Femoral Canal: Femoral Ring, Contents and Femoral Hernia

By Dr Richard Miller, MBChB FRCS · Reviewed 1 October 2026

The femoral canal is the small, innermost compartment of the femoral sheath, lying just medial to the femoral vein below the inguinal ligament. Its upper opening, the femoral ring, is bounded by the inguinal, lacunar and pectineal ligaments and the femoral vein; it contains fat, lymphatics and a lymph node, and it is the path taken by a femoral hernia.

Femoral Canal · key facts

Boundaries: Femoral ring: inguinal ligament in front, pectineal ligament behind, lacunar ligament medially, femoral vein laterally
Roof: Femoral septum of extraperitoneal tissue, covered by parietal peritoneum
Floor: Blind lower end, level with the saphenous opening
Contents: Loose fat, lymphatic vessels, a deep inguinal lymph node
Clinical relevance: Femoral hernia, high strangulation risk, abnormal obturator artery

Structure and boundaries

The femoral canal is a short, blind-ended, cone-shaped space forming the medial compartment of the femoral sheath, with its wide end at the top.

The femoral sheath

The femoral sheath is a funnel of fascia that surrounds the upper few centimetres of the femoral vessels as they pass under the inguinal ligament. Its front wall is continuous with the transversalis fascia and its back wall with the iliac fascia. Two septa divide it into three compartments:

Lateral: femoral artery and the femoral branch of the genitofemoral nerve.
Intermediate: femoral vein.
Medial: the femoral canal.

The femoral nerve lies outside the sheath, lateral to it.

The femoral ring

The femoral ring is the upper opening of the canal, facing the abdominal cavity.

Boundary	Structure
Anterior	Inguinal ligament
Posterior	Pectineal ligament on the pecten pubis, with pectineus and the superior pubic ramus behind
Medial	Lacunar ligament, the curved, sharp-edged extension of the inguinal ligament to the pecten
Lateral	Femoral vein, separated by a thin fascial septum

Three of these four boundaries are rigid ligaments, which is the anatomical reason that femoral hernias strangulate. The ring is closed from above by the femoral septum, a layer of extraperitoneal connective tissue, over which lies parietal peritoneum.

Contents and function

The femoral canal contains loose fatty tissue, lymphatic vessels and usually one lymph node, and it serves two functions.

Lymph node: the uppermost deep inguinal node often lies in the canal. It is known eponymously as the node of Cloquet or of Rosenmüller. It receives lymph from the superficial inguinal nodes and the deep lymphatics of the limb, and it is sampled in groin dissections for vulval, penile and lower limb cancers.
Lymphatic pathway: efferent lymph vessels from the deep inguinal nodes pass up through the canal to reach the external iliac nodes.
Space for the vein: the loose contents allow the femoral vein to expand when venous return rises, for example during straining or exercise.

Relations

The femoral canal lies below the inguinal ligament in the upper medial corner of the femoral triangle.

Lateral: femoral vein, then femoral artery, then the femoral nerve outside the sheath.
Medial: lacunar ligament and the pubic tubercle.
Above: the inguinal canal lies just above the inguinal ligament, which is why femoral and inguinal hernias are separated by their relation to the pubic tubercle.
Anterior and below: the saphenous opening in the fascia lata, where the great saphenous vein joins the femoral vein; a femoral hernia turns forward through this opening.
Posterior to the ring: pectineus and the superior pubic ramus. An abnormal obturator artery, arising from the inferior epigastric artery, may run down on the medial or lateral side of the ring.

Clinical relevance

The femoral canal is clinically important as the path of a femoral hernia, which carries a higher risk of strangulation than any other groin hernia.

Femoral hernia

Abdominal contents push the femoral septum down through the femoral ring into the canal. The sac descends to the level of the saphenous opening, then turns forward through it and upward towards the inguinal ligament. The lump lies below and lateral to the pubic tubercle, whereas an inguinal hernia emerges above and medial to it. Femoral hernias are more common in women than in men, although inguinal hernias remain the commoner type in women. The rigid ring means strangulation is common, so femoral hernias are repaired early, and many present as an emergency with small bowel obstruction.

Abnormal obturator artery

The obturator artery arises from the inferior epigastric artery, rather than the internal iliac, in a proportion of people. If it runs along the free edge of the lacunar ligament, incising that ligament to release a strangulated hernia can divide it and cause severe bleeding. This vessel and the related venous connections are known as the corona mortis.

Surgical approaches

Open repair uses a low (infrainguinal, Lockwood), transinguinal (Lotheissen) or high (McEvedy) approach; laparoscopic repair reaches the ring from within the abdomen. All aim to close the ring by suturing the inguinal ligament to the pectineal ligament or by placing mesh.

Differential diagnosis of a lump below the inguinal ligament

Femoral hernia, enlarged deep or superficial inguinal node, saphena varix, femoral artery aneurysm, psoas abscess and ectopic testis.

How it is examined

On a cadaveric spotter, in an OSPE and in MRCS Part B anatomy.

On a femoral triangle prosection, a pin in the empty gap medial to the femoral vein is the femoral canal. Name its contents (fat, lymphatics, lymph node), not a vessel.
Expect to list the boundaries of the femoral ring in order and to identify the lacunar ligament as the sharp medial edge.
Classic viva: how to tell a femoral from an inguinal hernia clinically (relation to the pubic tubercle) and why femoral hernias strangulate (rigid ligamentous ring).
Follow-up question: what the corona mortis is and why it matters when incising the lacunar ligament.
Do not place the femoral nerve inside the femoral sheath; only the artery, vein and canal are inside.

Key points

The femoral canal is the medial compartment of the femoral sheath, medial to the femoral vein.
The femoral ring is bounded by the inguinal, pectineal and lacunar ligaments and the femoral vein.
It contains fat, lymphatics and often a deep inguinal lymph node.
It lets the femoral vein expand and carries lymph to the external iliac nodes.
Femoral hernias pass through it, sit below and lateral to the pubic tubercle and often strangulate.

Common questions

What are the boundaries of the femoral ring?

The femoral ring is bounded in front by the inguinal ligament, behind by the pectineal ligament on the pecten pubis, medially by the lacunar ligament and laterally by the femoral vein. Because three of its four boundaries are unyielding ligaments, the ring cannot stretch, and anything forced through it, such as a loop of bowel in a femoral hernia, is easily trapped and strangulated.

What does the femoral canal contain?

The femoral canal contains loose fatty connective tissue, lymphatic vessels and usually one deep inguinal lymph node, often called the node of Cloquet or Rosenmüller. It contains no major nerve or blood vessel. The fat allows the neighbouring femoral vein to expand when blood flow rises, and the lymphatics carry lymph from the lower limb and perineum up to the external iliac nodes.

How do you tell a femoral hernia from an inguinal hernia?

Feel for the pubic tubercle. A femoral hernia emerges below and lateral to the tubercle, beneath the inguinal ligament, because it passes through the femoral canal. An inguinal hernia appears above and medial to the tubercle, emerging through the superficial inguinal ring. Femoral hernias are often small, irreducible and firm, are commoner in women than in men, and strangulate more often than inguinal hernias.

Why do femoral hernias strangulate?

Femoral hernias strangulate because the femoral ring is narrow and bounded mainly by rigid ligaments: the inguinal ligament in front, the pectineal ligament behind and the sharp lacunar ligament medially. Bowel or omentum pushed through this tight opening swells, its venous drainage becomes obstructed, and its blood supply is then cut off. For this reason femoral hernias are repaired promptly, even when they cause few symptoms.

References

Gray's Anatomy: The Anatomical Basis of Clinical Practice. Standring S (ed). Elsevier. 42nd edition, 2020.
Moore's Clinically Oriented Anatomy. Moore KL, Dalley AF, Agur AMR. Wolters Kluwer. 9th edition, 2022.
Last's Anatomy: Regional and Applied. Elsevier.