398 A^'AT03fICAL TECHNOLOGY. 



Ramus comtnunicans 3 — The branch or ramus connecting tlie vertebral ganglion of 

 the sympatliic with the 1st thoracic myelonal nerve. 



Rm, crv. 4 (7), Ramus communicans cervicalis (7th) — The branch connecting the 

 7th cervical nerve with the vertebral ganglion. 



N. crd. 5, Nervus cardiacus minor — The lesser cardiac nerve from the vertebral 

 ganglion. The heart receives several filaments from the vertebral and thyroid ganglia, 

 but only this large one is shown. 



N. sym. (cph.) 6, N. sympathicus (cephalicus)— The sympathic nerve extending 

 cephalad of the thyroid ganglion along the neck. It is somewhat displaced to the right ; 

 see Fig. 107. 



N. sym., N. sympathicus — The cut end of the sympathic nerves of the two sides, 

 showing their relations to other parts. That of the left side {N. sym.) is on the left of the 

 corresponding carotid artery, while the one on the right (N. s.) is dorsad of the right 

 carotid and very close to the vagus. 



N. v., N. vagfus — The cut ends of the vagus or pneumogastric nerves, showing their 

 relations. 



N. phrn., N. phrenicus — The cut ends of the phrenic nerves, showing their relations 

 to the other structures. 



CEs., CEsophagus (Fig. 103, 107, § 798)— The oesophagus is seen to be somewhat to 

 the left of the meson and dorso-sinistrad of the trachea. It is represented as somewhat 

 contracted, hence the wavy outline of the mucous membrane. 



Rx. et Gng. dorsalis, Radix et Ganglion dorsalis — The dorsal (posterior) root of 

 the 1st pair of myelonal nerves with its ganglion. (The adjective dorsalis belongs only to 

 radu', hence the feminine form.) 



Rx. vnt., Radix ventralis — The ventral (anterior) root of the 1st pair of myelonal 

 nerves (§ 1007). 



Spina neu. thr. (2), Spina neuralis thoracica (2) — The 2d neural thoracic spine. 



Trachea — The trachea is represented as slightly contracted so that the cartilaginous 

 rings overlap somewhat. 



VV. brcph., VV. brachio-cephalicae — The cut ends of the two brachiocephalic veins 

 (Fig. 101, ^923). 



§ 1047. Obvious Structure of Nervous Tissue. — Nervous tissue is obviously of two 

 kinds : — (A) Alba (ichite matter). This is found in the central nervous system, where it 

 has a dense, lusterless white appearance, but principally in the nerves (§ 995), where it is 

 white and glistening; the nerve also has a wavy or crimped appearance when relaxed. 

 The nerves themselves have something of the same obvious structure as striated muscle 

 (§ 704^ tliat is, a more or less cylindrical fasciculus, surrounded by a sheath {epinenriiivi), 

 and this mass in turn being composed of smaller bundles {funiculi) each funiculus having 

 its special sheath {perineurium, neurilemma). 



(B) Gray matter. The gray nervous matter is soft, so that it is easily crushed in the 

 hand ; in color it is of a delicate gray or reddish brown, and is collected in masses (s^ 994^, 

 the largest being in the brain and myelon (§ 997). 



§ 1048. Microscopic Structure of Nervous Matter.— (A) Widte matter {alba). Each 

 funiculus, like the fasciculus of a striated muscle, is composed of a variable number of cyl- 

 indrical fibejs which are of two kinds: — (1) Medullated, composed of three parts, ^^z., a 

 primitive sheath somewhat comparable to the sarcolemma of the muscle fiber (g 705) ; it 

 has a wavy outline and presents nuclei: 3Ii/eline or white substance of Scfnrann, this is a 

 white fatty substance just within the primitive sheath ; it is interrupted at regular intervals 



