Obliquus capitis inferior is the largest suboccipital muscle and the primary rotator of C1 on C2. It is unique in not attaching to the skull (unlike the other three suboccipital muscles). The greater occipital nerve (C2 dorsal ramus) passes inferior to it.
| Origin | Spinous process of the axis (C2) |
|---|---|
| Insertion | Transverse process of the atlas (C1) |
| Nerve Supply | Suboccipital nerve — dorsal ramus of C1 |
| Blood Supply | Vertebral artery muscular branches |
| Actions | Rotates the atlas on the axis — produces ipsilateral head rotation; The primary C1-C2 rotation muscle — responsible for 50% of total cervical rotation |
|---|
Obliquus capitis inferior entrapment of the greater occipital nerve produces occipital neuralgia. The nerve runs in the triangle between obliquus capitis inferior (inferiorly), obliquus capitis superior (superolaterally), and rectus capitis posterior major (superomedially). Suboccipital muscle release targets this triangle in greater occipital nerve decompression surgery.
Not directly palpable. Assessed by the atlanto-axial rotation test — reduced C1-C2 rotation suggests pathology.
Muscle tension or entrapment at the suboccipital triangle producing greater occipital nerve compression and occipital neuralgia, managed by suboccipital muscle release or GON injection.
