Gastrointestinal: Anatomy - Inguinal ligament and canal

Question 1

Where does the inguinal ligament run?

Answer 1

Between ASIS and pubic tubercle

Question 2

What structure forms the inguinal ligament? Where does it insert?

Answer 2

Inferior part of the external oblique aponeurosis
Most fibres insert into pubic tubercle
Some travel posteriorly and attach to superior pubic ramus (lateral to tubercle) to form lacunar ligament
Some superior fibres cross linea alba and blend with inferior contralateral external oblique aponeurosis to form the reflected inguinal ligament

Question 3

What forms the lacunar ligament?

Answer 3

Fibres from inguinal ligament which travel posteriorly and attach to superior pubic ramus (lateral to tubercle)

Question 4

What forms the medial border of the subinguinal space?

Answer 4

Lacunar ligament

Question 5

What structure forms the iliopubic tract?

Answer 5

Inferior part of transversalis fascia

Question 6

Describe the course of the iliopubic tract relative to the inguinal ligament

Answer 6

Runs parallel and posterior (deep) to inguinal ligament to reinforce the posterior wall and floor of the inguinal canal

Question 7

How long is the inguinal canal?

Answer 7

4cm

Question 8

Where is the inguinal canal located?

Answer 8

Parallel and superior to the middle half of the inguinal ligament

Question 9

What forms the coverings of the spermatic cord?

Answer 9

1. Internal spermatic fascia (from transversalis fascia)
2. Cremasteric fascia (investing fascia of superficial and deep surfaces of internal obliques) and muscle
3. External spermatic fascia (external oblique aponeurosis and investing fascia)

Question 10

Nine contents of the spermatic cord

Answer 10

1. Ductus deferens
2. Artery of ductus deferens
3. Testicular artery
4. Cremasteric artery
5. Pampiniform venous plexus
6. Lymphatic vessels
7. Sympathetic nerve fibres
8. Genital branch of genitofemoral nerve
9. Vestige of processus vaginalis

Question 11

What is the ductus deferens and how long is it?

Answer 11

~45cm muscular tube which conveys sperm from epididymis to ejaculatory duct

Question 12

What does the pampiniform venous plexus form?

Answer 12

Testicular vein

Question 13

What nerve innervates the cremaster?

Answer 13

Genital branch of the genitofemoral nerve (L1-2)

Question 14

Where do the lymphatic vessels of the spermatic cord drain to?

Answer 14

Lumbar lymph nodes

Question 15

Describe the contents of the inguinal canal in males and females

Answer 15

Male: spermatic cord
Female: round ligament of uterus
Both: ilioinguinal nerve

Question 16

How does the ilioinguinal nerve enter the inguinal canal?

Answer 16

Pierces transversus abdominis and internal oblique muscles (does not enter via deep ring)

Question 16

Where is the deep inguinal ring located relative to the inguinal ring and the inferior epigastric artery?

Answer 16

Superior to middle of inguinal ligament (2 fingers breadth above)
Lateral to inferior epigastric artery

Question 17

What forms the deep inguinal ring?

Answer 17

Invagination in transversalis fascia

Question 18

What forms the superficial inguinal ring?

Answer 18

Split in diagonal fibres of external oblique aponeurosis

Question 19

Where is the superficial inguinal ring in relation to the pubic tubercle?

Answer 19

Medial to the pubic tubercle

Question 20

What are the margins of the superficial ring called? Where do they attach?

Answer 20

Margins are crura
Lateral crus attaches to pubic tubercle
Medial crus attaches to pubic crest

Question 21

Posterior and anterior boundaries, floor and roof of lateral 1/3 of inguinal canal (deep ring)

Answer 21

Posterior: transversalis fascia
Anterior: internal oblique, lateral crus of external oblique aponeurosis
Floor: iliopubic tract
Roof: transversalis fascia

Question 22

Posterior and anterior boundaries, floor and roof of middle 1/3 of inguinal canal

Answer 22

Posterior: transversalis fascia
Anterior: external oblique aponeurosis
Floor: inguinal ligament
Roof: internal oblique and transversalis abdominis musculo-aponeurotic arches

Question 23

Posterior and anterior boundaries, floor and roof of medial 1/3 of inguinal canal (superficial ring)

Answer 23

Posterior: inguinal falx (conjoint tendon to internal oblique and transversalis abdominis), reflected inguinal ligament
Anterior: external oblique aponeurosis (intracrural), external oblique fascia (which becomes the external spermatic fascia)
Floor: lacunar ligament
Roof: medial crus of external oblique aponeurosis

Question 24

Seven layers of the scrotum, from superficial to deep

Answer 24

1. Skin
2. Subcutaneous tissue (dartos fascia) and dartos muscle
3. External spermatic fascia
4. Cremasteric muscle
5. Cremasteric fascia
6. Internal spermatic fascia
7. Tunica vaginalis with visceral layer (covering testis and epididymis) and parietal layer

Question 25

Describe the vascular supply of the scrotum

Answer 25

Arterial:
- Posterior scrotal branches of perineal artery (from internal pudendal)
- Anterior scrotal branches of deep external pudendal artery (branch of femoral)
- Cremasteric artery (branch of inferior epigastric)

Venous:
- Scrotal veins accompany arteries

Lymphatics:
- Drain to superficial inguinal lymph nodes

Question 26

Describe the innervation of the anterolateral, anterior, posterior, and posteroinferior surfaces of the scrotum

Answer 26

Anterolateral: genital branch of genitofemoral nerve (L1-2)
Anterior: anterior scrotal nerves from ilioinguinal nerve (L1)
Posterior: posterior scrotal nerves from perineal branch of pudendal nerve (S2-4)
Posteroinferior: perineal branches of posterior cutaneous nerve of thigh (S2-3)

Question 27

Describe the passage of sperm from the testis

Answer 27

1. Sperm produced in seminiferous tubules
2. Seminiferous tubules joined by straight tubules to form rete testis
3. Efferent ductules
4. Lobules of epididymis
5. Head, body and tail of epididymis
6. Ductus deferens
7. Ductus deferens joins seminal gland and empties into ejaculatory ducts
8. Ejaculatory ducts empty into prostatic urethra

Question 28

What are the predisposing factors for indirect vs direct hernias?

Answer 28

Direct (acquired):
- Weakness of anterior abdominal wall in inguinal triangle (e.g. due to distended superficial ring, narrow inguinal falx, attenuation of aponeurosis in males >40yo)

Indirect (congenital):
- Persistent patency of processus vaginalis in younger persons

Question 29

Which is more common: indirect or direct hernias?

Answer 29

Direct less common (1/3 to 1/4)
Indirect more common (2/3 to 3/4)

Question 30

How do direct hernias exit the abdominal cavity? How does this differ from indirect hernias?

Answer 30

Direct hernias:
- Peritoneum plus transversalis fascia (lies outside inner one or two fascial coverings of cord)

Indirect hernias:
- Peritoneum of persistent processus vaginalis plus all three fascial coverings of cord or round ligament

Question 31

Describe the course of direct vs indirect hernias

Answer 31

Direct hernias:
- Through or around inguinal cord
- Usually traversing only medial 1/3, external and parallel to vestige of processus vaginalis

Indirect hernias:
- Traverses inguinal canal (entire if sufficient size within processus vaginalis)

Question 32

How do direct hernias exit the inguinal canal? How does this compare to indirect hernias?

Answer 32

Direct hernias:
- Via superficial ring, lateral to cord
- Rarely enters scrotum

Indirect hernias:
- Via superficial ring, inside cord
- Commonly passes into scrotum/labia majora

Question 33

Describe the borders of the inguinal triangle. What is the clinical significance of the inguinal triangle?

Answer 33

Medial: lateral border of rectus abdominis
Lateral: inferior epigastric vessels
Inferior: inguinal ligament

Area of direct weakness through which direct hernias may arise