chapter 12 - the musculoskeletal system (skeleton)

Question 1

what is the axial skeleton

Answer 1

• 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

Question 2

what is the appendicular skeleton

Answer 2

• 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

Question 3

describe the macroscopic structure of the bone

Answer 3

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)

Question 4

describe the microscopic structure of compact bone

Answer 4

• 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)

Question 5

describe the microscopic structure of a spongy bone

Answer 5

• 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

Question 6

what are the functions of the skeleton

Answer 6

• 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

Question 7

what is a short bone

Answer 7

• structure: small, cube shaped
• function: gives strength with reduced movement
• eg: carpals and tarsals

Question 8

what is a flat bone

Answer 8

• structure: broad flat plates
• function: provide protection, surface area for attachments of muscles
• eg: pelvic blade

Question 9

what are long bones

Answer 9

• structure: consist of a shaft and enlarged ends

- example: femur, humerus, tibia, metacarpals

Question 10

what are irregular bones

Answer 10

• structure: those that aren’t long, short or flat

- example: vertebrae, facial bones, mandible

Question 11

explain growth and repair

Answer 11

• 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

Question 12

what is a joint

Answer 12

• site at which bones come together

Question 13

what is a fixed / fibrous joint

Answer 13

• function: fixed / immovable, no movement
• structure: held in place by fibrous connective tissue
• example: sutures of the skull, teeth in their sockets

Question 14

what is a slightly moveable / cartilaginous joint

Answer 14

• function: allows slight movement
• structure: held in place by fibrocartilage
• example: symphysis pubis, vertebrae, ribs + sternum

Question 15

what is a freely moveable / synovial joint

Answer 15

• 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

Question 16

what are the factors that keep articular cartilage / surfaces in contact with each other

Answer 16

• way bones come together at joint (ball and socket)
• strength of joint ligaments (hip joint)
• tension provided by muscles around the joint

Question 17

describe the different movements possible at a joint

Answer 17

• 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

Question 18

what is a ball and socket joint

Answer 18

• spherical head of one bone fits into the cup like cavity of another
• movement: most mobile joint
• example: shoulder, hip

Question 19

what is a hinge joint

Answer 19

• convex fits into the concave
• movement: one plane only
• example: elbow (humerus, ulna), knee (femur, tibia), ankle, between fingers and toes

Question 20

what is a pivot joint

Answer 20

• rounded, pointed or conical end of a bone articulates with a ring
• movement: rotation
• example: vertebrae (C1 atlas and C2 axis), radius and ulna

Question 21

what is a saddle joint

Answer 21

• two bones that are both saddle shaped, allows opposability
• movement: side to side, back and forth
• example: thumb (carpal and metacarpal)

Question 22

what is a gliding joint

Answer 22

• 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

Question 23

what is a condyloid / ellipsoid joint

Answer 23

• 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

Question 24

what is the synovial cavity / synovial membrane / articular membrane / fibrous capsule

Answer 24

• 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)

Question 25

what is synovial fluid

Answer 25

- secreted by SM - lubricates joint, provides nourishment for cells of articular cartilage, remove microorganisms and debris, prevents bones making contact

Question 26

what is articular cartilage

Answer 26

- covers articulating surface, shiny, white | - provides smooth surface for movement, reduces friction

Question 27

what is the meniscus

Answer 27

- cartilaginous disc - fibrocartilage - separates cavity into two, allows flow of fluid to areas of friction

Question 28

what is a bursa

Answer 28

- sac of synovial fluid | - prevents friction between bone and ligaments / tendons, or between bone and skin

Question 29

what are accessory ligaments

Answer 29

- hold bones together, different to cruciate ligaments

Question 30

what is cartilage

Answer 30

- connective tissue made up of chondrin and collagen | - found in joints, nose, larynx, trachea, bronchi, ear, vertebral column and pelvis

Question 31

what is chondrin and collagen

Answer 31

- 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

Question 32

describe the microscopic structure of cartilage

Answer 32

- 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

Question 33

what is hyaline cartilage

Answer 33

- structure: closely packed collagenous fibres (not distinguished with light microscope) - characteristics: provide strength and flexibility - location: trachea, bronchi, between moveable joints

Question 34

what is elastic cartilage

Answer 34

- 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)

Question 35

what is fibrocartilage

Answer 35

- 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

Question 36

how is blood supplied to cartilage

Answer 36

- 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)

Question 37

what is osteoporosis

Answer 37

- 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

Question 38

what is osteoarthritis

Answer 38

- 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