Chapter 10 Flashcards
origin
fixed end; usually the most stationary, proximal end of the muscle; some muscles have multiple origins
head
In the case of multiple origins, each origin is also called a head
insertion
mobile end; usually the distal end of the muscle attached to the bone undergoing the greatest movement.
belly
The part of the muscle between the origin and the insertion
tendons
how each muscle is connected to bone at the attachment point
aponeuroses
broad and sheetlike tendons
action
the movement accomplished when it contracts.
agonist
A muscle that accomplishes a certain movement, such as flexion
antagonist
A muscle acting in opposition to an agonist
synergists
Members of a group of muscles working together to produce a movement
prime mover
Among a group of synergists, this is the one muscle that plays the major role in accomplishing the movement
Fixators
muscles that hold one bone in place relative to the body while a usually more distal bone is moved.
pennate or bipennate muscles
The fasciculi of some muscles are arranged like the
barbs of a feather on two sides of a common tendon and called this
semipennate or unipennate
A muscle with all fasciculi on one side of the tendon
multipennate
a muscle with fasciculi arranged at many places around the central tendon
straight muscles
fasciculi are organized parallel to the long axis of the muscle
Orbicular or circular muscles
such as the orbicularis oris and orbicularis oculi have their fasciculi arranged in a circle around an opening and act as sphincters to close the opening.
lever
a rigid shaft capable of turning about a hinge, or pivot point, called a fulcrum (F) and transferring a force applied at one point along the lever to a weight (W) , or resistance, placed at another point along the lever.
pull (P)
When muscles contract, the pull (P), or force, of muscle contraction is applied to the levers (bones), causing them to move.
class I lever system
the fulcrum is located between the pull and the weight
class II lever system
the weight is located between the fulcrum and the pull
class III lever system
the most common type in the body, the pull is located between the fulcrum and the weight
sternocleidomastoid muscle
prime mover of the lateral group; easily seen on the anterior and lateral sides of the neck, especially if the head is extended slightly and rotated to one side
occipitofrontalis
raises the eyebrows and furrows the skin of the forehead.