1895. ] NEW YORK ACADEMY OF SCIENCES. 253 
The relation of this variation to the Brachialis anticus and 
Coraco-brachialis is obvious and will be referred to below. 
In the above series I have encountered this third internal 
head in the following instances : 
1. $, England, aet. 73. January 11, 1894. 
Left upper extremity. 
Internal bicipital head derived directly from the humerus, ex- 
ternal to and about 5 cm. above the Coraco-brachialis insertion, 
between it and the Brachialis anticus, completely free from the 
latter muscle. 
The musculo-cutaneous nerve, after piercing the Coraco-bra- 
chialis, passes between the additional head and the main portion 
of the Biceps muscle. 
2. &, Ireland, aet. 46. January 11, 1894. 
Third internal bicipital head arising from the outer margin of 
the Coraco-brachialis insertion, and in close connection with the 
superior and internal origin of the Brachialis anticus. 
3. 3, Ireland, aet. 37. October 17, 1893. 
Right upper extremity. 
Third bicipital head arising from inner surface of shaft of hu- 
merus at the Coraco-brachialis insertion. Separated from the 
main Biceps muscle by the large muscular branches of the mus- 
culo-cutaneous nerve, which perforates the Coraco-brachialis. 
The internal head has further been noted in the following 
cases : 
4. 3, Ireland, aet. 46. January 24, 1894. 
Right upper extremity. 
5. &, Ireland, aet. 62. November 28, 1893. 
Right upper extremity. 
6. ¢, Germany, aet. 28. October 5, 1893. 
Left upper extremity. 
Additional head, derived in this instance from the insertion of 
the Coraco-brachialis, goes mainly into the semilunar fascia. 
7. 9, Germany, aet. 84. November 9, 1893. 
Left upper extremity. 
8. 9, U.S., white, aet. 68. November 22, 1893. 
Right upper extremity. 
Small third internal head, derived chiefly from the tendon of 
of the Coraco-brachialis, with which it is continuous. 
9. ¢, Germany, aet. 60. December 14, 1893. 
Right upper extremity. 
10. 3g, Bohemia, aet. 30. December 19, 1893. 
Left upper extremity. : 
1]. ¢, Italy, aet. 40. December 14, 1893. 
Right upper extremity. 
