Obliquus capitis inferior muscle

Template:Short description Template:Infobox muscle The obliquus capitis inferior muscle (Template:IPAc-en) is a muscle in the upper back of the neck. It is one of the suboccipital muscles. Its inferior attachment is at the spinous process of the axis; its superior attachment is at the transverse process of the atlas. It is innervated by the suboccipital nerve (the posterior ramus of first cervical spinal nerve). The muscle rotates the head to its side.

Despite what its name suggest, it is the only capitis (Latin: "head") muscle that does not actually attach to the skull.

Anatomy

The obliquus capitis inferior is one of the suboccipital muscles (and the only one of these to have no attachment to the skull).<ref name="Moore-20112">Template:Cite book</ref> It is larger than the obliquus capitis superior muscle. It forms the inferolateral boundary of the suboccipital triangle.<ref name=":224">Template:Cite book</ref>

The muscle extends laterally and somewhat superiorly from its inferior attachment to its superior attachment.<ref name=":224" />

Attachments

its inferior attachment is at the lateral<ref name=":224" /> external aspect of the bifid spinous process<ref name=":022">Template:Cite book</ref> of the axis (cervical vertebra C2)<ref name=":224" /><ref name=":022" /> (inferior to the attachment of the rectus capitis posterior major muscle<ref name=":022" />) and the lamina of the axis.<ref name=":224" />

Its superior attachment is at (the inferoposterior aspect of<ref name=":224" />) the transverse process of the atlas (cervical vertebra C1).<ref name=":224" /><ref name=":022" />

Innervation

The muscle receives motor innervation from the suboccipital nerve (the posterior ramus of cervical spinal nerve C1).<ref name=":022" /><ref name=":224" />

Relations

It lies deep to the semispinalis capitis and trapezius muscles.Template:Citation needed

Actions/movements

The muscle acts to rotate the atlas<ref name=":022" /> (and thus<ref name=":022" /> the head) ipsilaterally.<ref name=":022" /><ref name=":224" /> It acts together with the rectus capitis posterior major muscle.<ref name=":224" />

Function

The muscle is responsible for rotation of the head and first cervical vertebra (atlanto-axial joint).<ref name=":022" />

The obliquus capitis inferior muscle, like the other suboccipital muscles, has an important role in proprioception. This muscle has a very high density of Golgi organs and muscle spindles which accounts for this.<ref>Template:Cite journal</ref> It is believed that proprioception may be the primary role of the inferior oblique (and indeed the other suboccipital muscles), allowing accurate positioning of the head on the neck.Template:Citation needed

Additional images

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  Position of obliquus capitis inferior muscle (shown in red).
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  Close up. Vertebral column, occipital bone and obliquus capitis inferior muscle. The muscle arises from the apex of the spinous process of the axis and insert into the lower and back part of the transverse process of the atlas.
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  Obliquus capitis inferior's relationship to other suboccipital muscles.