Cremaster muscle
Encyclopedia
Contraction
Its function is to raise and lower the testes in order to regulate the temperature of the testes and promote spermatogenesisSpermatogenesis
Spermatogenesis is the process by which male primary germ cells undergo division, and produce a number of cells termed spermatogonia, from which the primary spermatocytes are derived. Each primary spermatocyte divides into two secondary spermatocytes, and each secondary spermatocyte into two...
. 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.
Contraction can also occur during moments of extreme fear, possibly to help avoid injuring the testes while dealing with a fight or flight
Fight-or-flight response
The fight-or-flight response was first described by Walter Bradford Cannon....
situation.
Clinically, a reflex
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:...
arc termed the cremasteric reflex
Cremasteric reflex
The cremasteric reflex is a superficial reflex observed in human males.This reflex is elicited by lightly stroking the superior and medial part of the thigh...
can be demonstrated by lightly stroking the skin of the inner thigh
Thigh
In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...
downwards from the hip towards the knee. This causes the cremaster muscle on the same side to rapidly contract, raising that testicle.
The cremaster can also be contracted voluntarily, by contracting the pubococcygeus muscle
Pubococcygeus muscle
The pubococcygeus muscle or PC muscle is a hammock-like muscle, found in both sexes, that stretches from the pubic bone to the coccyx forming the floor of the pelvic cavity and supporting the pelvic organs. It is part of the levator ani group of muscles.-Function:The Pubococcygeus muscle controls...
(using Kegels), or by sucking in the abdomen.
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 human female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
s, the cremaster muscle is smaller and is found on the round ligament
Round ligament of uterus
The round ligament of the uterus originates at the uterine horns, in the parametrium. The round ligament leaves the pelvis via the deep inguinal ring, passes through the inguinal canal and continues on to the labia majora where its fibers spread and mix with the tissue of the mons...
.
In rats
RATS
RATS may refer to:* RATS , Regression Analysis of Time Series, a statistical package* Rough Auditing Tool for Security, a computer program...
, it has been shown that cremaster muscles developed from the gubernacular bulb.
Structure
In humanHuman
Humans are the only living species in the Homo genus...
male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
s, the cremaster muscle is a thin layer of skeletal muscle
Skeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
found in the inguinal canal
Inguinal canal
The inguinal canal is a passage in the anterior abdominal wall which in men conveys the spermatic cord and in women the round ligament. The inguinal canal is larger and more prominent in men.-Site:...
and 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...
between the external and internal layers of spermatic fascia
Spermatic fascia
The spermatic fascia is a bilayered fascia covering the testis; both layers are derived from abdominal muscle or fascia.* The more superficial of these two layers, the external spermatic fascia, lies deep to the skin and dartos fascia of the testes, superficial to the cremaster muscle, and is a...
, surrounding the testis and spermatic cord
Spermatic cord
The spermatic cord is the name given to the cord-like structure in males formed by the ductus deferens and surrounding tissue that run from the abdomen down to each testicle.-Contents of 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
Inguinal canal
The inguinal canal is a passage in the anterior abdominal wall which in men conveys the spermatic cord and in women the round ligament. The inguinal canal is larger and more prominent in men.-Site:...
, 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
Tunica vaginalis
The tunica vaginalis is the serous covering of the testis.It is a pouch of serous membrane, derived from the processus vaginalis of the peritoneum, which in the fetus preceded the descent of the testis from the abdomen into the scrotum....
underneath the testis.
Innervation and vascular supply
The cremaster muscle is innervated from the genital branch of the genitofemoral nerveGenitofemoral 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...
and supplied by the cremasteric artery.
It receives distinctly different innervation and vascular supply in comparison to the internal oblique.
Etymology
The word is derived from the Greek verb κρεμάννυμι = "I hang (transitive)", not from Latin cremareCremation
Cremation is the process of reducing bodies to basic chemical compounds such as gasses and bone fragments. This is accomplished through high-temperature burning, vaporization and oxidation....
.