MAMMALIA. 221 



back of the ear, but is chiefly distributed on the skin of this part. The 

 posterior trunk of the second, after giving branches to the splenius, complex, 

 and other muscles, close to the posterior part of the spine, also sends a 

 branch through the complex muscle to the skin of the occiput. The 

 posterior trunk of the third gives branches to the complex and other muscles 

 close to the spine, and then terminates on the skin. The posterior trunks of 

 the fifth and sixth also give branches to the muscles "and skin ; the seventh 

 was traced to the muscles only ; the three last are much smaller than the 

 preceding. 



3. Phrenic nerve ; it is formed of a branch from the fourth and fifth cervical 



nerves ; it passes over the pericardium to the diaphragm, and on the right 

 side is placed close to the inferior vena cava. 



4. Fifth cervical nerve ; the axillary plexus is constituted of the three inferior 



cervical and the first dorsal nerves, but the greatest part of the fifth, after 

 receiving a branch from the sixth, gives a large branch to the integuments 

 on the anterior part of the shoulder joint, and then passes to form the 

 superior scapular nerve, and terminate on the superior and inferior spinous 

 muscles. Branches from the fifth, sixth, and seventh cervical, and first 

 dorsal, are given to the pectoral muscles ; a branch from the sixth cervical is 

 given to the great serrated muscle, and branches from the fifth and sixth to 

 the subscapular. 



5. A branch from the seventh cervical nerve, passing down the side of the 



cutaneous muscle and skin, and communicating with the external branches of 

 several of the dorsal nerves. 



6. Circumflex nerve; it arises from the union of the fifth and sixth cervical 



nerves; it gives branches to the subscapular and teres muscles, and then 

 divides and sends a branch to the inferior spinous muscle and the deltoid, 

 and branches to the integuments on the outer side of the arm. 



7. Internal cutaneous nerve ; it is a slender nerve sent off by the ulnar ; it passes 



down the arm, and, near the inner condyle of the humerus, divides into 

 branches to be distributed on the skin at the ulnar side of the fore-arm. The 

 smaller internal cutaneous nerve is the external branch of the second dorsal 



