Rectus capitis posterior minor muscle
Rectus capitis posterior minor muscle is a paired muscle located in the suboccipital compartment of the neck. It is part of the suboccipital muscle group which comprises four muscles in total, the other three being rectus capitis posterior major, obliquus capitis inferior and obliquus capitis superior.
Rectus capitis posterior minor (Latin ‘Musculus rectus capitis posterior minor’) means ‘lesser posterior straight muscle of the head’. True to this description, the muscle looks like a small pyramid extending straight on either side of the midline. It can help you extend the head on the neck and rotate your head side to side. Unfortunately, it can also be the direct culprit for many of your headaches!
In this article, we’ll explore the anatomy of rectus capitis posterior minor muscle.
|Origin||Posterior tubercle of atlas|
|Insertion||Medial part of inferior nuchal line of occipital bone|
|Action||Bilateral contraction - Atlantooccipital joint: Head extension|
|Innervation||Posterior ramus of spinal nerve C1 (suboccipital nerve)|
|Blood supply||Vertebral artery
Occipital artery (via the deep descending branch)
Origin and insertion
Rectus capitis posterior minor has a pyramidal shape. It originates from the posterior tubercle of atlas (C1) via a narrow and pointed tendon. The muscle travels in a superolateral direction, fanning out to a broader attachment onto the medial part of the inferior nuchal line located on the occipital bone.
Rectus capitis posterior minor is located in the suboccipital muscle compartment. This compartment is located inferior to both the external occipital protuberance and inferior nuchal line of the occipital bone. Rectus capitis posterior minor is the most medial suboccipital muscle, located on either side of the midline. Rectus capitis posterior major is located lateral and superficial to it. Rectus capitis posterior minor is covered by semispinalis capitis, while the posterior atlantooccipital membrane is situated deep to it. The membrane is directly attached to the overlying rectus capitis posterior minor muscle by a soft tissue structure.
Rectus capitis posterior minor is innervated by the suboccipital nerve, also called the posterior ramus of the first (C1) spinal nerve. The suboccipital nerve reaches rectus capitis posterior minor by traveling between the cranium and the atlas.
Rectus capitis posterior minor receives arterial blood from the vertebral artery and deep descending branch of the occipital artery.
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Rectus capitis posterior minor extends across the atlantooccipital joint. Thus when both muscles contract bilaterally they act to extend the head on the neck. This action has an important postural role, stabilizing the head while standing and during various body movements. The muscle also stabilizes the atlantooccipital membrane.
If you want more explanations about general body movements or information about the main muscles of the trunk, take a look below:
Although rectus capitis posterior minor is a small muscle, its relations and location make it very important clinically. As you know, the muscle overlies the posterior atlantooccipital membrane, and is directly connected to it by a soft tissue attachment. In turn, the atlantooccipital membrane is connected to the surrounding dura mater via myodural bridges. Studies have shown that various changes of the rectus capitis posterior minor specifically (hypertrophy, tension, atrophy, trauma) can irritate the highly sensitive dura mater by acting via the myodural bridges. Resultant pain can manifest as chronic headaches.