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Flashcards in anatomy of muscles Deck (30):

functions of the muscular system

- allows movement of body
- maintains posture
- circulates blood


what are the types of muscles (structure / function)

- skeletal: voluntary, attached to bone, long cylindrical, stripes, striated, multi nucleated (peripheral), powerful, epimysium, perimysium and endomysium
- smooth: involuntary, no striations, uninucleate (basal), walls of hollow organs, follicles in skin, long tapered cells, work together / individually, endomysium
- cardiac: involuntary, walls of heart, striated, branched, uninucleate, auto rhythmic
(pacemaker, beat without nerves), independent, endomysium


what is a ligament vs tendon

- L: short band of tough flexible, fibrous connective tissue, connects two bones, holds joints together
- T: flexible but inelastic cord of strong fibrous collagen, attaches muscle to bone


summary of skeletal muscle function

- connect firmly to bones through tendons
- ~40% of body weight
- contraction: force exerted = pull, always contract / shorten
- generate ATP (mechanic / heat energy), stabilise moveable joints (at rest), work in pairs or larger groups


why is it called the musculoskeletal system

- skeletal system (endoskeleton) works very closely with muscles
- ability to move, collapse without it


name flexors, extensors, adductors and abductors of the upper leg (10)

- F: iliopsoas (iliacus, psoas major), quadriceps rectus femoris, sartorius
- E: gluteus maximus and hamstrings
- AD: adductor group
- AB: gluteus medius, gluteus minimus, piriformis, tensor fascia latae


what are two muscles in the upper leg with multiple actions

- quadriceps femoris: contraction = extension at knee and flexion at hip
- hamstrings: contraction = flexion at knee and extension at hip


name the 4 muscles of the lower leg (calf / knee)

- gastrocnemius (posterior crural)
- soleus (posterior crural)
- tibialis anterior (anterior crural)


types of skeletal muscle (arrangement of fassicles / fibres)

- fusiform: parallel muscular fibres to long axis of muscle (biceps brachii)
- parallel: transverse lines which divide muscle into several bellies (rectus abdominis)
- convergent: wide muscle where fibres convert into a common tendon (pectoralis major)
- pennate: short, oblique, attached to common tendon that runs through middle of muscle, unipenate (palmar interosseous) and bi pennate (rectus femoris)
- circular: concentric rings, openings (obicularis oculi)


name the 3 main abdominal muscles

- transverse abdominis
- internal / external oblique
- rectus abdominis (tendinous intersections and linea albs, same layer as internal oblique - middle)


name the 3 main back muscles

- trapezius
- rhomboid major
- rhomboid minor


name the 3 groups of facial expression

- orbital
- nasal
- oral


name the 2 main muscles of respiration

- diaphragm
- intercostal muscles (internal and external)


name the 4 main muscles of the trunk

- pectoralis major
- pectoralis minor
- serrates anterior
- subclavius


name the 3 main shoulder muscles

- deltoid
- rotator cuff (subscapularis, supraspinatus, infraspinatus, teres minor)
- latissimus dorsi


name the 3 main muscles of the elbow

- biceps brachii
- brachialis
- triceps brachii


name the 6 main muscles of the forearm

- flexor carpi ulnaris
- flexor carpi radialis
- palmaris longus
- pronator teres
- extensor carpi ulnaris
- flexor / extensors retinaculum (tendinous)


what is carpel tunnel syndrome

- transverse carpal ligament: nerve, runs through forearm to hand, sensory information, lateral portion of hand, first 3 fingers and half of fourth finger
- pressure on nerves by swelling and inflammation of carpal tunnel
- impacts everything that passes through nerve, tendons / muscles, numb / tingling
- painkillers or surgery


what are the 3 coverings of muscle

- epimysium: dense regular connective tissue surrounding entire muscle
- perimysium: fibrous connective tissue surrounding fascicles (groups of muscle fibres)
- endomysium: fine areolar connective tissue surrounding each muscle fibre
- each tissue extends beyond muscle belly and fuse together to form tendon and then bone


what are the two types of fascia (connective tissue)

- superficial fascia: loose connective tissue and fat underlying the skin
- deep fascia: dense irregular connective tissue around muscle (all)


describe the microscopic anatomy of a skeletal

- cylindrical cells up to 30 cm long
- multiple peripheral nuclei many mitochondria
- glycosomes for glycogen storage (energy), myoglobin for oxygen storage
- myofibrils (contraction, made up of sarcomeres) form muscle fibre
- sarcomere - myofibril - muscle fibre - fascicle - muscle


what is a sarcomere

- smallest contractile unit of muscle
- contain protein filaments (actin and myosin)
- comprised between two transverse Z lines
- I band: striations, light band, contain Z line
- A band: dark bands (actin and myosin)
- H zone: midline of sarcomere, between two Z lines


describe the structure of thick and thin filaments

- thin: actin, globular (G) subunits, G actin bears active sites for myosin head attachment during contraction, attached to Z disc / I band, contain tropomyosin / troponin (stabilise, regulate)
- thick: myosin tails (heavy polypeptide chains), myosin heads (light polypeptide chains, bridge binding site of ATP, ATPase detach P to form ADP + energy), attached to midline (H zone)


what is the sarcoplasmic reticulum / T tubules

- SR: forms two transverse channels (terminal cisternae), smooth ER surrounding myofibrils, regulation of Ca levels, production of energy
- TT: membrane of sarcolemma, carry impulses to sarcolemma from surface
- terminal cisternae + TT = triad


what are the requirements for skeletal muscle contraction

- activation: neural stimulation at a neuromuscular junction, binding of neurotransmitters = electric current
- exictation-contraction: generation and propagation of action potential, rise in Ca levels = contraction


describe the events in generation of action potential in a muscle cell

- resting = -70mV
- local depolarisation: ACh binding opens chemically ligand gated ion channels, inflow of Na outflow of K (interior of sarcolemma = negative)
- generation / propagation of action potential: end plate potential spreads to adjacent areas, increase Na inside (-55mV = threshold = rapid depolarisation = +30mV)
- repolarisation: Na channels close, voltage gated K channels open, K efflux restores resting polarity, ACh attaches to Na K pump (energy) = restores (active)


describe the steps involved with the sliding filament model of contraction

- no connection between A and M but have a high affinity for one another
- action potential triggers voltage sensitive proteins linked to Ca channels in sarcoplasmic reticulum to open
- Ca floods into cell, troponin + Ca bind = movement of tropomyosin away from active sites
- myosin heads + ADP + P + energy = head extends = binds to actin = releases stored energy and myosin changes shape = pull on strands and shrink sarcomere
- ADP + P unbind = new ATP binds in place on myosin head = release from actin, breakdown ATP to ADP + P and repeat process on another actin
- Ca unbinds and myosin cannot bind to actin anymore


what is the all or none law

- contraction is complete or not at all
- entire muscle contracts at same time (motor unit)
- reaches point where all fibres are distressed and no more force can be applied


relationship of tropomyosin and troponin and calcium levels

- low Ca: normal, tropomyosin blocks active site of actin, myosin cannot attach
- high Ca: Ca binds to troponin, changes shape and moves tropomyosin away from active sites, cross bridge cycle occur (contraction)


what is the nerve-muscle functional unit

- small motor unit = control fine movement
- large motor unit = weight bearing muscles
- muscle fibres spread throughout muscle = single motor unit causes weak contraction of whole muscle