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Neck
Neck Anatomy Diagram

Neck Anatomy Diagram

The Neck

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.

Nerves of the Neck

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.

Sternocleiodomastoid muscle : (ster’no-kli-do-mas-toyd)

Origin

Manubrium of the sternum

Anterior superior surface of medial clavicle

Insertion

Mastoid process

Action

Extension of the head at the head at the atlantooccipital joint

Flexion of the cervical spine

 

Splenius Muscles [2 muscles] (cervicis, capitis)

Origin 

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

Insertion

Splenius cervicis: transverse processes of the first three cervical vertebrae

Splenius capitis: mastoid process and occipital bone

 Action

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

 

 

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