THE SYMPATHETIC TRUNK 1033 



visceral motor fibres which have entered them in the white rami communicantes from the spinal 

 nerves of higher or lower levels, and which are coursing in them to terminate in other ganglia, 

 either in the trunks above or below or in ganglia not belonging to the trunks; (2) fibres arising in 

 sympathetic ganglia of a higher or lower level and passing upward or downward to terminate 

 in other ganglia of the trunk or to issue from the trunk and proceed to more peripheral ganglia or 

 to ganglia of the opposite trunk (both associative and commissural fibres); (3) afferent fibres 

 or sensory fibres arising either in the spinal ganglia, or sensory sympathetic fibres arising in 

 sympathetic ganglia and coursing in the trunk to pass into spinal ganglia above or below by way 

 of the grey rami communicantes. 



THE CEPHALIC AND CERVICAL PORTIONS OF THE SYMPATHETIC 



TRUNK 



The cephalic portion of the sympathetic system consists of numerous small 

 ganglia and of numerous plexuses connected with the internal carotid nerve, the 

 ascending branch given off by the superior cervical sympathetic ganglion. The 

 cephalic ganglia are all relatively small. There are four considered in the 

 ordinary macroscopic dissections, namely, the ciliary or ophthalmic, the spheno- 

 palatine or Meckel's ganglion, the otic, and the submaxillary. To these may be 

 added a portion of the superior cervical sympathetic ganglion, the sympathetic 

 portions of the nodosal, petrous, geniculate and semilunar ganglia, and the var- 

 ious small ganglia dispersed in the plexuses. These ganglia with their roots or 

 communicating branches have been described in their relations with the divisions 

 of the trigeminus and with the oculo-motor, glosso-palatine, vagus and facial 

 nerves. 



The internal carotid nerve, the ascending branch from the superior cervical 

 sympathetic ganglion, may be regarded as an upward prolongation of the primi- 

 tive sympathetic trunk. 



It arises from the upper end of the superior cervical ganglion and passes through the carotid 

 canal into the cranial cavity. It divides into two branches which subdivide to form a coarse 

 plexus, the internal carotid plexus, which partly surrounds the internal carotid artery before 

 the latter enters the cavernous sinus (fig. 787 and 788). It passes with the artery to the caver- 

 nous sinus, where it forms the finer meshed cavernous plexus. 



The internal carotid plexus supplies offsets to the artery and receives branches 

 from the tympanic plexus through the inferior carotico-tympanic nerve and 

 from the spheno-palatine ganglion through the great deep petrosal nerve. It also 

 communicates by fine branches with the semilunar (Gasserian) ganglion and 

 with the abducens nerve. 



The cavernous plexus gives branches of communication to the oculo-motor 

 and trochlear nerves and to the opthalmic division of the trigeminus. According 

 to Toldt and Spalteholz, it communicates with the tympanic plexus through the 

 superior carotico-tympanic (small deep petrosal) nerve. It also communicates 

 with the ciliary ganglion through the long root of the ciliary ganglion and usually 

 through a separate sympathetic root of this ganglion. These branches may pass 

 through the superior orbital (sphenoidal) fissure either separately or with the naso- 

 ciliary (nasal) nerve. 



The cavernous plexus also gives branches to the carotid artery and filaments of the plexus 

 accompany small branches of the artery to the hj'-pophysis (pituitary body) and to the dura 

 mater on the sphenoid bone. 



The terminal branches of the cavernous plexus consist of delicate filaments that anastomose 

 freely, forming fine plexuses, and pass from the cavernous plexus along the terminal divisions 

 of the internal carotid artery and their branches. These fine plexuses take the name of the 

 artery on which they lie. The four larger of them are the plexuses of the anterior and middle 

 cerebral arteries, the plexus of the chorioid artery, and the ophthalmic plexus. 



The cervical portion of the sympathetic cord extends upward along the great 

 vessels of the neck. No white rami communicantes connect it directly with the 

 spinal cord, but instead it receives visceral efferent fibres from the upper thoracic 

 spinal nerves through the sympathetic trunk, and probably also from the cervical 

 spinal cord through the spinal acessory nerve and the connections with the vagus. 

 It sends grey rami communicantes to each of the cervical nerves. It extends 

 from the subclavian artery to the base of the skull, lying dorsal to the sheath of 

 the great vessels and in front of the longus capitis and longus colli, which separate 

 is from the transverse processes of the cervical vertebrae (fig. 787). It usually 



