The Anteromedial Compartment of the Thigh, The Femoral Triangle and the Adductor Canal

Question 1

Describe the origin and insertion of gracilis.

Answer 1

Origin: [1] the anteroinferior part of the body of the pubis and [2] the anterior part of the inferior pubic ramus and a [3] small part of the adjoining surface of ischial ramus (its origin is an aponeurosis)

Insertion: medial surface of the proximal tibia via the pes anserinus

[Diagram]

Question 2

Describe the origin and insertion of adductor brevis.

Answer 2

Origin: the anterior surface of the body of the pubis and the outer surface of the inferior pubic ramus, between the origins of gracilis and obturator externus

Insertion: the muscle passes posterolaterally to be inserted along a line extending from the lesser trochanter to the upper part of the linea aspera (lateral to the insertion of pectineus and medial to the insertion of adductor magnus)

Question 3

Explain the division of the femoral nerve.

Answer 3

The femoral nerve is split into anterior and posterior divisions by the lateral circumflex femoral artery.

The anterior division gives off two cutaneous branches and one muscular branch. The cutaneous nerves are the medial femoral cutaneous nerve and the intermediate femoral cutaneous nerve. The muscular branch supplies the sartorius.

The posterior division gives off one cutaneous branch, the saphenous nerve and four muscular branches to supply the quadriceps femoris.

Question 4

Describe the boundaries of the femoral ring.

Answer 4

Anteriorly: inguinal ligament
Posteriorly: pectineal ligament
Medially: lacunar ligament
Laterally: medial septum of the femoral sheath
“SLIP”

Question 5

Describe the origin of rectus femoris.

Answer 5

Straight head: originates from the upper half of the anterior inferior iliac spine.
Reflected head: the supraacetabular groove (between the acetabular margin and the body of ilium)

Question 6

Explain the dual innervation of pectineus.

Answer 6

It is innervated by the femoral nerve and sometimes it is also innervated by a branch of the obturator nerve known as the accessory obturator nerve, in which case the anterior part of the muscle will be innervated by the femoral nerve and the smaller posterior part of the muscle will be innervated by the accessory obturator nerve. [Diagram: Pectineus]
Additional info: the nerve to pectineus branches off from the medial aspect of the femoral nerve

Question 7

State the root values of the accessory obturator nerve.

Answer 7

L2, L3

Question 8

What nerves comprise the sub-sartorial plexus.

Answer 8

1. The saphenous nerve
2. Branches from the medial cutaneous nerve of thigh
3. Anterior division of obturator nerve

Question 9

Describe the origin, insertion, innervation and actions of adductor longus.

Answer 9

1. Origin: arises by a rounded tendon from the front of the body of pubis in the angle between the pubic crest and the pubic symphysis
2. Insertion: inserts into the middle 1/3 of the linea aspera
3. Innervation: anterior division of obturator nerve
4. Actions: powerful adductor and medial rotator of thigh at hip joint

Question 10

State the pattern of blood supply of sartorius.

Answer 10

Segmental blood supply

Question 11

State the boundaries and contents of the adductor canal.

Answer 11

Boundaries
anteromedially: sartorius
anterolaterally: vastus medialis
floor (posteriorly): adductor longus proximally and adductor magnus distally

Contents
1. femoral artery
2. femoral vein
3. saphenous nerve
4. nerve to vastus medialis

Side notes:
a) The superficial femoral artery gives off a descending genicular branch before it leaves the adductor canal.
b) Just before leaving the adductor canal, the saphenous nerve gives off the infrapatellar branch.

Question 12

Which nerve pierces sartorius?

Answer 12

Infrapatellar branch of saphenous nerve
[Diagram]

Question 13

What are the root values of the saphenous nerve?

Answer 13

L3, L4

Question 14

1) Differentiate between the midinguinal point and midpoint of the inguinal ligament.
2) What neurovascular structures are these points related to?

Answer 14

1) The mid-inguinal point is a point midway between the ASIS and the pubic symphysis whereas the midpoint of the inguinal ligament is a point midway between the anterior superior iliac spine and the pubic tubercle (essentially the midpoint of the inguinal ligament).
2) The mid-inguinal point is a landmark for the femoral artery. The midpoint of the inguinal ligament is a landmark for the femoral nerve.

Question 15

a) What is meralgia paresthetica?
b) What are its causes?

Answer 15

a) This refers to numbness or pain in the lateral aspect of the thigh due to compression of the lateral femoral cutaneous nerve as it passes through or deep to the inguinal ligament. [Diagram]
b) tight clothing, obesity/weight gain, pregnancy

Question 16

The patellar plexus is a plexus of nerves present in front of the patella, ligamentum patellae, and the upper end of the tibia and supplies the skin over these structures. What nerves contribute to this plexus?

Answer 16

1. the lateral femoral cutaneous nerve
2. the intermediate cutaneous nerve of thigh
3. the medial cutaneous nerve of thigh
4. infrapatellar branch of saphenous nerve
5. [Diagram]

Question 17

State the cutaneous arteries arising from the femoral artery and the structures they supply.

Answer 17

1. superficial epigastric artery - supplies superficial tissue of abdominal wall
2. superficial circumflex iliac artery - supplies lower part of anterior abdominal wall
3. superficial external pudendal artery - supplies external genitalia (scrotum in males, labia majora in females)
4. [Diagram]

Question 18

State the innervation of iliacus and psoas major.

Answer 18

Iliacus: femoral nerve
psoas major: anterior rami of L1-L3