Suboccipital muscle group

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The suboccipital muscle group contains four paired muscles, three of which pairs belong to the suboccipital triangle. These muscles all lie below the occipital bone and are responsible for postural support of the head, as well as extension, lateral flexion and rotation. As these muscles are small and act in unison, they will be discussed in this single article, rather than individual articles.

Gross anatomy

The suboccipital triangle is paired and consists of three muscles: rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior. The function of the muscles in this triangle are to extend and rotate the head. The 3 boundaries are:

  • rectus capitis posterior major
  • obliquus capitis superior
    • superolateral boundary of the occipital triangle
    • origin: upper surface of the transverse process of the atlas
    • insertion: lateral half of the inferior nuchal line on the occipital bone
    • action: lateral flexion of the head
  • obliquus capitis inferior
    • inferolateral boundary of the occipital triangle
    • larger of the two obliquus muscles
    • origin: outer surface of the bifid spinous process of the axis, below the rectus capitis posterior major
    • insertion: transverse process of the atlas
    • action: rotate the head on the atlanto-axial joint ipsilaterally

The floor is formed by the posterior arch of the atlas and the posterior atlanto-occipital membrane. The roof is the  semispinalis muscle, greater occipital nerve (C2), occipital artery. The triangle contains the vertebral artery and suboccipital nerve (C1).

The rectus capitis posterior minor is separate to the occipital triangle and lies deep to the rectus capitis posterior major.

  • rectus capitis posterior minor
    • origin: tubercle on the posterior arch of the atlas
    • insertion: medial part of the inferior nuchal line of the occipital bone
    • action: weak extender of the head

Blood supply

Innervation

  • suboccipital nerve: dorsal ramus of the first cervical spinal nerve

Related pathology

Whiplash injuries can cause muscle spasm and disruption between the normal agonist/antagonist relationship between the left and right suboccipital muscle groups .