Spinalis Capitis
Back · Trunk
Spinalis capitis is the head-reaching part of the spinalis, the most medial of the three erector spinae columns. It arises from the spinous processes of the upper thoracic and lower cervical vertebrae and, in most people, is poorly defined because it blends intimately with the neighbouring semispinalis capitis. Its fibres ascend to attach to the occipital bone between the superior and inferior nuchal lines. Working with the other posterior neck muscles, it extends the head and neck. It is innervated by the posterior (dorsal) rami of the cervical spinal nerves. Because it lies so close to the midline and fuses with semispinalis capitis, it is often studied together with that larger muscle rather than in isolation.
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)
Remember spinalis capitis as the small, inconstant, most medial extensor that frequently merges with semispinalis capitis. Its defining feature is that it runs from spinous processes up to the occipital bone between the nuchal lines, so keep the word spinalis linked to spinous processes, which sets the whole spinalis column apart from the transverse-process origins of longissimus and semispinalis.
Because it is often indistinguishable from semispinalis capitis, study the pair together and let their shared occipital attachment and head-extension action reinforce each other. The practical takeaway is simple: spinalis capitis is a minor midline contributor to holding the head up, supplied by cervical dorsal rami, and its clinical importance is modest compared with the sturdier muscles it blends into.
Frequently asked questions
Where is the Spinalis Capitis located?
The Spinalis Capitis is a muscle of the Back group, located in the Trunk.
What is the origin of the Spinalis Capitis?
Spinous processes of the upper thoracic and lower cervical vertebrae (usually blended with semispinalis capitis)
What is the insertion of the Spinalis Capitis?
Occipital bone between the superior and inferior nuchal lines
What movements does the Spinalis Capitis produce?
Extends the head and neck
What nerve supplies the Spinalis Capitis?
Posterior (dorsal) rami of cervical spinal nerves
Is the Spinalis Capitis free to study in OIANS?
The Spinalis 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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