Subclavius
Musculus subclavius
A small, round muscle beneath the clavicle. It anchors and depresses the clavicle and protects the subclavian vessels in clavicle fractures.
Overview
Subclavius runs from the junction of the 1st rib and its costal cartilage laterally into the subclavian groove on the inferior surface of the middle third of the clavicle. It is enclosed in the clavipectoral fascia. It steadies the clavicle during shoulder movements, pulls it toward the sternum to stabilise the sternoclavicular joint, and depresses it. When the clavicle is fractured, its bulk acts as a cushion that protects the subclavian artery and vein and the brachial plexus from the bone fragments.
Anatomy
- Origin
Junction of the 1st rib and its costal cartilage.
- Insertion
Inferior surface of the middle third of the clavicle (subclavian groove).
- Action
Anchors and depresses the clavicle.
- Innervation
Nerve to subclavius (from the upper trunk of the brachial plexus).
- Nerve roots
C5–C6
- Arterial supply
Clavicular branch of the thoraco-acromial trunk.
Function
- Anchors and depresses the clavicle
- Stabilises the sternoclavicular joint
- Cushions the subclavian vessels in clavicle fractures
Clinical significance
Accessory phrenic nerve
The nerve to subclavius sometimes carries an accessory phrenic contribution (from C5). If such a nerve is cut, as in surgery, the hemidiaphragm on that side can be paralysed.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.