The cremaster is a continuation of the internal oblique muscle, wrapping around the spermatic cord and testis as a series of muscle loops. Its contraction elevates the testis in response to touch on the medial thigh (cremasteric reflex — L1 spinal level).
| Origin | Lowest fibres of the internal oblique muscle and transversus abdominis — at the internal inguinal ring |
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| Insertion | Genital branch of the genitofemoral nerve — forms a loop around the spermatic cord and testis |
| Nerve Supply | Genital branch of the genitofemoral nerve (L1, L2) |
| Blood Supply | Cremasteric artery — branch of the inferior epigastric |
| Actions | Elevates the testis — the cremasteric reflex; Thermoregulation of the testis by varying scrotal position |
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The cremasteric reflex (stroking the medial thigh produces ipsilateral testicular elevation) tests the L1 spinal reflex arc. Absent cremasteric reflex suggests L1 nerve root dysfunction or testicular torsion (the acutely inflamed testis loses reflex). Cremaster muscle hypertrophy causes painful testicular retraction (retractile testis versus cryptorchidism).
Tested by the cremasteric reflex — brisk testicular elevation with medial thigh stroking.
Loss of cremasteric reflex in acute testicular torsion due to ischaemic reflex arc disruption, a clinical sign supporting urgent surgical exploration.
