Spinalis Capitis

Back · Trunk

Spinalis Capitis belongs to the Back group of the Trunk. It arises from Spinous processes of the upper thoracic and lower cervical vertebrae (usually blended with semispinalis capitis) and attaches to Occipital bone between the superior and inferior nuchal lines. Functionally, it extends the head and neck. Innervation is provided by the Posterior (dorsal) rami of cervical spinal nerves.

Origin, Insertion, Action & Nerve

Origin

Spinous processes of the upper thoracic and lower cervical vertebrae (usually blended with semispinalis capitis)

Insertion

Occipital bone between the superior and inferior nuchal lines

Action

Extends the head and neck

Nerve

Posterior (dorsal) rami of cervical spinal nerves

Attachments explained

The Spinalis Capitis is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.

Origin

Spinous processes of the upper thoracic and lower cervical vertebrae (usually blended with semispinalis capitis)

Insertion

Occipital bone between the superior and inferior nuchal lines

Action & function

When the Spinalis Capitis contracts, it produces the following movement: Extends the head and neck.

As part of the Back group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.

Nerve supply & clinical relevance

The Spinalis Capitis receives its nerve supply from the Posterior (dorsal) rami of cervical spinal nerves.

Because a muscle can only contract when its nerve is intact, injury to the Posterior can weaken or paralyse the Spinalis Capitis, impairing the movements it normally produces (extends the head and neck). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Spinalis Capitis (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Spinalis Capitis, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.

Most students remember the Spinalis Capitis fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.