THE VISCERA. 205 



of the mm. constrictor pharyng. 2. F. pharyngea later alis arises from os 

 pctrosum (at the internal border of the inferior opening of canal, caroticus~), 

 passes to the lateral wall of the Pharynx, attaches itself in the fossa pterygoid. 

 between m. pterygoid. intern, and circumflex, palati, with a process to the m. 

 bticcinatorius, covers the tonsils, and attaches itself to the superior border of o* 

 hyoideum. 



Vessels : Branches of Art. pharyngea ascendens, thyreoidea super, and infer., 

 palatina ascend, and pterygo-palatina. 



Veins : they form plex. pharyngeus. 



Nerves : plex. pharyngeus superior and inferior (from N. vagus, glosso-pha- 

 ryngeus, accessor. Willis, and sympathicus~), and ganglion spheno-palatinum. 



435. 6. The (Esophagus, 



a flat, extensible, muscular canal, from eight to nine inches long, 

 reaches from the fifth cervical vertebra as far as the tenth dorsal, 

 that is, from the inferior opening of the pharynx to the superior 

 of the stomach ; narrowest in the cervical region, widest at the 

 inferior extremity; and closed in the remaining portion, since the 

 anterior comes in contact with the posterior wall. 



a. Cervical portion : 1. covered in front by the trachsea, to the 

 left (as the oesophagus deviates to the left) by m. sterno-thyreoid- 

 eus (sinister), the thyroid gland, N. recurrens (sinist.), Art. and 

 Ven. thyreoidea infer., connected above by condensed uniting 

 tissue with the trachsea ; 2. behind, attached by loose uniting 

 tissue to the vertebral column; N. recurrens dexter; 3. at the 

 sides : the thyroid gland, Carotis communis, Ven. jugularis in- 

 ternet. 



b. The thoracic portion passes along the posterior mediastinum. 

 1. Before it are placed: the trachsea, and farther down the 

 bronchus sinister, arcus aortas, and lastly the pericardium (with 

 the basis and posterior surface of the heart) ; below n. vagus 

 sinister. 2. Behind it: the vertebral column ; separated from it 

 by uniting tissue, lymphatic glands, Ven. azygos and ductus 

 thoracicus (above) ; quite below: Aorta thoracica and N. vagus 

 dexter. 3. At the sides: the lungs, separated from it by the 

 middle mediastinum ; the whole length of N. vagus; to the 

 right (from the fourth dorsal vertebra) on ven. azygos, duct, 

 thorac.; to the left: Aorta thoracica. In the thoracic portion 

 the oesophagus projects in a more marked manner to the right. 



c. The abdominal portion, very short (rarely an inch), passes 

 through foram. cesophageum of the diaphragm, and is immedi- 

 ately enveloped by peritonaeum before and to the right of the left 

 lobe of the liver, behind embraced by lobulus Spigelii. 



Structure. 1. Muscular coat, timica externa, thick, above red, below paler ; 

 consists of an external layer of longitudinal iibres, which descend from the 

 posterior surface of Carlilago cricoidea, and are lost in the first layer of the 



