36 DE. J. MUEIE ON THE MANATEE. 



memoir 1) dividing the nerves issuing from the one foramen. On the contrary, on the 

 left side I did not observe the presence of such a minute tendon. But though to appear- 

 ance absent, there was nevertheless a band of fascia, evidently belonging to the deep 

 cervical fascia, which took the position of the minute tendon in question. 



The third cervical nerve, then, distinctly issues from the foramen between the axis 

 and the succeeding vertebra. It passes thereafter outwards and over the scalene, joins, 

 as aforesaid, the loop of the second nerve, and courses somewhat parallel with the 

 branches of the latter. Its main trunk subdivides terminally into branchlets, which are 

 distributed to the trapezius and other parts of the neck above and around the scapula. 



IV. From the same foramen as the last, viz. between the axis and the succeeding 

 vertebra, is another nerve-trunk, which within the vertebral foramen unites with the 

 preceding by fascia or, it may be, nervous tissue. This I ascertained after I had made the 

 dissection and had the drawing done represented in PI. VIII. fig. 5, when I followed 

 the nerves right into the vertebral canal and through t!ie theca of the spinal cord. 

 But inasmuch as the dissection was a laborious proceeding, taking some days to finish, 

 likewise from the animal having died after an exhausting illness with the nervous tissue 

 tender in some places, and particularly from the great difficulty of cleaning the parts 

 around the intervertebral foramen and within the spinal canal, owing to the presence 

 of the rete mirabile, I could not trace the nerves distinctly as separately arising from 

 the spinal cord itself. 



However this may be, it is certain that immediately exterior to the intervertebral 

 foramen the fourth and the third cervical nerves are quite distinct and trend in difi'erent 

 directions. The third takes an upward and forward, the fourth a downward and back- 

 ward course. These two nervous cords are nearly of equal calibre, and barely as thick as 

 is the second nerve. Tracing the course of this fourth nerve outwards, I found that 

 fully one inch beyond its exit from the intervertebral foramen it forms a union with a 

 division of the fifth nerve. At this junction the phrenic nerve is given off; and it 

 descends (is directed rearwards) as usual into the chest, lying superficially to the brachial 

 plexus. Beyond the junction just mentioned the calibre of the compound nerve is 

 considerably increased, and it splits up into three divisions. 



One proceeds above the shoulder-joint, passes over the suprascapularis muscle, and 

 supplies the parts on the upper and outer side of the shoulder, including the trapezius 

 &c. The second division goes to the outer head of the humerus, being chiefly distri- 

 buted to the pectoralis major and the deltoid, in a manner therefore equivalent to a 

 supraclavicular branch. The third, deepest nerve-division pierces the tissues betwixt 

 the subscapularis and the supraspinatus, and it goes to the fleshy parts at the back of 

 the scapula, twigs penetrating the supraspinatus &c., and another proceeding through 

 the suprascapular notch. 



Comparing what has now been said with the general distribution of the cervical 

 ' Op. cit. pp. 137, 152, & 18-1, pi. xiiv. fig. 29. 



