The Cremasteric reflex reference article from the English Wikipedia on 24-Jul-2004
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Cremasteric reflex

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Cremasteric Reflex is a reflex in males only.

This reflex is elicited by stroking the superior and medial part of the thigh in a downward direction. The normal response is a contraction of the cremasteric muscle that pulls up the scrotum and testis on the side stroked.

In children, this reflex may be overexaggerated and this can lead to the mistaken diagnosis of undescended testes.

Upper and lower motor neuron disorders, as well as a spine injury of L1-L2, can cause an absence of the cremasteric reflex. It has also been reported to be absent in 100% of cases of testicular torsion, making it a useful sign in this difficult diagnosis.