Due to their position, the hip adductors shape the surface anatomy of the medial thigh. More specifically, these muscles extend from the anteroinferior external surface of the bony pelvis to the shaft of femur and proximal tibia. The majority of hip adductors are innervated by the obturator nerve (L2-L4) and supplied by blood mainly via the branches of the femoral and obturator arteries.
As their name suggests, the main action of this group of muscles is to produce adduction of the thigh at the hip joint, in which the thigh is pulled toward or past the median plane. The unilateral adduction is the strongest when the hip joint is in the anatomical position. Meanwhile, the bilateral synergic adduction is the strongest when the hip and knee are being flexed and extended, for example during weight-bearing exercises or horseback riding. Additionally, they contribute to the stabilization and balance of the pelvis and body posture while standing, walking, or running.
This article will introduce you to the anatomy and function of the hip adductors.
|Definition and function||The hip adductors are a group of muscles of the medial thigh that primarily perform thigh adduction|
|Muscles||Adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus|
|Innervation||Obturator nerve (L2-L4); tibial nerve (L4-S1); femoral nerve (L2-L4)|
|Blood supply||Branches of the femoral and obturator arteries|
|Function||Adduction of thigh, stabilization of pelvis and posture|
- Adductor longus muscle
- Adductor brevis muscle
- Adductor magnus muscle
- Gracilis muscle
- Pectineus muscle
- Clinical notes
Adductor longus muscle
Adductor longus is a triangular, most anteriorly placed muscle of the adductor group. Upon originating from the anterior surface of the body of the pubis, its muscle fibers course downwards and laterally to insert onto the middle third of the linea aspera.
This muscle is innervated by the anterior division of the obturator nerve (L2-L4). It receives its blood supply mainly from the deep femoral artery and contributions from the medial circumflex femoral and femoral arteries.
The main function of adductor longus is to adduct the thigh at the hip joint. Additionally, it contributes to the flexion of the extended thigh, as well as the extension of the flexed thigh. Its contribution to the internal (medial) rotation of the thigh is still under discussion.
Adductor brevis muscle
The adductor brevis is a triangular muscle and the shortest of the adductors. Its fibers originate from the lateral part of the body and inferior ramus of pubis, and course downwards, laterally and backwards to insert onto the superior half of the linea aspera. Adductor brevis is positioned anterior to the adductor magnus and posterior to adductor longus muscle.
Like the majority of the thigh adductors, adductor brevis is innervated by the obturator nerve (L2-L4) and vascularized mainly by the deep femoral artery (profunda femoris).
The main function of the adductor brevis muscle is the adduction of the thigh. Additionally, the adductor brevis muscle has a role in the flexion of the hip and some recent studies suggest it may also be involved in the external rotation of the thigh.
Feeling a bit overwhelmed? Learn the attachments, innervations and functions of the muscles of the hip and thigh faster and easier with our muscle charts!
Adductor magnus muscle
The adductor magnus is a massive fan-shaped sheet of muscle and the largest of the hip adductors. It consists of two distinct parts; the adductor part and the ischiocondylar (hamstring) part. The adductor part is considered to be part of the medial thigh (adductor) compartment, while the hamstring part functionally belongs to the posterior compartment of thigh. Its origin spans from the femoral surface of the ischiopubic ramus to the lateral part of the inferior surface of the ischial tuberosity. The adductor part of the muscle inserts onto the gluteal tuberosity, linea aspera and medial supracondylar line of femur, while the hamstring part inserts onto the adductor tubercle of femur.
Adductor magnus has a dual nerve supply; the adductor part is innervated by the posterior division of the obturator nerve (L2-L4), while the hamstring part is innervated by the tibial component of the sciatic nerve (L4-S3). The adductor magnus muscle has a complex blood supply, most of which comes via the branches of the femoral, deep femoral and obturator arteries.
Aside from being a strong adductor of the thigh, adductor magnus contributes to the flexion of the thigh (adductor part) and extension of the thigh (hamstring part).
Gracilis is the most medial and most superficial muscle of the medial thigh compartment, overlying the other hip adductors. It is the only muscle from this group that crosses two joints; the hip and the knee. It extends from the body of pubis and ischiopubic ramus to the medial surface of the proximal tibia (pes anserinus).
Gracilis is innervated by the obturator nerve (L2-L4). It receives its blood supply from the deep femoral and medial circumflex femoral arteries.
Gracilis is one of the weakest adductors of the thigh. However, it acts as a strong flexor and internal (medial) rotator of the leg at the knee joint.
The pectineus muscle is a short and quadrangular muscle positioned in the superomedial aspect of the thigh region. More specifically, it extends from the pubis to the line running between the lesser trochanter of femur and the upper part of the linea aspera.
Similarly to the adductor magnus muscle, pectineus frequently has dual innervation; the anterior part of the muscle is innervated by the femoral nerve (L2, L3), while the posterior part is supplied by obturator nerve (L2-L4). The pectineus receives its main blood supply from the medial circumflex femoral artery, and contributions from the femoral and obturator arteries.
The main function of the pectineus muscle is to flex and adduct the thigh at the hip joint.
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The adductor muscle tear (groin strain) ranks among the most common sport injuries (e.g. playing soccer, doing the splits, slipping on ice etc.) and affects favorably the origin tendon at the pubic region. It is caused by a disproportional strain of the muscles, often in combination with a poor warm-up and a lack of stretching. Hereby even ruptures and hemorrhages may occur. Symptoms include pain extending to the inguinal and knee region when stretching and straining the muscles. A malposition of the sacroiliac joint can restrict the function of the hip adductors in the long run as well and should be addressed clinically.
The orthopedic pathologies mentioned above are to be distinguished from the neurogenic adductor spasm. This is a common symptom in spastic diplegia (Little’s disease). Due to the spasticity in the hip adductors the affected children walk – if at all – with adducted, flexed and internally rotated legs (scissor gait).