The groin is not a single muscle but a convergence zone where at least a dozen muscles, tendons, and ligaments overlap in a compact space between the lower abdomen and the inner thigh. The most prominent group is the hip adductors, five muscles that pull the leg inward, but the iliopsoas, the lower abdominals, and several smaller rotator muscles all occupy the same territory and contribute to what people loosely call “the groin.” That anatomical crowding is exactly why groin pain is so common and so hard to pin down.
The Five Hip Adductors
When clinicians talk about groin muscles, they usually start with the medial compartment of the thigh, the inner strip of muscle running from the pelvis down toward the knee. This compartment contains five muscles: the pectineus, adductor longus, adductor brevis, gracilis, and adductor magnus. Together they pull your thigh toward midline, stabilize your pelvis while you walk, and keep you balanced any time you stand on one leg.1StatPearls Publishing. Anatomy, Bony Pelvis and Lower Limb: Thigh Adductor Magnus Muscle
Each adductor has a slightly different job depending on its position and where it attaches:
- Adductor longus: The most superficial of the group and the one athletes injure most often. It originates from the front of the pubic bone and fans down toward the middle of the femur. Because it sits right at the surface, it takes the brunt of sudden direction changes.
- Adductor brevis: Sits just behind the longus. Shorter and deeper, it connects the pubic bone to the upper femur and assists with both adduction and hip flexion.
- Adductor magnus: The largest of the five and arguably the most powerful, stretching from the pelvis nearly all the way to the knee. It has two distinct portions: one that acts like the other adductors and another that functions more like a hamstring.1StatPearls Publishing. Anatomy, Bony Pelvis and Lower Limb: Thigh Adductor Magnus Muscle
- Pectineus: A small, flat muscle at the very top of the inner thigh, right at the crease of the groin. It helps with both adduction and hip flexion and is one reason groin strains sometimes feel like they are in the hip joint itself.
- Gracilis: The only adductor that crosses two joints, running from the pubic bone all the way past the knee to attach on the inner shinbone. That length makes it relatively vulnerable to strain, though isolated gracilis tears are less common than adductor longus injuries.
All five adductors anchor onto the pubic bone at or near the pubic symphysis, the cartilage joint where the two halves of the pelvis meet.2Sports Health. Hip Imaging of Groin Pain: Magnetic Resonance and Ultrasound Imaging Features That shared origin is part of why a single hard kick or a bad split can damage more than one of them at once.
The Iliopsoas
The other dominant muscle in the groin area is the iliopsoas, often called the body’s primary hip flexor. It is actually two muscles that merge into a single tendon: the iliacus, which lines the inside of the pelvis, and the psoas major, which originates from the lumbar spine. They join together and pass over the front of the hip joint on their way to attaching on the inner femur. Ultrasound studies of healthy volunteers have consistently identified four distinct bundles within the iliopsoas at groin level, with an occasional fifth bundle appearing as a normal variant.3PubMed. Sonographic anatomy and dynamic study of the normal iliopsoas musculotendinous junction
Because the iliopsoas runs directly in front of the hip socket and labrum, pain from an irritated iliopsoas tendon can mimic a labral tear or a hip joint problem. That overlap makes clinical diagnosis tricky: MRI has limited sensitivity for detecting iliopsoas tendinitis and bursitis, which means a scan can look clean even when the muscle is the actual source of pain.4Journal of the American Academy of Orthopaedic Surgeons. The Iliopsoas: Anatomy, Clinical Evaluation, and Its Role in Hip Pain in the Athlete: A Scoping Review In athletes evaluated with MRI for groin pain, iliopsoas problems show up as either peritendinitis (inflammation around the tendon) or muscle-strain changes, and the two types have very different recovery timelines. Players with muscle-strain changes returned to sport in about nine weeks on average, while those with peritendinitis changes took roughly twenty weeks.5PubMed Central. Iliopsoas Disorder in Athletes with Groin Pain Prevalence in 638 Consecutive Patients Assessed with MRI and Clinical Results in 134 Patients with Signal Intensity Changes in the Iliopsoas
The Abdominal Wall and Inguinal Region
The groin is not purely a thigh story. Several abdominal muscles extend into the region and share attachment points with the adductors. The rectus abdominis (your “six-pack” muscle), the transversus abdominis, and the internal and external obliques all send fibers or aponeurotic tissue down to the pubic symphysis.2Sports Health. Hip Imaging of Groin Pain: Magnetic Resonance and Ultrasound Imaging Features In practical terms, the lower abs and the adductor longus share a common tendon plate at the front of the pubic bone, which is why a forceful kick or slap shot can strain both structures at once.
Layered over these muscles is the inguinal canal, a diagonal passageway through the lower abdominal wall. The external oblique aponeurosis folds back on itself to form the inguinal ligament, a tough band running from the front of the hip bone to the pubic tubercle. Below it, the lacunar ligament fans out and fuses with the fascia covering the pectineus muscle.6PubMed Central. Inguinal anatomy This region is clinically important because inguinal hernias push through weak spots in these layers, and the symptoms can feel identical to a muscle strain.
Smaller Muscles That Often Get Overlooked
Deeper in the pelvis sit several small rotator muscles that most people never hear about unless they get hurt. The obturator externus, which rotates the hip outward, lies beneath the adductors and close to the hip joint. It rarely makes the short list of “groin muscles,” but when professional soccer players present with what looks like an adductor or quadriceps strain, imaging sometimes reveals that the obturator externus is the actual source. In a case series of professional players, MRI confirmed obturator externus injuries that had been initially suspected as more typical adductor or quadriceps problems.7PubMed Central. Acute Obturator Externus Injury in Professional Soccer Players: A Case Series Pain on active hip external rotation and passive internal rotation were the distinguishing signs.
The obturator nerve, which supplies the adductor muscles, also threads through this area and can become trapped under a thick fascial band overlying the adductor brevis. When it does, electromyography shows denervation of the adductors, meaning the muscles lose their nerve signal and weaken, sometimes mimicking a muscle tear that never shows up on imaging.8PubMed Central. Obturator nerve entrapment. A cause of groin pain in athletes
Why Groin Injuries Are So Common in Sport
The groin’s anatomy explains its vulnerability. All those muscles pulling in different directions converge on a small piece of bone at the front of the pelvis. Any sport that involves rapid acceleration, sudden direction changes, or forceful hip movements puts enormous stress on that junction. Kicking a ball, performing a hockey slap shot, or cutting sideways at full speed generates tremendous forces across the common tendon attachment of the rectus abdominis and adductor longus.9PubMed Central. Athletic Pubalgia Secondary to Rectus Abdominis–Adductor Longus Aponeurotic Plate Injury: Diagnosis, Management, and Operative Treatment of 100 Competitive Athletes A single bad episode or repetitive microtrauma can partially or fully avulse that shared plate, a condition often called athletic pubalgia or “sports hernia.”
In more severe cases, the adductor longus tendon can completely detach from its bony anchor at the pubic bone, producing significant weakness and pain that may require surgical repair.10PubMed. Return to Preoperative Level of Sporting Function after Surgical Repair of the Pyramidalis-Anterior Pubic Ligament-Adductor Longus Complex in Professional Athletes
Even when the adductors are clearly the source of symptoms, the exact tissue involved matters for treatment. A tear in the muscle belly heals differently than a tendon injury at the origin. Treating tendinopathy of the adductor longus as if it were a simple muscle strain can actually be counterproductive, because the two conditions respond to different rehabilitation strategies.11PubMed Central. Adductor Strains in Athletes
How the Groin Muscles Work Together During Movement
Walking in a straight line is the simplest task these muscles perform, and even that requires continuous coordination. The adductors stabilize the pelvis so it does not drop toward the unsupported side with each step. The iliopsoas swings the leg forward. The lower abdominals brace the trunk. When you cut sideways at speed, the demands escalate sharply: the adductor longus of the stance leg fires hard to control the pelvis while the body redirects laterally. Electromyography during 45-degree run-to-cut maneuvers shows substantial adductor longus activation throughout the entire stance phase.12PubMed Central. Hip adductor activations during run-to-cut manoeuvres in compression shorts: implications for return to sport after groin injury
The way the groin muscles behave during walking and jumping also differs between men and women who have hip-related groin pain. Men tend to walk with less hip flexion, less internal rotation, and lower hip adduction angles compared to women with the same condition, suggesting that the muscular compensation strategies around the groin are not uniform across populations.13PubMed Central. Lower limb biomechanics during low- and high-impact functional tasks differ between men and women with hip-related groin pain
Predicting and Preventing Groin Strains
Because the adductors are the most frequently injured muscles in the groin, researchers have spent considerable effort trying to identify who is at risk before an injury happens. A prospective study of professional rugby league players found that the ratio of hip adductor to abductor strength, along with factors like bilateral differences in hip extension torque and body mass, were related to groin injury risk.14PubMed. Groin injuries in professional rugby league players: a prospective study Measuring the adductor-to-abductor strength ratio during preseason and in-season screening has been proposed as a practical tool for identifying athletes who could benefit from targeted strengthening, particularly in hockey and soccer.15PubMed. Measuring the Hip Adductor to Abductor Strength Ratio in Ice Hockey and Soccer Players: A Critically Appraised Topic
The Copenhagen adduction exercise has become one of the most widely studied interventions for building groin strength. It is a partner-based exercise where you lie on your side, have a partner hold your top leg, and lift your bottom leg up to meet it, loading the adductors eccentrically. A systematic review found that groups performing this exercise consistently showed significant increases in eccentric hip adduction strength and in the adductor-to-abductor strength ratio.16PubMed Central. The Neuromuscular Effects of the Copenhagen Adductor Exercise: A Systematic Review One trial documented roughly an 18% increase in adductor muscle thickness along with improved adductor flexibility, though both gains returned to baseline after a detraining period, underscoring the need for ongoing work.17PubMed Central. Effects of Copenhagen Adduction Exercise on Muscle Architecture and Adductor Flexibility
Isolated Injuries You Might Not Expect
While the adductor longus gets the most clinical attention, isolated tears of the gracilis do occur, particularly in athletes. Because the gracilis crosses both the hip and the knee, it can be strained during movements that stretch both joints simultaneously. Ultrasound evaluation of such injuries in athletes found lesions at the junction between the proximal and middle third of the muscle, classified as partial tears, with an average return to full performance within about five weeks.18PubMed Central. Isolated tears of the gracilis muscle That relatively quick recovery, compared to adductor longus tendon injuries, likely reflects the fact that these are mid-belly muscle tears rather than injuries at a tendon origin.
What Happens to the Groin Muscles as You Age
Groin muscles do not only matter for sport. The hip adductors and abductors play an essential role in lateral balance, the ability to catch yourself when you stumble sideways. A study comparing healthy younger and older adults found that older participants had reduced peak hip adduction and abduction torque, a slower rate of force development, and delayed neuromuscular activation when responding to lateral balance perturbations. The older group also took fewer lateral recovery steps, suggesting that age-related decline in groin muscle capacity contributes to fall risk.19PubMed Central. Effects of aging on hip abductor-adductor neuromuscular and mechanical performance during the weight transfer phase of lateral protective stepping
This is an underappreciated dimension of groin anatomy. Most public attention focuses on sports injuries in younger athletes, but the same muscles that let a soccer player cut sideways are the ones that keep a seventy-year-old from falling after a stumble on an uneven sidewalk. The rate at which these muscles can generate force, not just their maximum strength, appears to be a key factor in balance recovery.
Evolutionary Background of the Groin’s Layout
The dense convergence of muscles in the human groin is partly a product of how we evolved to walk and run upright. When our ancestors shifted from a crouched, bent-hip gait to the fully upright posture humans use today, major changes occurred in the volume and leverage of the gluteus maximus, quadriceps, hamstrings, and iliopsoas. The adductors and hip rotators, by contrast, changed relatively little in their functional anatomy during that transition.20Journal of Hip Preservation Surgery. Evolution of the human hip. Part 2: muscling the double extension The result is a groin that retains a muscular architecture suited for a wide range of hip positions and movements but is packed into a space that was redesigned around fully extended, bipedal walking. That mismatch may help explain why the groin is a recurring weak link, especially when sports demand rapid, multi-directional movements that push the region well beyond what steady upright locomotion requires.