Femoral Canal: Anatomy, Associated Ligaments, and Clinical Significance

What is the ligament of the femoral canal?

The femoral canal itself does not contain a distinct "ligament of the femoral canal" within its lumen; rather, it is an anatomical space defined by surrounding structures, notably the lacunar ligament (of Gimbernat), which forms its medial boundary and is critical to understanding the region.

Understanding the Femoral Canal

The femoral canal is the most medial compartment of the femoral sheath, a funnel-shaped fascial sleeve enclosing the femoral artery, femoral vein, and femoral canal itself in the upper thigh. Located inferior to the inguinal ligament and medial to the femoral vein, this small, conical space is approximately 1.25 cm long.

• Location: It lies within the femoral triangle, a region in the upper anterior thigh.
• Contents: Unlike the other compartments of the femoral sheath which house major blood vessels, the femoral canal primarily contains lymphatic vessels (including the deep inguinal lymph node, often called the lymph node of Cloquet or Rosenmüller), loose areolar tissue, and a small amount of fat.
• Function: Its primary physiological role is to provide a potential space for the expansion of the femoral vein during periods of increased venous return from the lower limb, preventing compression of the vein.
• Femoral Ring: The superior opening of the femoral canal, known as the femoral ring, is a crucial anatomical landmark due to its clinical significance in femoral hernias.

Key Ligaments Associated with the Femoral Canal

While no single ligament resides within the femoral canal, several strong fibrous bands form its boundaries, particularly at the femoral ring. The most directly relevant ligament when discussing the medial aspect of the femoral ring is the lacunar ligament.

• The Lacunar Ligament (Gimbernat's Ligament) The lacunar ligament is a crescent-shaped fibrous band that forms the sharp, medial boundary of the femoral ring.

  • Origin: It arises from the medial end of the inguinal ligament.
  • Insertion: It sweeps posteromedially to insert onto the pectineal line of the superior pubic ramus.
  • Role: Its oblique orientation and firm structure provide a rigid medial wall to the femoral ring, making it a critical anatomical feature in the context of femoral hernias. Its sharp, unyielding edge can constrict herniated tissue.

• The Pectineal Ligament (Cooper's Ligament) The pectineal ligament is a strong, fibrous band that runs along the pectineal line of the superior pubic ramus.

  • Origin: It is a thickening of the periosteum along the pectineal line.
  • Relation to Femoral Ring: It forms part of the posterior boundary of the femoral ring, providing a firm base.
  • Clinical Significance: It is often used as an anchoring point in certain hernia repair techniques due to its strength.

• The Inguinal Ligament (Poupart's Ligament) The inguinal ligament is a thick, fibrous band that stretches across the anterior hip region, forming the base of the femoral triangle.

  • Origin: It extends from the anterior superior iliac spine (ASIS) of the ilium.
  • Insertion: It inserts onto the pubic tubercle.
  • Relation to Femoral Ring: It forms the anterior boundary of the femoral ring, overarching the femoral vessels and canal. It is essentially the superior border from which the lacunar ligament extends.

Clinical Significance: Femoral Hernias

The femoral canal represents a natural anatomical weakness in the abdominal wall. This is where femoral hernias can occur, protruding through the femoral ring and down the femoral canal. Due to the small, rigid nature of the femoral ring, particularly its medial boundary formed by the unyielding lacunar ligament, femoral hernias are more prone to incarceration (trapping) and strangulation (compromised blood supply) compared to inguinal hernias. Understanding the precise anatomical relationships of these ligaments is therefore crucial for diagnosis and surgical repair of femoral hernias.

Anatomical Interrelationships and Importance

The "ligament of the femoral canal" is not a singular, isolated structure but rather a concept encompassing the critical ligaments that define and border this space. The lacunar ligament, pectineal ligament, and the overarching inguinal ligament collectively form the boundaries of the femoral ring, the gateway to the femoral canal. Their precise anatomical arrangement dictates the potential pathways for herniation and influences the clinical presentation and management of groin pathologies.

Conclusion

While there isn't one singular "ligament of the femoral canal" residing within its confines, the lacunar ligament (of Gimbernat) is the most directly associated and clinically significant ligament forming the medial border of the femoral ring, the opening to the canal. Understanding the interplay of the lacunar, pectineal, and inguinal ligaments is fundamental to comprehending the anatomy of the femoral triangle and the mechanics of femoral hernias, which are critical considerations for fitness professionals and healthcare practitioners alike.