Posterior Neck - LO6
6. What are the major vascular (artery, vein, and lymphatic) pathways of the head & neck and upper limbs?
The arch of aorta (aortic arch) connects the ascending aorta to the descending aorta. Typically, three branches - brachiocephalic trunk (giving rise to the R. subclavian a. & R common carotid a.), L. common carotid a., & L. subclavian a. - originate from the arch of aorta to supply blood to the head, neck, upper limbs, and thorax.
The common carotid a. bifurcates into the internal and external carotid aa.
The internal carotid has no branches in the neck. It travels to the cranium, where it is transmitted through the carotid canal, and supplies blood to the brain, orbit, and forehead.
The external carotid a. is the primary source of blood to the face and superficial head. The external carotid has eight branches:
superior thyroid a.
ascending pharyngeal a.
occipital a.
lingual a.
facial a.
posterior auricular a.
maxillary a.
superficial temporal a.
The subclavian a. (SCA) supplies the neck, cranial cavity (& brain), anterior wall of the thorax, and upper limbs. See learning objective 3 (above) for a more detailed treatment of the SCA.
The superior vena cava transmits blood from the head, neck, upper limbs, and thorax to the right atrium of the heart. The superior vena cava is formed by the confluence of the brachiocephalic vv., which are each formed by the confluence of the internal jugular (IJ) vv. and subclavian vv.
The lymphatics in this region very closely follow veins. There are three major lymphatic trunks returning lymph from the the head and neck (jugular trunks), upper limbs (subclavian trunks), and thorax (bronchomediastinal trunks). These trunks may either return lymph into the vicinity of the ipsilateral venous angles (the union of the internal jugular v. and subclavian v.), or feed into lymphatic ducts, which return lymph into the vicinity of the ipsilateral venous angle.
The trunks serving the right may feed into the right lymphatic duct. The ducts serving the left may feed into the thoracic duct, which also drains lymph from the regions inferior to the diaphragm. This explains the asymmetry associated with lymphatic drainage on the right versus the left.
