Muscles Flashcards
two ends of muscles
ORIGIN which is the fixed part of the muscle
INSERTION is the moving part of the muscle during contraction
origin is usually proximal to insertion
two parts of muscles
fleshy part is belly like and is contractile
fibroous part is non contractile inelastic, cord like or rope like is tendon and flat is aponeurosis.
STRUCTURE OF straited MUSLCE (Contractile unit)
each muscle is made up of many muscle fibers. each muscle fiber is multinucleated, cross striated, cylindrical shaped cell. it is made of up sarcolemma and sarcoplasm
each muscle fiber are made of small trasversely placed myofibrils which two bands A (anisotropic) dark band and I (Isotropic) light bad
between dark band there is H zone and between I band there is a dark line the Z disk (Krause membrane)
supporting tissue of striated muscle
the endomysium covers each muscle fiber, the perimysium covers each fascia (bundle) and epimysium covers the whole muscle.
types of fibers
type I (SLOW) - gluteus maximus. red in color, rich in myoglobin, mitochondria and oxidative enzymes. poor in phosphorylases. resistant to fatigue
type II (FAST) - white paler in colour, less myoglobin and mitochondria
abundant in glycogen and phosphorylases
glycogenic respiration make them fatigue faster
Intermediate- resistant to fatigue than fast but still not as resistant as slow
fascicular architecture of muscles
the arrangement of muscle fiber depends on the direction, forces and habitual movement around a certain joint
the force determines the size and number of muscle fibers and the range of movement decides the length of the muscle fiber
Parallel fasciculi with e.g
muscle fibers arranged parallel to the line of pull
quadrilateral- thyrohyoid
strap like- sternohyoid and sartorius
strap like with tendinous insertions - rectus abdominis
fusiform - bicep branchi and digastric
oblique fasciculi with e.g
muscle fibers are arranged obluqielly to the line of pull
triangular shaped or pennate (feather like)
Triangular- temporalis and adductor longus
unipennate - flexor pollicis longus, extensor digitorum longus, peroneus tertius
bipennate- peroneus longus, dorsum interossei, rectus femoris
multipennate- subscapularis, deltoid
circumpennate- tibialis anterior
twsiter - spiral muscles and crossed muscles
TWISTER/SPIRAL- trapezius, pectoralis major and supinator
CROSSED- cruciate sternocleidomastoid, adductor magnus, masseter
prime movers (agonist)
brings about the desire movement. prime muscle for the movement. eg the brachialis is the prime mover for the flexion of elbow joint
action of paradox
when a prime mover helps opposite action by active controlled lengthening against gravity is called action of paradox like putting the glass on the table
antagonist (oppose)
they oppose the prime movers, help the prime movers by active controlled relaxation to the movement is smooth and precise. due to reciprocal innervation of opposite group of muscles regulated by spinal cord. eg biceps and triceps
fixators
group of muscles which stabilize the proximal joint of limbs so desired movement of distal joints may occur on a fixed base
e.g shoulder joint (trapezius) and deltoid fix t for better movement of fingers
synergist
two or more muscles causing one movement is synergist
when prime movers cross more than one joints, the undesired movement of proximal joint is are prevented by a group of muscles known as synergist.
