Splenius cervicis muscle

Origin and insertion

Splenius cervicis is a paired, flat bow-shaped muscle in the posterolateral aspect of the neck. It originates from the spinous processes of thoracic vertebrae T3-T6. The obliquely oriented muscle fibers initially travel superolaterally then curve medially to insert on the tubercles of transverse processes of cervical vertebrae C1-C3. 

Relations

Like the other deep neck muscles, splenius cervicis is invested in the deep layer of deep cervical fascia. It is found superficial to semispinalis capitis and longissimus capitis, and deep to sternocleidomastoid and trapezius muscles. Splenius cervicis courses along the inferolateral margin of splenius capitis and blends almost indistinguishably with it.

Innervation

Splenius cervicis muscle is innervated by the lateral branches of the posterior rami of the lower cervical spinal nerves. 

Blood supply

The arterial blood supply to this muscle arises from:

• Vertebral artery
• Deep cervical artery
• Descending branch of occipital artery
• Transverse cervical artery
• Superior intercostal artery

The venous drainage of splenius cervicis mimics its arterial supply.

Function

Unilateral contraction of splenius cervicis causes ipsilateral lateral flexion and rotation of the neck. However, when contracting bilaterally, this muscle aids the trapezius muscle to extend the neck. 

The neck extension produced by this muscle has an important function during standing up from a sitting position, as it puts the neck into a stance from which the longus capitis can bring the head into the neutral position once the body’s upright.

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