Axial Muscle Terms & Definitions

Rectus abdominis

The 'six-pack' muscle responsible for trunk flexion and helping you sit up.

Masseter

A strong jaw muscle that elevates and protracts the mandible.

Infraspinatus

A rotator cuff muscle located inferior to the scapular spine; adducts and laterally rotates the arm.

Latissimus dorsi

A large back muscle that extends, adducts, and medially rotates the arm.

Levator palpebrae superioris

The muscle that raises the upper eyelid.

Buccinator

The cheek muscle that compresses the cheeks, helping you 'suck in' the cheeks.

Zygomaticus

A group of muscles (major and minor) that elevate the corners of the mouth for smiling.

Orbicularis oculi

A circular muscle around the eyes that closes the eyelids.

Frontalis muscle

Part of the epicranius; elevates the eyebrows and wrinkles the forehead.

Temporalis

A fan-shaped muscle on the side of the skull that elevates and retracts the mandible.

Epicranius

Includes the frontal and occipital bellies connected by the epicranial aponeurosis.

Pectoralis major

A large chest muscle that flexes, adducts, and medially rotates the arm.

Internal oblique

The middle layer of the lateral abdominal wall; assists in trunk rotation and flexion.

Orbicularis oris

The circular muscle around the mouth; closes and protrudes the lips.

Sternocleidomastoids

A pair of neck muscles that flex the head when acting together.

Subscapularis

A deep rotator cuff muscle on the anterior surface of the scapula; medially rotates the arm.

Diaphragm

The dome-shaped muscle separating the thoracic and abdominal cavities; essential for inhalation.

Trapezius

A large, kite-shaped muscle that moves, rotates, and stabilizes the scapula.

Internal intercostals

Muscles between the ribs that depress the ribcage during forced exhalation.

Supraspinatus

A rotator cuff muscle that assists the deltoid in abducting the arm.