<prompt> An elderly man with prostatic hyperophy returns to his urologist with another case of epididymitis. An acute infection involving the daos muscle layer of the scrotum most likely leads to an enlargement of which of the following lymph nodes?Preaoic nodesLumbar nodesExternal iliac nodesSuperficial inguinal nodes  <response>: The superficial inguinal lymph nodes receive lymph from the scrotum, penis, buttocks, and lower pa of the anal canal, and their efferent vessels enter primarily to the external iliac nodes and ultimately to the lumbar aoic nodes. The deep inguinal nodes receive lymph from the testis and upper pas of the vagina and anal canal, and their efferent vessels enter the external iliac nodes. 