There are over 600 muscle in the human body. Discovering the muscular mechanism often involves memorizing details about each muscle, prefer where a muscle attaches to bones and also how a muscle helps move a joint. In textbooks and lectures this details around muscles are explained using devoted vocabulary the is difficult to understand. Right here is an example: The triceps brachii has actually three bellies with varying origins (scapula and also humerus) and one insertion (ulna). It is a prime mover the elbow extension. The anconeus acts as a synergist in elbow extension.

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What go all the textbook jargon mean? The triceps brachii has 4 places whereby it attaches come the scapula, humerus, and ulna. This muscle theatre a big role (that’s what prime mover means) in prolonging the elbow share from a bent to a right position.

Keep analysis to discover what all the other muscle jargon means!

1. Muscles affix to Bones at Locations dubbed Origins and Insertions


A skeletal muscle attaches to bone (or periodically other muscles or tissues) at two or more places. If the ar is a bone that continues to be immobile for an action, the attachments is dubbed an origin. If the location is top top the bone the moves throughout the action, the attachment is called an insertion. The triceps brachii wake up to have four points that attachment: one insertion ~ above the ulna and three origins (two top top the humerus and also one top top the scapula).

2. Muscles Act top top Synovial Joints to relocate the Body

The muscles surrounding synovial joints room responsible for moving the human body in space. This muscle action are regularly paired, prefer flexion and also extension or abduction and adduction. Listed below the common terms are listed and defined, v animations to assist you snapshot the muscles and also joints in motion.

Flexion and extension are usually movements forward and also backward indigenous the body, such together nodding the head.

Flexion: to decrease the angle in between two skeleton (bending).

Extension: raising the angle between two bones (straightening a bend).

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


Abduction and also adduction space usually side-to-side movements, such as moving the arm laterally once doing jumping jacks.

Abduction: moving away indigenous the body midline.

Adduction: moving toward the body midline.

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


Pronation and also supination

Describing the rotation that the forearm back and forth requires special terms. Spread out your finger out and look at the palms of your hands and the fingers and also then turn your palms come look at her nails. Currently look at your palms again. That’s forearm supination and also pronation.

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

Supination: rotating the forearm for this reason the palm is dealing with forward or up.


Elevation and depression are up-and-down movements, such together chewing or shrugging your shoulders. Once you relocate the mandible under to open the mouth, it is mandible depression. Relocate the mandible back up, it is mandible elevation.

Elevation: relocating a body part up.

Depression: relocating a body component down.


Protraction and retraction

By moving your jaw earlier and soon in a jutting motion, you are protracting and retracting her mandible.

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

Retraction: relocating a bone behind without an altering the angle.


Inversion and eversion

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

Inversion: turning the single of the foot inward.

Eversion: turning the sole of the foot outward.

Dorsiflexion and also plantar flexion you dorsiflex her feet come walk on your heels, and plantar flex them to tiptoe.

Dorsiflexion: bringing her foot upward towards your shin.

Plantar flexion: depressing your foot.

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


While many muscles might be associated in any kind of given action, muscle role terminology permits you to conveniently understand the various roles various muscles pat in every movement.

Prime movers and also antagonist

The prime mover, sometimes called the agonist, is the muscle that gives the primary pressure driving the action. An antagonist muscle is in opposition come a element mover in the it gives some resistance and/or reverses a given movement. Element movers and also antagonists are regularly paired increase on opposite sides of a joint, with their prime mover/antagonist functions reversing together the movement transforms direction.

Synergists. One or more synergists are often affiliated in one action. Synergists are muscles that help the element mover in the role.

Stabilizers. Stabilizers plot to keep bones immobile when needed. Your back muscles, because that example, room stabilizers once they are maintaining your attitude sturdy.

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External Sources

Muscle Premium by visible Body provides a comprehensive reference that musculoskeletal structures and also function, plus common injuries and conditions.

Types that Muscle Contractions. This presentation defines in an ext detail 3 methods that bones muscles generate force. University of California, san Diego: nationwide Skeletal Muscle study Center. Http://

This table, indigenous a course at Marquette University concentrated on rehabilitation engineering, consists of descriptions of simple movements and explanations of an essential muscle biomechanics and movement terminology. Biomechanics & motion Science. Jack M. Winters, Ph.D, Marquette Univeristy. Http://