The Sternocleidomastoid muscle (SCM) is a large, paired muscle located in the neck region. It is responsible for many important functions, including head and neck movement, as well as supporting the respiratory and circulatory systems. Understanding the structure and function of the SCM is important for healthcare professionals, as well as individuals interested in maintaining proper neck and head posture.
Structure
Heads
The SCM is divided into two separate heads, the sternal head and the clavicular head. The sternal head originates from the manubrium of the sternum, while the clavicular head originates from the medial third of the clavicle. The two heads converge at the hyoid bone and then continue upwards to insert into the mastoid process of the temporal bone.
Innervation
The SCM is innervated by the spinal accessory nerve (CN XI). This nerve is responsible for supplying the SCM with the necessary signals to contract and move the head and neck.
Blood Supply
The SCM is supplied by the occipital artery, which is a branch of the external carotid artery. The occipital artery provides the SCM with the necessary blood flow and nutrients to function properly.
Surrounding Muscles
The SCM is surrounded by various other muscles, including the trapezius, splenius capitis, and the scalene muscles. These muscles work together with the SCM to allow for proper head and neck movement, as well as support the respiratory and circulatory systems.
Location
The SCM is located in the neck region and is easily visible and palpable. It is located on either side of the neck, and can be identified by its long, slender shape and the two distinct heads that originate from the sternum and clavicle.
Function
Head and Neck Movement
One of the primary functions of the SCM is head and neck movement. It is responsible for flexion and rotation of the head and neck, as well as lateral flexion of the neck. These movements allow us to turn our head and neck in different directions, as well as tilt our head from side to side.
Maintaining Posture
In addition to its role in movement, the SCM also helps to maintain proper posture by keeping the head and neck in alignment with the rest of the body. This is important for maintaining a healthy and functional body position, as well as preventing muscle strain and other issues.
Respiratory Support
The SCM also plays a role in supporting the respiratory system. It helps to expand the thoracic cavity during inhalation, which allows for proper breathing and oxygenation of the body.
Circulatory Support
In addition to its role in respiratory support, the SCM can also assist in blood flow to the head and neck region. This is important for maintaining proper blood pressure and circulation throughout the body.
Clinical significance
Torticollis
One common problem related to the SCM is torticollis, or wry neck. This condition is characterized by a tilted and rotated head, and can be caused by muscle spasms or imbalances in the SCM and other neck muscles. Torticollis can be painful and can cause difficulty moving the head and neck.
Treatment for torticollis often involves stretching and strengthening exercises for the SCM and other neck muscles, as well as physical therapy. In severe cases, surgery may be necessary to correct the problem.
Headaches
Problems with the SCM can also cause headaches. These headaches may be caused by muscle tension or strain in the SCM, and can be treated with a variety of approaches, including medications, physical therapy, and massage.
Neck Pain
The SCM can also be a source of neck pain. This pain may be caused by muscle strain, tension, or other underlying conditions, and can be treated with a variety of approaches, including medications, physical therapy, and surgery.
Difficulty Breathing
In some cases, problems with the SCM can cause difficulty breathing. This may be due to muscle tension or other underlying conditions, and can be treated with a variety of approaches, including medications, physical therapy, and surgery.
In summary, the clinical significance of the Sternocleidomastoid muscle includes torticollis, headaches, neck pain, and difficulty breathing. These problems may be caused by muscle strain, tension, or other underlying conditions and can be treated with a variety of approaches, including medications, physical therapy, and surgery.
