How Do Adductor Muscles Work in Human Movement?
The hip adductors are known as a group of five muscles that are located in the medial compartment of the thigh.
As the name suggests the adductor muscles are a group of muscles that primarily function to adduct the femur at the hip joint. As they originate in different places at the front of the pelvis, the adductor muscles are all present somewhere along the medial side of the thigh,
Most of them are surprisingly thin muscles.
There is an exception that the largest of them is the adductor Magnus muscle.
The adductor group includes the following muscles:
Pectineus
Adductor Brevis
Adductor longus
Gracilis
Adductor Magnus
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What Actions do the Adductors Do?
The pectineus assists in both adduction as well as in flexion of the femur at the hip joint.
The primary function of the adductor brevis is the adduction of the thigh at the hip joint and the adductor brevis is known to assist in flexion and in addition to that is the rotation of the femur at the hip joint in medical.
Also, the function of the adductor longus is adduction of the thigh at the hip joint. The adductor longus assists in flexion and medial rotation of the femur at the hip joint.
The primary action of gracilis is adduction of the thigh and to assist in flexion of the knee as well as medial rotation of that flexed knee, similar to what we’ll see when we look at sartorius.
Position of Hip Adductors
Due to the position of Hip adductors, the hip adductors are known to shape the surface anatomy of the medial thigh. More specifically, these hip adductors generally extend from the anteroinferior external surface of the bony pelvis to the shaft of the femur as well as extend to the proximal tibia. The majority of hip adductors are innervated by the obturator nerve (L2-L4) and blood is supplied mainly via the branches of the femoral and also via the obturator arteries.
What is Adductor Longus?
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Adductor longus is triangular in shape, the most anteriorly placed muscle of the adductor group. Upon originating from the anterior surface of the body of the pubis, the adductor longus muscle fibers course downwards and this muscle is laterally inserted onto the middle third of the linea Aspera and this muscle is innervated by the anterior division of the obturator nerve (L2-L4).
The blood supply of this muscle mainly from the deep femoral artery as well as contributions from the medial circumflex femoral and femoral arteries.
Coming to the main function of the adductor longus, the main function is to adduct the thigh at the hip joint.
Additionally, the adductor longus contributes to the flexion of the extended thigh, as well as the adductor longus contributes to the extension of the flexed thigh. The muscle’s contribution to the internal or the medial rotation of the thigh is still not known.
What is Pectineus Muscle?
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The pectineus muscle is a flat and quadrangular muscle.
This muscle is situated at the medial (inner) aspect and the upper part of the thigh.
The most anterior adductor of the hip is the pectineus muscle. The muscle does adduct as well as internally rotates the thigh but the primary function of the muscle is hip flexion.
It can be classified in the medial compartment of the thigh (when the function is emphasized) or the anterior compartment of the thigh (when the nerve is emphasized)
Actions: Thigh - flexion, adduction
Nerve: Femoral nerve, sometimes obturator nerve
Latin: Musculus pectineus
What is Gracilis Muscle?
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The gracilis muscle is the Latin term for slender.
The most superficial muscle on the medial side of the thigh is the Gracillis muscle.
Gracilis muscle is generally thin and flattened, broad above, narrow, and a little tapering below.
Artery: Medial circumflex femoral artery
Actions: flexes, medially rotates
Latin: musculus gracilis
What is Adductor Brevis?
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The Adductor brevis is a flat, triangular muscle and it is found in the inner thigh.
The muscle that runs from the pubis to the medial aspect of the femur is the adductor brevis. Together with adductor longus, adductor Magnus, gracilis, as well as pectineus muscles, it comprises a group of muscles known as the adductors of the thigh.
Action: Hip joint: thigh flexion, thigh adduction
Insertion: Linea Aspera of the femur (medial lip)
Origin: Anterior body of the pubis, inferior pubic ramus
Innervation: Obturator nerve (L2-L4)
What is the Adductor Magnus?
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The large triangular muscle of the lower limb is known as the adductor Magnus muscle, with its apex it is situated on the hip bone, and with the muscle’s base on the linea aspera of the femur.
It is situated both in the posterior as well as in medial fascial compartments of the thigh.
Insertion: Adductor part: Gluteal tuberosity
Innervation: Adductor part: Obturator nerve
Action: Adductor part: Hip joint - Thigh flexion
Origin: Adductor part: Inferior pubic ramus
Key Points About Adductor Muscles
FAQs on Adductor Muscle: Structure, Function & Importance
1. What are the adductor muscles and where are they located in the human body?
The adductor muscles are a group of muscles located in the medial (inner) compartment of the thigh. Their primary role is adduction, which means they pull the leg inward, toward the midline of the body. They are crucial for stabilising the pelvis and enabling movements like walking, running, and crossing your legs.
2. What is the primary function of the adductor muscle group in locomotion?
The main function of the adductor muscles is to produce adduction of the thigh at the hip joint, drawing the leg towards the body's centre. Beyond this primary action, they also assist in other movements. For example, some adductors contribute to hip flexion (bending the hip) and medial rotation (turning the thigh inward), providing essential stability and control during gait and athletic activities.
3. Which specific muscles form the adductor group of the thigh?
The adductor group is comprised of five main muscles. As per the CBSE/NCERT curriculum on human anatomy, these are:
Adductor Longus: A long, fan-shaped muscle in the inner thigh.
Adductor Brevis: A short muscle located underneath the adductor longus.
Adductor Magnus: The largest and most powerful muscle of the group.
Gracilis: A thin, strap-like muscle on the most medial side of the thigh.
Pectineus: A flat, quadrangular muscle situated at the top of the inner thigh.
4. From a biological perspective, what causes an adductor muscle strain or 'groin pull'?
An adductor muscle strain occurs when the muscle fibres are stretched beyond their capacity, leading to microscopic tears. This is often caused by a sudden, forceful movement, such as kicking, pivoting, or sprinting. Biologically, the injury is a result of excessive eccentric contraction, where the muscle lengthens while under tension. Risk factors include weak adductors, muscle fatigue, inadequate warm-up, and a history of previous groin injuries, all of which compromise the tissue's ability to handle stress.
5. How do adductor muscles differ from abductor muscles in function and location?
Adductor and abductor muscles are antagonistic pairs with opposite functions. The key differences are:
Function: Adductors pull the leg inward toward the body's midline (adduction), while abductors push the leg outward, away from the body's midline (abduction).
Location: Adductor muscles are found on the inner thigh (medial compartment). In contrast, the primary abductor muscles, like the gluteus medius and minimus, are located on the outer side of the hip.
This balance between adduction and abduction is critical for pelvic stability and controlled leg movement.
6. Where do the adductor muscles originate and insert?
The origin and insertion points are fundamental to a muscle's action. The adductor muscles generally originate from the pubis and ischium bones of the pelvis. They then run down the inner thigh and insert along the medial aspect of the femur (thigh bone). This specific arrangement allows them to act as powerful levers, pulling the femur medially when they contract.
7. How does the sliding filament theory explain the contraction of an adductor muscle?
The contraction of an adductor muscle, like any skeletal muscle, is explained by the sliding filament theory. When a nerve impulse from the obturator nerve reaches the neuromuscular junction, it triggers the release of calcium ions within the muscle fibres. This allows the myosin heads (thick filaments) to bind to the actin (thin filaments), forming cross-bridges. The myosin heads then pivot, pulling the actin filaments toward the centre of the sarcomere. This collective shortening of sarcomeres throughout the muscle fibres results in the overall contraction of the adductor muscle, causing the thigh to adduct.
