Lower Limb Blood Supply and Anatomical Correlations

The blood supply and venous drainage of the lower limb involve various arteries and veins that play crucial roles in circulation and maintaining healthy limb function. Understanding these elements is fundamental to the study of human anatomy and is particularly relevant for clinical applications.

Vasculature of the Lower Limb

The lower limb is primarily supplied by branches of the internal iliac artery in the pelvis and the femoral artery, which is a continuation of the external iliac artery. These arteries are crucial for the vascular supply to the lower limb.

Branches of the Internal Iliac Artery

The internal iliac artery gives rise to several important branches that supply the lower limb:

Superior Gluteal Artery: This artery exits the pelvis posteriorly via the greater sciatic foramen to supply the gluteal region.
Inferior Gluteal Artery: Similar to the superior gluteal artery, it also exits through the greater sciatic foramen but typically supplies the inferior aspect of the gluteal region.
Obturator Artery: It exits the pelvis anteriorly through the obturator foramen, supplying the medial thigh.

Femoral Artery

The femoral artery, clinically termed the superficial femoral artery, enters the anterior thigh beneath the inguinal ligament, encased within a femoral sheath formed from extensions of the deep fascia of the abdomen. As it traverses the thigh, the femoral artery gives rise to several branches:

Superficial Circumflex Iliac and Superficial Epigastric Arteries: These arteries supply the abdominal wall.
Superficial and Deep External Pudendal Arteries: These structures supply the inguinal region.
Descending Genicular Artery: This artery contributes to the vascular anastomosis surrounding the knee.
Deep Artery of the Thigh: Also known as profunda femoris, this is the main blood supply for the thigh, branching into:

The Medial Circumflex Femoral Artery: This artery primarily supplies the hip joint.
The Lateral Circumflex Femoral Artery: It supplies the hip joint and assists in knee joint anastomosis.
The Perforating Arteries: Typically 1st through 3rd (or sometimes 4th), these arteries supply the anterior, medial, and posterior muscles of the thigh.

Cruciate Anastomosis: This provides collateral blood supply to the hip. It comprises contributions from the medial and lateral circumflex femoral arteries, the first perforating artery, and the inferior gluteal artery.

The Popliteal Region

As the femoral artery progresses into the popliteal fossa, it becomes the popliteal artery. This space is located behind the knee joint.

Branches of the Popliteal Artery

The popliteal artery divides into two terminal branches:

Anterior Tibial Artery: This artery emerges from the popliteal artery and is responsible for supplying the anterior compartment of the leg.
Posterior Tibial Artery: This artery descends into the deep posterior leg compartment, supplying both deep and superficial muscles. It further divides into:

The Fibular Artery: Supplies muscles of the deep and lateral compartments of the leg.
The Medial and Lateral Plantar Arteries: These supply respective regions of the sole of the foot.

Anastomoses around the Knee

The knee joint receives its blood supply via a genicular anastomosis formed by several arteries including:

Medial and lateral superior and inferior genicular arteries,
The middle genicular artery,
The descending genicular artery,
Branches from the anterior and posterior tibial arteries.

Veins of the Lower Limb

The venous drainage of the lower limb consists of both deep and superficial systems that communicate through perforating veins, with each possessing numerous valves for blood flow regulation.

Deep Venous System

The deep veins accompany the major arteries and are typically named similarly. For instance:

The Femoral Vein: Drains deep thigh veins and ascends under the inguinal ligament becoming the external iliac vein.
Superior and Inferior Gluteal Veins: Drain the gluteal region and also empty into the internal iliac vein.

Superficial Venous System

The main superficial veins, the great saphenous and small saphenous veins, arise from the dorsal venous arch of the foot:

Great Saphenous Vein: It arises from the medial aspect of the dorsal venous arch, coursing up the leg and draining into the femoral vein at the saphenous opening in the upper thigh.
Small Saphenous Vein: Originating from the lateral side of the venous arch, it ascends posterior to the lateral malleolus and drains into the popliteal vein.

Lymphatics of the Lower Limb

Lymphatic flow from the lower limb progresses upwards following the corresponding veins:

Lymph from the gluteal region drains to internal iliac nodes.
Lymph from the thighs typically drains to deep inguinal nodes.
Lymph from the superficial areas culminates in superficial inguinal nodes.

Spaces of the Thigh

The femoral nerve, artery, and vein navigate through structural passages defined by muscle and ligament.

Retroinguinal Space

Structures transition from the abdomen to the thigh through the retroinguinal space, which consists of:

Lateral Muscular Compartment: Houses the femoral nerve and iliopsoas muscle.
Medial Vascular Compartment: Contains the femoral vessels enclosed by the femoral sheath.

Femoral Triangle

The femoral triangle encompasses the femoral artery, vein, and terminal branches of the femoral nerve. Its boundaries include:

Superiorly by the inguinal ligament,
Medially by the adductor longus muscle,
Laterally by the sartorius muscle,
The floor formed by the iliopsoas and pectineus muscles.

Clinical Correlations

Femoral Hernia

Femoral hernias are more commonly identified in women and occur as the intestine protrudes through the femoral canal into the femoral triangle.

Popliteal Aneurysm

Popliteal artery aneurysms are noted as the prevalent form of peripheral arterial aneurysm and may result in compression of the tibial nerve, leading to referred pain in the medial calf.

Pis Planus (Flatfoot)

This condition indicates a failure of both active and passive stabilizers of the medial longitudinal arch, leading to structural changes and potential discomfort, especially in older adults or those who stand for prolonged periods.

"Too many toes" sign is a notable clinical feature, indicating visible toes due to forefoot rotation and abduction in patients with flat feet.

Comprehensive Overview of Lower Limb Vasculature and Clinical Relevance

Comprehensive Overview of Lower Limb Vasculature and Clinical Relevance