Logan Steele
The subclavius muscle is a small, triangular muscle in the anterior thorax, located between the clavicle and the first rib. It originates at the upper border of the first rib and its cartilage and inserts onto the inferior surface of the middle third of the clavicle in a bony groove. The subclavius muscle helps to stabilize the sternoclavicular joint and prevent dislocation of the clavicle. It also protects the underlying neurovascular structures in the event of a clavicular fracture. The muscle is innervated by the nerve to the subclavius, a branch of the brachial plexus, and is supplied by the clavicular branch of the thoracoacromial artery.
| Characteristics | Values |
|---|---|
| Location | Anterior thorax, pectoral region, anterior chest wall |
| Shape | Small, triangular |
| Position | Between the clavicle and the first rib |
| Origin | Upper border of the first rib and its cartilage |
| Insertion | Inferior surface of the middle third of the clavicle, in a bony groove |
| Innervation | Nerve to the subclavius, a branch of the brachial plexus |
| Blood Supply | Clavicular branch of thoracoacromial artery |
| Function | Stabilizes and controls the mobility of the clavicle, depresses the clavicle, prevents dislocation of the clavicle at the sternoclavicular joint, protects underlying neurovascular structures in case of a clavicular fracture |
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What You'll Learn
- The subclavius is a small, triangular muscle in the anterior thorax
- It originates at the first rib and inserts at the middle third of the clavicle
- It is innervated by the nerve to the subclavius, a branch of the brachial plexus
- The subclavius helps to prevent dislocation of the clavicle
- It also protects the neurovascular structures beneath it
The subclavius is a small, triangular muscle in the anterior thorax
The subclavius muscle plays a crucial role in stabilizing the clavicle and preventing its dislocation at the sternoclavicular joint. It also helps protect the neurovascular structures, such as the brachial plexus and subclavian vessels, underneath it in the event of a clavicular fracture. The muscle is innervated by the nerve to the subclavius, a branch of the brachial plexus, and receives its blood supply from the clavicular branch of the thoracoacromial artery.
The function of the subclavius muscle is not limited to stabilization alone. Some studies suggest that it may also play a role in regulating or controlling the mobility of the upper extremity during movements of the pectoral (shoulder) girdle, especially during elevation. This hypothesis is supported by comparative non-human primate anatomical studies that indicate a similar function in primates.
Additionally, the subclavius muscle has a specific branch of the brachial plexus that is not shared by any other muscle. This unique innervation further emphasizes the importance of the subclavius muscle in providing information about the upper extremity. While the muscle's primary role may be in regulating movement and providing information, its anatomical variations and innervation suggest a more complex function that requires further investigation.
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It originates at the first rib and inserts at the middle third of the clavicle
The subclavius is a small, triangular muscle in the anterior thorax, located between the clavicle and the first rib. It is enveloped in the clavipectoral fascia along with the pectoralis minor, coracobrachialis, and short head of the biceps.
The subclavius originates at the first rib and its cartilage. The first rib is the most superior of the twelve ribs and is considered an atypical rib. It is wide and short, with two costal grooves and one articular facet. The subclavius originates specifically on the upper border of the first rib and its cartilage.
The subclavius inserts on the inferior surface of the middle third of the clavicle in a bony groove known as the subclavian groove. The clavicle, also known as the collarbone, is the bone that spans the top of the chest, connecting the sternum to the shoulder. The subclavius depresses and anchors the clavicle, helping to stabilize the sternoclavicular joint and prevent dislocation at this joint.
By protecting the underlying brachial plexus and subclavian vessels, the subclavius also plays a crucial role in safeguarding the neurovascular structures beneath it in the event of a clavicular fracture. This fracture is often associated with damage to adjacent neurovascular structures and compression of the brachial plexus and subclavian vessels as they exit through the thoracic outlet region.
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It is innervated by the nerve to the subclavius, a branch of the brachial plexus
The subclavius is a small, triangular muscle in the anterior thorax, located between the clavicle and the first rib. It originates on the upper border of the first rib and its cartilage, inserting on the inferior surface of the middle third of the clavicle in a bony groove.
The subclavius is innervated by the nerve to the subclavius, which arises from the C5-C6 nerve roots. This nerve is a branch of the brachial plexus, a network of nerve fibres that supplies the skin and musculature of the upper limb. The brachial plexus is formed by the anterior rami (divisions) of cervical spinal nerves C5, C6, C7, and C8, as well as the first thoracic spinal nerve, T1.
The brachial plexus is divided into roots, trunks, divisions, cords, and branches. The trunks are found within the posterior triangle of the neck, between the anterior and middle scalene muscles. The brachial plexus, along with the axillary artery, forms a large neurovascular bundle that travels through the axilla to supply the upper extremity.
The nerve to the subclavius arises from the superior trunk of the brachial plexus, which is formed by the union of the fifth and sixth cervical nerves. It is one of only two nerves that originate completely from the roots of the brachial plexus, the other being the dorsal scapular nerve.
The subclavius is enveloped in the clavipectoral fascia along with the pectoralis minor, coracobrachialis, and short head of the biceps. It functions to depress and stabilise the clavicle, as well as aid in preventing dislocation of the clavicle at the sternoclavicular joint.
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The subclavius helps to prevent dislocation of the clavicle
The subclavius is a small, triangular muscle in the anterior thorax located between the clavicle and the first rib. It originates on the upper border of the first rib and its cartilage and inserts on the inferior surface of the middle third of the clavicle in a bony groove.
The subclavius muscle helps to prevent dislocation of the clavicle at the sternoclavicular joint. It does so by actively stabilizing the clavicle during movements of the shoulder and arm. Its contraction leads to a depression of the sternal end of the clavicle and subsequent elevation of the first rib. This movement helps to prevent dislocation of the clavicle during certain types of activity.
Additionally, the subclavius is important in preventing injuries to the adjacent neurovascular structures, such as the brachial plexus, in the event of a clavicular fracture. The muscle contributes to controlling the position of the scapula in relation to the thorax, and its contraction is hypothesized to increase tension at the tendinous border and the aponeurosis.
Myofascial pain or muscle strain of the subclavius may result in pain along the clavicle, sternoclavicular joint, shoulder, or arm. This pain may be caused by heavy lifting, chronic forward shoulder positioning, or sleeping with the arm positioned overhead.
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It also protects the neurovascular structures beneath it
The subclavius muscle is a small, triangular muscle in the anterior thorax, located between the clavicle and the first rib. It originates on the upper border of the first rib and its cartilage and inserts on the inferior surface of the middle third of the clavicle in a bony groove. The subclavius is enveloped in the clavipectoral fascia along with the pectoralis minor, coracobrachialis, and short head of the biceps.
The subclavius plays a crucial role in protecting the neurovascular structures beneath it. In the event of a clavicular fracture, the subclavius acts as a shield, safeguarding the brachial plexus and subclavian vessels from potential damage. This protective function is particularly important given that the clavicle is the most frequently broken long bone.
The brachial plexus, a network of nerves that originate near the neck and supply the arm and shoulder, lies deep to the subclavius muscle. The subclavian artery and vein, which supply blood to and from the arm, also pass deep to the subclavius. By providing a layer of protection, the subclavius helps prevent injury to these vital neurovascular structures.
The subclavius muscle's role in protecting the neurovascular structures is closely linked to its function in stabilizing the clavicle. The subclavius actively stabilizes the clavicle at the sternoclavicular joint during movements of the shoulder and arm. This stabilization helps prevent dislocation of the clavicle, thereby reducing the risk of injury to the underlying neurovascular structures.
In summary, the subclavius muscle's protective function is essential for maintaining the integrity of the neurovascular structures beneath it. By stabilizing the clavicle and providing a layer of protection, the subclavius helps prevent injuries that could have significant consequences for the body's nervous and vascular systems.
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Frequently asked questions
The subclavius muscle is located in the pectoral region of the thorax, in the anterior chest wall, underneath the clavicle.
The subclavius muscle helps to stabilise the clavicle and prevent its dislocation at the sternoclavicular joint. It also protects the neurovascular structures beneath it in the event of a clavicular fracture.
The subclavius originates at the upper border of the first rib and its cartilage, inserting onto the inferior surface of the middle third of the clavicle.
