Posterior intertransversarii colli muscles
Intertransversarii are short slips of muscle that connect adjacent vertebral transverse processes in the cervical and lumbar spinal regions. Intertransversarii exist in the thoracic region of the spine as well, extending only between the T10 to L1 vertebral levels. Together with interspinales and levatores costarum, intertransversarii comprise the deepest layer of the deep (autochtone) back muscles.
Cervical intertransversarii, or intertransversarii colli, is a group of seven pairs of muscles located on the lateral aspect of the cervical spine. Each cervical intertransversarii consists of an anterior and a posterior component, with the posterior intertransversarii colli being further divided into medial and lateral slips. Their main function is to aid lateral flexion of the cervical spine. Together with other muscles of the neck region, posterior intertransversarii colli assist in stabilization of the cervical spine.
|Origin||Transverse processes of cervical vertebrae|
|Insertion||Transverse processes of adjacent vertebrae|
|Action||Assists in lateral flexion of the spine; Stabilizes cervical spine|
|Innervation||Posterior and anterior rami of spinal nerves|
|Blood supply||Ascending cervical artery|
In this article, we will discuss the anatomy and function of the posterior intertransversarii colli muscles.
Posterior intertransversarii colli muscles run on both sides of the cervical spine. They consist of seven pairs of short muscles situated between the transverse processes of adjacent cervical vertebrae; from the atlas (C1 vertebra) to the first thoracic vertebra (T1).
Posterior intertransversarii colli muscles originate from the superior border of the transverse processes of cervical vertebrae. The muscle fibers run distally and divide into two slips of muscle; medial and lateral. The medial slip of the posterior component is known as the intertransverse muscle ‘proper’. These 'proper' slips can further subdivide into medial and lateral components between which the dorsal rami of cervical spinal nerves pass. The muscle fibers insert onto the inferior border of the transverse processes of the adjacent superior vertebra
The medial 'proper' and lateral slips of posterior intertransversarii are innervated by the posterior and anterior rami of cervical spinal nerves respectively. These muscles are vascularized by the ascending cervical artery, which is a small branch of the inferior thyroid artery from the thyrocervical trunk of the subclavian artery.
To this day, the exact function of these muscles is not fully clarified. However, it is well established that these small muscles play a significant role in supporting other superficial muscles to act more efficiently. Due to their location, they assist lateral flexion of the neck and provide stability for the cervical spine. Cervical intertransversarii also have a role in monitoring, and adjusting for, movements of the cervical spine due to the presence of high-density muscle spindles that act as proprioceptors.
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