Adductor Muscles of the Hip
The adductor muscle group of the medial thigh – consisting of adductor longus, adductor brevis, adductor magnus (with its superior “minimus” portion) – is primarily responsible for thigh adduction and plays a key role in stabilizing the pelvis during gait.
Summary of Adductor Muscles
| Adductor Muscles | Origin | Insertion | Action | Nerve roots | Nerves |
|---|---|---|---|---|---|
| Adductor Brevis | Body and inferior ramus of pubis (lateral to origin of gracilis) | Pectineal line and proximal part of linea aspera of femur | Adducts thigh; weak hip flexor | Obturator nerve (anterior or posterior division L2–L4) | |
| Adductor Longus | External surface of body of pubis (triangular depression inferior to pubic crest and lateral to pubic symphysis) | Linea aspera on middle one-third of shaft of femur | Adducts thigh; assists in hip flexion (especially from extended position) and medial rotation | L2 L3 L4 | Obturator nerve (anterior division L2–L4) |
| Adductor Magnus | Adductor part – inferior pubic ramus and ischial ramus; Hamstring part – ischial tuberosity | Adductor part – posterior femur (gluteal tuberosity, linea aspera, medial supracondylar line); Hamstring part – adductor tubercle of femur | Adducts thigh (powerfully); Adductor part flexes thigh; Hamstring part extends thigh | Adductor part – Obturator nerve (posterior division L2–L4); Hamstring part – Tibial division of sciatic nerve (L4–S1) | |
| Adductor Minimus | Ischiopubic ramus (inferior pubic ramus to ischial ramus) | Linea aspera (proximal medial lip) and adductor tubercle (via shared tendon) | Adducts thigh; assists lateral rotation and extension of thigh | Obturator nerve (L2–L4) and tibial division of sciatic nerve (L4–L5) – same innervation as adductor magnus |
Muscle Type
These adductors are flat or fan-shaped muscles in the medial compartment of the thigh. Adductor longus and brevis are shorter, triangular muscles in the upper thigh, while adductor magnus is a large, triangular muscle spanning the entire medial thigh. The term “adductor minimus” often refers to the uppermost segment of adductor magnus (sometimes considered a separate small muscle). Collectively, these muscles form the bulk of the medial thigh and lie deep to the gracilis (except the easily palpable longus which is superficial near the groin).
Origin
All adductors originate on the pubis or ischium of the pelvis. Adductor longus arises from the anterior body of the pubis, just below the pubic crest (near the pubic symphysis). Adductor brevis originates from the inferior pubic ramus, on the anterior surface just inferior to the longus origin. Adductor magnus has a broad origin: its adductor (pubofemoral) portion originates from the inferior pubic ramus and the ischial ramus, while its hamstring (ischiocondylar) portion arises from the inferolateral aspect of the ischial tuberosity. The adductor minimus is essentially the superior part of adductor magnus – it corresponds to the upper fibers attaching to the pubic ramus and ischium, sometimes described separately when there is a distinct separation of those fibers.
Insertion
All adductors insert along the femur’s linea aspera or adjacent bone. Adductor longus inserts on the middle third of the linea aspera on the posterior femur (between the insertions of magnus and vastus medialis). Adductor brevis inserts on the pectineal line and the upper part of the linea aspera (medial lip) of the femur. Adductor magnus has a dual insertion: its adductor portion attaches along the entire length of the linea aspera (medial lip) and the medial supracondylar ridge of the femur, while its hamstring portion extends down to the adductor tubercle on the medial condyle of the femur. The gap between these two insertions forms the adductor hiatus, an opening for the femoral vessels to pass to the popliteal fossa. The so-called adductor minimus (upper magnus fibers) inserts on the proximal linea aspera and gluteal tuberosity, just medial to the gluteus maximus insertion.
Action
As a group, the primary action is hip adduction – pulling the thigh inward toward the body’s midline. Adductor magnus is the strongest adductor of the hip. In addition, the upper (pubic) portions of the adductors (longus, brevis, and the anterior part of magnus) assist in hip flexion, whereas the posterior part of adductor magnus (ischiocondylar portion) can help in hip extension (it acts like a hamstring). The adductors also contribute modestly to hip medial or lateral rotation depending on thigh position: generally, when the hip is flexed, they can assist lateral rotation, and when the hip is extended, they may assist medial rotation (though this role is minor and debated). Overall, they stabilize the pelvis on the femur during weight-bearing.
Synergists
All adductors work together, so each is a synergist to the others for thigh adduction. They also function with pectineus and gracilis to adduct the hip. During hip flexion, adductor longus and brevis assist the iliopsoas and rectus femoris; during hip extension, the hamstring part of adductor magnus assists the hamstring muscles (semimembranosus, semitendinosus, long head of biceps femoris). In stabilizing the pelvis, the adductors co-contract with the abductors (gluteus medius/minimus) to maintain balance in the frontal plane while walking.
Antagonists
The hip abductors (gluteus medius and minimus, tensor fasciae latae) are direct antagonists to the adductors, as they move the thigh laterally away from the midline. The gluteus maximus (upper fibers) also assists in thigh abduction and opposes adduction. For the flexor action of the anterior adductors, the antagonists are the hip extensors (gluteus maximus, hamstrings). Conversely, for the extensor action of the posterior magnus, the antagonists are the hip flexors (iliopsoas, rectus femoris).
Spinal Innervation
The adductor group is chiefly innervated by nerve fibers from L2, L3, and L4 spinal segments (lumbar plexus). These segments form the obturator nerve which supplies most of the adductors. Specifically, L2–L4 contribute to adductor longus, brevis, and the adductor portion of magnus. The hamstring portion of magnus receives fibers primarily from L4–S1 via the sciatic nerve (tibial division).
Peripheral Innervation
Adductor longus and adductor brevis are innervated by the anterior division of the obturator nerve (L2–L4). Adductor magnus has dual innervation: the adductor part by the posterior division of the obturator nerve (L2–L4), and the hamstring part by the tibial branch of the sciatic nerve (mostly L4). The small adductor minimus (upper part of magnus) is effectively innervated by the obturator nerve as part of magnus. (Pectineus, sometimes considered with this group, is innervated by femoral nerve as noted above.)
Vasculature
The obturator artery (a branch of the internal iliac artery) supplies the upper portions of the adductor compartment, including adductor brevis and longus. The deep femoral artery (profunda femoris) provides perforating branches that pierce and supply adductor magnus (primary blood supply for magnus). Additionally, the medial femoral circumflex artery contributes to the blood supply of the upper adductors, and the femoral and popliteal arteries give muscular branches to the lower part of adductor magnus. Venous drainage is via the obturator vein and deep femoral vein into the femoral vein.
Clinical Application
Tightness or strain of the adductors is common in athletes (a “groin pull”), particularly involving adductor longus (the most frequently injured). Such injuries cause pain in the groin or inner thigh and can be aggravated by rapid directional changes. The adductor magnus’s adductor hiatus is an important anatomical landmark: the femoral artery and vein pass through this hiatus to become the popliteal vessels behind the knee. Compression by an abnormal fibrous band (vastoadductor membrane) here can lead to vascular issues in the leg. The adductor magnus is sometimes used in flap surgeries due to its size and vascular supply. Neurologically, an obturator nerve injury (e.g. during pelvic surgery) can weaken thigh adduction, affecting gait stability. Adductor reflexes are not commonly tested, but weakness is noted by the patient’s inability to draw the legs together against resistance. Strength training of the adductors (e.g. “Copenhagen” adduction exercise) is employed to prevent groin injuries, and stretching these muscles helps maintain flexibility. In paralysis of the gluteus medius (Trendelenburg gait), patients may overuse the adductors to swing the leg, demonstrating the adductors’ compensatory role in gait.
