Anatomy and Origin
The muscle originates from the body of the pubis below the pubic crest. It inserts into the middle third of the medial lip of the linea aspera of the femur (linea aspera).
On axial cross-sections of the proximal third of the thigh, it is visible within the medial compartment alongside the adductor magnus (m. adductor magnus) and gracilis (m. gracilis) muscles.
Function
The primary action of the muscle is hip adduction. Additionally, it assists in hip flexion and lateral (external) rotation.
Blood Supply and Innervation
- Blood supply: Supplied by branches of the obturator artery (a. obturatoria) and deep artery of the thigh (a. profunda femoris). Near the proximal border of the adductor longus, the second perforating artery branches off the deep artery of the thigh. The adventitia of these perforating vessels is fused with the fascial sheaths of the adductor tendons. When injured, these vessel lumens do not collapse (they remain patent), leading to prolonged and difficult-to-control hemorrhage.
- Innervation: Supplied by the anterior branch of the obturator nerve (n. obturatorius), spinal segments L2–L3.
Topography and Relations
- Femoral triangle: The m. adductor longus forms its medial boundary. The lateral boundary is formed by the sartorius muscle (m. sartorius), and the base by the inguinal ligament (lig. inguinale). Within this triangle, the femoral artery (a. femoralis) rests upon the adductor longus and pectineus muscles.
- Adductor canal (canalis adductorius, Hunter's canal): The muscle forms the posterior wall of the canal in its superior part; more inferiorly, this role is taken over by the adductor magnus muscle. The lateral wall of the canal is formed by the vastus medialis muscle, and the roof by the vasto-adductor membrane (lamina vastoadductoria).
Clinical Significance
- Diagnosis of 5q SMA: In the differential diagnosis of proximal 5q spinal muscular atrophy in patients prior to genetic confirmation, a specific imaging pattern is observed. In advanced stages of the disease, hypertrophy and relative sparing of the adductor longus muscle are seen amidst widespread fatty replacement of other thigh musculature.
- Electroneuromyography (ENMG): The m. adductor longus is frequently used as a target muscle for needle EMG alongside the iliopsoas, quadriceps, and paraspinal muscles. This evaluation helps determine the level of a lesion—proximal or distal to the inguinal ligament—and rules out high lumbar plexopathy or radiculopathy. Contralateral comparison with the healthy side should always be performed.