THE HEAD AND NECK 1229 



the intrinsic muscles of the lajynx, except the crico-thyroid, which 

 is supplied by the external laryngeal nerve. Sensory branches, 

 however, are given to the laryngeal mucous membrane below the 

 true vocal cords, except over the lateral and posterior portions of 

 the cricoid cartilage. Within the larynx the ner\-e communicates 

 with a branch of the internal laryngeal nerve, under cover of the 

 lower part of the ala of the thyroid cartilage. 



For the explanation of the recurrent course of each inferior 

 Iar}-ngeal ner\-e, see p. 966. 



Cervical Cardiac Branches. — ^These are subject to variation as 

 regards numbers. As a rule, there are two, upper and lower, both 

 of which contain bulbar fibres from the spinal accessory. Those of 

 the right side pass behind the first part of the subclavian artery, 

 and end in the deep cardiac plexus. On the left side the upper 

 nerve passes to the deep cardiac plexus, but the lower nerve ter- 

 minates in the superficial cardiac plexus. 



Sammary of the Pneumogastric Nerve in the Neck — i. Motor Distribution. 



— The nerve supplies (i) the muscles of the soft palate, except the tensor 

 palati ; (2) the constrictor muscles of the pharynx ; (3) the intrinsic muscles 

 of the larynx ; and (4) the muscular tissue of the oesophagus and trachea. 

 2. Sensory Distribution. — It supplies (i) the pharynx, oesophagus, and 

 trachea ; (2) a limited portion of the dura mater ; and (3) a small portion of 

 the skin on the inner surface of the auricle, as well as of the lower and back 

 part of the external auditory meatus. 3. Communications. — Each pneumo- 

 gaistric nerve forms connections with the facial, glosso-pharyngeal, spinal 

 accessory, hypoglossal, and sympathetic nerves. It is also connected with 

 the loop between the first and second cervical spinal nerves. Its most im- 

 portant connection is that which is established with the bulbar or accessory 

 portion of the spinal accessory nerve. The bulbar fibres of the nerve are 

 probably chiefly concerned in the innervation of the muscles of the soft 

 palate (except the tensor palati), pharynx, and larynx, but also to a certain 

 extent in the innervation of the heart. 



Spinal Accessory Nerve. 



The spinal accessory or eleventh cranial nerve consists of two 

 parts, bulbar or accessory, and spinal. In the jugular foramen these 

 two parts either unite to form one trunk, or freely intermingle, and 

 a communication is established between the accessory part and the 

 ganglion of the root of the pneumogastric by means of two twigs. 

 The nerve emerges through the jugular foramen, being enclosed in 

 the same sheath of dura mater as the pneumogastric, behind which it 

 lies. Immediately beneath the jugular foramen the two parts of 

 the nerve separate from each other. 



The bulbar or accessory part passes over, but in intimate contact 

 with, the ganglion of the trunk of the pneumogastric, and its fibres 

 are continued partly into the pharyngeal and superior laryngeal 

 branches of the ganglion of the trunk, and partly into the trunk of 

 the vagus below the ganglion. These latter fibres are ultimately 

 prolonged into the cardiac and recurrent lar^Tigeal branches of the 

 nerve. The bulbar or accessory fibres of the spinal accessory are 

 regarded as (i) the motor nerves of (a) the muscles of the soft 



