THE TRUNK. 441 



sides by the internal borders of the muscuh sterno-mastoicki, and 

 the apex by the first piece of the sternum. 



1. The central portion consists, above, of the reg. laryngea 

 (larynx) ; the centre, of the reg. thyreoidea (thyroid cartilage and 

 thy. gland); below, of the fossa supra-sternalis s.jwguhtm, tra- 

 cheal fossa. 



2. Superior lateral portion, trigonum cervicale superius, is a 

 triangular fossa, bounded, above, by the posterior belly of digas- 

 tricus, in front, by the superior belly of omohyoideus, behind, by 

 the anterior border of sterno-mastoid., and above passing into the 

 reg. parotidea. Below lies the sterno-mast., close to and before 

 the trachea. 



Position of the parts: 1. Skin and loose fibre-cellular tissue, 

 with little fat. 2. Above, fascia cervicalis and mm.platysmam. ; 

 below, in the jugulum, a space between the anterior and middle 

 layer of thefasc. cervicalis, which sends a process externally into 

 the reg. supraclavicularis behind the m. sterno-mast., and contains 

 in the middle line a descending branch of ven. thyreoid. inf. (fre- 

 quently) ; some lymphatic glands ; laterally, the ven. jugularis 

 anterior. 3. Mm. sterno-hyoidei, above, m. omohyoideus. 4. 

 Mm. thyreo-hyoidei, branches of ri. hypogloss. and mm. sterno-thy- 

 reoidei. 5. Thyroid gland, with the deep layer offasc. cervical., 

 which is attached to the posterior surface of the sternum and larynx. 

 6. Plexus venosus thyreoidus, and, near the sternum, v. subclavia 

 sinistra and truncus anonymm (but the last rests entirely beneath 

 this region, as it ascends obliquely from left to right). In the angle 

 between the two : 7. The trachea. 8. Pharynx above ; below and 

 to the right, n. recurrens dexter ; below and to the left, oesophagus, 

 and on its anterior surface, n. recurrens sinistra, and a transverse 

 branch of art. thyreoid. inf. 9. Loose fibre-cellular tissue ; under 

 that mm. longi colli, and the fifth to the seventh cervical vertebra. 



In the trigonum cervicale superius ; 1. The skin and thin layer 

 of nbro-cellular tissue. 2. M.platysmam. 3. Nn. cervicale su- 

 perfic., and behind n. auricularis (s. plex. cervic.). 4. Yen. jugu- 

 lar, externa. 5. M. digastric, and stylohyoid. 6. Lymphatic 

 glands, surrounded with venous plexuses. 7. N. hypoglossus, 

 carotis externa, which is to be felt in the inferior angle of the tri- 

 gonmn. Farther inwards and backwards, carotis interna (which 

 see), with the parts surrounding it. 



693. Lateral surfaces of the Neck, Reg. supraclavicularis. 



1. Reg. sterno-mastoidea. The sterno-cleido-mast. is covered 

 by a loose fibro-cellular tissue, in which the ven. jugular, extern. 

 descends from before backwards. It covers.: v 



