muscles Flashcards
epimysium
dense irregular fibrous CT
surrounds whole muscle
perimysium
dense irregular CT sheet
around FASCICLES (groups of muscle fibers)
endomysium
fine areolar CT
surrounds each muscle fiber (cell)
deep fascia
still coarser layer of dense CT
binds muscles into functional groups
(ex. deep fascia separates quads from hamstrings)
skeletal muscle
CT sheaths
muscle attachments: origin
point of attachment to bone that doesn’t move during activity (stable point)
muscle attachment: insertion
part of the bone that moves when muscle contracts
parallel
fascicles run parallel to the long axis of the strap-like muscle
strap-like (sartorius) or fusiform: thicker in the middle (biceps brachii)
pennate
short fascicles attach obliquely to a central tendon running the length of the muscle
unipennate: extensor digitorum
bipennate: rectus femoris
multipennate: deltoid
circular
concentric rings surround external opening and contract to close opening (obicularis oris)
convergent
fascicles converge toward a single tendon insertion/muscle is triangular or fan-shaped (pectoralis major)
prime mover (agonist)
provides major force for a movement
(brachialis in elbow flexion)
antagonist
opposes movement
resistance to prevent overshoot or speed of movement
(triceps brachii in elbow flexion)
the same muscle can be a prime mover and antagonist in different movements
synergists
help the prime mover by
-promoting same movement
-reducing undesirable movement
-some are FIXATORS (holds things in place) (e.g posture muscles)
naming skeletal muscles
location
shape
size
direction of muscle fibers of fascicles
- rectus (straight) transverse (right angles) oblique (other angles)
number of origins
location of attachments (origin name then insertion)
muscle action
