Musculoskeletal system Flashcards
Bone functions
Provide body framework
* Give attachment to muscles & ligaments
* Allow movement via joints
* Protective boundaries of cranium, thorax, pelvis * Haemopoiesis
* Mineral storage (Ca phosphate)
Types of bone
Long bone-mainly in limbs
* Short, irregular, flat, sesamoid bones-no shaft
* Bone cells
* Osteoblasts-bone forming cells
* Osteocytes-mature monitoring cells.
* Osteoclasts-break down bone to release Ca and phosphate- multinucleated.
* Bone constantly remodelling
Adult long bone
Outside of bone is periosteum, 2 layers -tough outer layer
-Inner layer containing osteoblast and osteoclasts.
Where bones form joints, periosteum replaced with hyaline cartilage.
In growing bones, growth occurs at epiphyseal line
Hormonal regulation of bone
Growth hormone and thyroid hormones stimulate growth in infancy
* Testosterone & oestrogen mediate skeletal changes at puberty, increased levels
cause
-growth spurt
-closure of epiphyses stops long bones elongating Fall in oestrogens at menopause increases bone loss.
Blood calcium controllers:
Calcitonin-increases bone uptake of Ca (lowers blood Ca) Parathormone-releases Ca from bone (increases blood Ca)
Dietary regulation of bone
Main nutrients are:
Calcium-to mineralise bone
Vitamins
A-osteoblast activity
C – collagen synthesis
D—calcium & phosphate absorption from GI tract
Fracture of bone
Simple- bones do not protrude through skin Compound- bone protrude through skin Pathological-underlying bone weakness was cause
Healing of bone
- Haematoma-blood clot, swelling, attracts inflammatory cells
- Callus formation starts-fibrin from fibroblasts & osteoblasts lay down calcium – temporary spongy bone
- Week 2: Bony callus formation- extends previous stage to strengthen structure, haematoma being removed
- Remodelling & recanalization
3 types of joints
Fibrous-No or very little movement e.g., skull bones, tooth to jaw, tibia and fibula in lower leg (fig)
* Cartilaginous-tough pad of fibrocartilage gives shock adsorber effect-limited movement
Synovial joint
All contain:
* Hyaline cartilage at ends-smooth articular surfaces
* Capsule (capsular ligament)-sleeve of protective
fibrous tissue
* Synovial membranes-produce synovial fluid- thick
sticky fluid like egg white.
* Synovial fluid
-lubricant
-nourishes bones and Cartlidge
-Contains phagocytes
-Prevents separation (like fluid between 2 glass surfaces)
* Some contain-intracapsular structures-e.g., menisci of knee
Types of synovial joints
Main ones to remember:
humerus-scapula (& hip)- ball & socket
Elbow-hinge joint
Movements of joints
Main ones to remember
* Flexion-bend
* Extension-straighten
* Abduction-away from trunk * Adduction- towards trunk
* Rotation
Shoulder girdle (pectoral girdle)
Do not articulate with vertebral column.
Joints of shoulder girdles are freely movable in many directions.
Properties of Muscular Tissue
Muscular tissue has four special properties that enable it to function:
Electrical excitability; respond to stimuli by producing electrical signals called action potentials . Action potentials in muscles are called muscle action potentials; those in nerve cells are called nerve action potentials.
Contractility; ability of muscular tissue to contract forcefully when stimulated by action potential, generating tension (force of contraction) and shortening.
Extensibility; ability to stretch (within limits), without being damaged.
Elasticity; ability to return to its original length and shape after contraction or extension.
4 functions of muscles
- Producing body movements.
- Stabilizing body positions. e.g., neck muscles to hold head upright.
- Storing and moving substances within body. Storage accomplished by sphincters, prevent outflowing of contents of hollow organs.
Cardiac muscle contractions pump through blood vessels.
Contraction of smooth muscle in blood vessels adjust vessel diameter and regulate blood flow.
Smooth muscle contractions move food through gastrointestinal tract - Producing heat. Muscular contraction produces heat, used to maintain normal body temperature. Involuntary contractions of skeletal muscle, (shivering), increase rate of heat production.
Types of muscle
Smooth, involuntary, one nucleus, no striations
Cardiac, involuntary, one nucleus, cross striations, BRANCHED. Intercalated discs to really glue the cells together
Skeletal; voluntary, multinucleated, cross striations
Striations of cardiac & skeletal muscle
Nerve releases Acetyl choline- causes action potential
Action potential releases Calcium from intracellular stores
Actin and myosin bind each other.
Energy from ATP causes them to slide across each other-shortening length of cell.
Neuromuscular junction
When Acetyl choline stimulus removed, actin & myosin disengage-relax & lengthen
Muscle terms
Isometric-when muscle tension increases but length doesn’t change * Isotonic-tension stay the same but movement occurs
Shoulder/Arm muscles
Arm bones are radius and ulnar
Remember: Trapezius, deltoid, triceps
Long extensors (extensor carpi radialis and extensor carpi ulnaris, extensor digitorum)
Shoulder/Arm muscles
Remember: Trapezius, deltoid, biceps
Long flexors (Flexor carpi radialis and flexor carpi ulnaris)
Brachial plexus
Arm bones are radius and ulnar
Plexus mainly splits into radial, median & ulnar nerves
Median & ulnar nerves innervate flexors
Radial nerve innervates extensors
Abdominal muscles
Remember rectus abdominus, Obliques
Back muscles
Remember Trapezius Latisimus dorsi Erector spinae Gluteal muscles
Osteoporosis
Loss of bone density -fractures
-Compression of vertebrae
Peak bone mass 35 years Progressively falls with age Increased loss post menopause
Risk factors: Age, female, low calcium diet, early menopause, immobility/lack of exercise.
Corticosteroids, Cushing’s syndrome, hyperparathyroidism, chronic renal failure
Treatment: moderate exercise, calcium supplements
