Splenius Cervicis

Back · Trunk

The Splenius Cervicis is a Trunk muscle within the Back group. Its origin is Spinous processes of T3–T6, and it inserts onto Posterior tubercles of the transverse processes of C1–C3. It is responsible for several movements: Bilaterally extends the neck; unilaterally rotates and laterally flexes the head and neck to the same side. Innervation is provided by the Posterior (dorsal) rami of lower cervical spinal nerves.

Origin, Insertion, Action & Nerve

Origin

Spinous processes of T3–T6

Insertion

Posterior tubercles of the transverse processes of C1–C3

Action

Bilaterally extends the neck; unilaterally rotates and laterally flexes the head and neck to the same side

Nerve

Posterior (dorsal) rami of lower cervical spinal nerves

Attachments explained

The Splenius Cervicis 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 T3–T6

Insertion

Posterior tubercles of the transverse processes of C1–C3

Action & function

When the Splenius Cervicis contracts, it produces the following movements: Bilaterally extends the neck; unilaterally rotates and laterally flexes the head and neck 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 Cervicis receives its nerve supply from the Posterior (dorsal) rami of lower cervical spinal nerves.

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

How to study the Splenius Cervicis (the OIANS method)

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