Topics

Topic

design image
Rectus capitis posterior major muscle

The rectus capitis posterior major is a small but significant muscle located in the deep layer of the posterior neck, forming part of the suboccipital group. This muscle plays a crucial role in the fine motor control of head movement, particularly extension and rotation at the atlanto-occipital joint. Its anatomical relationships are vital for understanding various clinical conditions, especially those involving cervicogenic headaches and whiplash injuries.

Synonyms:

  • Rectus capitis posterior major muscle

  • Major posterior rectus capitis muscle

  • RCP major

Function:

  • Extends the head at the atlanto-occipital joint

  • Rotates the head to the same (ipsilateral) side

  • Stabilizes the atlanto-occipital joint during movement

Origin:

  • Spinous process of the axis (C2 vertebra)

Insertion:

  • Lateral part of the inferior nuchal line of the occipital bone

Nerve Supply:

  • Suboccipital nerve (dorsal ramus of C1 spinal nerve)

Arterial Supply:

  • Branches of the vertebral artery

  • Deep descending branch of the occipital artery

Venous Drainage:

  • Deep cervical vein

  • Vertebral vein plexus

MRI Appearance:

  • T1-weighted images:
    The rectus capitis posterior major appears as a well-defined muscle of intermediate (isointense) signal intensity relative to other skeletal muscles.

  • T2-weighted images:
    The muscle remains isointense to muscle tissue, but edema, injury, or pathology may increase signal intensity.

  • STIR sequence:Muscle shows low signal intensity in healthy tissue; hyperintensity is seen if there is edema, inflammation, or acute injury.

CT Appearance:

  • Appears as a soft tissue density posterior and lateral to the posterior arch of C1, deep to the trapezius and splenius capitis muscles. It is best visualized in the axial and sagittal planes, with clear delineation in cases of muscle injury or atrophy.

MRI images

Rectus capitis posterior major muscle AXIAL MRI IMAGE