This muscle is the biceps of the dog. It extends the shoulder and flexes
the elbow. The nerve supply to this muscle comes from the lower neck
and upper thoracic spine. If your dog has problems in extending the
front leg this muscle may be at issue as well as a subluxation in the
neck and or upper back. Many agility dogs that I adjust have an issue
with weave poles and jumps, sometimes this is the problem.