The anatomy of the decapod crustacean auxiliary heart.

The anatomy of an auxiliary heart found in many decapod crustaceans is described. This heart is found at the anterior end of the dorsal median artery before the artery divides to supply the cerebral nervous system. The heart is essentially two strips of modified somatic muscle located inside a sinus in the dorsal median artery. These muscles are innervated by four motoneurons located in the supraesophageal ganglion. Sensory innervation and possible neurosecretory elements are also described.