The sternocleidomastoid muscle (SCM) is a pair of long, thick muscles located on the sides of the neck, often visible when the head is turned. Named for its attachment points, the SCM runs diagonally from the mastoid process behind the ear down to the sternum (breastbone) and clavicle (collarbone). The SCM performs several important functions, including rotating the head to the opposite side, tilting the head laterally, and flexing the neck forward. Because of its position and constant use, the SCM is susceptible to strain and tension, making SCM pain a common experience.
Common Causes Related to Daily Habits
Chronic, low-level strain from everyday activities is the most frequent cause of SCM pain. The modern habit of looking down at phones or computer screens, often termed “Tech Neck,” forces the head forward. This forward head posture significantly lengthens the SCM and increases the mechanical load, forcing the muscle to work harder to keep the head upright.
Poor ergonomics at a desk also contribute to continuous strain. If a monitor is too low or too far to one side, the SCM must continuously contract to hold the head in an unnatural position. Sustained static positions, like holding a phone between the ear and shoulder or sitting for long periods, prevent the muscle from relaxing. Over time, this sustained tension leads to muscle fatigue and pain along the SCM.
Incorrect sleeping posture is another major contributor, particularly sleeping on the stomach. This position requires the head to be fully rotated to one side for hours, placing the SCM under prolonged torsion. Using a pillow that is too high or too flat can push the neck out of neutral alignment, causing muscle fibers to be overstretched or compressed.
Emotional and psychological stress also manifests physically in the neck and shoulder muscles. When a person experiences stress, they often unconsciously tense the muscles, leading to chronic clenching. This constant, low-grade contraction reduces blood flow and oxygen to the SCM tissue, accelerating fatigue and resulting in a dull, persistent ache.
Acute Strain and Overexertion
While chronic habits cause gradual discomfort, acute SCM pain often results from a sudden, forceful event that overstretches or tears muscle fibers. Whiplash injury, frequently associated with car accidents, is a common mechanism for acute SCM strain. During a collision, the head is rapidly accelerated forward and then snapped backward, subjecting the neck muscles to powerful forces.
The SCM plays a significant role in stabilizing the head during these sudden movements. The rapid, unexpected hyperextension and hyperflexion can cause a severe strain or micro-tear in the muscle, leading to immediate pain, stiffness, and reduced range of motion. Even minor bumps can cause this reaction, sometimes resulting in delayed onset of symptoms.
Sudden, forceful head movements outside of a traumatic event can also acutely strain the SCM. Examples include quickly turning the head during sports or accidentally jerking the head while exercising. Performing new or intense physical activities that heavily engage the neck, such as certain weightlifting movements or intense abdominal exercises, can also lead to overexertion. The SCM is activated during sit-ups to pull the head and neck forward, and an uncoordinated movement can place excessive strain on the muscle.
Identifying and Addressing Trigger Points
A specific source of SCM pain is the development of myofascial trigger points, often described as hyperirritable spots or “knots” within the muscle tissue. These points develop when muscle fibers remain contracted in a localized area due to chronic tension, injury, or overuse. Trigger points in the SCM are unique because they frequently cause referred pain, meaning the discomfort is felt in a location different from the muscle itself.
The SCM has two main divisions—the sternal and clavicular—each with distinct referral patterns.
Sternal Division Referral
Trigger points in the sternal division often refer pain to the face, causing discomfort around the eye, the cheek, or the throat. This pain sometimes mimics sinus congestion or atypical facial neuralgia.
Clavicular Division Referral
Trigger points in the clavicular division commonly refer pain to the forehead, deep inside the ear, or behind the ear. These symptoms are often confused with tension headaches or ear infections.
SCM trigger points can also be linked to symptoms beyond simple pain, such as dizziness, lightheadedness, or visual disturbances like blurred vision. These diverse symptoms arise because the muscle is closely involved with neck structures that influence balance and sensory input. Gentle palpation along the length of the muscle can help locate these tender nodules, which often reproduce the distant referred pain sensation. Releasing these tight bands is a direct path to relieving chronic, seemingly unrelated headaches or facial pain.
Immediate Home Relief and Medical Consultation
For non-traumatic SCM pain resulting from tension or minor strain, several strategies can provide relief. Applying heat, such as a warm compress or heating pad, helps increase blood flow, promoting relaxation and reducing stiffness. Alternately, cold therapy, like an ice pack wrapped in a towel, can be used immediately after an acute strain to minimize inflammation and dull the pain sensation.
Gentle stretching is beneficial for lengthening contracted muscle fibers and restoring normal movement. A simple, effective stretch involves sitting upright and gently tilting the head toward one shoulder until a light pull is felt on the opposite side of the neck. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can manage both pain and inflammation in the short term.
While most SCM pain resolves with self-care, certain “red flags” signal the need for professional medical evaluation. Any pain that follows significant trauma, such as a serious fall or car accident, should be assessed immediately to rule out structural damage. Consult a healthcare provider if the pain is accompanied by a fever, a severely stiff neck, or difficulty swallowing, as these symptoms can indicate a serious infection or other underlying condition. Persistent pain that does not improve after several days of home treatment, or pain accompanied by severe dizziness, persistent nausea, or neurological changes, also warrants a medical consultation.