Inguinal Canal & Spermatic Cord

INGUINAL  CANAL

(Find the Video Tutorial Here

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https://www.youtube.com/watch?v=n9wNsBhRsdw&t=126s)

• It’s a Musculo-aponeurotic tunnel.
• 4 cm in length.
• Located above & parallel with the medial half of inguinal ligament.
• Extends from deep inguinal ring to superficial inguinal ring.
• It is directed downwards, forwards and medially.
• In females it is narrow & in the newborn it is directed straight forward.

CONTENTS 

• Spermatic cord in males or Round ligament of uterus in females (entire / genuine content).
• Ilio-inguinal nerve (partial content).

BOUNDARIES  OF  THE  CANAL 

Anterior  Wall :-

• Skin
• Superficial fascia
• Aponeurosis of external oblique muscle
• Lateral 1/3^rd is supported by fleshy fibres of internal oblique muscle

Posterior  Wall :-

• Fascia transversalis
• Conjoint tendon in the medial half
• Reflected part of inguinal ligament in the medial 1/4^th

Roof :-

• Arched fleshy fibres of internal oblique & transversus abdominis muscles.

Floor :-

• Grooved upper surface of inguinal ligament
• Medially by lacunar ligament

Inlet :-

    Deep inguinal ring –

• It’s an oval gap in the fascia transversalis
• Lies 1.25 cm above the mid-inguinal point
• It is related medially with inferior epigastric artery

Outlet :- 

    Superficial inguinal ring –

• It is an oblique triangular gap in the aponeurosis of external oblique,
• Lies above & lateral to the pubic crest.
• Its base is formed by pubic crest, medially it is bounded by superior crus & laterally by inferior crus of external oblique aponeurosis.

DEFENSIVE  (SHUTTER)  MECHANISMS  OF  INGUINAL  CANAL 

Flap-Valve  Mechanism :-

• As the inguinal canal is oblique in direction, in increased intra-abdominal pressure the posterior wall is pushed forwards & comes in contact with the anterior wall obliterating the canal.

Ball-Valve  Mechanism :-

• In increased intra-abdominal pressure cremaster muscle in male contracts & pulls the testes towards the superficial ring, thus the outlet is closed (cremasteric plug).

Demi-Sphincteric  Mechanism :-

• The arched fibres of internal oblique & transversus abdominis act as demi-sphincters in increased intra-abdominal pressure and obliterate the canal by bringing the roof in contact with the floor.

APPLIED  ASPECTS 

INGUINAL  HERNIA :-

Definition –

• Protrusion of abdominal contents, covered by a sac of peritoneum, into the inguinal canal.

Inguinal hernia is 2 types – Indirect / Oblique & Direct inguinal hernias.

Indirect / Oblique  Inguinal  Hernia :-

• The hernial sac is preformed by persistent processus vaginalis of peritoneum.
• Contents enter the canal through deep inguinal ring.
• Neck of the hernial sac lies lateral to the inferior epigastric artery.

Coverings of the hernia – (from within outwards)

• Peritoneum of the sac
• Extra-peritoneal tissue
• Internal spermatic fascia
• Cremasteric muscle and fascia
• External spermatic fascia
• Dartos muscle
• Skin

Types of indirect hernia –

• Vaginal – Processus vaginalis remains patent along the entire extent, thus hernial sac reaches the bottom of scrotum.
• Funicular – Processus vaginalis is obliterated above the testis and remains patent in the proximal part.
• Infantile – A peritoneal recess extends from vaginal sac till the superficial ring.
• Interstitial – A diverticulum of the processus vaginalis extends between the layers of abdominal wall.

Direct  Inguinal  Hernia :-

• Hernial sac enters the canal through inguinal triangle of Hesselbach.
• Neck of the hernial sac passes medial to the inferior epigastric artery.

Hesselbach’s triangle-

• It is a peritoneal triangle located in the posterior wall of inguinal canal.
• Bounded laterally by inferior epigastric artery, medially by lateral border of rectus abdominis, below by the inguinal ligament.
• It is divided by the obliterated umbilical artery into medially supra-vesical fossa & laterally medial inguinal fossa.

Direct hernia presents 2 varieties- Lateral direct & Medial direct inguinal hernias.

Lateral direct inguinal hernia –

Hernial sac enters the scrotum through medial inguinal fossa.

Coverings of the hernia- (from within outwards)

• Peritoneum of the sac
• Extra-peritoneal tissue
• Fascia transversalis
• Cremasteric muscle & fascia
• External spermatic fascia
• Dartos muscle
• Skin

Medial direct inguinal hernia –

Hernial sac enters the scrotum through supra-vesical fossa.

Coverings of the hernia- (from within outwards)

• Peritoneum of the sac
• Extra-peritoneal tissue
• Fascia transversalis
• Conjoint tendon
• Reflected part of inguinal ligament
• External spermatic fascia
• Dartos muscle
• Skin

SPERMATIC  CORD

• It is a 7.5 cm long tubular sheath.
• It contains vas deferens, vessels, nerves of testis & epididymis.
• It extends from the deep inguinal ring to the upper end of testis.

Coverings of Spermatic Cord :-  

• During the descent of testis along the inguinal canal, the spermatic cord receives 3 tubular prolongations from abdominal wall.

From inside to outside the coverings are –

• Internal Spermatic Fascia- derived from fascia transversalis at the margin of deep ring.
• Cremasteric Muscle & Fascia- derived from the internal oblique muscle.
• External Spermatic Fascia- derived from the aponeurosis of external oblique at the margin of superficial ring.

Contents of Spermatic Cord :-

Vas Deferens –

• It passes along the posterior part of the cord.

Pampiniform plexus of veins –

• It produces the bulk of spermatic cord.

At the superficial ring the plexus unites to form 4 veins

2 veins accompany the testicular artery & 2 veins pass along the vas deferens throughout the inguinal canal

At the deep ring the veins unite to form 2 veins

Finally, a single testicular vein is formed in the posterior abdominal wall.

• Right testicular vein drains into inferior vena cava at an acute angle.
• Left testicular vein drains into left renal vein almost at a right angle.
• The heat conveyed by the arteries of testis is mostly absorbed back by the veins of pampiniform plexus.
• Eventually the scrotal temperature of testis is lower (3⁰ – 4⁰ C) than that of abdomen.
• This mechanism of heat transfer is known as counter-current heat exchange.

Arteries –

• Testicular artery – branch from abdominal aorta.
• Artery to the vas deferens – branch from superior or inferior vesical artery.
• Cremasteric artery – branch from inferior epigastric artery.

Lymphatics of Testis & Epididymis –

• They drain into pre-aortic & lateral aortic group of lymph nodes.

Nerves –

• Genital branch of genitofemoral nerve – supplies cremaster muscle.
• Testicular plexus of sympathetic nerves – conveys the fibres from T10 & T 11.

Loose connective tissue –

• It is continuous at the deep ring with the extra-peritoneal connective tissue.

Accessory Suprarenal cortical tissue –

• Sometimes it appears as additional content of the cord.

APPLIED  ASPECTS

Encysted Hydrocele :-

• It occurs due to patent processus vaginalis between the deep ring & the vaginal sac, forming a cyst within the spermatic cord.

Inguinal Hernia :-

• Occasionally, the processus vaginalis remains patent entirely & leads to indirect inguinal hernia, which receives all coverings of spermatic cord.
• In direct inguinal hernia the hernial sac pushes the contents of spermatic cord laterally.