1232 A MANUAL OF ANATOMY 



nerve to the genio-hyoid is generally regarded as being composed of 

 spinal fibres, derived from the first, second, and third cervical 

 nerves. 



The terminal or glossal branches pierce the under surface of the 

 tongue, and are distributed to its muscular tissue. 



The hypoglossal nerve receives many spinal fibres. Those 

 derived from the first cervical nerve, or the loop between the 

 first and second, soon become applied to it, and the most of them 

 pass off to form the descendens cervicis nerve. A few of these, 

 however, still pass along the main trunk. The spinal fibres derived 

 from the second and third cervical nerves in part ascend in the 

 descendens cervicis nerve, and then pass off from it to be applied 

 to the main trunk in its onward course. 



Summary — i. Distribution. — Tlie h5^oglossal fibres of the nerve supply 

 the stylo-glossus, hyo-glossus, genio-hyo-glossus, and intrinsic muscles of the 

 tongue. The spinal fibres supply both bellies of the omo-hyoid, the sterno- 

 hyoid, sterno-thyroid, thyro-hyoid, and genio-hyoid muscles. The hypo- 

 glossal nerve also supplies the dura mater in the vicinity of the cranial aspect 

 of the anterior condylar foramen. 2. Connections. — It establishes connec- 

 tions with (i) the ganglion of the trunk of the vagus ; (2) the superior cervical 

 ganglion of the sympathetic ; (3) the first, second, and third cervical nerves ; 

 (4) the pharyngeal plexus, through means of the lingual branch of the vagus ; 

 and (5) the lingual nerve from the inferior maxillary division of the fifth cranial 

 nerve. 



Gangliated Cord of the Sympathetic. 



Cervical Portion. — ^This portion of the sympathetic cord extends 

 from the base of the skull, at the foramen caroticum on the under 

 surface of the petrous part of the temporal bone, to the root of the 

 neck, where it enters the thorax, passing, on the right side, behind 

 the subclavian artery. It lies directly behind the carotid sheath, 

 and in front of the transverse processes of the cervical vertebrae, 

 resting upon the rectus capitis anticus major and longus colli 

 muscles. The cord presents three ganglia — superior, middle, and 

 inferior. 



Superior Cervical Ganglion. — ^This ganglion is elongated and fusi- 

 form. It is regarded as representing four ganglia united into one, 

 and corresponding to the first four cervical nerves. It is situated 

 in front of the transverse processes of the second and third cervical 

 vertebrae, and lies upon the rectus capitis anticus major, the pneu- 

 mogastric nerve being external to it. At either end it tapers, 

 being continued superiorly into its ascending branch, and interiorly 

 into the descending cord. 



Branches. — ^These are numerous and complicated. They may 

 be conveniently arranged into ascending, external or communi- 

 cating, internal or pharyngeal, superior cardiac, and anterior or 

 vascular. 



The ascending branch enters the carotid canal in the petrous part 

 of the temporal bone, in company with the internal carotid artery, 



