The rectus capitis posterior minor (or rectus capitis posticus minor) is a muscle in the upper back part of the neck. It is one of the suboccipital muscles. Its inferior attachment is at the posterior arch of atlas; its superior attachment is onto the occipital bone at and below the inferior nuchal line. The muscle is innervated by the suboccipital nerve (the posterior ramus of first cervical spinal nerve). The muscle acts as a weak extensor of the head.

Anatomy

The rectus capitis posterior major muscle is one of the suboccipital muscles. The muscle extends vertically superior-ward from its inferiro attachment to its superior attachment. The muscle becomes broader superiorly.

Attachments

The inferior attachment is (by a narrow tendon) onto the posterior tubercle of the posterior arch of atlas. Its superior attachment is onto the medial portion of the inferior nuchal line and the external surface of the

occipital bone The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lob ...

inferior to it (between this line superiorly and the

foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...

inferiorly). The muscle usually also additionally attaches onto the posterior atlantooccipital membrane (which is in turn attached onto adjacent dura mater of the spinal canal).

Innervation

The muscle receives motor innervation from the suboccipital nerve (the posterior ramus of cervical spinal nerve C1).

Variation

The muscle of either side may be doubled (along its length).

Actions/movements

The muscle is a weak extensor of the head. The synergists are the rectus capitis posterior major and the obliquus capitis superior.

Research

Role in headache

Connective tissue bridges were noted at the atlanto-occipital joint between the rectus capitis posterior minor (RCPm) muscle and the dorsal spinal dura. Similar connective tissue connections of the rectus capitis posterior major have been reported recently as well. The perpendicular arrangement of these fibers appears to restrict dural movement toward the spinal cord. The ligamentum nuchae was found to be continuous with the posterior cervical spinal dura and the lateral portion of the occipital bone. Anatomic structures innervated by

cervical nerve A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into t ...

s C1-C3 have the potential to cause headache pain. Included are the joint complexes of the upper three cervical segments, the dura mater, and spinal cord. The dura-muscular (myodural) and dura-ligamentous connections in the upper cervical spine and occipital areas may provide anatomic and physiologic answers to the cause of the cervicogenic headache. The level of strain at which RCPm muscle fibers began to tear as a result of overstretching has been estimated to be 30%. This would be expected to put them at risk of injury during whiplash-type distortions when the occipitoatlantal (OA) joint is flexed upon impact. Tearing of the muscle fibers would result in fatty infiltration (FI) that would be expected to impact the functional relationship between the RCPm muscles and the pain sensitive spinal dura. While FI and/or a reduction in the cross sectional area (CSA) of active muscle would not be expected to be the direct cause of chronic headache, it is known that muscle pathology will result in functional deficits. Pathologies in RCPm muscles in conjunction with the myodural bridge can compromise the normal functional relationship between the RCPm and the pain sensitive dura mater and result in referred head and neck pain. This could help to explain manipulation's efficacy in the treatment of cervicogenic headache.

Additional images

File:Rectus capitis posterior minor muscle animation small.gif, Position of rectus capitis posterior minor muscle (shown in red). Animation. File:Rectus capitis posterior minor muscle lateral.png , Lateral view of

human skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominen ...

(rectus capitis posterior minor shown in red.) File:Gray129.png, Occipital bone. Outer surface.

References

External links

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PTCentral
{{Authority control Muscles of the head and neck