SUBCLAVIAN MUSCLE: ORIGIN, FUNCTIONS, SYNDROMES, DISORDERS - ANATOMY AND PHYSIOLOGY - 2025

The subclavian muscle is a relatively small muscle, located between two bony structures (the clavicle and the first rib). It fulfills the stabilizing function of the sternoclavicular joint during shoulder movement. Likewise, its contraction lowers both the shoulder and the clavicle, while the first rib rises.

The muscle is cylindrical in shape and oriented horizontally. It is part of the muscles that make up the pectoral girdle. The origin occurs at the site where the first rib relates to the costal cartilage and inserts into the clavicle. It is a deep muscle largely covered by the pectoralis major.

Subclavian muscle. Source: Anatomography Henry Vandyke Carter Edited image.

Its name comes from the Latin musculus subclavius. Despite being a small muscle, it can be shortened and have trigger points. In this sense, there are self-massage techniques that can help improve symptoms.

On the other hand, a thickening of the subclavian muscle is the cause of compression of the subclavian vessels and nerves, which results in the suffering of pathologies, such as the costoclavicular syndrome and the Paget-Von Schrötter syndrome.

The latter has been associated with cases of patients who have an additional or aberrant subclavian muscle, called the subclavian posticus muscle.

Treatment for decompression of the subclavian nerves and vessels is mainly surgical, requiring the extraction of the first rib and total scalenectomy. In the case of Paget-Von Schrötter syndrome, thrombolytic treatment must be added in addition to the above.

Origin

This muscle originates at a key junction point between two structures, specifically at the site where the proximal end of the first rib joins the first costal cartilage (osteochondral junction). Right at that point this muscle is born.

Insertion

This muscle attaches to the clavicle on its lower surface, specifically in the sulcus of the middle third of the clavicle (subclavian sulcus).

Innervation

The nerve responsible for innervating this muscle comes from the brachial plexus and bears the same name: "subclavian nerve" (C5, C6).

Irrigation

It is supplied by a branch of the thoracoacromial artery, called the clavicular branch.

Features

This muscle moves the clavicle medially, lowering the shoulder and in turn stabilizing the function of the sternoclavicular joint.

Syndromes

- Trigger points

This muscle can, like others, suffer from tension, and trigger points can appear. The pain that these produce can affect the shoulder, arm, forearm and even the fingers of the hands.

Although this muscle is not one of the most susceptible to reloading, it can be shortened in patients with kyphosis (abnormal curvature of the spine). This situation generates the trigger points.

Self-massage

The muscle can be massaged with the fingers or using a special support instrument called the Trigger-Fairy. There are two techniques to massage the muscle, these being: precise massage and pressure-movement technique.

For precise massage, the fingers or the Trigger-Fairy are located below the clavicle and it is pressed horizontally looking for pain points, usually these are located in the medial part or towards the sternum.

Upon finding a trigger point, it is massaged with gentle movements in a horizontal direction.

The pressure-movement technique consists of pressing the painful point, while gently rotating the shoulder back.

- Costoclavicular syndrome

This syndrome is characterized by compression or irritation of the nerves and / or vessels that pass through the costoclavicular space. This space is surrounded by the clavicle, the subclavian muscle, the first rib, and the middle scalene muscle. Mainly, when compression occurs, the subclavian nerve of the brachial plexus and / or the subclavian vessels are affected.

This syndrome is also called thoracic outlet syndrome (TDS), there are two types: neurogenic TDS and venous TDS.

Neurogenic TDS is characterized by muscle atrophy and nerve involvement. This produces pain and paresthesia. One of the first symptoms is cervicobrachial neuralgia (radiating pain). Whereas, venous TDS produces thrombosis in the upper limbs. It is characterized by numbness, stiffness, paleness, edema of the upper limb, and difficulty moving the fingers.

The cause is varied, one of the triggers could be a car accident, which could cause subluxation of the clavicle (distal area) in relation to the acromial process of the shoulder blade.

It is also possible that it is caused by carrying excessive weight on the shoulder, which can put severe pressure on the caudal area of ​​the clavicle. An example of this are women who wear very heavy purses or bags slung over their shoulders.

Another possible cause is thickening of the muscle in question or nearby ligaments.

- Subclavian muscle

In 2006 Prakash et al. Found a muscular anatomical variation in a male corpse, where the right subclavian muscle was supernumerary.

The aberrant muscle was in the infraclavicular area. This originated at the upper edge of the first rib, next to the costal cartilage, and inserted between the suprascapular incisure in its medial part to the capsule of the acromioclavicular joint. It was innervated by the subclavian nerve. The authors concluded that it was a subclavian posticus muscle.

This anatomical variation could affect the movements of the patient's shoulder girdle, mainly in scapular rotation.

Although these cases are not frequent, they should be considered in patients who present symptoms that do not subside with usual therapies and that suggest compression.

In addition, the presence of a subclavian posticus muscle can cause compression of the subclavian artery, causing a picture of thoracic outlet syndrome, characterized by pain in the shoulder, arm and neck.

It is also believed to be related to the Paget-Von Schrötter syndrome, which is a venous thrombosis that affects the upper limbs, mainly in the subclavian and axillary veins.

References

1. Prakash S, Pai Mangala M, Prabhu Latha V, Vadgaonkar Rajanigandha, Nayak Soubhagya R, Shivanandan R. The Subclavius ​​Posticus Muscle: its Phylogenetic Retention and Clinical Relevance. J. Morphol, 2006; 24 (4): 599-600. Available in: scielo.
2. Sanz A, Carrero X, Pérez I, Pineda F, Baptista G, Al Awad A. Anatomic Approach to Costoclavicular Syndrome. Clinical Case Triggered by Cervical Deceleration Movement. Arg. Anat. Onl. 2013; 4 (3): 109 - 113.Available at: issuu.com
3. De León R, Chang D, Busse C, Call D, Freischlag J. First rib resection and scalenectomy for chronic subclavian vein occlusion: what are its real effects? Annals of Vascular Surgery. 2088; 22 (3): 431-438. Available at: Elsevier.
4. "Subclavian muscle" Wikipedia, The Free Encyclopedia. 22 Mar 2016, 03:16 UTC. 28 Sep 2019, 04:07
5. Rigberg D, Gelabert H. Treatment of thoracic outlet syndrome in adolescents. Annals of Vascular Surgery, 2009; 23 (3): 368-373. Available at: Elsevier