Where Is The Sternocleidomastoid?

The sternocleidomastoid muscle divides the neck a triangle along with  the anterior margin of the trapezius.

Sternocleidomastoid Problems from tightness and imbalance

Bad posture will cause the muscles in the front of the neck to shorten over time and the muscles in the back of the neck will become over stretched over time. This will cause the posture to remain poor because of the muscle imbalance and bodywork or deep tissue will be needed in the anterior neck muscles to restore proper posture.


Forward head posture (FHP) is the structural forward positioning of the head away from the centerline of the body, where lower cervical vertebrae are bent and upper cervical vertebrae are extended, and the weight of the head supported by the neck is increased. The bending moment of the head applies pressure on muscles and joints around the cervical vertebra), in addition to active myofascial trigger points of the suboccipital muscle which may induce tension type headaches), neck pain) and cervical headaches, while reducing the mobility of the neck.


Poor neck posture has always been a common cause of musculoskeletal dysfunction. Among the effects of using a computer on the musculoskeletal system, keeping a posture of staring at a monitor, located below the height of eyesight, for a long time makes the head move forward, which causes exaggerated anterior curve in the lower cervical vertebrae and exaggerated posterior curve in the upper thoracic vertebrae to maintain balance; this is known as the forward head posture (turtle neck posture).6-9 This turtle neck posture are becoming increasingly commonly, as it is becoming more common place to use VDTs in the leaning forward posture, particularly with the popularization of Smart phones.

The Effect of The Forward Head Posture on Postural Balance in Long Time Computer Based Worker
Jung-Ho Kang, M.D., Rae-Young Park, M.D., Su-Jin Lee, M.D., Ja-Young Kim, M.D., Seo-Ra Yoon, M.D.,corresponding author and Kwang-Ik Jung, M.D.


What is The Function of the Sternocleidomastoid

Rotates the head.
It also flexes the neck when both engaged.

Sternomastoid muscle

Where is the Origin and Insertion of the Sternocleidomastoid?

Anterior and superior manubrium and superior medial third of clavicle.


Lateral aspect of mastoid process and anterior half of superior nuchal line