Overview
The
femoral triangle is first described by Antonio Scarpa (see Scarpas’ Fascia). It
is a triangular subfascial space located in the anterio-medial aspect of the
proximal thigh. As this anatomical region allows for easy access to major vessels,
it is therefore often used for endovascular procedures such as coronary/peripheral
angiography, and endovascular surgical procedures.
Gross Anatomy
The Femoral Triangle
|
Roof |
Fascia
Lata |
|
Floor (Lateral to Medial) |
Iliacus |
|
|
Psoas
Tendon |
|
|
Pectineus |
|
|
Adductor
Longus |
|
Borders |
Medial:
Medial Border of Adductor Longus |
|
|
Lateral:
Medial Border of Sartorius |
|
|
Superior:
Inguinal Ligament |
|
Contents (Lateral to Medial) |
Femoral
Nerve |
|
|
Femoral
Artery |
|
|
Femoral
Vein – also saphenous opening |
|
|
Deep
Inguinal Lymph Nodes |
Fascia Lata
Fascia lata is the deep fascia of
the thigh and forms the roof of the femoral triangle. It is a layer of fibrous
connective tissue that encapsulates the muscles of the thigh, with
intermuscular septa separating each individual compartment of muscle groups. On
the anteromedial aspect of the fascia, around 3-4 cm inferior and lateral to
the pubic tubercle, lies an oval defect called saphenous opening. This is where
the long/great saphenous vein (LSV/GSV) feeds into the femoral vein, forming
the saphenofemoral junction (SFJ). Superficial inguinal lymphatics also pass
through this opening and join deep inguinal lymphatics here.
Contents of the Femoral Triangle
Femoral Nerve
The Femoral nerve (L2-L4) is the
most lateral lying structure, and is the largest branch of the lumbar plexus.
Its motor innervation supplies the hip flexor and knee extensor muscles. The
Femoral nerve also supplies sensation to the anterior and medial aspect of the
thigh via anterior cutaneous branches.
Femoral Sheath
Medial to the femoral nerve is the
femoral sheath, an extension of transversalis and iliopsoas fascia. Inside this
sheath, it is divided into three compartments. The most lateral compartment
contains the femoral artery, medial to the artery lies the femoral vein, with
the femoral canal being the most medial compartment of the femoral sheath.
Femoral Artery
The femoral artery, otherwise known
as the common femoral artery, is a continuation of the external iliac artery.
This subsequently splits into a deeper branch (profunda femoris, which supplies
the thigh) and a superficial branch (superficial femoral artery, which supplies
the leg) within the femoral triangle before entering the adductor canal.
Femoral Vein
Femoral vein accompanies the femoral
artery along its course in a similar distribution. It receives the LSV at the SFJ.
Clinical Anatomy
Femoral Pulse and Access
At
the level of the inguinal ligament, the femoral artery crosses underneath at
the mid-inguinal point (midpoint between the anterior superior iliac spine and
the pubic symphysis). The femoral pulse can therefore be palpated at this
point. Arterial puncture at this point allows access for angiography and
endovascular procedures. In the absence of femoral pulsation in peripheral
vascular disease, the femoral artery can be identified in thinner individuals
by rolling one’s fingers over the mid-inguinal point - a calcified tube may be
palpable here indicating a severely atherosclerotic femoral artery.
The
femoral artery is a relatively superficial large calibre vessel, which allows
relatively easy puncture for procedures such as coronary/peripheral
angioplasty. Furthermore, in patients who are peripherally shutdown, or in
resuscitation situations, femoral arteries can be accessed for arterial blood
gases/blood samples reliably.
Femoral hernia
A
Femoral hernia occurs when intraabdominal contents herniates through the
femoral canal. Clinically, the patient with a femoral hernia would complain of
a lump (sometimes tender) in their groin. Examination would reveal a lump below
the inguinal ligament and lateral to the pubic tubercle. This differs to an inguinal
hernia, which are typically found above the inguinal ligament and medial to the
pubic tubercle.
Femoral
hernias are more common in elderly females. This is often due to atrophy of
adipose tissue around the femoral canal, leaving a space for herniation to
occur. Treatment of a femoral hernia is surgical, requiring a repair. This is
often performed on an urgent/emergency basis due to the high risk of hernia
strangulation which comes from the tight confines of the femoral canal.
Saphenous Varix
Otherwise
known as saphena varix, is a localised dilatation of the proximal LSV at the
SFJ due to venous valvular incompetence. It can be associated with varicose
veins elsewhere within the superficial venous system. Clinically it can be
confused with a hernia as it can exhibit a cough impulse (a transmitted wave of
pressure down the vein induced by coughing). However, a saphena varix
disappears immediately when the patient is supine, and can have a bluish
appearance. Auscultation may reveal a venous hum. Diagnosis is usually made
with venous duplex ultrasonography and treatment by surgical ligation of the
SFJ.
Femoral Artery Pseudoaneurysm
Femoral
artery pseudoaneurysms occur as a consequence of arterial injury. It typically
presents as a painful and gradually expanding pulsatile mass within the femoral
triangle, with a history of previous vascular interventional procedures, or
repeated puncture from intravenous drug use. Erroneous diagnosis of localised
abscess is occasionally made if the overlying skin appears erythematous. Radiological
investigation to determine the nature of the lump is essential. Disastrous
consequences can occur if one proceeds with incision and drainage with a
presumed diagnosis of groin abscess without excluding the possibility of pseudoaneurysm.
Treatment options for femoral pseudoaneursysms include surgical repair/ligation
and endovascular sealing.
Quick Anatomy
Key Facts
Femoral Nerve:
- L2-L4
- Motor
Supply - Hip Flexors and Knee Extenders
- Sensory Supply – Anteromedial Thigh
Femoral Artery:
- Origin:
External Iliac Artery
- Branches:
Superficial Circumflex Iliac Artery, Superficial Epigastric Artery,
Superficial/Deep External Pudendal Artery, Profunda Femoris, Descending
Genicular Artery
- Corresponding
Veins: Femoral Vein
Aide-Memoire
The Borders of the Femoral Triangle
|
S: |
Sartorius |
|
A: |
Adductor
Longus |
|
IL: |
Inguinal
Ligament |
The
Contents of the Femoral Triangle
|
N: |
Femoral
Nerve |
|
A: |
Femoral
Artery |
|
V: |
Femoral
Vein |
|
E: |
Empty
Space (allows expansion of veins and lymphatics) |
|
L: |
Lymphatics
(deep inguinal lymph nodes) |
The
Floor of the Femoral Triangle
|
I |
Iliacus |
|
Pierced The |
Psoas
Tendon |
|
Patient’s |
Pectineus |
|
Artery Laboriously |
Adductor
Longus |
Summary
The
femoral triangle is somewhat of a favourite for examiners and frequently tested
in clinical anatomy examination. Located in the anterior aspect of proximal
thigh, it is a triangular subfascial space of great anatomical and clinical
importance. It provides easy access to the femoral neurovascular bundle and is
therefore frequently utilised for surgical and endovascular procedures where
vascular access is required. Groin lumps within the femoral triangle can be due
to many underlying pathologies as the region contains multiple different
structures, good understanding of anatomy is therefore essential to the
diagnostic process.