Naming muscles

Information

There are a lot of skeletal muscles in the human body, and skeletal muscles often have long and hard-to-remember names. However, the muscle names often reflect something about their action, their shape, or their locations. If you know the logic of how a muscle name was derived, it often makes it easier to remember that muscle’s name and location.

Figures 8-1 and 8-2 show and Table 8-1 lists the anatomical terms for the types of movements that can occur around joints. Often these terms are incorporated into the names of muscles that contribute to producing that type of movement at one of the body’s joints.

Sometimes the locations of muscles’s origins or insertions are incorporated into their names. Muscles are generally attached at two points in the body. One end is pulled by the muscle to create movement. The end of the muscle that creates movement is called the insertion of the muscle. The other end of the muscle stays fixed and the part of the muscle that moves is moved towards this fixed point. The fixed end of a muscle is called the origin of the muscle. Figure 8-3 illustrates muscle origins and insertions.

Sometimes, the way muscles interact with other muscles are incorporated into their names. Table 8-2 summarizes the anatomical terms associated with these kinds of muscle interactions.

Table 8-3 summarizes many of the ways that a muscle’s characteristics can be incorporated into its name.

Table 8-1. Anatomical terms describing movement around the body’s joints.

Term	Type of movement around the joint
Flexion	Decreasing the angle between two bones
Dorsiflexion	Decreasing the angle between the foot and shin
Plantar flexion	Decreasing the angle between the toes and bottom of the foot (pointing toes)
Extension	Increasing the angle between two bones
Abduction	Moving a body part away from the midline
Adduction	Moving a body part towards the midline
Circumduction	Movement in a circular or cone-shaped motion
Rotation	Turning movement of a bone about its long axis
Supination	Rotation of the forearm or foot so that the palm or sole is moved to face anteriorly
Pronation	Rotation of the forearm or foot so that the palm or sole is moved to face posteriorly
Inversion	Sole of the foot moved to face medially
Eversion	Sole of the foot moved to face laterally
Retraction	Movement in the posterior direction
Protraction	Movement in the anterior direction.
Elevation	Lifting a body part
Depression	Returning a body part to pre-elevated position

 

Table 8-2. Anatomical terms describing how muscles interact with other muscles.

Term	Type of interaction with other muscles
Agonist	Also known as the primer move. A muscle that is primarily responsible for the movement.
Synergist	A muscle that assists the prime mover muscle.
Fixator	A muscle that stabilizes the origin of the prime mover (i.e. holds it in place) so that the prime mover can act more efficiently.
Antagonist	A muscle in opposition to the action of a prime mover muscle.  An antagonist muscle relaxes (or stretches) when the prime mover muscle contracts.

 

Table 8-3. The different ways a muscle’s characteristics can be incorporated into its name

Characteristic	Examples	Human muscles named this way
Direction of muscle fascicles relative to muscle midline.	Rectus – parallel Transverse – perpendicular Oblique – at a 45° angle	Rectus abdominis Transversus abdominis External oblique
Location of or body part covered by the muscle	Frontal bone Tibia	Frontalis Tibialis anterior
Relative size	Maximus - largest Longus - longest Brevus – shortest Major – larger of a pair Minor – smaller of a pair	Gluteus maximus Palmaris longus Peroneus longus Teres major Teres minor
Number of origins	Biceps – two origins Triceps – three origins	Biceps brachii Triceps brachii
Location of origin or insertion	origin at sternum origin at clavicle insertion at mastoid process	Sternocleidomastoid
Shape	Deltoid – triangular Trapezius – trapezoidal Serratus – saw-tooth edge Orbicularis - circular	Deltoid Trapezius Serratus anterior Orbicularis oris
Action of muscle	Flexion Extension Adduction	Flexor carpi radialis Extensor digitorum Adductor longus

 

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