Muscles - Medial Thigh

Question 1

Give an overview of the medial thigh, including:

location
structure
function
muscles

Answer 1

Location:
The medial thigh compartment is located between the medial and posterior intermuscular septum, and the fascia lata. The medial thigh muscles span the hip joint medially between the pelvis and the femur, with only the gracilis crossing the knee joint to insert onto the medial tibia at the pes anserine attachment point.

Structure:
With the exception of the slender gracilis, the medial thigh muscles are predominantly thick strong muscles. The only two headed muscle in the medial compartment is the adductor magnus, which has both an adductor and hamstring component. Each of these components has distinct attachment points, innervation, and actions.

Function:
The primary function of the medial thigh muscles is adduction of the thigh.

In addition, adductor brevis, and adductor magnus flex the thigh, gracilis flexes the knee, gracilis internally rotates the leg, and obturator externus externally rotates the thigh.

Muscles:
There are 5 muscles in the medial thigh:
adductor brevis
adductor longus
adductor magnus
gracilis
obturator externus

Question 2

Which nerves innervate the medial compartment?

Answer 2

All muscles are innervated by the obturator nerve except the hamstring component of the adductor magnus, which is innervated by the tibial portion of the sciatic nerve.

Question 3

Give an overview of the muscles of the medial thigh:

Answer 3

Adductor Brevis:
PA: body and inferior ramus of pubis
DA: pectineal line and proximal linea aspera
NS: obturator
A: adducts thigh, and mildly flexes thigh

Adductor Longus:
PA: body of pubis, inferior to pubic crest
DA: middle third of linea aspera
NS: obturator nerve
A: adducts thigh 

Adductor Magnus:
PA: Adductor: inferior ramus of pubis and ischial ramus; Hamstring: ischial tuberosity
DA: Adductor: gluteal tuberosity, linea aspera and medial supracondylar line; Hamstring: adductor tubercle of medial femur
NS: Adductor: obturator; Hamstring: tibial component of sciatic nerve
A: Adductor: adducts thigh, flexes thigh: Hamstring: extends thigh

Gracilis:
PA: body and inferior ramus of pubis
DA: superior medial tibia (pes anserine)
NS: Obturator
A: adduction of thigh, flexion of leg, weak internal rotation of leg

Obturator Externus:
PA: external surface of obturator membrane and surrounding bones
DA: trochanteric fossa of femur
NS: obturator
A: external rotation of thigh