Femoral triangle, Anterior and Medial Thigh

Question 1

Adductor Magnus

Answer 1

The adductor magnus is the largest muscle in the medial compartment. It lies posteriorly to the other muscles. Functionally, the muscle can be divided into two parts; the adductor part, and the hamstring part.

Adductor part – Originates from the ischiopubic ramus, attaching to the linea aspera of the proximal femur.

Hamstring part – Originates from the ischial tuberosity and attaches to the adductor tubercle and medial supracondylar line of the femur.

Actions: They both adduct the thigh. The adductor component also flexes the thigh, with the hamstring portion extending the thigh.

Innervation: Adductor part is innervated by the obturator nerve (L2-L4), the hamstring part is innervated by the tibial nerve (L4-S3).

Question 2

Adductor Longus

Answer 2

The adductor longus is a large, flat muscle. It partially covers the adductor brevis and magnus. The muscle forms the medial border of the femoral triangle.

Attachments: Originates from the pubis, and expands into a fan shape, attaching broadly to the linea aspera of the femur

Actions: Adduction and medial rotation of the thigh.

Innervation: Obturator nerve (L2-L4).

Question 3

Adductor Brevis

Answer 3

The adductor brevis is a short muscle, lying underneath the adductor longus.

It lies in between the anterior and posterior divisions of the obturator nerve. Therefore, it can be used as an anatomical landmark to identify the aforementioned branches.

Attachments: Originates from the body of pubis and inferior pubic rami. It attaches to the linea aspera on the posterior surface of the femur, proximal to the adductor longus.

Actions: Adduction of the thigh.

Innervation: Obturator nerve (L2-L4).

Question 4

Obturator Externus

Answer 4

This is one of the smaller muscles of the medial thigh, and it is located most superiorly.

Attachments: It originates from the membrane of the obturator foramen, and adjacent bone. It passes under the neck of femur, attaching to the posterior aspect of the greater trochanter.

Actions: Laterally rotates the thigh.

Innervation: Obturator nerve (L2-L4).

Question 5

Gracilis

Answer 5

The gracilis is the most superficial and medial of the muscles in this compartment. It crosses at both the hip and knee joints. It is sometimes transplanted into the hand or forearm to replace a damaged muscle.

Attachments: It originates from the inferior rami of the pubis, and the body of the pubis. Descending almost vertically down the leg, it attaches to the medial surface of the tibia, between the tendons of the sartorius (anteriorly) and the semitendinosus (posteriorly).

Actions: Adduction of the thigh at the hip, and flexion of the leg at the knee.

Innervation: Obturator nerve (L2-L4).

Question 6

What is the fascia lata?

Answer 6

A deep fascial investment of the whole thigh musculature, analogus to a strong extesnible and elasticated stocking

Question 7

What is the iliotibial tract?

Answer 7

A longitudinal thickening of the fascia lata, which is strengthened posteriorly by fibres from the gluteus maximus.

Question 8

What is the action of the iliotibial tract?

Answer 8

An extensor, abductor and lateral rotator of the hip with an additional role in providing lateral stabilisation to the knee koint.

Question 9

What is a femoral hernia?

Answer 9

• Femoral hernias develop when an out-pouching of gastric viscera protrudes through the femoral canal
• The protrusion becomes noticeable when it exits through the saphenous opening within the fascia lata = swelling inferior to the inguinal ligament

Question 10

Which muscles act as hip flexors?

Answer 10

Pectineus, iliopsoas muscles (iliacus and psoas major) and the sartorius

Question 11

Pectineus

Answer 11

Origin: Pectineal line of pubis

Insertion: Pectineal line of the femoral shaft, inferior to the lesser trochanter

Innervation: Femoral nerve

Action: Adducts and flexes the hip

Question 12

Iliacus

Answer 12

Origin: Iliac fossa

Insertion: Lesser trochanter

Innervation: Femoral nerve

Action: Flexion at the hip and assists in lateral rotation

Question 13

Psoas Major

Answer 13

Origin: Transverse processes of the lumbar vertebrae

Insertion: Lesser trochanter

Innervation: Anterior rami of L1-L3

Action: Flexion at the hip and assists in lateral rotation

Question 14

Sartorius

Answer 14

Origin: Anterior superior iliac spine

Insertion: Superior medial surface of the tibia

Innervation: Femoral nerve

Action: Flexion, abduction and lateral rotation at the hip. Flexion at the knee joint.

Question 15

Which muscles make up the quadriceps femoris?

Answer 15

Vastus lateralis, vastus intermedius, vastus medialis and the rectus femoris

Question 16

Vastus lateralis

Answer 16

Origin: Greater trochanter

Insertion: Patella via the quadriceps femoris tendon

Innervation: Femoral nerve

Action: Extend at the knee joint

Question 17

Vastus intermedius

Answer 17

Origin: Anterior lateral surface of the femoral shaft

Insertion: Patella via the quadriceps femoris tendon

Innervation: Femoral nerve

Action: Extend at the knee joint

Question 18

Vastus medialis

Answer 18

Origin: Intertrochanteric line and medial lip of linea aspera

Insertion: Patella via the quadriceps femoris tendon

Innervation: Femoral nerve

Action: Horizontal fibres insert into patella and prevent lateral displacement

Question 19

Rectus femoris

Answer 19

Origin: Ileum (just superior to the acetabulum)

Insertion: Patella via the quadriceps femoris tendon

Innervation: Femoral nerve

Action: Extend at the knee and flex at the hip joint

Question 20

Which muscles are the thigh adductors?

Answer 20

Adductor longus

Adductor brevis

Adductor magnus (adductor part and hamstring part)

Gracilis

Obturator Externus

Question 21

What are the borders of the femoral triangle?

Answer 21

Superior border – Formed by the inguinal ligament, a ligament that runs from the anterior superior iliac spine to the pubis tubercle.

Lateral border – Formed by the medial border of the sartorius muscle.

Medial border – Formed by the medial border of the adductor longus muscle. The rest of this muscle forms part of the floor of the triangle.

Anteriorly, the roof of the femoral triangle is formed by the fascia lata.

Posteriorly, the base of the femoral triangle is formed by the pectineus, iliopsoas and adductor longus muscles.

Question 22

What are the contents of the femoral traingle?

Answer 22

N: Nerve.
A: Artery.
V: Vein.
E: Empty space (this is important as it allows the veins and lymph vessels to distend, so they can cope with different levels of flow).
L: Lymph canal.

Femoral nerve – Innervates the anterior compartment of the thigh, and provides sensory branches for the leg and foot.

Femoral artery – Responsible for the majority of the arterial supply to the lower limb.

Femoral vein – The great saphenous vein drains into the femoral vein within the triangle.

Femoral canal – A structure which contains deep lymph nodes and vessels.

The femoral artery, vein and canal are contained within a fascial compartment – known as the femoral sheath.

Question 23

Femoral artery

Answer 23

• Femoral artery is a continuation of the external iliac artery (terminal branch of the abdominal aorta)

• The external iliac becomes the femoral artery when it crosses under the inguinal ligament and enters the femoral triangle

Question 24

The great saphenous vein

Answer 24

• The great saphenous vein is formed by the dorsal venous arch of the foot, and the dorsal vein of the great toe
• It ascends up the medial side of the leg, passing anteriorly to the medial malleolus at the ankle, and posteriorly to the medial condyle at the knee
• The great saphenous vein terminates by draining into the femoral vein immediately inferior to the inguinal ligament.

Question 25

Femoral Nerve

Answer 25

• Nerve Roots: L2-L4
• Motor: Innervates the anterior thigh muscles (except psoas major)
• Sensory: Supplies cutaneous branches to the anteromedial thigh (anterior cutaneous branches of the femoral nerve) and the medial side of the leg and

foot (saphenous nerve)

Question 26

Obturator nerve

Answer 26

• Nerve roots: L2-L4
• Motor: Innervates the medial (adductor) compartment of the thigh – except for

hamstrings part of Adductor Magnus

• Sensory: Cutaneous branch innervates the skin of the medial thigh.