Scalene muscle

Scalene Muscles

The anterior scalene muscle (in red).

The Scalene Muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the brachial plexus and the cervical spinal nerves C3 and C4.

Structure

The scalene muscles originate from the transverse processes of the cervical vertebrae of C2 to C7 and insert at the first and second ribs. This allows them to perform their main function, which is to elevate the first and second ribs and aid in respiration.

Anterior Scalene

The Anterior Scalene originates from the transverse processes of the lower six cervical vertebrae and inserts onto the scalene tubercle on the inner border of the first rib.

Middle Scalene

The Middle Scalene is larger than the anterior scalene and originates from the transverse processes of the lower six cervical vertebrae and inserts onto the upper surface of the first rib.

Posterior Scalene

The Posterior Scalene is the smallest of the three and originates from the transverse processes of the lower six cervical vertebrae and inserts onto the outer surface of the second rib.

Function

The scalene muscles, when acting together, elevate the first and second ribs, aiding in inspiration. They also perform lateral flexion of the neck when acting individually.

Clinical Significance

Scalene muscles are clinically significant as they can be implicated in Thoracic Outlet Syndrome, a condition that can cause pain in the neck and shoulder, numbness and tingling of the fingers, and a weak grip.

See Also

• Neck Muscles
• Respiratory Muscles
• Thoracic Outlet Syndrome