Splenius Capitis
Back · Trunk
The splenius capitis is a strap-like muscle of the back of the neck that lies deep to the trapezius and helps wrap and stabilise the cervical region like a bandage, which is what its name suggests. It arises from the nuchal ligament and the spinous processes of C7 to T3 or T4 and runs upward and laterally to insert onto the mastoid process and the lateral part of the superior nuchal line of the occipital bone. Acting on both sides it extends the head and neck, while acting on one side it laterally flexes the head and rotates it to the same side, a useful contrast to muscles like sternocleidomastoid that turn the head to the opposite side. It is supplied by the dorsal rami of the 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)
Remember splenius capitis as the muscle that both extends the neck and turns the face toward its own side. Because its fibres run upward and outward from the midline spines to the mastoid process, a one-sided contraction naturally swings the chin to that same side, a same-side rule worth contrasting directly with sternocleidomastoid, which rotates the head the opposite way.
Fix the attachments by their shape: the muscle spreads from the lower spinous processes like a splint and narrows onto the mastoid process and superior nuchal line, mirroring where the trapezius attaches above it. Noting that it is supplied by dorsal rami of the middle cervical nerves keeps it grouped with the other true back muscles rather than the anterior neck flexors.
Frequently asked questions
Where is the Splenius Capitis located?
The Splenius Capitis is a muscle of the Back group, located in the Trunk.
What is the origin of the Splenius Capitis?
Nuchal ligament and spinous processes of C7–T3/T4
What is the insertion of the Splenius Capitis?
Mastoid process and lateral part of superior nuchal line of occipital bone
What movements does the Splenius Capitis produce?
Bilateral: extension of head and neck; Unilateral: lateral flexion and rotation of head to the same side
What nerve supplies the Splenius Capitis?
Dorsal rami of middle cervical spinal nerves
Is the Splenius Capitis free to study in OIANS?
The Splenius Capitis is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Trunk is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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