The sternocleidomastoid muscle (SCM) is one of the largest and most prominent muscles in the neck. This paired muscle is located on both the right and left sides, just beneath the skin, giving the neck its defined shape. The SCM contributes to the movement and stabilization of the head.
Where is the SCL Muscle Located?
The sternocleidomastoid is a long muscle that travels diagonally across each side of the neck. It has two points of origin: the sternal head attaches to the top of the breastbone (manubrium), and the clavicular head connects to the inner collarbone (clavicle).
From these points, the fibers travel upward, merging into a single belly that inserts on the mastoid process. This is the bony bump you can feel behind your ear at the base of the skull. You can often see and feel this muscle when you turn your head to one side.
Key Functions of the SCL Muscle
The SCL muscle enables several head movements. When one side of the muscle contracts, it tilts the head toward that same side while rotating it to the opposite side. For instance, the right SCM contracts to turn your head to the left.
When both SCL muscles contract together, they flex the neck, bringing the chin toward the chest, and can also help extend the head. The SCL acts as an accessory muscle for breathing by helping lift the breastbone and collarbones during forceful inhalation. It also assists in stabilizing the head during activities like chewing.
Common Problems Affecting the SCL Muscle
Pain and tightness in the SCL are common, often from muscular tension. A frequent source is poor posture, particularly the forward-head position from using phones and computers, known as “text neck.” Other causes include sleeping in awkward positions, whiplash injuries, or overhead work like painting.
These issues can lead to trigger points, which are tight knots in the muscle that cause referred pain—discomfort felt in areas other than the muscle itself. In some cases, chronic SCL issues contribute to torticollis, a condition where the neck is persistently twisted to one side. Symptoms from trigger points can include:
- Headaches around the forehead and eye
- Pain in the cheek or jaw
- Earaches
- Dizziness
- Nausea
Basic Care and When to Seek Help
Maintaining good posture is a primary way to prevent SCL strain. An ergonomic workspace that keeps your screen at eye level can reduce chronic tension. Gentle stretching, such as slowly tilting your ear toward your shoulder, also helps maintain flexibility.
While self-care can manage minor tightness, consult a healthcare professional for persistent or severe problems. You should seek medical advice for intense pain, a significant loss of motion, or pain that follows an injury. A professional evaluation is also needed for neurological symptoms like dizziness, facial numbness, or tingling to rule out more serious conditions.