Cremasteric reflex
Encyclopedia
The cremasteric reflex is a superficial reflex
observed in human males.
This reflex is elicited by lightly stroking the superior and medial (inner) part of the thigh. The normal response is a contraction of the cremaster muscle
that pulls up the scrotum
and testis on the side stroked.
More specifically, the reflex utilizes sensory and motor fibers of the genitofemoral nerve
, formed by fibers from both the L1 and L2 spinal nerves. When the inner thigh is stroked, sensory fibers of the femoral branch of the genitofemoral nerve and the ilioinguinal nerve are stimulated. These synapse in the spinal cord and activate the motor fibers of the genital branch of the genitofemoral nerve which causes the cremaster muscle to contract and elevate the testis.
In boys, this reflex may be exaggerated, and this can lead to the mistaken diagnosis of undescended testes.
Cremasteric reflex may be absent with: testicular torsion
, upper and lower motor neuron
disorders, as well as a spine injury of L1-L2. It can also occur if the ilioinguinal nerve is accidentally cut during a hernia 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, 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 scan or exploratory surgical intervention should be implemented to prevent loss of the testicle.
Reflex
A reflex action, also known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. A true reflex is a behavior which is mediated via the reflex arc; this does not apply to casual uses of the term 'reflex'.-See also:...
observed in human males.
This reflex is elicited by lightly stroking the superior and medial (inner) part of the thigh. The normal response is a contraction of the cremaster muscle
Cremaster muscle
-Contraction:Its function is to raise and lower the testes in order to regulate the temperature of the testes and promote spermatogenesis. Contraction may also occur during arousal which can prevent injury to the testicles during sex....
that pulls up the scrotum
Scrotum
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...
and testis on the side stroked.
More specifically, the reflex utilizes sensory and motor fibers of the genitofemoral nerve
Genitofemoral nerve
In human anatomy, the genitofemoral nerve originates from the upper part of the lumbar plexus of spinal nerves. Its roots are L1 and L2 .The genitofemoral nerve is responsible for both the efferent and afferent limbs of the cremasteric reflex...
, formed by fibers from both the L1 and L2 spinal nerves. When the inner thigh is stroked, sensory fibers of the femoral branch of the genitofemoral nerve and the ilioinguinal nerve are stimulated. These synapse in the spinal cord and activate the motor fibers of the genital branch of the genitofemoral nerve which causes the cremaster muscle to contract and elevate the testis.
In boys, this reflex may be exaggerated, and this can lead to the mistaken diagnosis of undescended testes.
Cremasteric reflex may be absent with: testicular torsion
Testicular torsion
Testicular torsion is when the spermatic cord to a testicle twists, cutting off the blood supply. The most common symptom is acute testicular pain and the most common underlying cause is a congenital malformation known as a "bell-clapper deformity". The diagnosis is often made clinically but if it...
, upper and lower motor neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
disorders, as well as a spine injury of L1-L2. It can also occur if the ilioinguinal nerve is accidentally cut during a hernia 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, 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 scan or exploratory surgical intervention should be implemented to prevent loss of the testicle.