Superior Mediastinum and Root of Neck LO 4
4. How are the parts of the subclavian artery (SCA) delimited? What are the major branches (arteries) from each part of the SCA, and what do these branches supply? When does the SCA become the axillary artery?
The subclavian a. is conceptually divided into three parts, with respect to the vessel’s relationship to the anterior scalene m. The first part of the subclavian a. is found medial to the anterior scalene, the second part of the subclavian a. is posterior to the anterior scalene m., and the third part is lateral to the anterior scalene m.
The first part of the subclavian a. typically hosts three major branches:
- Vertebral a. (supplies the brain & spinal cord)
- Thyrocervical trunk,
- Inferior thyroid a. (supplies the thyroid and parathyroid glands)
- Ascending cervical a. (supplies deep muscles of the neck)
- Suprascapular a. (supplies supra- and infraspinatus mm.)
- Transverse cervical a. (supplies trapezius m. & often gives rise to the dorsal scapular a.)
- Internal thoracic a. (supplies anterior thoracic & abdominal walls & the diaphragm).
The second part of the subclavian a. typically hosts one major branch, the:
- Costocervical trunk
- Deep cervical a. (supplies deep neck muscles)
- Highest (supreme) intercostal a. (supplies 1st & 2nd intercostal spaces).
The third part of the subclavian a. typically hosts one major branch, the:
- Dorsal scapular a. (supplies rhomboid mm. and levator scapulae m.). The dorsal scapular a. may also be a branch of the transverse cervical a.
Beyond the lateral border of the first rib, the subclavian a. transitions into the axillary a.