Splenius capitis
A flat bandage-like muscle wrapping the back of the neck, rotating the head to its own side.
- Type
- Muscle
- Region
- Neck
- Standard name
- m. splenius capitis
- Origin
- Lower half of the nuchal ligament and the spinous processes of the seventh cervical and upper thoracic vertebrae
- Insertion
- Mastoid process and the lateral third of the superior nuchal line
- Actions
- neck extensionneck rotationneck sidebending
- Verify
- TA2 2273 TA98 A04.3.02.103
What it is
A broad flat muscle covering the back and side of the neck, running upward and outward from the spine to the base of the skull, beneath trapezius. Splenion is Greek for a bandage, which is what it looks like wrapped around the deeper neck muscles.
Splenius cervicis lies below and lateral to it, with the same fibre direction, attaching to the upper cervical vertebrae rather than the skull. The two are usually described together.
What it does
Both sides together extend the neck — tip the head back.
One side alone rotates the head towards its own side and side-bends it the same way. This is worth contrasting with sternocleidomastoid, which rotates the head to the opposite side. Turning your head to the right uses the right splenius capitis and the left sternocleidomastoid together, one pulling from behind and one from in front.
What loads it
Holding the head up against gravity, which it does continuously, and resisted neck extension and rotation.
What is commonly got wrong about it
That head-turning is one muscle's job. It is a coordinated pair pulling from opposite sides, front and back.
That neck extensors are trained by shrugging. Shrugging elevates the shoulder blade. The neck extensors hold the head, which is a different job with a different load.
That the weight of the head is a problem to be solved. Holding it up is what these muscles are for, and they do it all day without complaint in most people.