Femoral Triangle and Nerves and Vessels of front of the thigh

Femoral Triangle

The femoral triangle is a triangular, fascia-lined space located on the anterior aspect of the upper one-third of the thigh. It lies immediately below the inguinal ligament and serves as an important anatomical region through which major neurovascular structures pass.

Boundaries, Roof, and Floor

Boundaries

The femoral triangle has a triangular shape with a base, apex, medial boundary, lateral boundary, roof, and floor.

• Base (Superior boundary): Inguinal ligament
• Medial boundary: Medial border of the adductor longus muscle
• Lateral boundary: Medial border of the sartorius muscle
• Apex: Formed at the point where the medial border of the sartorius meets the medial border of the adductor longus.

Floor

The floor of the femoral triangle is gutter-shaped and is formed by four muscles arranged from lateral to medial:

1. Iliacus
2. Psoas major
3. Pectineus
4. Adductor longus

Roof

The roof of the femoral triangle is formed by three layers:

1. Skin
2. Superficial fascia
3. Deep fascia (fascia lata)

The superficial fascia forming the roof of the femoral triangle contains the following structures:

1. Superficial inguinal lymph nodes
2. Femoral branch of the genitofemoral nerve
3. Branches of the ilioinguinal nerve
4. Superficial branches of the femoral artery with their accompanying veins
5. Terminal part of the great saphenous vein

Features of the Deep Fascia (Fascia Lata)

The deep fascia (fascia lata) forming the roof of the femoral triangle includes:

1. Saphenous opening – An oval opening that allows the great saphenous vein to pass through and join the femoral vein.
2. Cribriform fascia – A thin, perforated layer of fascia that covers the saphenous opening and transmits the superficial blood vessels and lymphatic vessels. It is also known as fascia cribrosa or Hesselbach’s fascia.

Contents of Femoral Triangle

The femoral triangle contains the following important structures:

1. Femoral artery and its branches
2. Femoral vein and its tributaries
3. Femoral nerve
4. Deep inguinal lymph nodes
5. Lateral cutaneous nerve of the thigh
6. Femoral branch of the genitofemoral nerve
7. Femoral sheath
8. Fibrofatty tissue filling the spaces between the neurovascular structures

Key description

Femoral Artery

The femoral artery begins at the midinguinal point as the continuation of the external iliac artery. It descends downward and medially through the femoral triangle to reach its apex.

Branches of the Femoral Artery

The femoral artery gives six branches within the femoral triangle.

Superficial branches

1. Superficial epigastric artery
2. Superficial circumflex iliac artery
3. Superficial external pudendal artery

Deep branches

1. Profunda femoris artery (largest branch)
2. Deep external pudendal artery
3. Muscular branches

Femoral Vein

The femoral vein lies medial to the femoral artery at the base of the femoral triangle. As it descends towards the apex, it passes posteromedial to the femoral artery.

Tributaries of the Femoral Vein

The femoral vein receives the following tributaries:

1. Great saphenous vein
2. Profunda femoris vein
3. Medial circumflex femoral vein
4. Lateral circumflex femoral vein
5. Deep external pudendal vein

Femoral Nerve

The femoral nerve lies lateral to the femoral artery and remains outside the femoral sheath. Within the femoral triangle, it is situated in the groove between the iliacus and psoas major muscles.

Femoral Branch of the Genitofemoral Nerve

The femoral branch (crural branch) of the genitofemoral nerve lies in the lateral compartment of the femoral sheath alongside the femoral artery. It pierces the anterior wall of the femoral sheath and the fascia lata to provide cutaneous sensation to the skin over the upper anterior thigh.

Lateral Cutaneous Nerve of the Thigh

The lateral cutaneous nerve of the thigh is a branch of the lumbar plexus. It enters the femoral triangle by passing deep to the inguinal ligament, just medial to the anterior superior iliac spine (ASIS).

Distribution

It supplies the skin of:

• Anterolateral aspect of the thigh
• Lateral part of the gluteal region

Deep Inguinal Lymph Nodes

The deep inguinal lymph nodes are usually 3 to 5 in number. They lie medial to the femoral vein, deep to the cribriform fascia.

The highest deep inguinal node, located within the femoral canal, is known as the node of Cloquet or Rosenmüller’s node.

The vertical group of superficial inguinal lymph nodes lies along the upper part of the great saphenous vein.

Femoral Sheath

The femoral sheath, also called the crural sheath, is a funnel-shaped fascial sleeve that encloses the upper parts of the femoral artery and femoral vein within the femoral triangle. Its broad end is directed superiorly toward the abdomen.

Formation

The femoral sheath is formed by the downward continuation of two fascial layers from the abdomen into the thigh.

• Anterior wall: Formed by the downward extension of the transversalis fascia.
• Posterior wall: Formed by the downward extension of the iliac fascia (fascia iliaca) covering the iliacus muscle.

Termination

Inferiorly, the femoral sheath blends with the tunica adventitia of the femoral vessels and gradually disappears. Therefore, its lower limit is not clearly defined.

Compartment and contents

The femoral sheath is divided by two vertical septa into three compartments.

1. Lateral Compartment

Contains:

• Femoral artery
• Femoral branch of the genitofemoral nerve

2. Intermediate Compartment

Contains:

• Femoral vein

3. Medial Compartment (Femoral Canal)

Contains:

• Deep inguinal lymph node, known as the node of Cloquet or Rosenmüller’s node

Femoral canal

The femoral canal is the medial compartment of the femoral sheath. It lies medial to the femoral vein and is separated from it by the medial septum of the femoral sheath.

Shape

The femoral canal is conical in shape. It is wide superiorly at its base and gradually narrows inferiorly.

Dimensions

• Length: Approximately 1.5 cm
• Width at the base: Approximately 1.5 cm

Base (Femoral Ring)

The superior opening of the femoral canal is called the femoral ring.

Boundaries of the Femoral Ring

• Anterior: Inguinal ligament
• Posterior: Pectineus muscle
• Medial: Lacunar ligament
• Lateral: Medial septum separating the femoral canal from the femoral vein

Femoral Septum

The femoral septum is a layer of condensed extraperitoneal connective tissue that closes the femoral ring. It forms a barrier between the femoral canal and the abdominal cavity.

Femoral Fossa

The femoral fossa is a shallow depression of the parietal peritoneum that lies directly over the femoral ring.

Contents of the Femoral Canal

The femoral canal contains:

1. The deep inguinal lymph node (node of Cloquet or Rosenmüller’s node)
2. Loose connective tissue

Femoral hernia

Definition

A femoral hernia occurs when abdominal contents protrude through the femoral canal, which is the medial compartment of the femoral sheath.

Incidence

• Femoral hernia is more common in females because the femoral canal is wider and the femoral blood vessels are relatively smaller.
• It occurs more frequently in adults than in children.
• Femoral hernia is an acquired condition and is not congenital.

Components of a Femoral Hernia

A femoral hernia consists of:

• Hernial sac formed by the peritoneum
• Herniated abdominal contents, usually a loop of intestine
• Blood vessels supplying the herniated tissue
• Covering layers of the hernia

The hernia has two important parts:

• Neck: The narrow proximal portion of the hernial sac
• Sac: The expanded distal portion containing the herniated contents

Course of a Femoral Hernia

A femoral hernia follows a characteristic path:

1. Passes downward through the femoral canal
2. Emerges forward through the saphenous opening
3. Turns upward into the superficial fascia along the superficial epigastric vessels

Direction of herniation:
Downward → Forward → Upward

During manual reduction, the hernia should be returned by following the reverse of this course.

Types of Femoral Hernia

1. Reducible Femoral Hernia

The herniated contents can be returned to the abdominal cavity by gentle pressure.

2. Irreducible Femoral Hernia

The herniated contents cannot be reduced because of adhesions between the hernial sac and its contents.

3. Obstructed Femoral Hernia

The intestinal loop within the hernial sac becomes obstructed, usually due to compression or twisting, while its blood supply remains intact.

4. Strangulated Femoral Hernia

The blood supply to the herniated intestine is compromised, leading to ischemia. This is a surgical emergency and requires prompt operation to enlarge the femoral ring and reduce the hernia.

Femoral Artery

The femoral artery is the principal artery of the lower limb. It is the continuation of the external iliac artery and supplies most structures of the thigh and lower limb.

Beginning

The femoral artery begins as the continuation of the external iliac artery at the midinguinal point, immediately below the inguinal ligament.

Course

The femoral artery descends downward and medially from the midinguinal point to the adductor hiatus.

• The upper part of the artery lies within the femoral triangle.
• The lower part passes through the adductor canal.

Termination

The femoral artery enters the popliteal fossa by passing through the adductor hiatus, where it continues as the popliteal artery.

Relations

Relations in the Femoral Triangle

Anterior

• Skin
• Superficial fascia
• Fascia lata
• Anterior wall of the femoral sheath

Posterior

• Posterior wall of the femoral sheath
• Psoas major
• Pectineus
• Adductor longus

Medial

• Femoral vein (in the upper part of the femoral triangle)

Lateral

• Femoral nerve

Important Note:
The femoral vein lies medial to the femoral artery at the base of the femoral triangle and gradually shifts to a posterior position as it approaches the apex.

Relations in the Adductor Canal

Anterolateral

• Vastus medialis

Posteromedial

• Adductor longus
• Adductor magnus

Medial

• Sartorius

Important Note:

• The saphenous nerve crosses the femoral artery from lateral to medial in the adductor canal.
• The femoral vein lies posterior to the artery in the upper part of the canal and lateral to it in the lower part.

Branches

In the femoral triangle

Branches in the Femoral Triangle

Superficial branches

1. Superficial epigastric artery
2. Superficial circumflex iliac artery
3. Superficial external pudendal artery

Deep branches

1. Profunda femoris artery (largest branch)
2. Deep external pudendal artery
3. Muscular branches

Branches in the Adductor Canal

1. Descending genicular artery
2. Muscular branches

Key description

Deep External Pudendal Artery

The deep external pudendal artery arises from the femoral artery and runs deep to the superficial external pudendal artery. It passes medially beneath the spermatic cord in males or the round ligament of the uterus in females.

Supply

• Male: Scrotum
• Female: Labia majora

Descending Genicular Artery

The descending genicular artery is the terminal branch of the femoral artery. It arises within the adductor canal, just proximal to the adductor hiatus. It is also known as the highest genicular artery.

Branches

The descending genicular artery divides into two branches:

1. Saphenous branch – Accompanies the saphenous nerve to the medial side of the knee and contributes to the vascular supply around the knee joint.
2. Muscular branch – Supplies the adjacent muscles in the distal part of the thigh.

Profunda Femoris Artery

The profunda femoris artery, also known as the deep femoral artery or deep artery of the thigh, is the largest branch of the femoral artery. It is the chief arterial supply to the muscles of the thigh and lies deep to the femoral artery.

Beginning

The profunda femoris artery arises from the lateral side of the femoral artery, approximately 4 cm below the inguinal ligament.

Course

After its origin, the artery passes downward and posteriorly behind the femoral vessels.

It then:

• Leaves the femoral triangle by passing between the pectineus and adductor longus muscles.
• Continues downward between the adductor longus and adductor brevis muscles.
• Descends further between the adductor longus and adductor magnus muscles.
• Finally pierces the adductor magnus muscle and continues as the fourth perforating artery to reach the posterior compartment of the thigh.

Termination

The profunda femoris artery terminates by continuing as the fourth perforating artery.

Branches

The profunda femoris artery gives rise to:

1. Medial circumflex femoral artery
2. Lateral circumflex femoral artery
3. Muscular branches
4. Four perforating arteries

Note: The fourth perforating artery represents the continuation of the profunda femoris artery.

Key description

Lateral Circumflex Femoral Artery

The lateral circumflex femoral artery usually arises from the lateral side of the profunda femoris artery.

Course

• It passes laterally between the anterior and posterior divisions of the femoral nerve.
• It is covered anteriorly by the sartorius and rectus femoris muscles.

Branches

Ascending Branch

• Ascends beneath the tensor fasciae latae.
• Anastomoses with the superior gluteal artery and deep circumflex iliac artery.

Descending Branch

• Descends between the rectus femoris and vastus lateralis muscles.
• Contributes to the arterial network around the knee joint.

Transverse Branch

• Passes laterally around the femur.
• Anastomoses with the medial circumflex femoral artery, inferior gluteal artery, and first perforating artery.
• Contributes to the formation of the cruciate anastomosis below the greater trochanter.

Medial Circumflex Femoral Artery

The medial circumflex femoral artery arises from the medial side of the profunda femoris artery.

Course

It passes between the pectineus and psoas major muscles before winding posteriorly around the femur.

Branches

1. Ascending branch
2. Descending branch
3. Transverse branch

Distribution

The branches of the medial circumflex femoral artery:

• Participate in the arterial anastomoses around the proximal femur.
• Provide the principal blood supply to the head and neck of the femur.
• Supply the adductor muscles of the thigh.

Femoral Vein

Beginning

The femoral vein is the main vein of the lower limb. It accompanies the femoral artery and drains the deep structures of the thigh and leg.

The femoral vein begins as the continuation of the popliteal vein after the latter passes through the adductor hiatus at the lower end of the adductor canal.

The femoral vein ascends through the adductor canal and the femoral triangle, accompanying the femoral artery. As it ascends, its position changes in relation to the femoral artery.

• In the adductor canal, it lies posterior to the femoral artery in the upper part and lateral to the artery in the lower part.
• In the femoral triangle, it lies posteromedial to the artery near the apex and becomes medial to the artery at the base.

Termination

The femoral vein passes deep to the inguinal ligament, where it continues as the external iliac vein.

Tributaries

The femoral vein receives the following tributaries:

1. Great saphenous vein
2. Medial circumflex femoral vein
3. Lateral circumflex femoral vein
4. Deep external pudendal vein
5. Profunda femoris (deep femoral) vein
6. Veins accompanying the muscular branches of the femoral artery
7. Popliteal vein (formative tributary)

Femoral Nerve

The femoral nerve is the largest branch of the lumbar plexus and is the main nerve of the anterior compartment of the thigh. It supplies the anterior thigh muscles and provides sensory innervation to the anterior and medial aspects of the thigh and the medial side of the leg.

Beginning

The femoral nerve arises from the posterior divisions of the ventral rami of the L2, L3, and L4 spinal nerves.

• Root value: L2, L3, L4
• Length in the thigh: Approximately 2.5 cm before dividing into terminal branches

Course and relations

In the Abdomen

• The femoral nerve is formed within the psoas major muscle on the posterior abdominal wall.
• It emerges from the lateral border of the psoas major.
• It descends on the iliacus muscle, deep to the fascia iliaca, towards the inguinal ligament.

In the Thigh

• The femoral nerve enters the femoral triangle by passing deep to the inguinal ligament, lateral to the femoral artery.
• It lies outside the femoral sheath because it is located posterior to the fascia iliaca, which forms the posterior wall of the femoral sheath.
• About 2.5 cm below the inguinal ligament, it divides into anterior and posterior divisions.

Important Relation:
The lateral circumflex femoral artery passes between the anterior and posterior divisions of the femoral nerve.

Branches and distribution

Branches in the Abdomen

Muscular Branches

• Iliacus
• Pectineus

Branches in the Thigh

Anterior Division

Muscular branch

• Sartorius

Cutaneous branches

• Medial cutaneous nerve of the thigh
• Intermediate cutaneous nerve of the thigh

Posterior Division

Muscular branches

• Rectus femoris
• Vastus medialis
• Vastus lateralis
• Vastus intermedius
• Articularis genu (through the nerve to vastus intermedius)

Cutaneous branch

• Saphenous nerve (largest cutaneous branch of the femoral nerve)

Articular branches

• Nerve to the rectus femoris supplies the hip joint.
• Nerves to the vasti muscles supply the knee joint.

Note:
The lateral cutaneous nerve of the thigh is not a branch of the femoral nerve. It arises independently from the lumbar plexus. Small vascular branches of the femoral nerve also accompany and supply the femoral artery.

Click to see: Medical Disclaimer and Copyright Notice