Medial Circumflex Femoral Artery

The medial circumflex femoral artery is an important artery of the proximal thigh and hip region. It usually arises from the profunda femoris artery and passes medially and posteriorly around the proximal femur. Its branches supply muscles of the proximal thigh, participate in arterial anastomoses around the hip, and provide the principal arterial supply to the femoral head and neck in adults through retinacular vessels.^[1][2]

The artery has particular anatomical and clinical importance because of its close relationship to the femoral neck and hip joint. Damage to its branches, especially the superior retinacular vessels derived from its deep branch, can compromise blood flow to the femoral head. This relationship is especially relevant in displaced intracapsular fractures of the femoral neck and during surgical procedures around the hip.

Although a typical course can be described, the origin and branching pattern of the medial circumflex femoral artery vary. It may arise directly from the femoral artery rather than from the profunda femoris, and the arrangement of its branches is not identical in all individuals.

Origin

The medial circumflex femoral artery most commonly arises from the profunda femoris artery, also called the deep artery of the thigh. It usually originates near the proximal part of the profunda femoris, shortly after that vessel arises from the femoral artery.^[1][3]

The artery may instead arise directly from the femoral artery. Variation in origin is important during angiographic interpretation and surgical exposure because the vessel cannot always be assumed to arise from the profunda femoris.

Course

From its usual origin, the medial circumflex femoral artery passes medially and posteriorly through the proximal thigh. It courses between muscles near the proximal femur before reaching the posterior aspect of the hip region.

Proximally, the artery passes between pectineus and iliopsoas. It then continues posteriorly between obturator externus and adductor brevis. Its deeper continuation passes toward the posterior aspect of the femoral neck, where important branches enter the vascular network supplying the proximal femur.^[1][2]

The vessel is commonly described in terms of superficial, deep, ascending, and acetabular branches, although terminology and subdivision can vary among anatomical descriptions. The deep branch is particularly important because it gives rise to vessels that contribute substantially to the blood supply of the femoral head and neck.

Relations

The medial circumflex femoral artery has important relationships with the muscles surrounding the proximal femur and hip joint. These relationships change as the vessel curves from the anterior-medial proximal thigh toward the posterior hip.

Structure	Relationship
Pectineus	Related to the proximal course of the artery
Iliopsoas	The artery passes in the interval between iliopsoas and pectineus proximally
Obturator externus	Closely related as the artery passes posteriorly toward the femoral neck
Adductor brevis	Related to the medial and posterior course of the vessel
Femoral neck	Deep branches approach the posterior aspect of the neck and give rise to retinacular vessels
Hip joint capsule	Retinacular branches ascend in close relationship to the capsule and femoral neck

The posterior relationship of the artery to the proximal femur is particularly important because the major retinacular vessels approach the femoral head along the femoral neck.

Branches

The branching pattern of the medial circumflex femoral artery is variable. Several branches are commonly recognized according to their direction and distribution.

Superficial Branch

A superficial branch courses medially and supplies muscles in the proximal medial thigh. It contributes to the local arterial network and communicates with neighboring vessels.

Its size and exact distribution vary, and it is generally less important to the femoral head than the deep branch.

Deep Branch

The deep branch is the most clinically important continuation of the medial circumflex femoral artery. It passes posteriorly around the proximal femur in close relationship to obturator externus and the posterior aspect of the femoral neck.

Near the posterior hip, branches of this vessel contribute to the extracapsular arterial network and give rise to retinacular arteries that ascend along the femoral neck. The superior retinacular vessels are particularly important sources of blood to the adult femoral head.^[1][2]

Ascending Branches

Ascending branches pass toward the greater trochanter and participate in arterial networks around the proximal femur. They communicate with branches of the lateral circumflex femoral and gluteal arteries.

These vessels contribute to the trochanteric anastomosis and to the vascular network from which vessels supplying the proximal femur arise.

Acetabular Branch

An acetabular branch may pass toward the hip joint and contribute to the vascular supply of structures around the acetabulum. It may communicate with the acetabular branch of the obturator artery.

The artery within the ligament of the head of the femur, usually derived from the obturator artery, can contribute to the blood supply of the femoral head. Its relative importance is greater in children than in most adults, in whom the retinacular arteries are the dominant supply.

Retinacular Arteries

The retinacular arteries are small vessels that ascend along the femoral neck within synovial folds or retinacula associated with the hip joint capsule. They are among the most important branches derived from the vascular network supplied predominantly by the medial circumflex femoral artery.

These vessels travel along the surface of the femoral neck toward the junction between the neck and the articular cartilage of the femoral head. They then enter the bone and contribute to the intraosseous arterial supply of the head.

The superior retinacular vessels, which approach the posterosuperior aspect of the femoral neck, provide a particularly important component of the blood supply to the weight-bearing portion of the adult femoral head.

This vascular arrangement explains why injury near the femoral neck can threaten the viability of the femoral head even when the more proximal medial circumflex femoral artery remains intact.

Blood Supply of the Femoral Head

The arterial supply of the femoral head changes during development. In the adult, the dominant supply is provided by retinacular arteries derived predominantly from the medial circumflex femoral artery.^[1][3]

Several arterial sources may contribute:

• Retinacular arteries: The principal source in adults, especially the superior retinacular vessels associated with the medial circumflex femoral artery.
• Lateral circumflex femoral artery: Contributes to arterial networks around the proximal femur but usually provides a smaller contribution to the adult femoral head.
• Artery of the ligament of the head: Usually derived from the acetabular branch of the obturator artery and generally provides a limited contribution in adults.

The relative importance of these vessels is clinically significant because the retinacular arteries may be damaged by fractures or surgical dissection around the femoral neck.

Blood Supply of the Femoral Neck

The femoral neck receives blood from vessels forming an extracapsular arterial network near its base and from ascending cervical or retinacular branches that travel toward the femoral head.

The medial circumflex femoral artery is a major contributor to this system. Branches approach the posterior femoral neck and then ascend toward the head, supplying the neck and adjacent bone along their course.

The intracapsular location of much of the femoral neck places these vessels in close relationship to the hip joint capsule and retinacular folds.

Trochanteric Anastomosis

The trochanteric anastomosis is an arterial network around the greater trochanter and proximal femur. It receives contributions from branches of the medial and lateral circumflex femoral arteries and from gluteal arteries.

The medial circumflex femoral artery contributes substantially to this network through ascending branches. The network provides communication between arterial territories surrounding the hip and contributes to the vascular supply of the proximal femur.

Traditional anatomical descriptions often discuss the trochanteric anastomosis in relation to femoral head perfusion. More specifically, the adult femoral head depends primarily on retinacular branches associated with the medial circumflex femoral arterial system.

Cruciate Anastomosis

The medial circumflex femoral artery also contributes to the cruciate anastomosis on the posterior aspect of the proximal thigh. Its transverse branch communicates with vessels from the lateral circumflex femoral, inferior gluteal, and first perforating arteries.

Contributor	Parent Vessel
Transverse branch of medial circumflex femoral artery	Usually profunda femoris artery
Transverse branch of lateral circumflex femoral artery	Usually profunda femoris artery
Descending branch of inferior gluteal artery	Internal iliac artery
Ascending branch of first perforating artery	Profunda femoris artery

The cruciate anastomosis creates communication between the gluteal and profunda femoris arterial territories around the posterior proximal thigh.

Distribution

The medial circumflex femoral artery supplies both muscular and osseous structures in the proximal thigh and hip region. Its distribution includes:

• Femoral head: Predominantly through retinacular vessels derived from the deep arterial system.
• Femoral neck: Through ascending cervical and retinacular branches.
• Hip joint: Through articular branches supplying the capsule and adjacent structures.
• Proximal thigh muscles: Through muscular branches to structures along its course.
• Trochanteric region: Through branches participating in the arterial networks around the proximal femur.

Comparison with the Lateral Circumflex Femoral Artery

The medial and lateral circumflex femoral arteries commonly arise from the profunda femoris artery but follow different courses and have different major distributions.

Feature	Medial Circumflex Femoral Artery	Lateral Circumflex Femoral Artery
Direction	Passes medially and posteriorly around proximal femur	Passes laterally through proximal thigh
Major proximal relationship	Posterior femoral neck and hip region	Anterior and lateral proximal thigh
Adult femoral head supply	Principal arterial source	Smaller contribution
Cruciate anastomosis	Contributes	Contributes
Trochanteric network	Contributes	Contributes

The distinction is especially important clinically because interruption of the medial circumflex femoral arterial system poses a greater threat to the adult femoral head than interruption of a comparable branch of the lateral circumflex femoral artery.

Anatomical Variations

The medial circumflex femoral artery varies in its origin, caliber, and branching pattern. The classic origin from the profunda femoris artery is common but not universal.

Variation in Origin

The artery may arise directly from the femoral artery. Its relationship to the origin of the profunda femoris and lateral circumflex femoral artery can also vary.

Occasionally, branches normally derived from the medial circumflex femoral artery may arise independently. Such variation is important during surgery and angiographic assessment because preservation of the vessels supplying the femoral head depends on identifying the actual arterial pattern.

Variation in Branching

The number and arrangement of muscular, ascending, transverse, acetabular, and retinacular branches are variable. The precise nomenclature applied to these branches also differs somewhat among anatomical and surgical descriptions.

Despite this variation, the clinically important pattern is consistent: vessels derived predominantly from the medial circumflex femoral arterial system reach the posterior femoral neck and provide major retinacular branches to the femoral head.

Clinical Significance

Femoral Neck Fractures

The vascular relationship between the medial circumflex femoral artery and the femoral neck is especially important in intracapsular femoral neck fractures. A displaced fracture can disrupt retinacular vessels ascending along the neck toward the femoral head.

Because these vessels provide most of the arterial supply to the adult femoral head, their disruption can substantially reduce perfusion. The risk depends on the fracture pattern, displacement, vascular injury, and remaining collateral supply.

Avascular Necrosis of the Femoral Head

Loss of blood flow to the femoral head can result in osteonecrosis, also called avascular necrosis. Traumatic disruption of the retinacular arterial supply is one anatomical mechanism by which this can occur after femoral neck injury.

The vulnerability of these vessels reflects their course along the femoral neck within the capsular region. Damage may occur even without direct injury to the main trunk of the medial circumflex femoral artery.

Hip Dislocation

Traumatic dislocation of the hip can place vessels around the femoral head and neck at risk. The vascular consequences depend on the direction and severity of displacement and the associated soft tissue injuries.

The close relationship of the medial circumflex femoral arterial system to the posterior hip and femoral neck is therefore relevant when evaluating injuries involving major displacement of the femoral head.

Hip Surgery

The medial circumflex femoral artery and its deep branches are important during surgical approaches to the hip. Procedures involving the posterior or medial aspects of the proximal femur must account for the course of vessels supplying the femoral head.

Preservation of the deep branch and retinacular arterial system is particularly important in procedures intended to preserve the native femoral head.

Imaging and Angiography

The medial circumflex femoral artery can be evaluated with CT angiography, MR angiography, conventional angiography, and other vascular imaging techniques. Imaging may demonstrate its origin, course, and major branches as well as anatomical variation.

Because the vessel may arise directly from the femoral artery and because its branching pattern is variable, the actual anatomy should be identified when detailed vascular mapping is required.

The medial circumflex femoral artery is distinguished by its course around the proximal femur and its major contribution to the vascular supply of the femoral head and neck. Its deep branch and associated retinacular vessels are especially important, making the artery a central anatomical consideration in femoral neck fractures, hip-preserving surgery, and other procedures involving the proximal femur.