motor units, muscle fiber types, and muscle knowledge

motor units

a motor neuron and all the muscle fibers it controls

small motor units

recruit few neurons and recruit few muscle fibers

-for lifting light loads, like a pencil

large motor units

recruit many neurons and many muscle fibers

-for moving heavy loads, like a bowling ball

slow fibers

fibers that contract slowly and are resistant to fatigue. They are primarily used for endurance activities.

fast fibers

fibers that contract quickly and are prone to fatigue. They are primarily used for short bursts of strength or speed.

parallel muscles

Fibers run parallel to each other, allowing long-range motion but less force.

Example: rectus abdominis.

convergent muscles

Fibers spread out and converge at a common attachment site. This allows for versatile movement.

Example: pectoralis major.

circular muscles

Fibers arranged in a ring, controlling openings in the body. Example: orbicularis oris (mouth) and orbicularis oculi (eye).

pennate muscles

Fibers attach at an angle to a central tendon, producing more force but less movement.

origin

the part of the muscle that stays fixed during contraction, serving as the attachment point for the muscle.

insertion

the part of the muscle that moves during contraction, allowing for movement at the joint.

origin movement

The proximal end of attachment of a muscle to a bone that will not be moved by the action of that muscle.

insertion movement

The distal end of attachment of a muscle to a bone that will be moved by the muscle when it contracts.

Intermediate FIbers

a faster contraction speed than slow fibers and a moderate fatigue resistance compared to both

ex. light jogging