The obliquus capitis inferior muscle (/əˈblaɪkwəs ˈkæpᵻtᵻs/) is the larger of the two oblique muscles of the neck. It arises from the apex of the spinous process of the axis and passes laterally and slightly upward, to be inserted into the lower and back part of the transverse process of the atlas.

DM: Digastric muscle; EAC: External auditory canal; IOM: Obliquus capitis inferior muscle; LEM: levator scapulae muscle; MP: mastoid process; SOM: Obliquus capitis superior muscle.

It lies deep to the semispinalis capitis and trapezius muscles.

The muscle is responsible for rotation of the head and first cervical vertebra (atlanto-axial joint).

It forms the lower boundary of the suboccipital triangle of the neck.

The naming of this muscle may be confusing, as it is the only capitis (L. “head”) muscle that does NOT attach to the cranium.