Femoral Triangle

The femoral triangle is a triangular anatomical region in the upper anterior thigh immediately inferior to the inguinal ligament. It is an important surface and clinical landmark because several major structures entering or leaving the lower limb pass through this region, including the femoral nerve, femoral artery, and femoral vein.^[1][2]

The triangle is bounded superiorly by the inguinal ligament, laterally by sartorius, and medially by adductor longus. Its floor is formed primarily by iliopsoas and pectineus, while its roof consists of skin, superficial fascia, and fascia lata.

The femoral triangle is clinically important for palpation of the femoral pulse, arterial and venous access, assessment of the femoral nerve, examination of inguinal lymph nodes, and understanding the anatomical pathway of femoral hernias.

Location

The femoral triangle lies in the upper third of the anterior thigh, immediately inferior to the inguinal ligament.

Its broad base faces superiorly toward the inguinal ligament, while its apex points inferiorly where sartorius crosses adductor longus.

At the apex, the femoral vessels continue into the adductor canal, providing continuity between the proximal anterior thigh and deeper vascular pathway toward the popliteal region.

General Anatomy

Feature	Anatomy
Region	Upper anterior thigh
Superior boundary	Inguinal ligament
Lateral boundary	Medial border of sartorius
Medial boundary	Medial border of adductor longus
Apex	Intersection of sartorius and adductor longus
Floor	Iliopsoas and pectineus, with adductor longus contributing medially
Roof	Skin, superficial fascia and fascia lata
Major contents	Femoral nerve, artery, vein, femoral canal and lymphatics

Boundaries

The boundaries of the femoral triangle can be identified using three major anatomical structures:

• Superiorly: inguinal ligament
• Laterally: medial border of sartorius
• Medially: medial border of adductor longus

These boundaries create an inverted triangular space with its base directed superiorly and apex directed inferiorly.

Superior Boundary

The superior boundary, or base, of the femoral triangle is formed by the inguinal ligament.

The inguinal ligament extends from the anterior superior iliac spine to the pubic tubercle and separates the anterior abdominal wall from the proximal thigh.

Major neurovascular structures pass deep to the inguinal ligament as they enter the femoral triangle from the pelvis.

Lateral Boundary

The lateral boundary is formed by the medial border of sartorius.

Sartorius begins at the anterior superior iliac spine and travels inferomedially across the anterior thigh.

Its oblique course creates the lateral margin of the triangle before crossing adductor longus at the apex.

Medial Boundary

The medial boundary is formed by the medial border of adductor longus.

Adductor longus originates from the pubis and passes inferolaterally toward the linea aspera of the femur.

The divergence between sartorius and adductor longus superiorly creates the triangular configuration of the region.

Apex

The apex of the femoral triangle is located where the medial border of sartorius crosses the medial border of adductor longus.

At this level, the femoral artery and vein leave the open triangular region and continue into the adductor canal.

The apex therefore represents an important transition between the femoral triangle and the deeper vascular pathway of the middle thigh.

Floor

The floor of the femoral triangle is muscular and is formed primarily by iliopsoas laterally and pectineus medially. Adductor longus contributes to the medial part of the floor.

The femoral nerve lies on the iliopsoas portion of the floor, whereas the femoral vessels occupy a more medial position.

The muscular floor separates the neurovascular structures from deeper skeletal elements and contributes to their anatomical relationships within the triangle.

Roof

The roof of the femoral triangle consists of skin, superficial fascia, and fascia lata.

The superficial fascia contains superficial veins, cutaneous nerves, lymphatic vessels, and superficial inguinal lymph nodes.

The fascia lata forms the deep fascial covering of the thigh and contains the saphenous opening in the upper medial portion of the region.

Contents

The major contents of the femoral triangle can be arranged from lateral to medial:

• Femoral nerve
• Femoral artery
• Femoral vein
• Femoral canal and lymphatic structures

This arrangement is commonly remembered using the sequence NAVEL: nerve, artery, vein, empty space or femoral canal, and lymphatics.

Femoral Nerve

The femoral nerve enters the thigh deep to the inguinal ligament and lies lateral to the femoral artery.

It rests on iliopsoas and lies outside the femoral sheath. Within or near the femoral triangle, it divides into muscular and cutaneous branches supplying the anterior thigh and contributing sensory innervation to the medial leg through the saphenous nerve.

The nerve is derived primarily from the posterior divisions of the L2, L3, and L4 ventral rami.

Femoral Artery

The femoral artery is the continuation of the external iliac artery distal to the inguinal ligament.

It enters the femoral triangle near the midinguinal point and descends through the triangle toward its apex.

Within this region, the artery gives rise to several branches supplying the proximal thigh and superficial tissues.

Femoral Pulse

The femoral artery can be palpated immediately inferior to the inguinal ligament near the midinguinal point, halfway between the anterior superior iliac spine and pubic symphysis.

The artery can often be compressed against the underlying femoral head in this region.

The femoral pulse is an important clinical indicator of arterial perfusion to the lower limb and a useful landmark during vascular procedures.

Femoral Vein

The femoral vein accompanies the femoral artery through the triangle.

Near the inguinal ligament, the vein lies medial to the artery. Its relationship changes progressively farther down the thigh as the vessels continue toward the apex and adductor canal.

The femoral vein receives several tributaries, including the great saphenous vein near the saphenous opening.

Femoral Sheath

The femoral sheath is a funnel-shaped fascial sleeve surrounding the proximal femoral vessels immediately inferior to the inguinal ligament.

It is divided into compartments containing the femoral artery, femoral vein, and femoral canal.

The femoral nerve is not contained within the femoral sheath and lies lateral to it.

Compartments of the Femoral Sheath

Compartment	Principal Content
Lateral	Femoral artery
Intermediate	Femoral vein
Medial	Femoral canal

The arrangement allows the femoral vessels some freedom to expand and move beneath the inguinal ligament.

Femoral Canal

The femoral canal is the small medial compartment of the femoral sheath.

It contains loose connective tissue, lymphatic vessels, and commonly a deep inguinal lymph node. Its space also permits expansion of the adjacent femoral vein when venous return increases.

The superior opening of the canal is the femoral ring.

Femoral Ring

The femoral ring forms the superior entrance to the femoral canal.

Its boundaries are closely related to the inguinal ligament anteriorly, lacunar ligament medially, pectineal region posteriorly, and femoral vein laterally.

The ring is clinically important because abdominal contents can protrude through it to form a femoral hernia.

Great Saphenous Vein

The great saphenous vein ascends along the medial lower limb and enters the proximal thigh.

Near the femoral triangle, it passes through the saphenous opening in the fascia lata and drains into the femoral vein.

The saphenofemoral junction is an important landmark in venous imaging and procedures involving the superficial venous system.

Saphenous Opening

The saphenous opening, also called the fossa ovalis, is an opening in the fascia lata of the upper medial thigh.

It allows the great saphenous vein and associated superficial vessels and lymphatics to pass through the deep fascia.

The opening is covered by cribriform fascia and lies inferolateral to the pubic tubercle.

Inguinal Lymph Nodes

Both superficial and deep inguinal lymph nodes are associated with the region of the femoral triangle.

Superficial inguinal nodes lie in the superficial fascia, while deep nodes lie deeper in relation to the femoral vessels.

These nodes receive lymph from extensive regions of the lower limb and adjacent superficial territories.

Deep Inguinal Lymph Nodes

The deep inguinal lymph nodes lie medial to the femoral vein and along the proximal femoral vessels.

A superior deep node, commonly called the node of Cloquet, may occupy the femoral canal near the femoral ring.

Efferent vessels from the deep inguinal nodes pass toward the external iliac lymph nodes.

Branches of the Femoral Artery

Several branches may arise from the femoral artery within the femoral triangle, including:

• Superficial epigastric artery
• Superficial circumflex iliac artery
• Superficial external pudendal artery
• Deep external pudendal artery
• Profunda femoris artery

The precise level and branching pattern can vary between individuals.

Profunda Femoris Artery

The profunda femoris artery, or deep artery of the thigh, usually arises from the posterolateral aspect of the femoral artery within the femoral triangle.

It passes deeper into the thigh and gives rise to the medial and lateral circumflex femoral arteries and perforating branches.

It is the principal arterial supply to much of the thigh musculature.

Relationship to Sartorius

Sartorius forms the lateral boundary of the femoral triangle.

As it travels inferomedially, sartorius eventually crosses the femoral vessels near the apex of the triangle.

Below this point, sartorius contributes to the roof of the adductor canal.

Relationship to Adductor Longus

Adductor longus forms the medial boundary of the femoral triangle and contributes to its medial floor.

The muscle originates from the pubis and extends inferolaterally toward the femur.

Its intersection with sartorius identifies the apex of the triangle.

Relationship to Iliopsoas

Iliopsoas forms the lateral portion of the floor of the femoral triangle.

The femoral nerve lies on its anterior surface after entering the thigh beneath the inguinal ligament.

The iliopsoas tendon continues toward the lesser trochanter of the femur and functions as a powerful hip flexor.

Relationship to Pectineus

Pectineus contributes to the medial part of the floor of the femoral triangle.

The femoral vessels lie anterior to this muscular plane in the proximal thigh.

The pectineus therefore provides an important deep muscular relationship for structures within the triangle.

Relationship to the Adductor Canal

At the apex of the femoral triangle, the femoral artery and vein enter the adductor canal.

The canal extends through the middle portion of the thigh and provides a passage for the femoral vessels toward the adductor hiatus.

The saphenous nerve accompanies the vessels through much of the canal but does not pass through the adductor hiatus.

Surface Anatomy

The femoral triangle can be approximated on the surface of the upper thigh using three palpable or functionally identifiable landmarks.

The inguinal ligament forms its superior boundary and can be projected between the anterior superior iliac spine and pubic tubercle. Sartorius can be made more prominent by flexing, abducting, and laterally rotating the hip, while adductor longus can be identified during resisted thigh adduction.

These landmarks allow the approximate boundaries of the femoral triangle to be mapped on the body surface.

Midinguinal Point

The midinguinal point lies halfway between the anterior superior iliac spine and the pubic symphysis.

The femoral artery enters the thigh deep to the inguinal ligament near this point, making it an important surface landmark for locating the femoral pulse.

The midinguinal point should not be confused with the midpoint of the inguinal ligament, which lies halfway between the anterior superior iliac spine and pubic tubercle.

Clinical Significance

Femoral Pulse Examination

The femoral triangle provides direct access to the femoral pulse.

The pulse is palpated just inferior to the inguinal ligament near the midinguinal point. Comparison between the two sides can provide information about proximal arterial flow to the lower limbs.

The artery's relatively superficial position in this region also permits compression against deeper structures when control of arterial bleeding is required.

Femoral Arterial Access

The femoral artery within the femoral triangle has historically been an important site for percutaneous arterial access.

Access to the arterial circulation through this region can provide a route for angiographic and endovascular procedures.

Accurate knowledge of the artery's relationship to the femoral head, inguinal ligament, vein, and surrounding structures is important for minimizing complications.

Femoral Venous Access

The femoral vein can provide a route for central venous access.

Near the inguinal ligament, the vein lies medial to the femoral artery, although anatomical variation and positional changes can occur.

Ultrasound guidance allows direct visualization of the vein and surrounding structures during vascular access.

Femoral Nerve Block

The femoral nerve can be targeted for regional anesthesia in the femoral triangle region.

The nerve lies lateral to the femoral artery and outside the femoral sheath, typically on the iliopsoas muscle.

Ultrasound can demonstrate the nerve, artery, fascia iliaca, and surrounding muscular landmarks.

Femoral Hernia

A femoral hernia occurs when abdominal contents pass through the femoral ring into the femoral canal.

Because the canal lies medial to the femoral vein, a femoral hernia appears in a characteristic anatomical relationship to the proximal femoral vessels.

The relatively rigid boundaries of the femoral ring can predispose herniated contents to incarceration or strangulation.

Relationship to the Pubic Tubercle

The position of a groin swelling relative to the pubic tubercle can help anatomically distinguish femoral from inguinal hernias.

Femoral hernias characteristically emerge inferior to the inguinal ligament and generally inferolateral to the pubic tubercle, whereas inguinal hernias arise above the inguinal ligament.

Clinical findings alone may not always establish the diagnosis, particularly in small or complicated hernias.

Femoral Artery Compression

The superficial course of the femoral artery within the triangle permits manual compression when temporary control of arterial flow is required.

Compression is applied in the proximal thigh where the artery can be pressed against deeper structures.

This relationship also contributes to the ability to achieve hemostasis after some femoral arterial procedures.

Femoral Neuropathy

Injury or compression of the femoral nerve can produce weakness of muscles supplied by the nerve, particularly the quadriceps femoris, resulting in impaired knee extension.

The patellar reflex may be reduced, and sensory abnormalities can involve the anterior thigh and medial leg depending on the level and extent of the lesion.

The nerve's course through the pelvis and beneath the inguinal ligament should be considered when localizing femoral neuropathy.

Inguinal Lymphadenopathy

Enlarged inguinal lymph nodes may be palpable in the region overlying or adjacent to the femoral triangle.

Knowledge of the normal arrangement of superficial and deep nodes helps with anatomical examination of lymphatic drainage from the lower limb and neighboring regions.

Trauma

Penetrating or severe blunt trauma to the femoral triangle can damage major neurovascular structures because the femoral artery, vein, and nerve are concentrated within a relatively small region.

Vascular injury can result in substantial hemorrhage, while femoral nerve injury can impair motor and sensory function in the lower limb.

The superficial location of these structures makes rapid anatomical assessment particularly important in traumatic injuries of the proximal thigh.

Imaging

Ultrasound is especially useful for examining the femoral triangle because it can demonstrate the femoral artery, vein, nerve, lymph nodes, and surrounding muscles in real time.

CT and MRI provide broader cross-sectional evaluation of the region and can demonstrate vascular abnormalities, masses, lymphadenopathy, hernias, muscular pathology, and deeper anatomical relationships.

The predictable arrangement of structures within the femoral triangle makes it an important reference region in lower-limb imaging.