Logan Steele
The sternocleidomastoid (SCM) is a superficial neck muscle that originates at the manubrium of the sternum and the clavicle. It has a cylindrical, strap-like shape and emerges from the side of the neck, tapering at the ends. The SCM is involved in neck movement and posture, helping with head rotation, tilt, and flexion. SCM injuries can lead to pain and stiffness, requiring treatments such as stretching, physical therapy, and osteopathic manipulation. The SCM is also susceptible to conditions like torticollis, where the head persistently turns to one side due to a shortened SCM.
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What You'll Learn
The sternocleidomastoid muscle is a neck muscle
The sternocleidomastoid muscle, or SCM, is a neck muscle that plays an important role in neck movement and posture. It is a powerful muscle that allows you to bend your neck and turn or tilt your head. Located in the anterior portion of the neck, the SCM is a superficial muscle, which means it is located just below the skin and can be felt on both sides of the neck. It is one of the largest and most superficial cervical muscles, originating from two locations: the manubrium of the sternum (sterno- and the clavicle (cleido-).
The SCM has a cylindrical, strap-like shape, with two heads that originate from the collarbone/clavicle and the breastbone/manubrium. These two heads are separated by a triangular surface depression, known as the lesser supraclavicular fossa. As they ascend, they spiral behind each other and blend below the middle of the neck, forming a thick, rounded belly. The SCM is inserted by a strong tendon into the lateral surface of the mastoid process, a section of bone located at the base of the skull behind the ear.
The primary functions of the SCM include rotation of the head to the opposite side and flexion of the neck. When acting together, the muscles on both sides of the neck flex the neck and extend the head. When acting alone, the SCM rotates the head to the opposite side and flexes laterally to the same side. Additionally, it assists in breathing by working with other neck muscles to lift the breastbone and collarbone during inhalation, creating space for the lungs to take in air.
The SCM is innervated by the accessory nerve, also known as Cranial Nerve XI, which supplies motor fibres to the muscle. The cervical plexus provides sensory innervation and proprioception. Impairment or injury to this nerve can cause weakness or paralysis of the SCM, leading to atrophy and difficulty in turning the head and bending the neck. Treatment for SCM injuries may include strengthening exercises, physical therapy, osteopathic manipulation, and surgery in severe cases.
In summary, the sternocleidomastoid muscle is a large and complex neck muscle that plays a crucial role in neck movement, posture, and breathing. Its unique structure and function make it an important landmark in the anatomy of the neck.
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It is involved in neck movement and posture
The sternocleidomastoid (SCM) muscle is a powerful neck muscle that allows you to bend your neck and turn or tilt your head. It is the largest muscle in the front of the neck and is located just below the skin. It is involved in neck movement and posture.
The SCM muscle helps with head rotation, head tilt, and pointing the chin towards the breastbone. It also assists in breathing and maintaining neck posture. The SCM works alongside the deeper structures in your neck to provide support and ease of movement. It is innervated by the spinal accessory nerve (cranial nerve XI) and has dual innervation and multiple functions.
The SCM muscle becomes chronically shortened in cases of torticollis, a movement disorder where the head is persistently turned to one side. Treatment for this condition involves gentle stretching and strengthening exercises for the SCM muscle. Maintaining good posture and practicing daily neck stretches can also help prevent tension and strain in the SCM muscle, especially for those who sit most of the day or work in uncomfortable postures.
The SCM muscle is an important anatomical landmark in the neck, dividing it into an anterior and posterior triangle. It originates at the manubrium of the sternum and the clavicle, with an insertion at the mastoid process of the temporal bone of the skull. The SCM muscle is thick and narrow at its center, broadening and thinning at either end.
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The SCM is innervated by the spinal accessory nerve
The sternocleidomastoid (SCM) is a muscle located in the anterior portion of the neck. It is involved in neck movement and function, including head rotation, tilt, and flexion. The SCM is innervated by the spinal accessory nerve, also known as the eleventh cranial nerve (CN XI). This nerve is responsible for supplying motor fibres to the SCM, allowing it to contract and facilitate neck movements.
The spinal accessory nerve arises from the spinal cord and exits the skull through the jugular foramen, entering the anterior triangle of the neck. From there, it travels downward, going anterolateral to the internal jugular vein. As it continues its course, the nerve passes behind the digastric and stylohyoid muscles before reaching the upper part of the SCM. This branch of the nerve then enters the deep surface of the SCM to provide motor innervation.
The spinal accessory nerve plays a crucial role in the function of the SCM. It provides the necessary stimulation for the muscle to contract and perform its actions. The SCM, in turn, is responsible for various movements of the neck, including lateral flexion, rotation, and extension. When acting unilaterally, the SCM allows for lateral flexion and rotation of the neck. Meanwhile, when acting bilaterally, it contributes to the extension of the neck at the atlanto-occipital joints.
Any impairment or injury to the spinal accessory nerve can have significant consequences for the SCM. Damage to the nerve can lead to weakness or even paralysis of the SCM, impacting the individual's ability to turn their head and bend their neck. In some cases, atrophy of the SCM may occur due to nerve damage, resulting in a decreased range of motion and potential difficulties with neck posture and head positioning.
The innervation of the SCM by the spinal accessory nerve is an important aspect of its anatomy and function. This relationship between the nerve and the muscle highlights the intricate workings of the human body and the reliance of muscles on their respective nerves for proper function. Understanding the innervation of the SCM is crucial for diagnosing and treating conditions related to this muscle, such as torticollis, and for ensuring optimal neck function and overall well-being.
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SCM syndrome can cause neck stiffness and pain
The sternocleidomastoid (SCM) muscle is a powerful neck muscle that is located at the base of the skull on both sides of the neck, behind the ears. It is the largest neck muscle in the front of the neck and is involved in neck movement and function. SCM syndrome can cause neck stiffness and pain due to various factors, and these effects can be mitigated through various treatments.
SCM syndrome is a condition that involves neck stiffness, pain, and other symptoms. It occurs when the SCM muscle develops tightened, sensitive areas, or trigger points. The SCM muscle's size and complexity make it susceptible to strain and injury, which can lead to the development of trigger points within the muscle. These trigger points can cause referred pain, where the pain originates in the SCM muscle but is felt in another part of the body, such as the sinuses, forehead, or near the eyebrows.
There are several factors that can contribute to SCM syndrome and its associated neck stiffness and pain. One common cause is muscle tension, which can be the result of stress and anxiety. Poor posture, aging, frequent sleeping on the stomach, neck trauma (such as whiplash), certain occupations (like violinists), weightlifting, incorrect swimming styles, and abrupt sit-ups can also lead to SCM syndrome. Additionally, health conditions like asthma and acute respiratory infections, including sinusitis, bronchitis, and pneumonia, can contribute to SCM pain.
To alleviate the neck stiffness and pain associated with SCM syndrome, various treatments can be employed:
- Physical therapy: This can help improve posture and provide guidance on daily life activities to reduce strain on the SCM muscle.
- Stretching: Gentle stretches and yoga poses can help lengthen and relax the SCM muscle, reducing tension and stiffness.
- Strengthening exercises: Specific exercises, such as cervical isometrics (flexion, side bending, and rotation), can strengthen the SCM muscle and improve its function.
- Hot or cold therapy: The application of hot or cold compresses can help ease inflammation and pain in the affected area.
- Osteopathic manipulation treatment: This involves manipulating the SCM muscle to reduce tension and improve its function.
- Self-care practices: Managing stress and anxiety, maintaining good posture, and avoiding activities that may strain the SCM muscle can help prevent and reduce symptoms.
In more severe cases of SCM syndrome, where conservative treatments have not been effective, surgery may be considered. Surgery is typically reserved for situations where there is severe structural damage, such as a major tear or a tumor that has damaged the tissue. It is important to consult with a healthcare professional to determine the most appropriate treatment plan for SCM syndrome and associated neck stiffness and pain.
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SCM is the largest muscle in the front of the neck
The sternocleidomastoid muscle, or SCM, is the largest muscle in the front of the neck. It is a powerful neck muscle that allows you to bend your neck and turn or tilt your head. The SCM muscle borders two neck regions known as triangles—the anterior triangle and the posterior triangle. The SCM divides the neck into these two regions.
The SCM muscle is a unique muscle with a variable innervation arrangement. It is innervated by the spinal accessory nerve (cranial nerve XI). The SCM has a cylindrical, strap-like shape that emerges from the side of your neck and tapers at the ends. It is a superficially located muscle, just below your skin, and you can feel it on both the right and left sides of your neck.
The SCM helps with functions such as head rotation, head tilt, and pointing the chin toward the breastbone. It also assists in breathing and maintaining neck posture. The SCM works with other neck muscles to lift your breastbone and collarbone when you inhale. It is an important landmark in the neck that protects the vertical neurovascular bundle, branches of the cervical plexus, deep cervical lymph nodes, and soft tissues of the neck from damage.
The SCM is susceptible to strain and injury due to its size and complexity. Conditions such as sternocleidomastoid syndrome can cause neck stiffness, pain, and other symptoms like dizziness, frontal headaches, and lack of coordination of movement. Treatment for SCM syndrome includes stress-relieving techniques, physical therapy, and stretching and strengthening exercises for the SCM muscle.
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Frequently asked questions
The sternocleidomastoid (SCM) is a large, powerful, superficial neck muscle that runs from the breastbone and collar bone to the back of the head.
The SCM helps with head rotation, head tilt, and tilting the chin toward the breastbone. It also assists in breathing, maintaining neck posture, and supporting the temporomandibular joint (TMJ) function.
The SCM has a cylindrical, strap-like shape that emerges from the side of the neck and tapers at the ends.
SCM injuries can lead to pain, stiffness, and difficulty in turning the head and bending the neck. Treatment includes gentle stretching, physical therapy, and osteopathic manipulation.
