Athena Vale
The sternocleidomastoid (SCM) is a powerful and large neck muscle that is thick and narrow at its centre, and broader and thinner at both ends. It is an important landmark in the neck region, dividing it into anterior and posterior triangles. The SCM is responsible for moving the vertebral column and head, allowing us to bend, turn and tilt our heads. SCM injuries are common in car accidents and can lead to stiffness, pain and other symptoms.
Explore related products
![Manga Muscles: An Artist's Guide to Drawing Powerful Male Bodies [With Over 500 color and B&W illustrations]](https://m.media-amazon.com/images/I/81Gw3RIrdpL._AC_UL320_.jpg)
What You'll Learn
The sternocleidomastoid muscle is a powerful neck muscle
The sternocleidomastoid (SCM) muscle is a powerful and large neck muscle that allows you to bend your neck and turn or tilt your head. It is a two-headed muscle, with the sternal head originating from the manubrium of the sternum and the clavicular head from the medial third of the clavicle. The two heads merge into a single muscle belly that is directed upwards and laterally, ending at the mastoid process of the temporal bone. The SCM is a significant anatomical landmark within the neck region, dividing it into anterior and posterior cervical triangles. This division helps define the location of structures such as lymph nodes, the common carotid artery, the accessory nerve, and the brachial plexus.
The SCM plays a crucial role in neck posture and stabilisation, even when the body is at rest. It also aids in breathing by lifting the sternum and clavicle, thereby expanding the thoracic cavity. Additionally, the SCM supports the temporomandibular joint (TMJ), which enables the opening and closing of the mouth. The SCM is susceptible to various injuries, strains, and conditions, such as whiplash, torticollis (wry neck), and SCM syndrome, which can result in pain, stiffness, and restricted movement.
The SCM has a complex organisational pattern, consisting of five distinct topographical parts: the superficial sternomastoid, profound sternomastoid, sterno-occipital, cleidomastoid, and cleido-occipital. These parts are arranged in superficial and deep layers, with muscle fibres lying within a common fascial sheath and traversing in the same direction. The SCM is innervated by the spinal accessory nerve (XI) and receives sensory input from C2 and C3 for proprioception.
The SCM is closely associated with certain neurovascular structures that pass through the neck towards the head or the periphery of the body. It helps protect the vertical neurovascular bundle of the neck, branches of the cervical plexus, deep cervical lymph nodes, and soft tissues of the neck from damage. The blood supply to the SCM is provided by the superior thyroid artery, a branch of the external carotid artery.
The SCM is an essential muscle for various complex physiological movements. Its functions include rotating the head to the opposite side, flexing the neck, and extending the head when acting in conjunction with the muscle on the other side. When acting alone, it causes the head to rotate to the opposite side and flexes laterally to the same side. The SCM also plays a role in inspiratory breathing, acting as an accessory muscle.
Training Your Abs: A Guide to Strong Core Muscles
You may want to see also
Explore related products
It originates from two locations
The sternocleidomastoid muscle is a powerful neck muscle that allows you to bend your neck and turn or tilt your head. It is an important landmark in the neck region, helping to divide it into anterior and posterior triangles. This muscle originates from two locations: the manubrium of the sternum and the clavicle.
The sternal head of the muscle arises from the upper edge of the manubrium sterni, or the upper part of the front of the sternum. It is a round fasciculus, tendinous in front and fleshy behind. The clavicular head, on the other hand, arises from the upper frontal surface of the medial third of the clavicle. This head is composed of fleshy and aponeurotic fibres and is directed almost vertically upward.
The two heads of the sternocleidomastoid muscle are separated from one another at their origins by a triangular interval known as the lesser supraclavicular fossa. However, as they ascend, they gradually blend below the middle of the neck to form a thick, rounded muscle belly. This muscle belly is inserted by a strong tendon into the lateral surface of the mastoid process of the temporal bone of the skull.
The sternocleidomastoid muscle is unique in that it has variable origins and innervation arrangements. The occurrence of variations in the muscle can be explained by fusion failure or abnormal mesodermal splitting during development, as described by Sinohara's law of fusion. This law states that a muscle supplied by two different nerves is formed by the fusion of two separate muscle masses.
The SCM muscle plays a crucial role in various functions, including neck flexion, head rotation, and breathing. It also aids in maintaining posture and protecting the vital structures of the neck, such as the neurovascular bundle, cervical plexus, lymph nodes, and soft tissues.
Muscle Macromolecules: Building Blocks of Strength and Movement
You may want to see also
Explore related products
It is thick and narrow at its centre
The sternocleidomastoid (SCM) muscle is a powerful neck muscle that allows you to bend your neck and turn or tilt your head. It is one of over 20 pairs of muscles acting on the neck. The SCM has dual innervation and multiple functions. It is thick and narrow at its centre, and broader and thinner at either end.
The SCM is a large, easily recognisable, and palpable muscle. It is a two-headed muscle, which means it originates at two separate points and then converges to insert at one point. 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 join into one muscle belly that goes on to insert on the lateral surface of the mastoid process of the temporal bone. The SCM's main responsibility is moving the vertebral column and head.
The SCM can be arranged into five distinct topographical parts: the superficial sternomastoid, profound sternomastoid, sterno-occipital, cleidomastoid, and cleido-occipital parts. These are arranged in superficial and deep layers. The muscle fibres of all these layers lie within a common fascial sheath and traverse in the same direction.
The SCM plays an important role in the posture of the neck and the body. It also works with other neck muscles to lift the breastbone and collarbone when you inhale. The movement creates space for the lungs to take air.
Muscle Dysmorphia: Understanding the Body Image Disorder
You may want to see also
Explore related products
It is an important landmark in the neck
The sternocleidomastoid muscle is an important landmark in the neck, dividing it into anterior and posterior cervical triangles. This thick, superficially palpable muscle is easily recognisable and can be felt on each side of the neck when a person moves their head to the opposite side.
The sternocleidomastoid muscle 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. The muscle is named after these three bony landmarks: sterno- (sternum), cleido- (clavicle), and -mastoid (mastoid process).
The two heads of the muscle are separated at their origins by a triangular interval (lesser supraclavicular fossa) but gradually blend below the middle of the neck into a thick, rounded muscle belly. This belly is inserted by a strong tendon into the lateral surface of the mastoid process and by a thin aponeurosis into the lateral half of the superior nuchal line of the occipital bone.
The anterior triangle, located in front of the sternocleidomastoid muscle, is delimited by the posterior border of the muscle, the inferior border of the mandible, and the medial line of the neck. Within this triangle lie the suprahyoid and infrahyoid muscles. The posterior triangle, located behind the muscle, is delimited by the SCM anteriorly, the clavicle inferiorly, and the trapezius muscle posteriorly. The scalene muscles reside in this triangle.
The triangle formed by the clavicle and the sternal and clavicular heads of the sternocleidomastoid muscle is used as a landmark for identifying the correct location for central venous catheterization. The muscle's thickness varies, and it can be affected by tendinous intersections, which indicate the origin of the muscle from different myotomes.
Meat Composition: Muscles and More
You may want to see also
Explore related products
It is closely related to certain neurovascular structures
The sternocleidomastoid muscle is closely related to several neurovascular structures that pass through the neck. These structures include the common carotid artery, the accessory nerve, and the brachial plexus. The internal carotid artery also reaches the sternocleidomastoid muscle, along with the trapezius muscle.
The sternocleidomastoid muscle is a two-headed neck muscle that 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. The muscle is thick and narrow at its centre, broadening and thinning at each end. The two heads of the muscle join into a single muscle belly, which inserts into the lateral surface of the mastoid process of the temporal bone and the lateral half of the superior nuchal line of the occipital bone.
The muscle is a prominent landmark of the neck, dividing it into anterior and posterior cervical triangles. This division helps define the location of structures such as the lymph nodes for the head and neck. The muscle is also used as a landmark for central venous catheterization, with the medial edge serving as a lead structure.
The sternocleidomastoid muscle has multiple functions, including rotating the head to the opposite side of contraction and flexing the neck laterally and anteriorly. It also acts as an accessory muscle of respiration and inspiration. The muscle is innervated by the accessory nerve (Cranial Nerve XI) and direct branches of the cervical plexus (C2-C3). The blood supply to the muscle is provided by the superior thyroid artery, a branch of the external carotid artery.
Groin Muscle Pain: Understanding the Anatomy and Location
You may want to see also
Frequently asked questions
The sternocleidomastoid (SCM) is a powerful neck muscle that allows you to bend your neck and turn or tilt your head. It is one of over 20 pairs of muscles acting on the neck.
The SCM has multiple functions. It helps to flex the neck, rotate the head, and aids in various complex physiological movements beyond its principal function as a lateral neck flexor. It also acts as an accessory muscle of respiration.
Injuries to the SCM can lead to pain, stiffness, and in some cases, neck stiffness and trigger points, a condition known as sternocleidomastoid syndrome. Treatment options include massage, osteopathic manipulation, physical therapy, and in severe cases, surgery.
