THE HYPOGLOSSAL NERVE 



915 



aspect of the central canal. The fibers run forward through the medulla oblongata, 

 and emerge in the antero-lateral sulcus between the pyramid and the olive. 



The rootlets of this nerve are collected into two bundles, which perforate the 

 dura mater separately, opposite the hypoglossal canal in the occipital bone, and 

 unite together after their passage through it; in some cases the canal is divided 

 into two by a small bony spicule. The nerve descends almost vertically to a point 

 corresponding with the angle of the mandible. It is at first deeply seated beneath 

 the internal carotid artery and internal jugular vein, and intimately connected with 

 the vagus nerve; it then passes forward between the vein and artery, and lower 



To Dura mater 



To Ganglion nodosum of vagus 

 - Hypoglossal nerve 



Branch from first cervical 

 to hypoglossal 



To Lingual nerve 



TO GENIOHYOIDEUS 



TO SUPERIOR BELLY OF OMOHYO1DE.US 



TO STERNOHYOIDEUS 



TO STERNOTHYREOIDEUS 

 TO INFERIOR BELLY OF OMOrfYOIDEUS 



FIG. 795. Plan of hypoglossal nerve. 



down in the neck becomes superficial below the Digastricus. The nerve then loops 

 around the occipital artery, and crosses the external carotid and lingual arteries 

 below the tendon of the Digastricus. It passes beneath the tendon of the Digas- 

 tricus, the Stylohyoideus, and the Mylohyoideus, lying between the last-named 

 muscle and the Hyoglossus, and communicates at the anterior border of the Hyo- 

 glossus with the lingual nerve; it is then continued forward in the fibers of the 

 Genioglossus as far as the tip of the tongue, distributing branches to its muscular 

 substance. 



Branches of Communication. Its branches of communication are, with the 



Vagus. First and second cervical nerves. 



Sympathetic. Lingual. 



The communications with the vagus take place close to the skull, numerous 

 filaments passing between the hypoglossal and the ganglion nodosum of the vagus 





