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

 

 

 

 

 

 

 

 

Figure 8-1. Types of movements about and around joints, part 1.

 

 

Figure 8-2. Types of movements about and around joints, part 2.

 

 

 

Figure 8-3. The biceps brachii muscle of the arm has two origins that are fixed to the scapula bone and one insertion that is attached to and moves the radius bone.

 

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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Lab 8 Exercises 8.1

  1. Give the reasons the following muscles were given their names. For muscles with multi-word names, identify the meaning of or reason for each component of the muscle’s name.
  • Deltoid muscle
  • External oblique muscle
  • Platysma muscle
  • Rectus abdominis muscle
  • Frontal epicranius muscle
  • Zygomaticus major muscle