Muscle Terminology 1
Terms
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- action
- the dynamic motion or movement produced when the muscles contract
- insertion
- the part of the muscle attached to the moving point
- origin
- the part of the muscle attached to the stable point
- axial muscles
-
muscles that:
- usually originate and insert on the axial skeleton
- position the head
- position the vertebral column
- move the ribs
- compress the abdomen - appendicular muscles
- muscles that stabilize the pectoral and pelvic girdles and move the upper and lower limbs.
- fascicle
- bundle of muscle cells (muscle fibers)
- parallel muscle
-
fascicles are parallel to the long axis of the muscle;
terminates at either end in a broad tendon;
example: biceps brachii - fusiform muscle
-
parallel fascicle with a thicker belly (central body);
terminates at either end in a broad tendon;
example: biceps brachii - pennate muscle
- fascicle forms an oblique angle to the tendon (like a feather)
- unipennate muscle
-
short pennate fascicles run down one side of the tendon;
example: extensor digitorum longus - bipennate muscle
-
short pennate fascicles run down both sides of the tendon;
example: rectus femoris - multipennate muscle
-
muscle where the tendon branches within the muscle and short pennate fascicles are attached to each tendon branch;
example: deltoid - convergent muscle
-
long fascicles of muscles based over a broad area that converge, coming together at a common attachment site;
example: pectoralis major - sphincter
-
circular muscle;
fascicles are concentrically arranged around an opening or recess;
examples: orbicularis oris (around mouth), orbicularis oculi (around eye) - aponeuroses
-
collagenous sheets or ribbons that resemble flat, broad tendons;
may cover the surface of a muscle and assist in attaching superficial muscles to another muscle or structure - tendons
-
cords of dense regular tissue that attach skeletal muscles to bone;
the collagen fibers run along the longitudinal axis of the bone - fascicular arrangement
-
the arrangement of fascicles determines range and power;
example: parallel muscle - longer fascicles produce greater range of movement;
example: multipennate muscle - more fascicles produce more power - lever
-
rigid structure that moves at a fixed point called the fulcrum;
anatomically, the bone is the lever and the joint is the fulcrum - fulcrum
-
the fixed point upon which a lever moves;
anatomically, the joint is the fulcrum and the bone is the lever - applied force
-
the force applied to the lever to move a load or weight or counteract a resistance;
anatomically, muscle contraction is the applied force - resistance
- the load or weight being moved by the applied force to a lever
- first-class lever
-
lever in which the fulcrum is between the applied force and the resistance;
common example: seesaw;
anatomical example:
fulcrum: atlanto-occipital joint;
force: splenius capitis;
weight: head - second-class lever
-
lever in which the resistance is between the applied force and the fulcrum;
common example: wheelbarrow;
anatomical example:
fulcrum: metatarsophalangeal joints (ball of foot);
force: gastrocnemius;
weight: body mass on middle of foot during plantar flexion while standing - third-class lever
-
lever in which the applied force is between the resistance and the fulcrum;
common examples: baseball bat, tweezers;
anatomical example:
fulcrum: elbow;
force: biceps brachii;
weight: forearm and hand - linea alba
- (white line) tendinous band that runs along the midline of the rectus abdominis
- group action
-
the action produced at a joint by a group of muscles working together;
a muscle in the group may play the role of agonist, antagonist, synergist, or fixator in order to perform the action;
example:
group action: flex forearm at elbow;
agonist: biceps brachii;
antagonist: triceps brachii;
synergist: brachialis, brachioradialis;
fixator: deltoid, pectoralis major, etc. - agonist
-
the muscle that contracts to produce the action;
it is the muscle whose contraction is chiefly responsible for producing the particular movement - prime mover
- agonist
- antagonist
- the muscle that relaxes when the agonist contracts
- synergist
- the muscle that also contracts to help the agonist
- fixator
- the muscle that contracts in order to stabilize the joint