|The cremaster muscle appears as a thin layer just superficial to the tunica vaginalis.|
|Gray's||subject #118 414|
|Nerve||Genital branch of genitofemoral nerve|
|Actions||raise and lower the scrotum|
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.
In a cool environment, the cremaster draws the testis closer to the body and reduces surface area, thereby reducing heat loss, while when it is warmer, the cremaster relaxes, allowing the testis to cool by increasing exposed surface area.
Clinically, a reflex arc termed the cremasteric reflex can be demonstrated by lightly stroking the skin of the inner thigh downwards from the hip towards the knee. This causes the cremaster muscle on the same side to rapidly contract, raising that testicle.
Development and sex differences
The cremaster develops to its full extent only in males; in females it is represented by only a few muscle loops.
In rats, it has been shown that cremaster muscles developed from the gubernacular bulb.Hrabovszky, Z.; Pilla, N. D.; Yap, T.; Farmer, P. J.; Hutson, J. M.; Carlin, J. B. (2002). "Role of the gubernacular bulb in cremaster muscle development of the rat". The Anatomical Record 267 (2): 159–165. doi:10.1002/ar.10092. PMID 11997885.
In human males, the cremaster muscle is a thin layer of skeletal muscle found in the inguinal canal and scrotum between the external and internal layers of spermatic fascia, surrounding the testis and spermatic cord. The cremaster muscle is a paired structure, there being one on each side of the body.
Anatomically, the lateral cremaster muscle originates from the internal oblique muscle, just superior to the inguinal canal, and the middle of the inguinal ligament. The medial cremaster muscle, which sometimes is absent, originates from the pubic tubercle and sometimes the lateral pubic crest. Both insert into the tunica vaginalis underneath the testis.
Innervation and vascular supply
The cremaster muscle is innervated from the genital branch of the genitofemoral nerve and supplied by the cremasteric artery.
It receives distinctly different innervation and vascular supply in comparison to the internal oblique.
The cremaster muscle occasionally experiences painful spasms or cramps in adult males which can be chronic and debilitating. Treatment for these spasms ranges from minor surgery to injection with botulinum-a toxin to the regular application of heat to relax the muscle. Surgery, including the excision of the cremaster muscle, has apparently been able to provide complete relief from this condition without significant side effects.
The word is derived from the Greek verb κρεμάννυμι = "I hang (transitive)".
- Baty, John A. (5 May 1956). "Cremasteric cramp with testicular retraction". British Medical Journal 1 (4974): 1014–1015. ISSN 0959-8138. PMC 1979762. PMID 13304412. Retrieved 11 March 2012.
- Mori, Ryan; Sandip Vasavada, Diana Baker, Edmund Sabanegh Jr. (July 2011). "Treatment of debilitating cremasteric synkinesia With intracremasteric botulinum-a toxin injections". Urology (Cleveland, OH: Glickman Urological and Kidney Institute) 78 (1): 214–216. ISSN 0090-4295. Retrieved 11 March 2012.
- -731185075 at GPnotebook
- LUC crem
- SUNY Labs 36:07-0102 - "Inguinal Region, Scrotum and Testes: Layers of the Spermatic Cord"
- Cremaster+muscle at eMedicine Dictionary