Overview
The suboccipital triangle is an area bordered by three of the suboccipital muscles.
Boundaries
- Superomedial: Rectus capitus posterior major
- Superolateral: Obliquus capitus superior
- Inferior: Obliquus capitus inferior
- Floor: Posterior atlanto-occiptal membrane and posterior arch of the C1 vertebrae (atlas)
- Roof: Semispinalis capitus
Muscles
The suboccipital muscles are a group of four muscles situated underneath the occipital bone, located within the suboccipital compartment of the neck; deep to the sternocleidomastoid, trapezius, splenius and semispinalis muscles. The purpose of these muscles is to provide fine motor function in movements of the head. The actions of trapezius, sternocleidomastoid and other larger muscles that move the head are refined by the relatively small suboccipital triangle muscles.
Rectus Capitis Posterior Major
The rectus capitis posterior major is the larger of the rectus capitis muscles. It is located laterally to the rectus capitis posterior minor.
- Attachments: Originates from the spinous process of the C2 vertebrae (axis), and inserts into the lateral part of the inferior nuchal line of the occipital bone.
- Actions: Extension and rotation of the head.
- Innervation: Suboccipital nerve (posterior ramus of C1).
Obliquus Capitis Inferior
As its name suggests, the obliquus capitis inferior is the most inferiorly positioned of the suboccipital muscles. Additionally, it is the only capitis muscle that has no attachment to the cranium.
- Attachments: Originates from the spinous process of the C2 vertebra, and attaches into the transverse process of C1.
- Actions: Extension and rotation of the head.
- Innervation: Suboccipital nerve (posterior ramus of C1)
Obliquus Capitis Superior
The obliquus capitis superior is located laterally in the suboccipital compartment.
- Attachments: Originates from the transverse process of C1 and attaches into the occipital bone (between the superior and inferior nuchal lines).
- Actions: Extension of the head.
- Innervation: Suboccipital nerve (posterior ramus of C1)
Contents
- Third part of the vertebral artery
- Suboccipital venous plexus
- Suboccipital nerve – posterior ramus of nerve C1