Sternocleidomastoid: the neck muscle behind headaches

The sternocleidomastoid (SCM) runs from behind the ear to the front of the chest and collarbone, and it is really two functional units. The sternal division — the vertical strap you see when you turn your head — refers pain across the cheek and temple, into the eye and the forehead, sometimes with a tearing or reddened eye. The clavicular division, thinner and closer to the collarbone, refers into the ear itself: a deep earache, a sense of fullness, and in Travell's classic description even postural dizziness and nausea when its trigger points are active (travell1942, simons2004).

What makes the SCM clinically treacherous is that the muscle itself rarely hurts. Patients are investigated for migraine, sinus infection, ear disease or vestibular problems while the source sits palpable a finger's width from the midline of the neck. A careful palpation that reproduces the familiar headache or ear sensation is the single most informative test (simons2004).

For the terminology and interpretation used here, compare What are trigger points?; Primary vs secondary trigger points; How to read referred pain maps. These guides distinguish the definition of a trigger point, its classification and the limits of a referred-pain map.

The SCM is a head-position muscle: it works constantly to keep a four-to-five-kilogram head balanced on the neck. Anything that pushes the head forward — a screen set too low or too far, hours of driving, reading in bed with the chin on the chest — keeps it in a sustained low-level contraction, the exact condition under which trigger points develop and persist (lucas2009).

It is also an accessory breathing muscle. People who breathe with the chest rather than the diaphragm recruit the SCM with every breath, thousands of times a day. Whiplash is the classic acute cause: the head is thrown forward and back faster than the muscle can protect it, and SCM trigger points are among the most persistent findings after rear-end collisions (travell1942). Coughing fits, sleeping on two high pillows and habitually holding a phone between shoulder and ear complete the usual list.

Sit or lie down and turn your head slightly to the opposite side: the sternal division stands out and can be pinched gently between thumb and index finger, away from the midline. Slide along it from behind the ear to the breastbone, a centimetre at a time. A trigger point feels like a tender, firm nodule inside a taut band, and sustained pressure on it for 30 to 90 seconds typically reproduces — and then eases — the headache or ear sensation you know (simons2004, cummings2001).

Two cautions matter here. First, the carotid artery runs deep and medial to the muscle: if you feel a pulse under your fingers, move laterally onto the muscle belly and never compress toward the midline. Second, treat one division at a time and re-test afterwards — turn your head, look up, note whether the ear fullness or the headache has changed — so you know the pressure is actually doing something.

Follow the release with the correction that keeps it away: raise the screen, breathe with the diaphragm for a few minutes several times a day, and take the neck gently through its full rotation after each session. Consistency over one to two weeks matters more than pressure in any single session (shah2008).

A muscular headache changes with palpation, position and load, and eases — at least partially — after release work. A headache that is new and thunderclap-sudden, that worsens steadily over days, that comes with fever, stiff neck, confusion, weakness or vision loss, or that follows a head injury, needs medical assessment first, not self-treatment. The same applies to ear pain with discharge or hearing loss, and to true spinning vertigo rather than a vague sense of imbalance: those warrant an ear and neurological examination before any muscle is blamed (cummings2001).