobile joint
- example: shoulder, hip
what is a hinge joint
- convex fits into the concave
- movement: one plane only
- example: elbow (humerus, ulna), knee (femur, tibia), ankle, between fingers and toes
what is a pivot joint
- rounded, pointed or conical end of a bone articulates with a ring
- movement: rotation
- example: vertebrae (C1 atlas and C2 axis), radius and ulna
what is a saddle joint
- two bones that are both saddle shaped, allows opposability
- movement: side to side, back and forth
- example: thumb (carpal and metacarpal)
what is a gliding joint
- two flat bones, held together by ligaments, gives flexibility but reduced strength, easily sprained
- movement: side to side
- example: between scapula and clavicle, sternum and clavicle, tarsal / carpal bones
what is a condyloid / ellipsoid joint
- slightly convex fits into a slightly concave depression
- movement: up and down, side to side
- example: between radius and carpal, metacarpal and phalange, metatarsal and phalange
what is the synovial cavity / synovial membrane / articular membrane / fibrous capsule
- SC: space between two bones
- SM: surrounds synovial cavity (inner layer of capsule)
- AM: covers epiphyses of bones
- FC: dense fibrous connective tissue holds bones together, attached to periosteum, flexibility and strength, permits movements / resists dislocation (outer layer)
what is synovial fluid
- secreted by SM
- lubricates joint, provides nourishment for cells of articular cartilage, remove microorganisms and debris, prevents bones making contact
what is articular cartilage
- covers articulating surface, shiny, white
- provides smooth surface for movement, reduces friction
what is the meniscus
- cartilaginous disc
- fibrocartilage
- separates cavity into two, allows flow of fluid to areas of friction
what is a bursa
- sac of synovial fluid
- prevents friction between bone and ligaments / tendons, or between bone and skin
what are accessory ligaments
- hold bones together, different to cruciate ligaments
what is cartilage
- connective tissue made up of chondrin and collagen
- found in joints, nose, larynx, trachea, bronchi, ear, vertebral column and pelvis
what is chondrin and collagen
- chondrin: firm matrix of protein (carbohydrate complex) that produces cartilage with structural support, and that contains collagen (fibres made of protein) which give cartilage flexibility
describe the microscopic structure of cartilage
- cartilage -> chondrin -> collagen -> chondroblasts (immature cartilage cells)
- chondroblasts: produce matrix (chondrin and collagen) and become surrounded by matrix until they are trapped in spaces call lacunae
- chondrocytes: cells that are trapped are now mature
what is hyaline cartilage
- structure: closely packed collagenous fibres (not distinguished with light microscope)
- characteristics: provide strength and flexibility
- location: trachea, bronchi, between moveable joints
what is elastic cartilage
- structure: elastic fibres (collagen fibres similar to those in hyaline cartilage but not as closely packaged)
- characteristics: flexible elastic support
- location: in ear (springs back)
what is fibrocartilage
- structure: coarse appearance (parallel bundles of collagen fibres), not as closely packed (can be compressed)
- characteristics: good in places where body weight is being supported
- location: intervertebral discs, pubis symphysis, articular cartilage of knee
how is blood supplied to cartilage
- no blood vessels, diffusion of nutrients and waste is through the matrix
- very slow, hence why chondrocytes have a slow rate of cell metabolism and division
- perichondrium: inner layer producing blood supply to cartilage, covers external surface (except where articular cartilage is present)
what is osteoporosis
- loss of bone mass / density, results in an increased risk of fractures
- example: vertebrae, ribs, pelvis, wrist, upper arm (of ageing bones)
- prevention / treatment: adequate calcium intake, vitamin d (sunlight / dietary intake), plenty of exercise, some medication
what is osteoarthritis
- gradual change in the joints (ageing, irritation, wear, abrasion), deterioration of cartilage (bones no longer protected), bony spurs / growths develop (restricted / decreased movement)
- examples: hands, feet, limbs, swelling of joints
- treatment: no treatment, pain relief, physiotherapy, surgery (realignment or replacement) mag provide temporary relief
