third part of right subclavian artery (anatomy)
Last reviewed 01/2018
The third part of the subclavian artery originates as the continuation of the second part at the lateral margin of scalenus anterior. It terminates in continuity with the axillary artery at the lateral margin of the first rib.
The third part of the subclavian artery is invested in prevertebral fascia extending from the medial margin of scalenus anterior. The fascia passes laterally in continuity with the axillary fascia.
The relations of the third part of the subclavian artery include:
- anterior: external jugular vein
- anteromedial: scalenus medius
- anteroinferior: subclavian vein
- inferiorly: groove on superior surface of first rib
- posteriorly, from inferior to superior:
- first rib running obliquely
- lowest trunk of brachial plexus
- middle trunk of brachial plexus
The fifth branch of the subclavian artery arises from its third part. This is the dorsal scapular artery that arises from its superior surface and passes laterally, posteriorly and slightly superiorly through the lower roots of the brachial plexus.