L3: Inguinal canal and Spermatic cord

Question 1

What are the layers of the abdominal wall from inside to outside

Answer 1

Parietal Peritoneum, Membranous superficial fascia (Scarpa’s fascia), Transversalis fascia,
Transversus Abdominis, Internal oblique, external oblique

Question 2

Describe the course of the inguinal canal

Answer 2

Oblique passage through the abdominal wall layers starting at deep inguinal ring more laterally and superiorly to the superficial inguinal ring more medially and inferiorly.

Question 3

How to find the superficial inguinal ring and the deep inguinal ring

Answer 3

SIR: Triangular defect in the aponeurosis of Ext Oblique muscle. Superior and lateral to the pubic tubercle. Margins of the hole give rise to the External spermatic fascia of the spermatic cord.
DIR: Found at the mid-inguinal point : halfway between the ASIS and the pubic SYMPHYSIS. 1cm above the inguinal ligament. Lateral to the inferior epigastric artery.
Gives rise to the internal spermatic fascia of the spermatic cord.

Question 4

What are the borders of the inguinal canal- covering either the DIR or SIR= Anterior, Posterior, roof and floor

Answer 4

Anterior: Aponeurosis of Ext oblique + Internal oblique (in the lateral 1/3)
Posterior: Transversalis fascia + conjoint tendon of internal oblique and transversus abdominis (medial 1/3)
Roof: Fibres of the internal oblique and Transversus abdominis
Floor: Inferior rolled edge of the ext oblique aponeurosis -> Inguinal ligament + Lacunar ligament

Question 5

What is Hesselbach’s triangle (inguinal triangle), borders and what is the significance

Answer 5

Inferior border: Inguinal ligament
Medial border: Lateral border of rectus abdominis
Lateral border: Inferior epigastric artery
This area is a weak in the anterior wall and is the site of direct hernia when pushed through
The deep inguinal ring is lateral to this triangle.

Question 6

What are the male and female structures that pass through the inguinal canal

Answer 6

Males: Contents of the spermatic cord to and from the abdomen and testis.
Females: Round ligament of the uterus from the pelvis to the labia majora + genital branch of the genitofemoral nerve
Both + the ilioinguinal nerve (L1) although it doesn’t go through the DIR only exits the SIR.

Question 7

What are the contents of the spermatic cord

Answer 7

3 Arteries:

• Testicular artery from L2 Ao supplying the testes and epididymis
• Artery of vas deferens
• Cremasteric artery

3 Nerves:

• Genital branch of the genitofemoral nerve (L1-2)
• Sympathetic nerves from the Testicular plexus (L1-2)
• (ilioinguinal nerve

3 Other structures

• Vas deferens: muscular duct for transport of spermatozoa from epididymis to urethra
• Lymphatics: Drain Para-aortic nodes L2
• Tunica Vaginalis: embryological remnant of peritoneal outpouching in forming the spermatic cord.

1 Venous plexus : Pampiniform plexus -> Testicular vein at the DIR. R-> IVC and L-> Left renal vein.

Question 8

What are the corresponding layers between the abdo wall, spermatic cord and the scrotum- what does the scrotum contain and its blood supply

Answer 8

The Scrotum is an outpouching of the skin from the abdominal wall containing the testes, epididymis and lower end of the spermatic cords.
Inner most layers are the same as the spermatic cord. Next is the Dartos fascia which is continuous with the abdo scarpers fascia and perineum (colle’s fascia).
The scrotum receives supply from the internal and EXTERNAL pudendal arteries.

Question 9

What is the usual function of the cremaster muscle and dartos fascia

Answer 9

Cremaster: raises the testes and scrotum upwards for warmth and protection.
Dartos: causes wrinkling of the skin to decrease SA exposed to external environment for heat retention.

Question 10

What is the cremasteric reflex and what is absence of this reflex indicative of

Answer 10

Normal: stroking of the inner thigh stimulates sensory fibres of the femoral branch of the genitofemoral n and ilioinguinal nerve which stimulates motor fibres of the genital branch causing contraction on the ipsilateral reflex.
This is absent in Testicular torsion which is twisting of the spermatic cord causing ischaemia: presents with acute testicular/scrotal pain, nausa/vomiting, maybe also groin or lower abdomen.
However not infallible, so US used to confirm lack of blood flow to differentiate from epididymitis. Has to be saved within 6 hours.

Question 11

How do you differentiate between direct, indirect inguinal hernias and femoral hernia

Imaging US, MRI, CT used for confirmation for surgery

Answer 11

• Femoral herniation is through the femoral canal which is below and more lateral to the pubic tubercle. Below the inguinal ligament. More likely in females as there is more space under. Have to cut the lacuna ligament to release it.
  Inguinal: more superior and likely in males.
• Indirect herniation: is Lateral to Inf epigastric artery through the DIR and through the whole inguinal canal into the scrotum within the spermatic cord. More likely in juveniles due to lack of oblique passageway yet.
• Direct herniation: is Medial to the Inf epigastric artery through Hesselbach’s triangle weak spot of the posterior wall of the inguinal canal- more common in adult/elderly. A direct hernia will bulge at the DIR if cough - not indirect.