Splenius capitis muscleSplenius capitis is one of the deep, or intrinsic muscles of the back of the neck. It is located in the superficial layer, meaning that it is closer to the surface compared to the rest. The name originates from the Greek word ‘Splenion’ meaning bandage, and the Latin word ‘caput’ meaning head, hence it has a bandage-like appearance.
Splenius capitis extends from the spinous processes of the last cervical and first three thoracic vertebrae until the occipital and temporal bones of the skull. As a result, it acts as an extensor and lateral flexor of the neck, and assists with its rotation. The muscle also forms part of the floor of the posterior triangle of the neck.
In this article we will discuss the gross and functional anatomy of the splenius capitis muscle.
|Origin||Spinous processes of vertebrae C7-T3, nuchal ligament|
|Insertion||Lateral superior nuchal line of occipital bone, mastoid process of temporal bone|
Bilateral contraction: Extends head/neck
Unilateral contraction: Lateral flexion and rotation of head (ipsilateral)
|Innervation||Lateral branches of posterior rami of spinal nerves C2-C3|
|Blood supply||Muscular branches of occipital artery|
Origin and insertion
The badge-like splenius capitis arises from the lower half of the nuchal ligament and spinous processes of the seventh cervical to the third thoracic vertebrae (C7-T3).
The muscle fibers run superiorly and laterally, in order to insert into the mastoid process of the temporal bone. The mastoid process is a pyramidal shaped eminence on the base of the skull and is a pneumatised bone due to the mastoid air cells. The muscle also inserts in part onto the external surface of the occipital bone, below the lateral section of the superior nuchal line.
Splenius capitis overlies semispinalis capitis and longissimus capitis and it is located underneath the trapezius muscle. The superior part of splenius capitis is covered by the sternocleidomastoid muscle and forms part of the floor of the posterior triangle of the neck.
This triangle is formed by the posterior border of sternocleidomastoid, the anterior border of trapezius and the superior margin of the clavicle as the base. The accessory nerve passes obliquely across this space, and innervates the sternocleidomastoid muscle, and passes through the muscle to innervate the trapezius. At the lower part of the triangle is where the supraclavicular, transverse cervical (cutaneous branches of the cervical plexus) and superior part of the brachial plexus can be found. A sequence of lymph nodes is also located running along the posterior border of sternocleidomastoid.
The innervation to the muscle arises from the lateral branches of posterior rami of second and third cervical spinal nerves (C2-C3).
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The blood supply to the muscle arises from the muscular branches of the occipital artery, a branch of the external carotid artery.
Biletaral contraction of splenius capitis results in extension of the head on the neck. When it contracts unilaterally, it acts in synergy with the contralateral sternocleidomastoid muscle, resulting in lateral flexion and rotation of the head towards the ipsilateral side. Therefore, splenius capitis acts as a shaker of the head. Other muscles that extend and rotate the head include semispinalis capitis and semispinalis cervicis, which also flex the head laterally. The superior portion of trapezius also acts as a lateral flexor of the neck.
If you want to find out more about splenius capitis, take a look at the following resources:
- The splenius capitis is a deep muscle of the neck.
- It originates from the lower half of the nuchal ligament and the spinous processes of the 7th cervical vertebra and the superior 3 thoracic vertebrae.
- It inserts onto the mastoid process of the temporal bone.
- It acts to laterally flex and rotate the neck.
- It is innervated by the posterior rami of the 3rd and 4th cervical spinal nerves.
- It forms part of the floor of the posterior triangle of the neck.