Femoral Triangle

The femoral triangle is a wedge-shaped (pyramid-shaped) depression in the upper anterior thigh, at the junction between the anterior abdominal wall and the lower limb. It provides a gateway for major neurovascular structures entering the limb.

Boundaries

Boundary	Structure
Base (superior)	Inguinal ligament (from ASIS to pubic tubercle)
Lateral border	Medial margin of sartorius muscle
Medial border	Medial margin of adductor longus muscle
Roof	Fascia lata (with the saphenous opening - fossa ovalis)
Floor	Laterally - iliopsoas; medially - pectineus and adductor longus
Apex	Junction of sartorius and adductor longus (points inferiorly, leads into the adductor canal)

Contents (Lateral to Medial - "NAVY")

N - A - V - Y: Nerve, Artery, Vein, Y-fronts (lymphatics/canal)

From lateral to medial:

Femoral nerve (L2, L3, L4) - lies in the muscular (lateral) compartment, outside the femoral sheath
Femoral artery - continuation of the external iliac artery below the inguinal ligament; palpable midway between the ASIS and pubic symphysis
Femoral vein - medial to the artery
Femoral canal - most medial compartment; contains lymphatic vessels and the deep inguinal (Cloquet's) lymph node at its upper end

Contents of the Femoral Triangle - Gray's Anatomy for Students

The Femoral Sheath

The femoral artery, vein, and lymphatics are enclosed in a funnel-shaped fascial sleeve called the femoral sheath:

Continuous superiorly with transversalis fascia (anterior) and iliac fascia (posterior)
Merges inferiorly with connective tissue of the vessels
Divided into three compartments:
- Lateral: femoral artery
- Middle: femoral vein
- Medial: femoral canal (lymphatics)
The femoral nerve is NOT inside the sheath - it lies lateral to it in the muscular compartment

The Femoral Canal

Most medial compartment of the femoral sheath
Conical shape, approximately 1.25 cm long
Femoral ring = the superior opening of the canal (covered by femoral septum)
Contains: lymphatic vessels, areolar tissue, Cloquet's (Rosenmüller) node
The femoral ring is bounded by: inguinal ligament (anteriorly), femoral vein (laterally), lacunar ligament (medially), pectineal ligament (posteriorly)
Clinical significance: the femoral ring is a potential weak point - site of femoral hernias (more common in women due to wider pelvis)

Inguinal region - muscular and vascular compartments - THIEME Atlas

Apex and Continuation

The apex leads into the adductor canal (Hunter's canal), which descends medially down the thigh
The femoral artery and vein travel through the adductor canal and exit via the adductor hiatus in adductor magnus to become the popliteal artery and vein in the popliteal fossa behind the knee

Femoral Artery Pulse Point

The femoral artery is palpable (and easily located with ultrasound) just inferior to the inguinal ligament, midway between the ASIS and pubic symphysis. This is the standard landmark for:

Femoral artery cannulation (cardiac catheterization, coronary angiography)
Femoral vein access (right heart catheterization, pulmonary artery catheters, renal vein sampling)
Emergency vascular access

Clinical Relevance

Condition	Relevance
Femoral hernia	Viscera protrudes through the femoral ring into the femoral canal; appears below and lateral to the pubic tubercle (vs. inguinal hernia which is above/medial)
Femoral artery access	Key site for cardiac catheterization and angiography
Femoral nerve block	Anaesthesia for anterior thigh and knee surgery
Femoral vein thrombosis	Can propagate to iliofemoral DVT
Lymphadenopathy	Inguinal lymph nodes drain the lower limb, perineum, and lower abdominal wall; enlarged nodes palpable in this region
Psoas abscess	Can track along iliopsoas into the femoral triangle

Sources: Gray's Anatomy for Students, pp. 675-676; THIEME Atlas of Anatomy - General Anatomy and Musculoskeletal System, p. 573

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