Muscles of the Anterior and Lateral Neck

Sternocleidomastoid O

Sternum and clavicle

Sternocleidomastoid I

Mastoid process and nuchal line

Sternocleidomastoid N

Spinal accessory nerve

Sternocleidomastoid A

B: Flexion* of the head

U: Lateral flexion (same side) and rotation (opposite side) of the head

Scalene Anterior O

Transverse process C3-6

Scalene Anterior I

Rib 1

Scalene Anterior I

Rib 1

Scalene Anterior A

Origin fixed: rise upper ribs

Insertion fixed: B: Flexion of the neck; U: Lateral flexion of the neck (same side)

Scalene Middle O

Transverse process C3-7

Scalene Middle I

Rib 1

Scalene Middle N

Cervical and brachial plexus

Scalene Middle A

Origin fixed: rise upper ribs

Insertion fixed: B: Flexion of the neck; U: Lateral flexion of the neck (same side)

Scalene Posterior O

Transverse process C5-7

Scalene Posterior I

Rib 2

Scalene Posterior N

Cervical and brachial plexus

Scalene Posterior A

Origin fixed: rise upper ribs

Insertion fixed: B: Flexion of the neck U: Lateral flexion of the neck (same side)