Inguinal Canal and Spermatic Cord Anatomy

Inguinal Canal

• Definition: A passage in the lower anterior abdominal wall, located above the inguinal ligament, approximately 4 cm long.
• Function: Allows the passage of the spermatic cord (or round ligament in females) through the lower abdominal wall.
• Course: Passes obliquely from the deep inguinal ring to the superficial inguinal ring.

Deep Inguinal Ring

• Location: Halfway between the anterior superior iliac spine and the pubic tubercle.
• Characteristic: An opening in the transversalis fascia.
• Relation: Inferior epigastric vessels pass medial to the deep ring.

Superficial Inguinal Ring

• Location: Above and medial to the pubic tubercle.
• Characteristic: A triangular-shaped defect in the external oblique aponeurosis.

Walls of the Inguinal Canal

• Anterior: External oblique aponeurosis, reinforced by internal oblique in its lateral third.
• Superior: Internal oblique arches posteriorly to form the roof of the canal.
• Posterior: Transversalis fascia forms the lateral part, and the conjoint tendon forms the medial part.
• Inferior: Inguinal ligament.

Contents of the Inguinal Canal

• Spermatic cord (or round ligament in females).
• Ilioinguinal nerve (L1).

Inguinal Hernias

• Definition: Protrusion of a viscera through an opening.
• Types: Direct and Indirect inguinal hernias.
• Indirect inguinal hernia: Arises from persistence of the processus vaginalis, bulges through the deep inguinal ring, into the canal, and eventually into the scrotum.
• Direct inguinal hernia: Arises from weakness in the posterior wall of the inguinal canal, cannot be controlled by digital pressure over the deep ring, and rarely passes into the scrotum.

Surface Markings of Abdominal Viscera

• Liver: Lower border is usually just palpable on deep inspiration in slim individuals, upper border follows the undersurface of the diaphragm.
• Spleen: Lies below the left hemidiaphragm, deep to the 9th, 10th, and 11th ribs posteriorly, and reaches the midaxillary line anteriorly.
• Gall-bladder: Fundus lies in the transpyloric plane (L1), surface marking corresponds to a point where the lateral border of rectus abdominis (linea semilunaris) crosses the costal margin.
• Pancreas: Neck lies on the level of the transpyloric plane (L1), head lies to the right and below the neck, and body and tail pass upwards and to the left.
• Aorta: Bifurcates to the left of the midline at the level of L4.
• Kidneys: Hila lie on the level of the transpyloric plane (L1), lower pole of the right kidney usually extends 3 cm below the level of the left.
• Appendix: McBurney's point represents the surface marking for the base of the appendix, located one-third of the way along a line joining the anterior superior iliac spine and the umbilicus.
• Bladder: In adults, it is a pelvic organ, can be palpated above the symphysis pubis only when full or enlarged.

Spermatic Cord

• Coverings: External spermatic fascia, cremasteric fascia and muscle, and internal spermatic fascia.
• Contents: Ductus (vas) deferens, testicular artery, pampiniform plexus of veins, lymphatics, and autonomic nerves.