The scalene muscles are a group of deep, layered muscles located on the side of the neck, playing a significant role in both movement and breathing. This group consists of three distinct muscles on each side—the anterior, middle, and posterior—situated beneath the larger sternocleidomastoid muscle. They connect the cervical spine to the upper ribs, influencing the stability and function of the neck and upper chest.
Precise Anatomical Location
The three scalene muscles originate high up on the cervical vertebrae, specifically from the bony protrusions on C2 through C7. From these origins, the muscles descend toward the chest, attaching to the upper ribs. The anterior and middle scalenes insert onto the first rib, while the smallest of the group, the posterior scalene, attaches to the second rib.
This arrangement means the muscles create a triangular space in the lower neck. The anterior scalene and the middle scalene form a passage through which the brachial plexus and the subclavian artery must pass. The subclavian vein and the phrenic nerve, which controls the diaphragm, run in front of the anterior scalene. Their proximity to these vital structures explains why dysfunction can lead to widespread symptoms beyond simple neck pain.
Primary Roles in Movement and Respiration
The scalene muscles serve a dual purpose, contributing to both the movement of the neck and the mechanics of breathing. When only one side contracts, they facilitate lateral flexion, tilting the head toward the shoulder. They also assist in slight rotation of the head and, when both sides contract simultaneously, they contribute to the forward bending of the neck.
More notably, the scalenes are classified as accessory muscles of respiration, meaning they are not typically active during quiet, relaxed breathing. They become actively engaged during forced or labored inhalation, such as during intense exercise or respiratory distress. By contracting, they lift and elevate the first and second ribs, helping to increase the volume of the chest cavity so the lungs can take in a greater amount of air.
Common Symptoms and Conditions Linked to Scalene Dysfunction
When the scalene muscles become overworked, strained, or chronically tight, they can develop small, hyperirritable spots known as myofascial trigger points. These trigger points are notorious for causing referred pain, which is felt in an area distant from the actual muscle problem. A tight scalene muscle can generate deep, aching pain that radiates into the shoulder blade, down the arm, or even into the chest area, sometimes mimicking cardiac issues.
The most significant clinical condition associated with scalene dysfunction is Thoracic Outlet Syndrome (TOS), caused by compression of the nerves or blood vessels between the collarbone and the first rib. When the anterior and middle scalenes become hypertonic, they narrow the passageway, compressing the brachial plexus nerves. This compression leads to neurological symptoms like numbness, tingling, and weakness in the arm and hand. Tightness can also compress the subclavian artery, leading to circulatory symptoms such as a cold or pale hand.
Strategies for Maintaining Scalene Health
Maintaining the health of the scalenes primarily involves addressing posture and breathing patterns, which are the most common sources of chronic strain. Gentle stretching is one of the most effective self-care techniques, focusing on side-neck flexion away from the affected muscle to restore its resting length. A common stretch involves gently tilting the head to the opposite side while simultaneously depressing the shoulder on the side being stretched. Ergonomic adjustments, such as ensuring proper monitor height and avoiding a forward-head posture while sitting, are important to prevent chronic tension.
Proper breathing mechanics are also a powerful tool for reducing scalene overuse. When people breathe shallowly from the chest, they rely on accessory muscles like the scalenes, causing them to become constantly active and fatigued. Practicing diaphragmatic breathing, where the abdomen expands during inhalation, can retrain the body to use the primary breathing muscle, allowing the scalenes to relax.