There are over 600 muscle in the human being body. Discovering the muscular system often requires memorizing details around each muscle, favor where a muscle attaches to bones and also how a muscle helps move a joint. In textbooks and lectures this details around muscles are defined using dedicated vocabulary the is difficult to understand. Here is an example: The triceps brachii has actually three bellies with varying origins (scapula and humerus) and one insertion (ulna). The is a element mover the elbow extension. The anconeus acts together a synergist in elbow extension.

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What does all the textbook slang mean? The triceps brachii has four places wherein it attaches come the scapula, humerus, and ulna. This muscle dram a large role (that’s what element mover means) in expanding the elbow share from a bent come a straight position.

Keep reading to find out what every the other muscle slang means!

1. Muscles attach to Bones at Locations referred to as Origins and also Insertions


A skeleton muscle attaches to bone (or occasionally other muscles or tissues) at two or an ext places. If the ar is a bone that remains immobile because that an action, the attachment is dubbed an origin. If the ar is top top the bone that moves during the action, the attachment is referred to as an insertion. The triceps brachii wake up to have 4 points that attachment: one insertion ~ above the ulna and also three origins (two on the humerus and one on the scapula).

2. Muscles Act ~ above Synovial Joints to move the Body

The muscles neighboring synovial joints space responsible for moving the human body in space. This muscle actions are regularly paired, choose flexion and extension or abduction and also adduction. Below the common terms are provided and defined, with animations to aid you photo the muscles and also joints in motion.

Flexion and extension are usually movements forward and backward from the body, such as nodding the head.

Flexion: decreasing the angle in between two bones (bending).

Extension: increasing the angle in between two skeletal (straightening a bend).

The triceps brachii and anconeus room muscles that prolong the elbow. The biceps brachii, brachialis, and also brachioradialis flex the elbow.


Abduction and adduction space usually side-to-side movements, together as relocating the eight laterally when doing jumping jacks.

Abduction: relocating away indigenous the body’s midline.

Adduction: moving toward the body’s midline.

The gluteus medius, gluteus minimus, tensor fasciae latae, and sartorius are muscles the abduct the hip. The pectineus, adductor longus, adductor brevis, adductor magnus, and gracilis adduct the hip.


Pronation and also supination

Describing the rotation the the forearm back and forth needs special terms. Spread out your finger out and also look in ~ the palms of your hands and also the fingers and then turn your palms to look at her nails. Now look at her palms again. That’s forearm supination and also pronation.

Pronation: rotating the forearm for this reason the palm is facing backward or down.

Supination: rotating the forearm therefore the palm is encountering forward or up.


Elevation and also depression are up-and-down movements, such as chewing or shrugging her shoulders. Once you move the mandible under to open the mouth, that’s mandible depression. Relocate the mandible back up, it is mandible elevation.

Elevation: relocating a body component up.

Depression: moving a body component down.


Protraction and retraction

By relocating your jaw back and forth in a jutting motion, you room protracting and retracting your mandible.

Protraction: moving a bone forward without an altering the angle.

Retraction: relocating a bone backward without transforming the angle.


Inversion and eversion

You invert your foot when you rotate it inward to watch what is grounding under her shoe. Friend evert her foot to placed the sole of your shoe back on the floor.

Inversion: turning the sole of the foot inward.

Eversion: turning the single of the foot outward.

Dorsiflexion and plantar flexion friend dorsiflex her feet come walk on her heels, and plantar flex them come tiptoe.

Dorsiflexion: bringing your foot upward towards your shin.

Plantar flexion: depressing your foot.

3. Muscle Actions have actually Prime Movers, Synergists, Stabilizers, and also Antagonists


While numerous muscles may be involved in any type of given action, muscle role terminology enables you to conveniently understand the miscellaneous roles different muscles beat in each movement.

Prime movers and antagonist

The prime mover, sometimes dubbed the agonist, is the muscle that provides the primary pressure driving the action. One antagonist muscle is in opposition to a prime mover in that it gives some resistance and/or reverses a provided movement. Element movers and antagonists are frequently paired increase on opposite political parties of a joint, with their element mover/antagonist functions reversing as the movement transforms direction.

Synergists. One or an ext synergists are often affiliated in one action. Synergists space muscles that assist the element mover in its role.

Stabilizers. Stabilizers act to keep bones immobile when needed. Your ago muscles, for example, space stabilizers once they are keeping your posture sturdy.

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External Sources

Muscle Premium by visible Body supplies a substantial reference that musculoskeletal structures and also function, plus typical injuries and conditions.

Types that Muscle Contractions. This presentation describes in much more detail 3 ways that skeletal muscles generate force. University of California, san Diego: nationwide Skeletal Muscle study Center. Http://

This table, from a course at Marquette University focused on rehabilitation engineering, includes descriptions of an easy movements and also explanations of an essential muscle biomechanics and also movement terminology. Biomechanics & movement Science. Jack M. Winters, Ph.D, Marquette Univeristy. Http://