C25 - Scrotum, testis, epididymis, blood supply and innervation

Question 1

Structures to mention

Answer 1

Scrotum:

• Cutis scroti
• Raphe scroti
• Tunica dartos
  
  • Septum scroti

Testis:

• Extremitas capitata
• Extremitas caudata
• Facies lateralis
• Facies medialis
• Margo liber
• Margo epididymalis
• Tunica albuginea
• Mediastinum testis (Ø eq)
  
  • Septula testis
• Lobuli testis
• Parenchyma testis
  
  • Tubuli seminiferi contorti
  • Tubuli seminiferi recti
  • Rete testis
• Appendix testis (eq)

Epididymis

• Caput epididymidis
  
  • Ductuli efferentes testis
• Corpus epididymidis
• Cauda epididymidis
• Lobuli epididymidis
• Ductus epididymidis
• Paradidymis

Funiculus spermaticus

• Fascia spermatica externa
• M. cremaster
• Fascia cremasterica
• Fascia spermatica interna
• Tunica vaginalis
  
  • Lamina parietalis
  • Lamina visceralis
  • Anulus vaginalis
  • Canalis vaginalis
  • Cavum vaginale
• Mesofuniculus
  
  • Mesorchium
    
    • Mesorchium proximale [= Plica vasculosa]
    • Mesorchium distale
  • Mesoductus deferens [= Plica ductus deferentis]
  • Mesepididymis
• Lig. testis proprium
• Lig. caudae epididymidis
• Lig. scroti
• Bursa testicularis

Question 2

Scrotum

Location

Answer 2

• Located behind the penis, and in front of the anus
• External sac of skin (continous with the lower abdomen)
• Divided into 2 compartments, each compartment contains:
  
  • Testes
  • Glands that produce sperm (which one???)
  • Epeididymis
• Horse and dog: Located in regio inguinalis
• Ruminants: Located below regio inguinalis
• Pig: Perineal
• Cat: Subanal

Question 3

Scrotum

Function

Answer 3

• Protect the testes and keep them at a temperature lower normal body temperature
  
  • Cold: contracts (conserves heat)
  • Warm: relax (permitting circulation of air)

Question 4

Scrotum

Give the layers of the scrotum

Answer 4

1. Cutis scroti (skin)
   
   • Contains many sweat gland and sebaceous gland
   • Hairless skin (ø fe)
2. Tunica dartosa
   
   • ​Can not be separated from the skin
   • Consists of smooth muscle bundles
   • Forms septum scroti, marked externally by raphe scroti
     
     • ​Continued cranially with raphe preputalis
3. Fascia spermatica externa
   
   • ​Detached from deep and superficial fascia of the abdomen at the scrotum
   • Adherent with cauda epididymis → lig. scroti
4. M. cremaster
   
   • Derived from m. obliquus interna
   • Cremaster reflex: raises the tunica vaginalis and brings testis and epididymis closer to the external inguinal ring
5. Fascia spermatica interna
   
   • ​​Detached from deep and superficial fascia of the abdomen at the scrotum
   • ​Fused with tunica vaginalis
6. Tunica/processus vaginalis
   
   • Formed by transvers fascia and peritoneum
     
     • ​An evagination of pariteal peritoneum→ passing through canalis inguinalis → scrotum
   • Distal part surrounds: testis and epididimys
   • Proximal part surrounds: spermatic cord
   • The vaginal cavity communicates with the abdominal cavity through ostium vaginae located within the internal opening of canalis inguinalis

Question 5

Scrotum

Ligaments

Answer 5

Ligaments of spermatic cord:

• Lig. scroti
  
  • ​Connective tissue between tunica dartos and:
    
    • Un: lig. caudae epididymis
    • Car: cauda epididymis
• Mesorchium
  
  • ​Suspension of testis
  • Mesorchium proximale: from origin of a/v. testicularis → mesoepididymis
  • Mesorchium distale: from mesepididymis → testis
• Lig. testis proprium: from testis → epididymis
• Lig. caudalis epididymis: between cauda epididymis →
  
  • Un: l**amina parietalis
  • Car: fascia spermatica interna

Question 6

Testis

Location

Answer 6

• Contained in the scrotum
  
  • ​Together with epididymis

Question 7

Testis

1. List the strucutres of the testis
2. Draw the testis

Answer 7

• Extremitas capitata (Related to caput epididymis, cranial directed)
• Extremitas caudata (Related to cauda epididymis, caudal directed)
• Facies lateralis (Ru: caudal)
• Facies medialis (Ru: cranial)
• Margo liber (Ventral directed)
• Margo epididymalis (Dorsal directed)
• Tunica albuginea (Dense with capsule)
• Mediastinum testis (Ø eq) (Axial strand of connective tissue from which the septula radiate)
  
  • Septula testis (Interlobular partitions extending from the mediastinum testis → tunica albuginea)
• Lobuli testis
• Parenchyma testis (Semiferous tubules)
  
  • Tubuli seminiferi contorti (Convoluted seminiferous tubules)
  • Tubuli seminiferi recti (Straight seminiferous tubules, from the convoluted tubules to the rete testis)
  • Rete testis (Network of ducts in the mediastinum testis connecting the tubuli semiferi recti to the ductuli efferents)
• Appendix testis (eq) (Near caput epididymis)

Question 8

Testis

Give the axis of the testis

Answer 8

• Horse:
  
  • Horizontal orientation
  • Extremitas capitata points cranially
  • Extremitas caudata points caudally
• Ruminant:
  
  • Vertical orientation
  • Extremitas capitata points dorsally
  • Extremitas caudata points ventrally
• Ca, sus:
  
  • Oblique orientation

Question 9

Epididymis

Structures

Answer 9

• Consists of coils of the elongated convoluted tubules
  
  • Held together by connective tissue
• Can be divived into:
  
  • Caput epididymis (head)
    
    • Attached to testicular capsule
    • Receives efferent ducts of the testis
  • Corpus epididymis (body)
  • Cauda epididymis (tail)
    
    • The epididymal duct continues as cauda epididymis
    • Attached to:
      
      • *Extremitas caudalis* bylig. testis proprium**
      • Processus vaginalis by lig. caudae epididymis
        
        • ​Fibers of this ligament extends fibers into deep layer of scrotum
• Ductus epeididymis: where spermatazoa mature

Structures:

• Caput epididymidis (Contains the lobulis epididymis)
  
  • Ductuli efferentes testis (Efferent ductules, lead from the rete testis → ductus epididymis. Coiled to form lobuli epididymis)
• Corpus epididymidis (Consists of the coiled duct)
• Cauda epididymidis (Continuous with the ductus deferens)
• Lobuli epididymidis (Containing the coiled ductuli efferents testis in the caput epididymisia)
• Ductus epididymidis (Convoluted to form the epididymis)
• Paradidymis (Detached mesoneprhic tubules in the spermatic cord just proximal to caput epididymidis)

Question 10

Epididymis

Location

Answer 10

• Firmly attached along the testis

Question 11

Name the area between the testis and corpus epididymis

Answer 11

Bursa testicularis

Question 12

Spermatic cord (funiculus spermaticus)

Answer 12

• Formed by ductus deferens and surrounding tissue
• Runs from deep inguinal ring → to each testicle
• The spermatic cord can be divided into 3 layers of tissue:
  
  • Fascia spermatica externa
    
    • ​Continuous with fascia m. oblqui externi abdominis
  • M. cremasterica and fascia
    
    • ​Continous with m. obliqui interna abdominalis and its fascia
  • Fascia spermatica interna
    
    • ​Continuous with fascia transversalis
• Content:
  
  • A. testicularis
  • A. ductus deferentis
  • A. cremasterica
  • N. genitofemoralis → r. genitalis
  • N. testicularis
  • Ductus deferens
  • Plexus pampiniformis
  • Lymphatic vesses
  • Tunica vaginalis (remains of processus vaginalis)
• Tunica vaginalis: extension of peritoneum, passing through transversalis fascia

Structures

• Fascia spermatica externa (Continuous with fascia m. oblqui externi abdominis)
• M. cremaster (Muscle on tunica vaginalis. Lies between the internal and external spermatic fascia and draws the testis towards canalis inguinalis)
• Fascia cremasterica (Cremasteric fascia on the m. cremaster)
• Fascia spermatica interna (Continuous with fascia transversalis)
• Tunica vaginalis (Serous membranes covering the spermatic cord and testis)
  
  • Lamina parietalis (Continuous with the parietal peritoneum)
  • Lamina visceralis (Adherent to the testis, epididymis and spermatic cord)
  • Anulus vaginalis (Vaginal ring. Where the peritoneum is evaginated to form lamina parietalis on tunica vaginalis)
  • Canalis vaginalis (Potential space between lamina parietalis of the tunica vaginalis)
  • Cavum vaginale (Between lamina parietalis and lamina visceralis around the testis)
• Mesofuniculus (Strip of mesorchium between origin of mesoductus deferens and lamina parietalis)
  
  • Mesorchium (Peritoneal fold containing vessels and nerves of testis)
    
    • Mesorchium proximale [= Plica vasculosa] (Extends from the origin of the testicular vessels → mesepididymis)
    • Mesorchium distale (Extends from mesepididymis to the testis)
  • Mesoductus deferens [= Plica ductus deferentis] (Attaches the ductus deferens to the mesorchium and to the abdominal and pelvic walls)
  • Mesepididymis (Attaches the epididymis)
• Lig. testis proprium (From testis → cauda epididymis)
• Lig. caudae epididymidis (Betwen the cauda epididymis → lamina parietalis (Un))
• Lig. scroti (Between tunica dartos and lig. caudae epididymis (Un) or the caudae epididymis (Car))
• Bursa testicularis (Formed by mesorchium distale, testis and epididymis)

Question 13

Blood supply

Answer 13

Scrotum:

• A. pudenda externa → r. scrotalis → a. cremasterica (to m. cremaster)

Testis:

• A. abdominalis → a. testicularis (forms numerous of coils)
• V. testicularis → plexus pampiniformis (surrounds the coil of the artery

Epididymis:

• A. testicularis
• Rr. epididymales

Question 14

Innervation

Answer 14

Scrotum:

• Motor, sensory and parasympathetic:
  
  • N. pudendus from plexus sacralis → nn. scrotales dorsales
• N. genitofemorale → r. genitalis (goes through canalis inguinalis)
  
  • ​Supply:
    
    • M. cremaster
    • Scrotum
    • Tunica vaginalis
    • Preputium
    • Mammae

Testis & epididymis:

• Sympathetic
  
  • Plexus testicularis (accompanies a/v. testicularis)​