Musculus sternocleidomastoideus

Musculus Sternocleidomastoideus is a prominent muscle in the neck that plays a vital role in head and neck movement. It is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoideus is innervated by the Accessory nerve.

Anatomy

The Musculus Sternocleidomastoideus originates from two locations: the manubrium of the sternum and the clavicle. It travels obliquely across the side of the neck and inserts at the mastoid process of the temporal bone of the skull. This muscle has a broad and strong attachment at its origin and a small, rounded and firm attachment at its insertion.

Function

The Musculus Sternocleidomastoideus has several functions. It is primarily responsible for rotation of the head to the opposite side and flexion of the neck. When both sides of the muscle act together, it flexes the neck and extends the head. When one side acts alone, it causes the head to rotate to the opposite side and flexes the neck to the same side.

Clinical significance

Dysfunction of the Musculus Sternocleidomastoideus can result in a condition known as Torticollis, also known as wry neck. This condition is characterized by an abnormal, asymmetrical head or neck position, which is often due to abnormal muscular contractions. The sternocleidomastoideus may also be affected by muscle strain, or sternocleidomastoid syndrome, a condition which can cause a variety of symptoms, including pain, tightness, and restriction of neck movement.

See also

• Neck muscle
• Accessory nerve
• Torticollis
• Muscle strain