Anterior intertransversarii colli muscles
Intertransversarii are short back muscles that connect adjacent transverse processes of vertebrae. For the most part, they are located in the cervical and lumbar regions of the spine, although small muscular slips are present in the lower thoracic region as well. Together with interspinales and levatores costarum, intertransversarii comprise the deepest layer of the deep (autochtone) back muscles.
Cervical intertransversarii, or intertransversarii colli muscles, are better developed than their lumbar counterparts. They consist of seven pairs of anterior and posterior intertransversarii muscles, each found between adjacent transverse processes from vertebrae C1 to T1 on either side of the vertebral column. Anterior intertransversarii colli are usually absent from the first intertransverse interval (between the atlas and axis), but rather fill in the intertransverse spaces from C2 to T1. Their functions are to assist in lateral flexion and stabilization of the cervical spine.
|Origin||Transverse processes of cervical vertebrae|
|Insertion||Transverse processes of adjacent vertebrae|
|Action||Assists in lateral flexion of the cervical spine; Stabilises cervical spine|
|Innervation||Anterior rami of spinal nerves|
|Blood supply||Occipital, deep cervical and vertebral arteries|
This article will discuss the anatomy and function of the anterior intertransversarii colli muscles.
Anterior intertransversarii colli originate from the anterior tubercles of transverse process of one cervical vertebra and insert onto the anterior tubercle of transverse process of the adjacent vertebra. They lie deep to the posterior cervical intertransversarii, from which they are separated by the anterior rami of cervical spinal nerves. Located anterior and lateral to the cervical intertransversarii are the longus cervicis muscles and scalene muscles, respectively.
Intertransversarii are homologous to certain muscles of the ventral trunk due to a common pattern of attachments and innervation. Anterior intertransversarii colli are homologous to the intercostal muscles and just like them, they are innervated by the anterior rami of spinal nerves. Blood supply to anterior intertransversarii colli comes from branches of the occipital, deep cervical and vertebral arteries.
The function of intertransversarii muscles is yet to be fully determined. It is clear that they are not strong enough to produce prime movements of the spine, but it has been suggested that they assist sternocleidomastoid, scalenes, splenius capitis and cervicis in lateral flexion of the head on the neck to the same side when contracting unilaterally. In addition, research suggests that these muscles contain many muscle spindles, indicating that they play an important role in proprioception and consequential stabilization of the cervical spine during body and trunk movements.
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