The structure that lies posterior to the anterior scalene muscle in the scalene gap is the brachial plexus. The brachial plexus is a network of nerves that originates from the spinal cord in the neck and travels down the arm. It is responsible for innervating the muscles and providing sensation to the upper limb.
The scalene muscles, including the anterior scalene muscle, play an important role in maintaining the stability and movement of the neck and shoulder. They are located in the side of the neck, deep to the platysma muscle and superficial to the cervical vertebrae.
The scalene muscles form the boundaries of the scalene triangle, which is an anatomical space in the neck. The anterior scalene muscle forms the anterior border of this triangle, while the posterior border is formed by the scalenus medius muscle. The inferior border is formed by the first rib.
Within the scalene triangle, the brachial plexus passes through a small gap called the scalene gap. This gap is formed between the anterior and middle scalene muscles. The brachial plexus travels posterior to the anterior scalene muscle and anterior to the middle scalene muscle as it passes through this space.
The brachial plexus is formed by the ventral rami of the lower cervical and upper thoracic nerves. These nerves come together and form a complex network of nerves that supply the upper limb. The brachial plexus is divided into roots, trunks, divisions, cords, and branches.
In the scalene gap, the brachial plexus is vulnerable to compression or entrapment. This can occur due to various reasons, such as tightness or hypertrophy of the scalene muscles, traumatic injury, or anatomical variations. Compression of the brachial plexus can result in symptoms such as pain, numbness, tingling, weakness, or loss of function in the upper limb.
As a healthcare professional, I have encountered patients with brachial plexus compression in the scalene gap. These patients often present with symptoms such as neck and shoulder pain, radiating pain down the arm, weakness, and sensory disturbances. Diagnosis is typically made through a combination of clinical examination, imaging studies, and nerve conduction studies.
Treatment for brachial plexus compression in the scalene gap may involve conservative measures such as physical therapy, stretching exercises, and anti-inflammatory medications. In some cases, more invasive interventions such as corticosteroid injections or surgical decompression may be necessary.
The structure that lies posterior to the anterior scalene muscle in the scalene gap is the brachial plexus. Understanding the anatomy and potential compression of the brachial plexus in this area is crucial for healthcare professionals in diagnosing and managing conditions affecting the upper limb.