The sternocleidomastoid, or SCM, muscle originates on the breastbone and attaches to the collarbone and the temporal bone on the back of the skull. You have one SCM on each side of your neck. These muscles tilt and rotate your head to the right and left. Sudden movements, such as whiplash, can cause SCM injury.
SCM strain may cause headaches, especially at the muscle's attachment point at the base of your skull. Other symptoms may include face or head pain, ringing in your ears, dizziness and blurred vision.
Sternocleidomastoid muscle pain pattern - SCM muscle pain can affect many areas in the head, face and neck. Along with pain and stiffness, dizziness can be a symptom of SCM dysfunction.
Sternal Division – This is the muscle head that connects to the sternum or breast bone.
Pain maybe felt in these areas:
Cheek and jaw
Sinuses
Back of head at the bottom of the skull
Around one eye
Top of head
May also be associated with these symptoms:
Tearing of eye
Visual disturbances when viewing parallel lines
Chronic “sore throat” when swallowing,
Chronic dry cough.
Clavicular Division – This is the muscle head that connects to the clavicles or collarbones.
Symptoms may be felt in these areas:
Pain across the forehead
Frontal sinus-like headache
Ear ache
Nausea
Dizziness
Car-sickness
Faulty weight perception of held objects
Hearing loss in one ear
It is an interesting muscle and can create many issues. Injury results a lot of times from whiplash.