The subclavius is a small triangular muscle, placed between the

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the r ...

and the

first rib The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a ...

. Along with the

pectoralis major The pectoralis major () is a thick, fan-shaped or triangular convergent muscle, situated at the chest of the human body. It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor, ...

and

pectoralis minor muscle Pectoralis minor muscle () is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major in the human body. Structure Attachments Pectoralis minor muscle arises from the upper margins and outer surface ...

s, the subclavius muscle makes up the anterior axioappendicular muscles, also known as anterior wall of the

axilla The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superior ...

Structure

It arises by a short, thick tendon from the first rib and its cartilage at their junction, in front of the

costoclavicular ligament The costoclavicular ligament, also known as the rhomboid ligament or Halsted's ligament, is a ligament of the shoulder girdle. It is short, flat, and rhomboid in form. It is the major stabilizing factor of the sternoclavicular joint and is the a ...

. The fleshy fibers proceed obliquely superolaterally, to be inserted into the groove on the under surface of the clavicle.

Innervation

The nerve to subclavius (or subclavian nerve) innervates the muscle. This arises from the junction of the fifth and sixth cervical nerves, from the superior/upper trunk of the

brachial plexus The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in t ...

Variation

Insertion into

coracoid process The coracoid process (from Greek κόραξ, raven) is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula (hence: coracoid, or "like a raven's beak"). Pointing laterally forward, it, together with t ...

instead of clavicle or into both clavicle and coracoid process. Sternoscapular fasciculus to the upper border of scapula. Sternoclavicularis from

manubrium The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. S ...

to clavicle between

and

coracoclavicular fascia The clavipectoral fascia (costocoracoid membrane; coracoclavicular fascia) is a strong fascia situated under cover of the clavicular portion of the pectoralis major. It occupies the interval between the pectoralis minor and subclavius, and pro ...

. Rarely, the subclavius may be missing entirely.

Function

It depresses the lateral

, acts to stabilize the clavicle while the shoulder moves the arm. It also raises the first rib while lowering the clavicle during breathing. The subclavius protects the underlying

and subclavian vessels from a broken

- the most frequently broken

long bone The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities ...

Additional images

File:Subclavius muscle animation2.gif, Subclavius muscle (shown in red).

Humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a r ...

and

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

are shown in semi-transparent. Animation. File:Subclavius muscle frontal3.png, Subclavius muscle (shown in red). File:Gray115.png, Anterior surface of sternum and costal cartilages. File:Gray201.png, Left clavicle. Inferior surface. File:Gray523.png, The axillary artery and its branches. File:Gray809.png, The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front. File:Slide7b.JPG, Subclavius muscle - left view File:Slide10d.JPG, Subclavius muscle- right view File:1118 Muscles that Position the Pectoral Girdle anterior.png, Subclavius (labeled top left) — frontal view

References

External links

PTCentral

Pivotal Places: help for problem shoulders
{{Authority control Muscles of the upper limb