The posterior scalene is one of the scalene muscles of the neck, and is the smallest and the deepest among them. It originates from the posterior tubercles of the transverse processes of C5-C7 and attaches to the second rib. Its function is mainly to elevate the second rib and ipsilateral lateral flexion of the neck.
The posterior scalene is innervated by the anterior rami of C6-C8, and is largely supplied with blood by the ascending cervical branch of the inferior thyroid artery.
In addition to its primary kinetic function of elevation of the second rib and ipsilateral lateral flexion of the neck, the posterior scalene can also contribute to the movement of the neck in many other ways. For example, it can assist in flexion and lateral flexion of the neck and shoulder by working symmetrically with the other scalene muscles, and it can also support in the stabilization of the neck. It has also been noted that the posterior scalene can play a role in the dynamic support of the thoracic region when the arms are working in movement.
The posterior scalene, like other muscles of the neck, is very important in the stabilization of the cervical fascia - a continuous fibrous sheath connecting the muscles in the neck and shoulder area. The cervical fascia helps to support the head and neck in its upright position, while also helping to protect the neck from injury. Consequently, any damage to the posterior scalene can have a significant impact on the stability of the cervical fascia, as well as on the overall stability of the neck and shoulder.
Beyond the implications of the posterior scalene for the cervical fascia, the posterior scalene also has implications for the thoracic region. It is important to note that the posterior scalene muscles are directly related to the mobility of the intercostal muscles, which control the rib cage and support the thoracic cavity. Consequently, any damage to the posterior scalene can have a significant impact on the mobility of the intercostal muscles, and in turn, on the stability of the thoracic cavity.
Further, the posterior scalene can also play a role in the movements of the head in various directions. As the cervical muscles control the movement of the head and neck, any damage to the posterior scalene can result in limited or absent head movement. Consequently, it is important to maintain the posterior scalene in optimal condition for proper head and neck motion.
The posterior scalene can also contribute to the development of certain postural imbalances, such as kyphosis and forward head posture. If the posterior scalene is weak or overused, it can result in an inability to stabilise the thoracic region, leading to an increased curvature of the spine. Similarly, when the posterior scalene is weak, it can result in poor head posture, as the head is unable to be held in a neutral position.
Overall, the posterior scalene is an important muscle of the neck that can contribute to both static and dynamic postural support, as well as to the mobility of the head and thoracic region. It is essential to maintain the health of the posterior scalene in order to maintain proper neck and head movements, and to prevent the development of postural imbalances.
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