Muscles responsible for Neck Extension

Longissimus Capitis

Action: Extension of the head and cervical spine Nerve: Dorsal primary rami of C4 to T5

Semispinalis Capitis

Action: Extension, rotation and lateral flexion of the head and cervical spine Nerve: Dorsal primary rami of C4 to T6

Splenius Capitis

Action: extend and laterally flex head and neck, slight rotation Nerve: Dorsal Rami of (C3, C4)

Obliquus Capitis Superior and Inferior

Action: extend and rotate the atlantoaxial joint Nerve: Suboccipital Nerve, Dorsal Ramus of C1

Rectus Capitis Posterior Major and Minor

Action: extends and rotates the head Nerve: Suboccipital Nerve, Dorsal Ramus of C1

Sternocleidomastoid

Action: flexes neck, extends head, turns head side to side Nerve: CN XI, C2,3

Levator Scapulae

Action: flexes the neck Nerve: Dorsal Scapular nerve C5

Trapezius

Action: hyperextends the neck Nerve: Spinal root of CN XI, Ventral Rami of C3,4

Splenius Cervicis

Action: laterally flex and extend neck Nerve: Dorsal primary rami of C5 to C7