336 ABRAM T. KERR 



4 times, 2.28 per cent of the cases; from the fifth and sixth 4 

 times, 2.28 per cent of the cases; from the fourth, fifth, sixth and 

 seventh cervicals 98 times, 56 per cent of the cases; from the 

 fifth, sixth and seventh 54 times, 30.85 per cent of the cases; 

 from the fourth to the eighth cervical inclusive, 2 times, 1.14 per 

 cent of the cases; from the fourth cervical to the first thoracic 

 inclusive 6 times, 3.42 per cent of the cases; from the fifth cer- 

 vical to the first thoracic 7 times, 4 per cent of the cases. 



Herringham found the seventh entering the musculocutaneous 

 in only 4 out of 39 cases, and in 28 examined to see if both the 

 fifth and sixth entered he found the sixth absent in only one. 

 Wichmann reports, from the literature, its origin from the fourth, 

 fifth and sixth in 1 case, and from the fifth and seventh in another, 

 from the fifth and sixth in 60 cases and from the fifth, sixth and 

 seventh in 44 cases. Schumacher found the fifth and sixth 

 entering 5 times, the fifth, sixth and seventh 4 times, and the 

 fourth, fifth and sixth once. 



If these 155 records are added to my 175 cases we have a total 

 of 330 records of the musculocutaneous nerve. In 6 of these, or 

 1.82 per cent, it may receive fibers from the fourth, fifth and sixth 

 cervical nerves. In 103, or 31.21 per cent, its fibers may come 

 from the fifth and sixth. In 204, or 61.82 per cent, the seventh 

 also sends fibers to the musculocutaneous, which in 98 of these, or 

 29.70 per cent is formed by the fourth, fifth, sixth and seventh, 

 and in 106, or 32.12 per cent, by the fifth, sixth and seventh. 

 In two its fibers come from the fourth to the eighth cervical 

 nerves inclusive; in 6 or 1.82 per cent, from the fourth cervical 

 to the first thoracic inclusive and in 7, or 2.12 per cent, from the 

 fifth cervical to the first thoracic inclusive. In 1 instance it is 

 formed from the fifth and seventh cervical nerves and in 1 from 

 the fifth cervical alone. The seventh cervical nerve appears to 

 take part in the formation of the musculocutaneous nerve in 

 220 instances, or more than two-thirds of the cases. In nearly 

 a third of the cases, however, the seventh cervical sends no fibers 

 to the musculocutaneous and it is not at all impossible that 

 maceration with acid would show it to be absent more often. 



