scrotum A&P

scrotum

• thin sac of skin and thin muscle in which lie the testicles

• acts as a climate control system

cremaster muscles

most the testicles slightly within the scrotum depending on the surrounding temperature

normal measurements of the testis:

• 3-5 cm in L

• 2-4 cm in W

• 3 cm H

sonographic appearance of the testis:

smooth, medium grey structures with a fine echo texture

epididymis

• 6-7 cm tubular structure

• begin superiorly and then coursing posterolateral to the testis

• divided into head, body, tail

epididymal head

• largest part of the epididymis

• 6-15 mm

• located superior to the upper pole of the testis

epididymal body and tail

• smaller than the head

• difficult to see on US

• follows the posterolateral aspect of the testis from the upper to the lower pole

sonographic appearance of the epididymis:

• appears isoechoic or hypoechoic compared to the testis

• echo texture is coarser

appendix testis

• located between the testis and epididymis

• present in 92% of testes unilaterally and 69% bilaterally

tunica albuginea

a dense, fibrous tissue that completely covers the testis

mediastinum

• supports the vessels and ducts coursing within the testis

• posterior aspect of the tunica albuginea reflects into the testis to form a vertical septum

sonographic appearance of the mediastinum:

bright hyperechoic line coursing craniocaudal wiithin the testis

tunica vaginalis

• lines the inner walls of the scrotum

• covers each testis and epididymis

• composted of a parietal and visceral layer

parietal layer of the tunica vaginalis:

inner lining of the scrotal wall

visceral layer of the tunica vaginalis:

surrounds the testis and epididymis

ductal system

• head contains 10-15 efferent ductules

• converge to form a single duct, the ductus epididymis, and then it becomes the vas deferens and continues in the spermatic cord

spermatic cord

• extends from the scrotum through the inguinal canal to the pelvis

• suspends the testis in the scrotum

what forms the spermatic cord?

• vas deferens

• testicular arteries

• venous pampiniform plexus

• lymphatics

• nerves

the primary source of blood flow to the testis is supples by:

the right and left testicular arteries

the R and L testicular arteries course along the posterior surface of each testicle forming:

the capsular arteries

the capsular arteries give rise to:

the centripetal arteries

the centripetal arteries curve backward forming:

the centrifugal arteries

spectral doppler waveforms obtained from the testicular, capsular and centripetal arteries show a:

low-resistance waveform pattern

venous drainage of the scrotum occurs through:

• the veins of the pampiniform plexus

• R testicular vein drains into the IVC

• L testicular vein joins the L renal vein