Longus colli muscle
Longus colli is a paired muscle located on the anterior aspect of the vertebral column. As such, it is often referred to as an anterior prevertebral muscle together with longus capitis, rectus capitis anterior and scalenus anterior muscles. The longus colli muscle (‘long muscle of the neck’) is also known as longus cervicis since it spans the entire cervical spine and the first three thoracic vertebrae. By acting on the cervical vertebrae, longus colli is responsible for forward and lateral flexion of the neck, as well as rotation of the neck.
In this article, we will discuss the gross and functional anatomy of the longus colli muscle, together with some clinical points about it.
Superior part: Anterior tubercles of transverse processes of vertebrae C3-C5
Intermediate part: Anterior surface of bodies of vertebrae C5-T3
Inferior part: Anterior surface of bodies of vertebrae T1-T3
Superior part: Anterior tubercle of vertebra C1
Intermediate part: Anterior surface of bodies of vertebrae C2-C4
Inferior part: Anterior tubercles of transverse processes of vertebrae C5-C6
Bilateral contraction: Neck flexion
Unilateral contraction: Neck contralateral rotation, neck lateral flexion (ipsilateral)
|Innervation||Anterior rami of spinal nerves C2-C6|
|Blood supply||Branches of the vertebral, ascending pharyngeal and inferior thyroid arteries|
Origin and insertion
Longus colli runs the entire length of the neck; between the atlas (first cervical vertebra) and T3 (third thoracic vertebra). It is narrow at its superior and inferior ends and has a broad central section. The muscle consists of three parts which are attached to the vertebral column via tendinous slips:
- Superior oblique part - originates from the anterior tubercles of transverse processes of the third, fourth and fifth cervical vertebrae (C3-C5). The muscle ascends gradually in a superomedial direction to terminate on the anterior tubercle of anterior arch of atlas (C1).
- Vertical intermediate part - arises from the anterior surfaces of bodies of lower three cervical and superior three thoracic vertebrae (C5-T3). This muscle section inserts onto the anterior surface of bodies of second, third and fourth cervical vertebrae (C2-C4).
- Inferior oblique part - is the smallest section of the longus colli muscle. It arises from the anterior surfaces of bodies of first three thoracic vertebrae (T1-T3). It ascends superolaterally, terminating onto the anterior tubercles of transverse processes of fifth and sixth cervical vertebrae (C5-C6).
Longus colli, and all prevertebral muscles, are located deep to the prevertebral fascia, which is a layer of the deep cervical fascia of the neck. The muscle sits in the groove formed by the junction of the transverse process with the vertebral body, posterior to the retropharyngeal space. Therefore, the esophagus, trachea, thyroid gland and muscles of the hyoid (supra-, infra-) all sit anterior to it. Longus colli is bordered medially by the cervical plexus, brachial plexus and subclavian artery.
The medial border of scalenus anterior muscle lies close to the lateral border of longus colli. Here, a pyramidal space is formed, with the first section of the subclavian artery forming its base. The thoracic duct, cervical sympathetic trunk and first part of the vertebral artery (V1) all lie within this pyramidal space, passing between the longus colli and scalenus anterior muscles. The cervicothoracic ganglion also lies lateral to the longus colli muscle at the level of the seventh cervical vertebra.
Posterior to longus colli, one can find the carotid artery (including the carotid sheath) and phrenic nerve. These lie anterosuperiorly to the tubercle of transverse process of the sixth cervical vertebra. In addition, the inferior thyroid artery follows a medial course inferior to this tubercle and then descends along the longus colli muscle towards the thyroid gland.
The origins of the vertical and inferior parts of longus colli represent the deepest structures of the superior mediastinum.
The blood supply to longus colli comes from the muscular branches of the following three arteries:
- Vertebral artery
- Inferior thyroid artery
- Ascending pharyngeal artery
Longus colli muscle is innervated by the anterior rami of the second to sixth cervical spinal nerves (C2-C6).
Bilateral contraction of the muscle causes flexion of the neck (i.e. forward movement). Unilateral contraction, especially of the inferior oblique part, also results in weak lateral flexion (ipsilaterally) and contralateral rotation of the neck. However, some sources doubt the unilateral action of longus colli due to its almost mid-sagittal position. These actions have important stabilizing functions for the vertebral column, aligning the head and neck for upright posture. For further details about these movements and the muscles of the neck, take a look below:
Calcific tendinitis of the longus colli muscle is caused by deposition of calcium hydroxyapatite crystals in the tendons of the longus colli muscle. Symptoms include:
- Neck pain
- Pain on swallowing
- Abnormal swallow
- Reduced neck movement
Treatment includes non steroidal anti-inflammatory drugs.