Anatomy, Abdomen and Pelvis, Femoral Triangle


Article Author:
Hayden Basinger


Article Editor:
Jeffery Hogg


Editors In Chief:
Chaddie Doerr


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Trevor Nezwek
Radia Jamil
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
4/29/2019 12:13:51 PM

Introduction

The femoral triangle in the anterior superior third of the thigh is a sub-fascial space that appears as a triangular depression inferior to the inguinal ligament; the depression is visible when the thigh is abducted, flexed, and laterally rotated. The borders of the femoral triangle are composed of the inguinal ligament superiorly, the adductor longus muscle medially, and the sartorius muscle laterally. The apex of the triangle is located distally and is formed by the intersection of the lateral border of the femoral triangle, the sartorius, crossing over the medial border of the triangle, the adductor longus. The floor of the femoral triangle is composed of several muscles, medially the floor is formed by the pectineus and adductor longus, and laterally by the iliopsoas. The roof of the femoral triangle from superficial to deep is composed of skin, subcutaneous tissue, superficial fascia, and deep fascia known as the fascia lata.

From lateral to medial, the contents of the femoral triangle include the femoral nerve, femoral artery, femoral vein, and lymphatics. The femoral artery, femoral vein, and deep inguinal lymph nodes and associated lymphatics are within a conical fascial sheath, the femoral sheath. The sheath is continuous with the transversalis fascia of the abdomen and the inguinal ligament; it encases the vessels as they pass through the femoral triangle.[1] The femoral sheath merges inferiorly with connective tissue associated with the vessels. Each vessel has a separate sub-compartment of the femoral sheath as it passes through the femoral triangle. The femoral nerve is not within the sheath.[1]

Structure and Function

Structure of the Femoral Triangle

  • Superior border - inguinal ligament
  • Medial border - adductor longus muscle
  • Lateral border - sartorius muscle
  • Medial floor - adductor longus and pectineus muscle
  • Lateral floor - iliopsoas muscle
  • Roof - (from superficial to deep) skin, subcutaneous tissue, superficial fascia, and fascia lata
  • Internal structures - (from lateral to medial) femoral nerve, femoral artery, femoral vein, deep inguinal lymph nodes, and associated lymphatic vessels

The function of the Femoral Triangle

The femoral triangle itself does not have an intrinsic function but contains many vital structures that can be located quickly using the landmarks of the femoral triangle. The muscles that form the borders of the triangle also allow many different movements.

Embryology

The extremities of the body initially form as limb buds containing an outer layer of ectoderm with an inner layer of mesoderm. The lower limbs begin development after the upper limbs, at about week 4 of gestation with limbs being well differentiated by about 8 to 10 weeks.[2]

The muscles and fascia of the femoral triangle derive from mesoderm contained within developing limb buds at the time of extremity formation.

The blood vessels, as well as the lymphatics of the femoral triangle, are also derived from mesoderm.

The epidermis above the femoral triangle and femoral nerve form from the ectoderm contained in limb buds at the time of extremity formation.

Blood Supply and Lymphatics

The major vessels that run through the femoral triangle include the femoral artery and femoral vein. In the area of the femoral triangle, the great saphenous vein connects to the femoral vein on its anterior medial surface just inferior to the inguinal ligament through an anterior aperture in the fascia lata. The femoral artery gives rise to several branches near its posterior lateral surface near the center of the femoral triangle: slightly superiorly the deep femoral artery, and slightly inferiorly the medial and lateral circumflex arteries; although, there is a well known anatomical variation.[3] The superficial epigastric artery emerges from the femoral artery near the proximal portion of the femoral triangle; it provides blood supply to the skin overlying the femoral triangle as well as the skin of the lower abdomen.[4] The external pudendal artery and the superficial iliac circumflex artery can also provide blood supply to the skin overlying the femoral triangle.[4]

Lymphatics are the most medial major structures contained within the femoral triangle. The deep inguinal lymph nodes are positioned within the femoral triangle and are separated from the superficial inguinal nodes by the fascia lata. The deep inguinal nodes receive drainage from the glans, clitoris, deep leg structures and superficial inguinal nodes. The Cloquet node is located within the femoral triangle just inferior to the inguinal ligament and is the most superior inguinal node; therefore, it receives drainage from both the superficial and deep inguinal lymph nodes and can be removed to assess metastasis in cases of cancer within its region of drainage. The perineum, genitalia, abdomen below the umbilicus, lower anus, and lower back all drain to the superficial inguinal nodes.[5]

Nerves

The primary nerve contained within the femoral triangle is the femoral nerve, arising from L2, L3, and L4.  It enters the femoral triangle inferior to the inguinal ligament, external to the femoral sheath, and is the most lateral of the significant structures contained within the triangle. The nerve is encased within the iliopsoas during its course through the femoral triangle. The femoral nerve has anterior and posterior divisions that arise near the level of the lateral circumflex artery; although, there are known anatomical variations of the branch point.[6] The anterior division provides innervation to the sartorius and gives rise to the medial femoral cutaneous nerve. The posterior division innervates the quadriceps femoris muscles and gives rise to the saphenous nerve.[7] The genitofemoral nerve originates from L1-L2 and provides innervation to the skin overlying the femoral triangle as well as the cremaster muscle and scrotal skin in males and the mons pubis and labia majora in females. The femoral branch of the genitofemoral nerve follows a course within the femoral sheath. It lies lateral and superficial to the femoral artery.  The femoral branch of the genitofemoral nerve pierces the anterior layer of the sheath and fascia lata at the saphenous opening to innervate the skin and subcutaneous tissue above.

Muscles

The femoral triangle includes the inguinal ligament and the following muscles:

Adductor Longus - forms the medial border as well as a portion of the medial floor of the femoral triangle. Its origin is the superior ramus of the pubis and insertion is on the linea aspera of the femur.[8]

Sartorius - is the longest muscle in the body and it makes the lateral border of the femoral triangle.[8] It originates at the anterior superior iliac spine and inserts into the pes anserine.

Pectineus - forms a portion of the medial floor of the femoral triangle, it is a quadrangular muscle that originates from the pectinate line of the pubis and inserts on the pectinate line of the femur.[8]

Iliopsoas - forms the lateral floor of the triangle. Iliopsoas refers to the two muscles, iliacus and psoas, that originate as separate muscles in the abdomen and join into one in the hip to serve as the most powerful hip flexing muscle.[8]

Physiologic Variants

The basic structure of the femoral triangle is highly conserved and could theoretically undergo alteration by the congenital absence of a muscle that composes one of its borders, or rare anatomical malformation of its contents.  The overall size of the femoral triangle can vary based upon the size of the individual. Many of the structures that pass through the femoral triangle are critical to the viability of the limb and are also highly conserved.[9] The branches of the femoral artery such as the deep femoral artery and lateral circumflex arteries display more anatomic variance in their origin, with most diverging from the artery posterior-laterally, and some diverging posteriorly or posterior-medially.[3]

Surgical Considerations

Thorough knowledge of the anatomy of the femoral triangle and the structures contained within is critical before surgical intervention. The structures of the femoral triangle are of high importance to the health of the limb and could potentially suffer damage during femoral hernia repairs, nerve blocks, or other surgical procedures in the area. The femoral triangle is also an important area for lymphatic drainage and can be evaluated to assess for cancer spread into the superficial and deep inguinal lymph nodes.[10]

Clinical Significance

The femoral triangle is an important location for many reasons: it provides palpable access to the vital femoral artery, it is a common location for quick vascular access and can be used to locate many important structures for interventions. Many radiologic interventions such as coronary and peripheral angioplasty, interventional embolization, and many other interventional endovascular procedures obtain catheterization through the femoral artery or vein to gain access to the many significant vessels of the body.[11] The large diameter of these vessels within the femoral triangle allows the introduction of larger catheters. Venipuncture of the femoral vein in the femoral triangle can be used for venous access when peripheral veins cannot be accessed. The femoral triangle can be easily visualized with ultrasound, and many of the procedures that require access to the femoral vessels can initiate under ultrasound guidance. The area of the femoral triangle and its roof contain both deep and superficial inguinal lymph nodes; this area can be a target for lymphadenectomy in the staging of cancer involving the inguinal lymphatic drainage.[12]

Other Issues

Many different pathologies can exist within the femoral triangle. Femoral hernias can emerge below the inguinal ligament and bulge directly into the femoral triangle. Peripheral arterial disease can develop within the femoral artery as it passes through the triangle. Deep vein thrombosis can develop in the femoral vein. Hematomas or arterio-venous fistulas can develop in the femoral triangle after a vascular intervention. Cancer spread within the superficial or deep inguinal lymph nodes can lead to lymphadenopathy.


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Anatomy, Abdomen and Pelvis, Femoral Triangle - Questions

Take a quiz of the questions on this article.

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A patient comes into the clinic with complaints of numbness and tingling in his anterior thigh. The area is just inferior to the inguinal ligament and superficial to the femoral artery in the area of the femoral triangle. He reports no recent trauma and his vital signs are within normal limits. The only recent change is that he has been wearing new underwear given to him by his girlfriend and they have a very tight waistband. Nerve entrapment is suspected. Where does the nerve innervating this area enter the femoral triangle?



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A 45-year old patient with a history of intravenous drug use needs urgent laboratories and no peripheral draw is possible. An ultrasound is used to locate the major structures contained within the femoral triangle. What order will structures be visualized in the neurovascular bundle from lateral to medial?

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A 60-year-old-male presents with nausea, vomiting, and extreme pain in his right groin. He stated he had had a non-painful lump in his groin for some time, but it has become increasingly painful throughout the day. A strangulated femoral hernia is suspected. What is the lateral border of the space in which the strangulated bowel is trapped?



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A structure is medial and below a large vein. Using the image below to identify the region, what muscle composes a portion of the floor of the space colored below?

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A 65-year-old patient presents to the clinic shortly after undergoing an endovascular procedure with access to the femoral artery through her anterior thigh. She has a past medical history of hypertension and often forgets to take her lisinopril and metoprolol. The site of her endovascular procedure has healed well and has no visible abnormalities. Upon auscultation of the area, a soft whooshing sound is heard during systole. A small arteriovenous fistula has likely developed after endovascular access. If the nerve that runs in the femoral sheath with this artery was compressed what deficits would be expected?



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A 65-year-old female presents to the emergency department with intensifying severe pain of her right foot for the last 2 hours. She has a past medical history of hyperlipidemia, hypertension, coronary artery disease, and type 2 diabetes. She also has a 50 pack year history of smoking. She had two stents placed in her left leg for peripheral artery disease three years ago. Pulses of the right lower leg are not palpable and cannot be found with doppler. Urgent workup reveals that the patient needs a femoral artery bypass 2 cm inferior to the inguinal ligament. During rapid surgical access, the lateral border of the femoral triangle is injured. What nerve innervates this structure?



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A 21-year-old male presents to the emergency department after accidentally being stabbed in his anterior thigh with a steak knife while intoxicated cooking with his roommate. Blood pressure is 130/85 mmHg, heart rate is 98 beats per minute, respiratory rate is 19 breaths per minute, and his temperature is 37 Celsius. The patient is visibly in pain but not experiencing major blood loss. Ultrasound shows that the knife penetrated the medial border of the femoral triangle. What nerve supplies this structure?



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A student is studying the anatomy of the femoral triangle. He notices that it contains a nerve, artery, and vein. Which of the following is most consistent with the function of the nerve the student observed?

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A 51-year-old male presents to the doctor with a lump in his groin that has recently increased in size. He has noticed the lump off and on for the last several years, but it has never been this big before. On physical exam, a soft, non-painful, reducible hernia is palpated. A femoral hernia is a common pathology affecting the femoral triangle. What is the most likely course that the contents of the hernia entered the femoral triangle?



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A 62-year-old female has been suffering from rest pain bilaterally in her lower extremities for the last several months. She has a 45 pack year history of smoking. She is undergoing endovascular stenting for peripheral artery disease this morning. If an error is made during catheterization of the femoral artery in the femoral triangle and the major structure immediately lateral to the artery is injured, what consequence would be most likely?



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A student is conducting a physical exam while under the supervision of their preceptor. They are asked to palpate the femoral artery but are having difficulty finding the pulse. What maneuver can they ask the patient to perform to make the borders of the femoral triangle appear as a triangular depression and assist them in finding the femoral artery?



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A 23-year-old male patient was brought into the emergency department after a bar fight. During the fight, he was stabbed in the right thigh with a large shard of glass in the area of the femoral triangle. After imaging and evaluation, it was found that the piece of glass just narrowly missed his femoral nerve. It punctured into the muscle that composes the portion of the floor of the femoral triangle below the nerve. Which of the following muscle was likely injured by the glass shard?



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A 23-year-old female patient comes to the doctor's office with a 6 cm x 4cm protuberant mass within the region of the femoral triangle. The mass is off-center, soft, and non-painful. The diagnosis of lipoma is made after more investigation. It is found that the mass is growing directly adjacent to a muscle that forms both a portion of the floor of the femoral triangle as well as one of its borders. What muscle is directly adjacent to the mass?



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Anatomy, Abdomen and Pelvis, Femoral Triangle - References

References

Correlation of ultrasound appearance, gross anatomy, and histology of the femoral nerve at the femoral triangle., Lonchena TK,McFadden K,Orebaugh SL,, Surgical and radiologic anatomy : SRA, 2016 Jan     [PubMed]
Pakhiddey R,Pangtey B,Mehta V,Suri RK, Unilateral atypical disposition of femoral vessels: clinico- embryological annotations. La Clinica terapeutica. 2014;     [PubMed]
Yao K,Zou ZJ,Li ZS,Zhou FJ,Qin ZK,Liu ZW,Li YH,Han H, Fascia lata preservation during inguinal lymphadenectomy for penile cancer: rationale and outcome. Urology. 2013 Sep;     [PubMed]
Micheletti L,Bogliatto F,Massobrio M, Groin lymphadenectomy with preservation of femoral fascia: total inguinofemoral node dissection for treatment of vulvar carcinoma. World journal of surgery. 2005 Oct;     [PubMed]
Sheeba CJ,Andrade RP,Palmeirim I, Getting a handle on embryo limb development: Molecular interactions driving limb outgrowth and patterning. Seminars in cell     [PubMed]
Nasr AY,Badawoud MH,Al-Hayani AA,Hussein AM, Origin of profunda femoris artery and its circumflex femoral branches: anatomical variations and clinical significance. Folia morphologica. 2014 Feb;     [PubMed]
Glenesk NL,Lopez PP, Anatomy, Bony Pelvis and Lower Limb, Thigh Nerves 2019 Jan;     [PubMed]
Lew V,Kang M, Anatomy, Abdomen and Pelvis, Femoral Sheath . 2019 Jan     [PubMed]
Tremblay C,Grabs D,Bourgouin D,Bronchti G, Cutaneous vascularization of the femoral triangle in respect to groin incisions. Journal of vascular surgery. 2016 Sep     [PubMed]
Rao AS,Rajmanickam K,Narayanan GS, Study of distribution of inguinal nodes around the femoral vessels and contouring of inguinal nodes. Journal of cancer research and therapeutics. 2015 Jul-Sep     [PubMed]
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