13. Sterno-thyroid muscle, cut.

[Illustration: Right side of the head and neck, showing blood vessels, muscles and other internal organs.] Plate 5 PLATE 6. A. Root of the common carotid artery. B. Subclavian artery at its origin. C. Trachea. D. Thyroid axis of the subclavian artery. E. Vagus nerve crossing the origin of subclavian artery. F. Subclavian artery at the third division of its arch. G. Post scapular branch of the subclavian artery. H. Transversalis humeri branch of subclavian artery. I. Transversalis colli branch of subclavian artery. K. Posterior belly of omo-hyoid muscle, cut. L. Median nerve branch of brachial plexus. M. Musculo-spiral branch of same plexus. N. Anterior scalenus muscle. O. Cervical plexus giving off the phrenic nerve, which takes tributary branches from brachial plexus of nerves. P. Upper part of internal jugular vein. Q. Upper part of internal carotid artery. R. Superior cervical ganglion of sympathetic nerve. S. Vagus nerve lying external to sympathetic nerve, and giving off t its laryngeal branch. T. Superior thyroid artery. U. Lingual artery separated by hyo-glossus muscle from V. Lingual or ninth cerebral nerve. W. Sublingual salivary gland. X. Genio-hyoid muscle. Y. Mylo-hyoid muscle, cut and turned aside. Z. Thyroid cartilage.