Deep Inguinal Ring

The deep inguinal ring is the internal entrance to the inguinal canal, serving as a critical anatomical structure within the lower anterior abdominal wall. It is an oval-shaped opening in the transversalis fascia and marks the point where structures such as the spermatic cord or round ligament enter the inguinal canal. The deep ring lies lateral to the inferior epigastric vessels and plays a key role in the formation of indirect inguinal hernias. Though not visible externally, its position is essential in both anatomy and surgical practice.

Anatomical Structure

The deep inguinal ring is not a hole in the abdominal wall itself but an invagination of the transversalis fascia. This creates a pathway into the inguinal canal from the inside of the abdominal cavity.

Shape and Boundaries

• Shape: Oval or slit-like, approximately 1–1.5 cm in diameter
• Anterior boundary: Transversalis fascia
• Posterior boundary: Preperitoneal connective tissue and peritoneum

Location

• Situated approximately midway between the anterior superior iliac spine (ASIS) and pubic symphysis
• Located just above the inguinal ligament
• Lies lateral to the inferior epigastric vessels

Relation to Inguinal Canal

The deep inguinal ring marks the entrance into the inguinal canal, which then travels inferomedially to exit via the superficial inguinal ring. It forms the internal opening, while the superficial ring forms the external opening.

Course of the Inguinal Canal

Region	Start	End
Deep Ring	Transversalis fascia (mid-inguinal point)	Beginning of the canal
Canal	Between muscle layers	Above the inguinal ligament
Superficial Ring	External oblique aponeurosis	End of the canal

Structures Passing Through

The contents of the deep ring differ between males and females, reflecting their developmental anatomy:

In Males

• Spermatic cord: Includes vas deferens, testicular artery, pampiniform plexus of veins, genital branch of the genitofemoral nerve, and lymphatics
• Ilioinguinal nerve: Enters the canal laterally but not through the deep ring

In Females

• Round ligament of uterus: Enters via the deep ring and travels through the inguinal canal to reach the labia majora
• Ilioinguinal nerve: Same course as in males

Embryological Development

The deep inguinal ring forms during fetal development as part of the descent of the gonads. In males, the processus vaginalis invaginates the abdominal wall and creates the inguinal canal through which the testes descend. The deep ring corresponds to the initial site of this outpouching of peritoneum.

• In males: Testes pass through the deep ring during their descent into the scrotum
• In females: The round ligament follows a similar but shorter path to the labia majora

Clinical Significance

Indirect Inguinal Hernias

• Originate lateral to the inferior epigastric vessels
• Enter the inguinal canal via the deep ring and may exit via the superficial ring
• More common in males due to persistent processus vaginalis

Surgical Relevance

• Laparoscopic hernia repair: Identifying the deep ring is crucial for placing mesh or tacks correctly
• Open hernia repair: Deep ring is often reinforced or partially closed to prevent recurrence
• Vasectomy: The vas deferens is accessed near the superficial ring, but knowledge of the deep ring is essential in testicular procedures

Palpation and Imaging

• Not palpable during routine exam but may be inferred in the presence of an indirect hernia
• Can be visualized via CT or MRI, especially in preperitoneal or laparoscopic views

Deep Ring Occlusion Test

A clinical maneuver used to distinguish direct from indirect hernias. During coughing or straining, pressure is applied over the deep ring (midway between ASIS and pubic tubercle):

• If no hernia protrudes: Suggests an indirect hernia
• If hernia still protrudes: Suggests a direct hernia (medial to the ring)

Vascular Relations

• Medial to the deep ring: Inferior epigastric artery and vein
• Posterior to the ring: Peritoneum and underlying bowel loops or bladder (depending on location)
• Lateral to the ring: Deep circumflex iliac vessels

Understanding these relationships is critical during laparoscopic surgery to avoid vascular injury.

Comparison with Superficial Ring

Feature	Deep Inguinal Ring	Superficial Inguinal Ring
Location	In transversalis fascia, lateral to inferior epigastric vessels	In external oblique aponeurosis, above pubic tubercle
Function	Entrance to inguinal canal	Exit from inguinal canal
Structures Entering	Spermatic cord / round ligament	Same structures emerge
Clinical Importance	Site of indirect hernia origin	Site where hernia becomes externally visible
Palpability	Not palpable	Palpable during physical exam