There are over 600 muscles in the human being body. Learning the muscular mechanism often entails memorizing details about each muscle, like where a muscle attaches come bones and also how a muscle helps move a joint. In textbooks and lectures these details around muscles are explained using specialized vocabulary the is difficult to understand. Right here is one example: The triceps brachii has three bellies v varying origins (scapula and humerus) and one insertion (ulna). The is a element mover of elbow extension. The anconeus acts as a synergist in elbow extension.

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What walk all that textbook jargon mean? The triceps brachii has four places wherein it attaches to the scapula, humerus, and also ulna. This muscle dram a large role (that’s what prime mover means) in prolonging the elbow joint from a bent to a right position.

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

1. Muscles affix to Bones in ~ Locations referred to as Origins and also Insertions


A bones muscle attaches to bone (or occasionally other muscles or tissues) at two or an ext places. If the location is a bone that remains immobile for an action, the attachments is dubbed an origin. If the location is on the bone the moves during the action, the attachment is dubbed an insertion. The triceps brachii happens to have four points of attachment: one insertion ~ above the ulna and also three origins (two top top the humerus and also one top top the scapula).

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

The muscles bordering synovial joints are responsible for relocating the human body in space. This muscle plot are regularly paired, favor flexion and also extension or abduction and also adduction. Below the typical terms are detailed and defined, v animations to aid you snapshot the muscles and joints in motion.

Flexion and extension room usually motions forward and backward from the body, such as nodding the head.

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

Extension: enhancing the angle between two skeleton (straightening a bend).

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


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

Abduction: relocating away native the body midline.

Adduction: relocating toward the body midline.

The gluteus medius, gluteus minimus, tensor fasciae latae, and also sartorius space 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 ago and forth requires special terms. Spread your fingers out and also look at the palms of your hands and the fingers and also then revolve your palms come look at her nails. Currently look at your palms again. It is forearm supination and also pronation.

Pronation: rotating the forearm so the palm is dealing with backward or down.

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


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

Elevation: relocating a body part up.

Depression: moving a body part down.


Protraction and also retraction

By moving your jaw ago and soon in a jutting motion, you space protracting and also retracting your mandible.

Protraction: moving a bone forward without transforming the angle.

Retraction: moving a bone behind without changing the angle.


Inversion and eversion

You invert her foot when you turn it inward to check out what is stuck under your shoe. Friend evert her foot to put the sole of her shoe back on the floor.

Inversion: transforming the single of the foot inward.

Eversion: transforming the sole of the foot outward.

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

Dorsiflexion: bringing your foot upward toward your shin.

Plantar flexion: depressing your foot.

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


While countless muscles may be involved in any kind of given action, muscle function terminology enables you to quickly understand the assorted roles various muscles pat in every 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 come a element mover in the it provides some resistance and/or reverses a offered movement. Prime movers and also antagonists are regularly paired increase on opposite sides of a joint, with their element mover/antagonist duties reversing as the movement changes direction.

Synergists. One or more synergists are often connected in one action. Synergists are muscles that help the prime mover in that is role.

Stabilizers. Stabilizers action to keep bones immobile once needed. Your back muscles, for example, space stabilizers once they are keeping your attitude sturdy.

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External Sources

Muscle Premium by visible Body offers a an extensive reference of musculoskeletal structures and function, plus common injuries and also conditions.

Types of Muscle Contractions. This presentation describes in an ext detail 3 means that bones muscles generate force. College of California, mountain Diego: national Skeletal Muscle study Center. Http://

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