Splenius Capitis

Back · Trunk

Splenius Capitis belongs to the Back group of the Trunk. Originating at Nuchal ligament and spinous processes of C7–T3/T4, it inserts at Mastoid process and lateral part of superior nuchal line of occipital bone. It is responsible for several movements: Bilateral: extension of head and neck; Unilateral: lateral flexion and rotation of head to the same side. It is innervated by the Dorsal rami of middle cervical spinal nerves.

Origin, Insertion, Action & Nerve

Origin

Nuchal ligament and spinous processes of C7–T3/T4

Insertion

Mastoid process and lateral part of superior nuchal line of occipital bone

Action

Bilateral: extension of head and neck; Unilateral: lateral flexion and rotation of head to the same side

Nerve

Dorsal rami of middle cervical spinal nerves

Attachments explained

The Splenius 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

Nuchal ligament and spinous processes of C7–T3/T4

Insertion

Mastoid process and lateral part of superior nuchal line of occipital bone

Action & function

When the Splenius Capitis contracts, it produces the following movements: Bilateral: extension of head and neck; Unilateral: lateral flexion and rotation of head to the same side.

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 Splenius Capitis receives its nerve supply from the Dorsal rami of middle cervical spinal nerves.

Because a muscle can only contract when its nerve is intact, injury to the Dorsal rami of middle cervical spinal nerves can weaken or paralyse the Splenius Capitis, impairing the movements it normally produces (extension of head and neck). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Splenius Capitis (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Splenius 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 Splenius 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.