posterior view

gastrocnemius

Large thick muscle forming the curve of the calf and allowing the foot to extend; it also helps the knee to extend.

gracilis

Muscle enabling the thigh to draw near the median axis of the body, and the leg to flex on the thigh and to rotate inwardly (toward the median axis).

biceps of thigh

Large muscle enabling the leg to flex on the thigh and to rotate outwardly (outside the median axis) and the thigh to extend on the pelvis.

semimembranosus

Flat muscle enabling the thigh to extend on the pelvis, the knee to flex, and the thigh and the leg to rotate inwardly (toward the median axis).

semitendinosus

Long muscle enabling the thigh to extend on the pelvis, the knee to flex, and the thigh and the leg to rotate inwardly (toward the median axis).

gluteus maximus

Thick muscle enabling the hip to extend and to rotate outwardly (outside the median axis); it also allows the trunk to return to a vertical position.

short radial extensor of wrist

Muscle enabling the hand to extend and to draw away from the median axis of the body.

ulnar flexor of wrist

Muscle enabling the hand to flex and to draw near the median axis of the body.

brachioradialis

Flat muscle primarily enabling the forearm to flex; it also helps it to rotate outwardly, bringing the palm of the hand toward the front.

triceps of arm

Powerful muscle enabling the forearm to extend on the arm; it contracts whereas the biceps relaxes.

latissimus dorsi

Large flat muscle especially enabling the arm to draw near the median axis of the body, to extend and to rotate inwardly.

infraspinatus

Flat triangular muscle enabling the arm to rotate outwardly (outside the median axis); it also stabilizes the shoulder joint.

splenius capitis

Muscle enabling the head to tilt sideways and to rotate; the simultaneous action of the two splenii allows the head to extend.

short peroneus

Muscle attached to the fibula enabling the foot to extend and to draw away from the median axis of the body.

plantaris

Small muscle that, with the gastrocnemii, allows the knee to flex or the ankle to extend, depending on whether or not the foot is resting on the ground.

adductor magnus

Powerful muscle enabling the thigh to draw near the median axis of the body, to rotate outwardly (outside the median axis), to flex and to extend.

vastus lateralis

Large outer thigh muscle mainly allowing the knee to extend; it also stabilizes the knee.

external oblique

Large thin muscle enabling the trunk to flex and to rotate on the pelvis and the internal organs to compress; it also aids in expiration.

ulnar extensor of wrist

Muscle enabling the hand to extend and to draw near the median axis of the body.

common extensor of fingers

Muscle enabling all the fingers, except the thumb, to extend; it also helps the hand to extend on the forearm.

anconeus

Short muscle reinforcing the action of the triceps; it allows the forearm to extend on the arm and also stabilizes the elbow joint.

long radial extensor of wrist

Muscle enabling the hand to extend and to draw away from the median axis of the body.

teres major

Muscle enabling the arm to draw near the median axis of the body and to rotate inwardly.

teres minor

Muscle enabling the arm to rotate outwardly (outside the median axis); it also stabilizes the shoulder joint.

trapezius

Large flat triangular muscle enabling many shoulder movements; it also helps to extend the head.

semispinalis capitis

Muscle enabling the head to tilt sideways; the simultaneous action of the two complexi allows the head to extend.

occipitalis

Muscle pulling the scalp toward the back.