Torticollis: Which SCM is Tight When Head Turns Left
When the head is turned to the left in torticollis, the RIGHT sternocleidomastoid muscle is tight. 1, 2, 3
Anatomical Mechanism
The pathophysiology of torticollis involves shortening of the sternocleidomastoid muscle, which creates a characteristic head posture:
- The shortened SCM causes the head to tilt TOWARD the affected (tight) side 1, 2, 3
- The chin rotates AWAY from the affected side (to the opposite side) 1, 2, 3
Therefore, if the head is rotated to the left (chin pointing left), the tight muscle is on the RIGHT side, pulling the head into a right lateral tilt while the chin compensates by rotating leftward. 2, 3
Clinical Presentation Features
When examining a patient with the head turned left, expect to find:
- Right SCM that is short, tight, and band-shaped 1
- Spastic contralateral (left) SCM 1
- Decreased range of motion of the neck 1, 4
- Facial asymmetry with the face rotated opposite to the tight muscle 1, 5
- Possible palpable tumor or thickening within the right SCM 4, 6
Common Pitfall to Avoid
The confusion arises because clinicians may mistakenly assume the muscle on the side of chin rotation is tight. Remember: the tight SCM tilts the head toward itself, forcing the chin to rotate away. 2, 3 The direction of chin rotation is opposite to the side of the shortened muscle.