Subclavius
Shoulder & Scapula · Upper Limb
The subclavius is a small muscle tucked between the clavicle and the first rib. It arises at the junction of the first rib and its costal cartilage and runs laterally to the inferior surface of the middle third of the clavicle. It depresses and stabilises the clavicle and steadies the sternoclavicular joint during movements of the shoulder girdle. It is supplied by its own named branch, the nerve to subclavius (C5, C6). Positioned as it is, the muscle also acts as a protective cushion for the underlying subclavian vessels should the clavicle fracture.
Origin, Insertion, Action & Nerve
Origin
Junction of 1st rib and its costal cartilage
Insertion
Inferior surface of middle third of clavicle
Action
Depresses and stabilizes clavicle; steadies sternoclavicular joint
Nerve
Nerve to subclavius (C5, C6)
Attachments explained
The Subclavius is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Junction of 1st rib and its costal cartilage
Insertion
Inferior surface of middle third of clavicle
Action & function
When the Subclavius contracts, it produces the following movements: Depresses and stabilizes clavicle; steadies sternoclavicular joint.
As part of the Shoulder & Scapula group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Subclavius receives its nerve supply from the Nerve to subclavius (C5, C6). This nerve carries fibres from spinal segment(s) C5, C6.
Because a muscle can only contract when its nerve is intact, injury to the Nerve to subclavius or to its spinal roots (C5, C6) can weaken or paralyse the Subclavius, impairing the movements it normally produces (depresses and stabilizes clavicle). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Subclavius (the OIANS method)
Remember subclavius by its location, which is written into its name: it lies under the clavicle, running from the first rib to the underside of the clavicle. That short, near-horizontal course explains its modest job of depressing and steadying the clavicle at the sternoclavicular joint.
The point most often tested is protective: sitting between the clavicle and the subclavian vessels, it cushions those vessels if the clavicle fractures. Pair that with its dedicated nerve to subclavius, and this otherwise minor muscle becomes easy to recall.
Frequently asked questions
Where is the Subclavius located?
The Subclavius is a muscle of the Shoulder & Scapula group, located in the Upper Limb.
What is the origin of the Subclavius?
Junction of 1st rib and its costal cartilage
What is the insertion of the Subclavius?
Inferior surface of middle third of clavicle
What movements does the Subclavius produce?
Depresses and stabilizes clavicle; steadies sternoclavicular joint
What nerve supplies the Subclavius?
Nerve to subclavius (C5, C6)
Is the Subclavius free to study in OIANS?
Yes. The Subclavius is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Subclavius
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