abnormal skeletal muscle morphology abnormal cremaster muscle morphology 2012-11-30T02:55:12Z In rats, it has been shown that cremaster muscles develop from the gubernacular bulb. MP:0011833 MPheno.ontology abnormal cremaster morphology any structural anomaly of the thin layer of skeletal muscle that envelops the spermatic cord and testis of most male mammals in a series of loops; it is a continuation of the obliquus internus, arising from the inguinal ligament and inserting into the crest of the pubis and into the sheath of the rectus abdominis; it is innervated by the genital branch of the genitofemoral nerve and functions to draw the testis up toward the superficial inguinal ring in response to cold or to stimulation of the nerve; in females it is represented by only a few muscle loops that envelop the round ligament of the uterus csmith