3.2 : Medial Thigh

 

Adductor compartment; separated from (anterior) extensor compartment by medial intermuscular septum  (cf no septum between it and the (posterior) flexor  compartment). 

Medial intermuscular septum

Downward continuation of pectineus fascia, attached to linea aspera laterally and FL medially.

-           see position on middle slice of plate 471; separates adductors & extensors.

Thin, cf LIS thick. 

 

There are 4 muscles; the nerve is obturator, artery is PFA assisted proximally by obturator artery.

(1) Gracilis (467)

Most superficial

Arises: inferior pubic ramus and adjoining ischial ramus ¨ tendon ¨ Inserts: tibia behind sartorius. 

AKA Ôcustodes virginitatisÕ as acts to Ôprotect the virginityÕ.

(2) Adductor longus (467)

Most superficial and anterior of 3 adductors, forming posterior wall of adductor canal.

Arises: body of pubis between pectineus and gracilis ¨ Inserts: middle 1/3 of linea aspera of femur.

(3) Adductor brevis (467)

Deep.

Arises: body & inferior pubic ramus deep to pectineus.

Inserts: upper linea aspera above adductor longus, below & behind pectineus.

-           profunda femoris vessels & anterior branch of obturator nerve lie anteriorly. 

-           The superior border thus divides ant & post branches of obturator like adductor longus divides FA and PFA.

(4) Adductor magnus (459)

2 muscle masses: 1 adductor and 1 hamstring. 

Hamstring component arises from lateral aspect of ischial tuberosity ¨ adductor tubercle (medial epicondyle of femur; distal part of tendon has degenerated into tibial collateral ligament of KJ).

Adductor component arises from ischiopubic ramus ¨ linea aspera & gluteal tuberosity of femur. 

-           perforating branches of PFA pass via tendinous arches in its insertion.

-           upper border lies horizontal, level with lower border of quadratus femoris, medial circumflex femoral artery passes between the two, to reach cruciate anastomosis.

-           Note the gap on Pl459 where the femoral vessels pass ¨ popliteals (near top of supracondylar line)

Nerve supply of adductors

Obturator nerve:  anterior division ¨ brevis, longus, gracilis;

-           posterior division ¨ obturator externus and magnus.

Tibial part of sciatic ¨ hamstring component of add magnus. 

Action

Adducts, but this is less important than synergist activity in posture & gait.

Test

Lying on back, knee straight, adduct thigh against resistance.  Palpate gracilis and longus.

Obturator externus (459)

Deep and posterior to uppermost adductors.

Arises: whole of obturator membrane & bony margin of obturator foramen

-           gap below obturator notch allows passage of obturator nerve & vessels

Inserts: passes behind neck of femur to medial trochanter, inserting into the deep trochanteric fossa.

-           this marks the lower extent of the hip joint capsule (1/2 of neck cf whole neck anteriorly).

Nerve: obturator (L3,4)

Action: stabilises and supports proximal limb, and can laterally rotate femur.

Obturator Artery and Nerve

Artery

Emerges from foramen with nerve ¨ anterior and posterior branches (pl373), these encircle foramen between obturator externus and membrane.   Anastomose with each other and medial circumflex artery.

-           posterior sends an arterial twig to the hip jt which runs in the ligament of head of femur.

Nerve

Divides in the notch ¨ anterior and posterior divisions.

-           anterior passes above externus, branching to the hip, then descending behind adductor longus, passing over adductor brevis and then goes on to gracilis (supplies all of these).  Also gives some direct branches to skin at level of subsartorial plexus.

-           Posterior passes through externus (supplying it) then passes on magnus deep to other muscles (supplies magnus), then gives a terminal branch with femoral artery through hiatus to popliteal fossa ¨ capsule of knee with middle genicular artery.