

If you are a fan of baseball, you know that we are well into the  playoffs.  My Dad asked me a question the other day that I thought would  make a good blog post.  His question was how could Edgar Renteria, a  shortstop for the San Francisco Giants, continue to play with a torn  biceps tendon?  This is a good question, and from media reports, it  seems Renteria tore the tendon in his left biceps brachii while 
swinging  at a pitch against the Braves last week.  The biceps brachii is the  large (well, large in some people) muscle located on the anterior  (front) part of the upper arm.  There are actually two parts to the  biceps brachii, as biceps means two heads.  In the picture to the left,  the number 5 is pointing to the tendon that attaches the long head of  the biceps brachii to the upper part of the scapula (shoulder), and the  number 9 is pointing to the short head of the biceps brachii, which  attaches to the lower part of the scapula.  The number 4 points to the  common tendon of both heads that attaches to the radius (elbow).  The  biceps brachii actually has 3 jobs, or functions.  1)  It helps with  shoulder flexion (raising your arm straight up in front of you), 2) it  helps with elbow flexion (bending your elbow), and 3) it helps with  supination of the proximal radiounlar joint (holding your palms up).  I  say it helps with these motions because there are other muscles that  cause these motions as well, such as the anterior deltoid for shoulder  flexion, the brachialis for elbow flexion, and supinator for supination.   It is not clear from the 
article  which biceps brachii tendon that Renteria tore, but since there are  other muscles that cause the same motions as the biceps brachii, it is  possible to perform without the muscle.  Renteria is probably in less  pain now that the tendon has completely torn than he was when it was  only a partial tear.