The cremasteric reflex is a superficial (i.e., close to the skin's surface)

reflex In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...

observed in human males. This reflex is elicited by lightly stroking or poking the superior and medial (inner) part of the thigh—regardless of the direction of stroke. The normal response is an immediate contraction of the cremaster muscle that pulls up the

testicle A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

ipsilaterally (on the same side of the body). The reflex utilizes sensory and motor fibers from two different nerves. When the inner thigh is stroked, sensory fibers of the

ilioinguinal nerve The ilioinguinal nerve is a branch of the first lumbar nerve (L1). It separates from the first lumbar nerve along with the larger iliohypogastric nerve. It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, ...

are stimulated. These activate the motor fibers of the

genital branch The genital branch of the genitofemoral nerve, also known as the external spermatic nerve in males, is a nerve in the abdomen that arises from the genitofemoral nerve. The genital branch supplies the cremaster muscle and anterior scrotal skin in ...

of the genitofemoral nerve which causes the cremaster muscle to contract and elevate the testis.

Clinical conditions

In some males this reflex may be exaggerated which can occasionally lead to a misdiagnosis of

cryptorchidism Cryptorchidism, also known as undescended testis, is the failure of one or both testes to descend into the scrotum. The word is . It is the most common birth defect of the male genital tract. About 3% of full-term and 30% of premature infant boy ...

. The cremasteric reflex may be absent with

testicular torsion Testicular torsion occurs when the spermatic cord (from which the testicle is suspended) twists, cutting off the blood supply to the testicle. The most common symptom in children is sudden, severe testicular pain. The testicle may be higher tha ...

, upper and lower motor

neuron A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...

disorders, as well as a spine injury of L1-L2. It can also occur if the ilioinguinal nerve has accidentally been cut during a

hernia A hernia (: hernias or herniae, from Latin, meaning 'rupture') is the abnormal exit of tissue or an organ (anatomy), organ, such as the bowel, through the wall of the cavity in which it normally resides. The term is also used for the normal Devel ...

repair. The cremasteric reflex can be helpful in recognizing testicular emergencies. The presence of the cremasteric reflex does not eliminate testicular torsion from a differential diagnosis, but it does broaden the possibilities to include

epididymitis Epididymitis is a medical condition characterized by inflammation of the epididymis, a curved structure at the back of the testicle. Onset of pain is typically over a day or two. The pain may improve with raising the testicle. Other symptoms may ...

or other causes of scrotal and testicular pain. In any event, if testicular torsion cannot be definitively eliminated in an expeditious manner, a testicular

Doppler ultrasound Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), and their relative velocity to the probe. By calculating the frequency shift of a ...

or exploratory surgical intervention is usually implemented to prevent possible loss of the testicle to

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

References

{{reflex Andrology Reflexes