Cremaster muscle

Formation and location

The cremaster muscle originates from the internal oblique abdominal muscle (m. obliquus internus abdominis). Some of the lower muscle fascicles of this muscle, running along the inguinal ligament, separate and form m. cremaster.

Topographically, the muscle passes through the inguinal canal (canalis inguinalis). It is part of the male contents of the inguinal canal, accompanying the spermatic cord. From the inguinal canal, the muscle descends into the scrotum (scrotum), where it becomes part of the tunics of the testis and spermatic cord.

Structure and fascial layers

Unlike the superficial dartos tunic of the scrotum (tunica dartos), which contains smooth myocytes, m. cremaster is formed by striated muscle tissue.

The muscle is covered by its own fascia — the cremasteric fascia (fascia cremasterica). Within the spermatic cord (funiculus spermaticus) and the scrotum, it forms a strictly defined layer:

• Superficial to it lies the external spermatic fascia (fascia spermatica externa), derived from the aponeurosis of the external oblique abdominal muscle.
• Deep to it lies the internal spermatic fascia (fascia spermatica interna), which is a derivative of the transversalis fascia (fascia transversalis).

In the general layered structure of the testicular tunics, m. cremaster is distinguished as a separate muscular layer (layer VI). In the structure of the scrotum, it is the fifth layer.

Function and cremasteric reflex

The name of the muscle belongs to the group of functional designations (third declension masculine nouns) — m. cremaster (ēris) translates as "the muscle that suspends the testicle". Its main task is the elevation of the testis.

An important neurological test is associated with this muscle — the cremasteric reflex.

• Method of elicitation: stroking the skin of the medial aspect of the thigh with a blunt object (tested in males).
• Response: contraction of m. cremaster.
• Level of the reflex arc integration: spinal cord segments L I – L II.

Blood supply

The blood supply to the muscle is provided by the cremasteric artery (a. cremasterica).

Venous drainage from the scrotum goes into the external pudendal veins and the pampiniform plexus (plexus pampiniformis), which forms the testicular vein (v. testicularis).

Clinical significance (hernia surgery)

Knowledge of the topography of m. cremaster is important in inguinal hernia repair surgeries, such as Bassini inguinal canaloplasty.

During surgical access and isolation of the hernia sac, the surgeon secures the spermatic cord with a retractor. To locate the wall of the hernia sac, which has a characteristic whitish color, the layers of the spermatic cord with the fibers of the cremaster muscle (m. cremaster) are incised. The wall of the sac is found among the elements of the cord, then isolated, opened, and managed, while the posterior wall of the inguinal canal is reinforced.

Class and exam questions

What else to study on this topic

• Inguinal canal (canalis inguinalis)
• Spermatic cord (funiculus spermaticus)
• Testicular and scrotal tunics
• Internal oblique abdominal muscle (m. obliquus internus abdominis)

Other topics in the "Anatomical Structures" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.