1276 



HUMAN ANATOMY. 



medulla. The cortico-nuclear fibres then bend dorso-medially and, for the most part but 

 not entirely, cross the raphe to enter the ventro-lateral surface of the hypoglossal nucleus of 

 the opposite side and end in arborizations around the root-cells. 



Course and Distribution. The hypoglossal takes its superficial origin 

 from the surface of the brain-stem in the form of from ten to fifteen slender fasciculi, 

 which emerge from the ventral surface of the medulla in the groove between the 

 olivary eminence and the pyramid (Fig. 1046). 



FIG. 1082. 



Digastric muscle, 



I. cervical nerve 

 Spinal accessory nerve 

 Small occipital nerve 



II. cervical nerve 



Hypoglossal nerve 



Superior cervical gang! 



Branch of II. cervical to spinal accessory 



III. cervical nerve 



Communicans hypoglossi 



Stumps of great auricular and superficial 



cervical nerves) , v _ CCTvica i nerve 



VI. cervical nerve 

 Branch of communication to 

 spinal accessory 

 Cutaneous branch 

 VII. cervical nerve 

 Nerve to subcla' 

 VIII. cervical nerve 

 Posterior thoracic 



ner 



Supra scapula 

 nerve 



I. thoracic nerve 



External pterygoid muscle 

 Lingual branch of V. nerve 

 f Chorda tympani nerve 

 Internal pterygoid muscle 

 Edge of oral mucous membrane 



losso-pharyngeal nerve 

 -Mental nerve 

 Inferior dental nerve, cut 

 Sublingual gland 

 Submaxillary ganglion 

 'Stylo-hyoid muscle 



Thyro-hyoidbranchofXII. nerve 



Superior laryngeal nerve 



Descendens hypoglossi ; sympathetic 



cord is toils outer side 



Vagus nerve 



External laryngeal nerve 



Omo-hyoid muscle, cut 



Phrenic nerve 



Middle cervical ganglion of sympathetic 



Scalenusanticus muscle 



lavian artery 



Deep dissection of neck showing branches of vagus, spinal accessory and hypoglossal nerves. 



These root-bundles pass outward, dorsal to the vertebral artery, and assemble 

 into two groups, which pierce the dura mater separately at a point opposite the 

 anterior condyloid foramen. Either within this canal or as they leave the 

 cranium through its external opening they unite into a single trunk. Arriving at 

 the inferior aspect of the base of the skull, the deeply placed hypoglossal nerve 

 descends and hooks around the ganglion of the trunk of the vagus, to which it is 

 closely attached by connective tissue. It then takes a downward and forward 

 course between the internal carotid artery and the internal jugular vein. Arriving 

 at the inferior margin of the 'posterior belly of the digastric, the nerve winds around 

 the occipital artery and courses downward and forward to the outer side of .the 

 external and internal carotid arteries. It then continues forward above the hyoid 

 bone to the under surface of the tongue, passing beneath the tendon of the digastric, 



