L L*. Subclavian artery of the right side overlying the pleural sac. M M*. Right subclavian vein. N. Right common carotid artery cut at its origin. O. Trachea. P. Thyroid body. Q. Oesophagus. R. Genio-hyo-glossus muscle. S. Left tonsil beneath the mucous membrane. T. Section of the lower maxilla. U. Section of the upper maxilla. V. Velum palati in section. W. Inferior spongy bone. X. Middle spongy bone. Y. Crista galli of oethmoid bone. Z. Frontal sinus. 2. Anterior cartilaginous part of nasal septum. 3. Nasal bone. 4. Last molar tooth of the left side of lower jaw. 5. Anterior pillar of the fauces. 6. Posterior pillar of the fauces. 7. Genio-hyoid muscle. 8. Opening of Eustachian tube. 9. Epiglottis. 10. Hyoid bone. 11. Thyroid bone. 12. Cricoid bone. 13. Thyroid axis. 14. Part of anterior scalenus muscle. 15. Humeral end of the clavicle. 16. Part of posterior scalenus muscle. [Illustration: Head and neck, in section, from front to back; showing blood vessels, muscles and other internal organs.] Plate 20 PLATE 21. A. Zygoma. B. Articular glenoid fossa of temporal bone. C. External pterygoid process lying on the levator and tensor palati muscles. D. Superior constrictor of pharynx. E. Transverse process of the Atlas. F. Internal carotid artery. Above the point F, is seen the glosso-pharyngeal nerve; below F, is seen the hypoglossal nerve. G. Middle constrictor of pharynx. H. Internal jugular vein. I. Common carotid cut across. K. Rectus capitis major muscle. L. Inferior constrictor of pharynx. M. Levator anguli scapulae muscle. N. Posterior scalenus muscle. O. Anterior scalenus muscle. P. Brachial plexus of nerves. Q. Trachea. R R*. Subclavian artery. S. End of internal jugular vein. T. Bracheo-cephalic artery. U U*. Roots of common carotid arteries. V. Thyroid body. W. Thyroid cartilage. X. Hyoid bone. Y. Hyo-glossus muscle. Z. Upper maxillary bone. 2. Inferior maxillary branch of fifth cerebral nerve. 3. Digastric muscle cut. 4. Styloid process. 5. External carotid artery. 6 6. Lingual artery. 7. Roots of cervical plexus of nerves. 8. Thyroid axis; 8*, thyroid artery, between which and Q, the trachea, is seen the inferior laryngeal nerve. 9. Omo-hyoid muscle cut. 10. Sternal end of clavicle. 11. Upper rings of trachea, which may with most safety be divided in tracheotomy. 12. Cricoid cartilage. 13. Crico-thyroid interval where laryngotomy is performed. 14. Genio-hyoid muscle. 15. Section of lower maxilla. 16. Parotid duct. 17. Lingual attachment of styloglossus muscle, with part of the gustatory nerve seen above it. [Illustration: Head and neck, showing blood vessels, muscles and other internal organs.] Plate 21 COMMENTARY ON PLATE 22. THE RELATIVE POSITION OF THE SUPERFICIAL ORGANS OF THE THORAX AND ABDOMEN.