Obliquus inferior capitis muscle
Musculus obliquus inferior capitis
Obliquus capitis inferior is a thick suboccipital muscle joining the spine of the axis to the atlas and turning the head.
At a glance
- English
- Obliquus inferior capitis muscle
- Latin (TA2)
- Musculus obliquus inferior capitis
- System
- Muscle
- Region
- Neck
- Side
- Paired, left and right
About the obliquus inferior capitis muscle
Obliquus capitis inferior is the bigger of the paired oblique muscles high at the back of the neck and one of the four suboccipital muscles. It lies deep to semispinalis capitis and trapezius. Despite its name it is the only muscle of this group that does not reach the skull: both its ends are on the first two vertebrae.
It starts on the side of the axis spine, near its tip, and from the nearby lamina. The thick belly runs outwards and a little upwards and ends on the lower rear part of the atlas transverse process. With obliquus capitis superior and rectus capitis posterior major it frames the suboccipital triangle, forming its lower side. The vertebral artery and the suboccipital nerve lie in the floor of this triangle, and the greater occipital nerve curls round the lower border of the muscle.
Its main action is to turn the atlas, and with it the skull, towards the same side at the atlanto-axial joint, where most head rotation takes place. Because it spans only one joint and is packed with muscle spindles, it is also thought to sense and fine-tune the position of the head on the neck. Tissue bridges connecting it and its neighbours to the dura mater have been described and may help keep the dura from folding during movement.
It is supplied by the suboccipital nerve, the dorsal ramus of the first cervical spinal nerve, with some fibres from the greater occipital nerve, and receives blood from the vertebral and occipital arteries. Tightness of the suboccipital muscles is a common feature of neck-related headache, and the greater occipital nerve can be irritated where it passes this muscle.
Attachments, action and supply
- Origin
- Spinous process and adjacent lamina of the axis (C2).
- Insertion
- Lower rear part of the atlas transverse process (C1).
- Action
- Rotates the atlas and head to the same side at the atlanto-axial joint.
- Nerve supply
- Suboccipital nerve (dorsal ramus of C1).
- Blood supply
- Vertebral and occipital arteries.
Anthromica
See the obliquus inferior capitis muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
