The neck has two major muscles that allow the head to move in four different directions. These directions are cervical flexion , cervical extension (hyperextension), cervical lateral flexion , cervical rotation. These are the four distinct movements of the neck.
The range of motion of the neck is a flexion of 45 degrees and externally at 45 degrees. The cervical area laterally flexes 45 degrees and can rotate approximately 60 degrees.
Cranial nerve 11 and the spinal nerves of C2 and C3 innervate the sternocleidomastoid muscle. The splenius muscles are controlled through the posterior lateral branches of C4 through C8 which innervate the splenius muscle.
Manubrium of the sternum
Anterior superior surface of medial clavicle
Extension of the head at the head at the atlantooccipital joint
Flexion of the cervical spine
Splenius cervicis: spinous processes of the third through the sixth thoracic vertebrae
Splenius capitis: lower half of the ligamentum nuchae and spinous processes of the seventh cervical and the upper three or four thoracic vertebrae
Splenius cervicis: transverse processes of the first three cervical vertebrae
Splenius capitis: mastoid process and occipital bone
Both sides: extension of the head (splenius capitis) and neck
Right side: rotation and lateral flexion to the right
Left side: rotation and lateral flexion to the left