Answer
Muscles that extend the neck:
Trapezius.
The trapezius extends (also laterally flexes) the neck
Splenius capitis and Splenius cervicis
These muscles extend the neck --when contracting bilaterally
Semispinalis capitis and semispinalis cervicis:
Extend the neck/head when acting bilaterally
Work Step by Step
Flexors of the neck:
Sternocleidomastoid:
Unilateral action tilts head upward and toward opposite side
Unilateral contraction, draws head straightforward down as in reading, or eating.
Anterior, middle and posterior scalenes:
Ipsilateral contraction tilts head towards same shoulder or rotates face away,
Bilateral contraction flexes neck. If spine is fixed, scalenes elevate ribs and aid in breathing
