Splenius capitis

The splenius capitis is a strap-like muscles that, along with the splenius cervicis, comprise the superficial layer of intrinsic back muscles.

Gross anatomy

Attachments

• origin: ligamentum nuchae, and the tips of the spinous processes and associated supraspinous ligaments of C7 and the upper three to four thoracic vertebrae
• insertion:  mastoid process and rough surface of the occipital bone below the lateral third of the superior nuchal line

Relations

• deep to the trapezius
• superficial to the semispinalis capitis and the longissimus capitis
• forms the floor of the posterior neck triangle, lying between the sternocleidomastoid and the trapezius

Blood supply

• occipital artery, descending branch
• deep cervical artery

Innervation

• lateral branches of the 2 and 3 cervical dorsal rami from the cervical plexus

Action

• rotates the head to the same side: when acting unilaterally and synergistically with the sternocleidomastoid
• extends the head: when acting bilaterally