10.2 Medial Compartment of the Thigh

Question 1

Identify the muscles of the medial compartment of the thigh:
Describe the general function of these muscles.
Describe the innervation of these muscles (exceptions will be listed individually).
Adductor longus
Adductor brevis
Adductor magnus
Gracilis
Obturator externus

Answer 1

• Innervation: obturator n. (L2-L4)
  1. Anterior division to adductor longus, adductor brevis, gracilis, and pectineus (inconstant)
  2. Posterior division to obturator externus and adductor part of adductor magnus

-Fxn: adduction of thigh, stabilize stance, flex thigh.

Adductor longus

1. Attachments: Proximally, inferior to pubic crest; Distally, middle third of linea aspera
2. Actions: Adducts thigh

Adductor brevis

1. Attachments: Proximally, body and inferior pubic ramus; Distally, pectineal line and linea aspera
2. Actions: Adducts thigh, and flexes thigh some

Adductor magnus (Adductor part & Hamstring part)

1. Adductor part Attachments: Proximally, inferior pubic ramus, ischial ramus; Distally, gluteal tuberosity, linea aspera, medial supracondylar line
2. Hamstring part: Proximally, ischial tuberosity; Distally, adductor tubercle of femur
3. Actions: Adduct thigh, flexes thigh (adductor part), and extends thigh (hamstring part)
4. Innervation: tibial n (to hamstring part); posterior division of obturator n (to adductor part)

Gracilis

1. = only adductor muscle to cross and (therefore) act on the knee joint in addition to hip joint
2. Attachments: Proximally, pubic body and inferior pubic ramus; Distally, superior part of medial tibial surface
3. Actions: adducts thigh, flexes leg, helps in medial rotation

Obturator externus

1. Attachments: Proximally, margins of obturator foramen and obturator membrane; Distally, trochanteric fossa of femur
2. Actions: Laterally rotates thigh, steadies femoral head in acetabulum
3. Innervation: posterior division of obturator n.

Question 2

Identify the obturator nerve, describe course and spinal roots.

Answer 2

passing from the pelvis to the medial aspect of the thigh via the obturator canal. It innervates the muscles of the medial compartment.
L2-L4