10-1. The Muscular System Flashcards
Skeletal muscles produce motion by ___, which in turn ____.
exerting force on tendons; pull on bones
Most muscles ____.
cross a joint (attached to articulating bones that form the joint)
As muscle contracts, one ___ is drawn to ____, and the ___ of the joint decreases.
bone; the other bone; angle of the joint decreases
origin
attachment of a muscle to the more stationary bone of an articulation
Where is the origin of biceps brachii?
scapula (corocoid process and glenoid cavity)
insertion
attachment of a muscle to the bone it moves
Where is the insertion of biceps brachii?
radius (radial tuberosity)
When a muscle contracts, the ___ moves to the ___.
insertion; origin
belly
fleshy part between the tendons of the origin and insertion
Muscle fibers are arranged in parallel within a bundle called a ____.
fascicle
What are the four types of fascicle arrangements?
parallel
convergent
pennate
circular
parallel
fascicles run parallel to the long axis of the muscle, terminating at either end in a flat tendon
What is an example of a parallel arrangement?
sartorius
convergent
a broad origin converges to a narrow insertion, giving the muscle a triangular or fan shape
What is an example of a convergent arrangement?
pectoralis major
pennate
The fascicles are short, and they attach to a central tendon that runs the length of the muscle, like the plumes of a feather
What is an example of a pennate arrangement?
rectus femoris
circular
fascicles are arranged in concentric rings around an opening in the body, which closes as they contract
What is an example of a circular arrangement?
orbicularis oris
prime mover
muscle that causes the desired action by contracting
What is the prime mover for elbow flexion?
biceps brachii
antagonist
muscle whose action opposes that of the prime mover; it relaxes when the prime mover contracts
What is the antagonist for elbow extension?
biceps brachii
synergist
a muscle that assists a prime mover, helping to steady the movement
fixator
a muscle that stablizes the origin of the prime mover so it can move more efficiently
What happens if a prime mover and antagonist both contract at the same time and with equal force?
isometric contraction
How many skeletal muscles are there in the human body
nearly 700
What are some characteristics that muscles may be named after?
- location (indicating the bone or body region they are near)
- shape (named for a distinctive shape)
- size
- direction (of fibers)
- number of origins
- location of origin and insertion
- action of the muscle
What are some examples of muscles named for their location?
frontalis, tibialis anterior, rectus abdominus
What are some muscles named for their shape?
deltoid, trapezius
maximus
largest
minimus
smallest
longus
long
brevis
short
What are some muscles named for their size?
gluteus maximus, palmaris longus
rectus
fibers run parallel to midline
transverse
fibers run perpendicular to midline
oblique
fibers run diagnol to midline
What are some muscles named for the number of origins?
biceps (2), triceps (3), quadriceps (4)
flexor
bends a joint
extensor
straighten a joint
adductor
moves a bone closer to midline
levator
produces an upward movement (eg. levator labii)
tensor
makes a body part rigid
What can you tell from the name flexor carpi radialis
action - bends wrist; location - next to radius
