Adductor longus muscle
The medial compartment of the thigh consists of numerous muscles which are adductor longus, magnus and brevis together with pectineus and gracilis. The compartment allows us to adduct and medially rotate the hip. The muscles in this compartment are believed to be evolved from both extensor and flexor columns. In this article we will discuss the anatomy of the adductor longus muscle, and also its clinical relevance.
The adductor longus, a muscle of the medial compartment of the thigh, is triangular in shape and present in the floor of the femoral triangle and adductors canal. The muscle originates from the pubic body below the pubic crest i.e. the superior pubic rami (just lateral to the pubic tubercle), and inserts onto the middle third of the medial lip of the linea aspera. This insertion point is lateral to the adductor magnus and brevis insertions, but medial to the insertion of vastus medialis (one of the four components of quadriceps femoris).
The adductor longus muscle lies in front of the adductor magnus, adductor brevis muscle, the anterior branch of the obturator nerve, and profunda femoris vessels. Pectineus muscle is lateral to it while gracilis lies medially. Anterior relations to its upper part are the spermatic cord and fascia lata, while the femoral artery and vein are present anterior to it in the lower part near its attachment.
The adductor longus is supplied by the anterior division of the obturator nerve. All three adductors (except the hamstring part of the adductor magnus) and gracilis are supplied by the obturator nerve (anterior divisions of the ventral rami of L2-L4). The obturator nerve is a branch of the lumbar plexus, and descends medial to the psoas major muscle in order to enter the pelvis. It runs behind the common iliac vessels, and lateral to the internal iliac artery and ureter. Next, it runs in the lateral wall of the pelvis, and will reach the superior part of the obturator foramen. It passes through the foramen and emerges into the obturator canal, and divides into an anterior and posterior branch. These branches are separated by obturator externus and adductor brevis.
The posterior branch pierces and supplies obturator externus, and descends in the medial compartment to supply adductor brevis and adductor magnus. The nerve also supplies sensation to the upper medial thigh. The anterior branch runs in front of obturator externus, and runs posterior to adductor longus (which it supplies) and pectineus (supplied by the femoral nerve).
As the nerve passes the hip, it also gives an articular branch to the joint. It supplies adductor longus, adductor brevis and gracilis.
The blood supply to adductor longus comes from two arteries, profunda femoris artery (a branch of the femoral artery) and obturator artery (a branch of the internal iliac artery).
The proximal part of the muscle is supplied by the medial circumflex artery (branch of the profunda femoris artery). Profunda femoris vein receives tributaries that correspond to the branches of the artery.
The main action of the adductor group of muscles is to adduct the thigh from anatomical position. Adductor longus and magnus are also the medial rotators and flexors of the thigh. The adductors help to stabilize the stance while standing, and also have an important role in balancing the body on the lower limb during walking.
The adductor longus muscle forms the medial border of the femoral triangle. The superior border is formed by the inguinal ligament, and the lateral border by sartorius. The femoral nerve, artery and vein are located in this triangular region. The nerve runs most laterally, close to the anterior superior iliac spine (ASIS), and runs under the inguinal ligament. The nerve supplies iliacus in this region, and descends to supply the anterior (extensor) compartment of the thigh.
The NAVY acronym is an easy way of remembering the order of the structures from lateral to medial in this region i.e. nerve most lateral, then the artery, then the vein and finally the ‘y-front’ aka the pubic region. There is some space between the femoral vein and femoral artery, which allows for expansion of the vein.