Adductor
Musculus adductor
Overview
The adductor muscle (musculus adductor) is a large, powerful muscle occupying the medial compartment of the equine thigh. It originates from the ventral surface of the pelvis, primarily the pubis and ischium, and inserts along the caudal aspect of the femur, extending to the medial femoral condyle and associated fascia. In the horse the muscle is relatively massive compared with many other species and functions principally to adduct the hind limb (draw it toward the midline) while also contributing to hip extension. During the stance phase it stabilizes the limb against lateral splaying forces; during propulsion it assists in driving the body forward. The muscle is innervated by the obturator nerve (segments L4–L6), which exits the pelvis through the obturator foramen. Blood supply is derived from branches of the deep femoral and obturator arteries. Because the obturator nerve can be compressed against the pelvic brim or stretched during difficult foaling, bilateral or unilateral adductor paralysis is an uncommon but recognized postpartum complication in mares. Affected mares stand with the hind limbs splayed ("splay-legged") and may be unable to rise or may damage the medial thigh and pelvic floor. The muscle also works synergistically with the other medial thigh muscles (gracilis, pectineus, semimembranosus) to control limb position during turns, lateral work, and sudden stops. Clinically, strain or partial rupture can occur from slipping on ice or hard ground, producing medial thigh swelling and reluctance to adduct the limb. Palpation of the medial thigh in the standing horse reveals the bulk of the adductor; ultrasound can differentiate muscle fiber disruption from hematoma. In rehabilitation, controlled adduction exercises and proprioceptive work help restore function once acute inflammation subsides.
Anatomical Details
Origin: Ventral surface of the pelvis (pubis and ischium)
Insertion: Caudal surface of the femur and medial femoral condyle
Action: Adducts the hindlimb; extends the hip; stabilizes the hindlimb during stance
Innervation: Obturator nerve (L4-L6)
Clinical Significance
Obturator nerve paralysis (post-partum) produces characteristic splay-legged stance, inability to adduct, and risk of secondary myopathy or pelvic fracture. Diagnosis is clinical; electromyography or nerve conduction studies are rarely practical. Treatment: anti-inflammatories, sling support, deep bedding, and time; many mares recover over days to weeks. Adductor strain or partial tear: medial swelling, pain on palpation or forced adduction, elevated muscle enzymes. Ultrasound confirms fiber disruption. Rest, controlled exercise, and physical therapy are mainstays. Differential diagnoses include pelvic fracture, sacroiliac pain, and other medial thigh muscle injuries.
Common Conditions & Injuries
Obturator nerve paralysis (post-foaling)
## Overview Obturator nerve paralysis can occur in mares after difficult foaling when the nerve is compressed in the pelvis. It paralyzes the adductor muscles, so the mare cannot bring the hind limbs
Adductor strain from slipping
## Overview Adductor strain is an injury to the muscles that pull the hind limb toward the midline (primarily the adductor, gracilis, and pectineus muscles). In horses it commonly occurs when a horse
What Horse Owners Should Know
After foaling, watch for a mare that cannot keep her hind legs under her or that stands with legs spread wide. Provide deep, non-slip bedding and assist her to rise if necessary; call the veterinarian immediately; early anti-inflammatory treatment and sling support improve recovery. During winter, avoid icy surfaces that can cause sudden medial-thigh strains.
Frequently Asked Questions
What is Obturator nerve paralysis (post-foaling) in horses?
## Overview Obturator nerve paralysis can occur in mares after difficult foaling when the nerve is compressed in the pelvis. It paralyzes the adductor muscles, so the mare cannot bring the hind limbs together and may splay dangerously on slippery surfaces. Hobbles are often used to prevent the splits. Recovery usually occurs over days to weeks. ## Causes Compression of the obturator nerve during parturition. ## Diagnosis Clinical signs of adductor weakness immediately after foaling, with inability to adduct the hind limbs. ## Treatment Hobbles or slings to prevent splaying, excellent footing, anti-inflammatories, and nursing care. Most mares recover if secondary muscle tearing or hip luxation is avoided. ## Recovery and Prognosis Good if complications are prevented. Splaying injuries worsen the outlook. ## Prevention Assistance with difficult births and immediate use of hobbles if weakness is recognized. Signs include: inability to bring the hind limbs together; splaying on slippery surfaces; need for hobbles; usually recognized after foaling
What is Adductor strain from slipping in horses?
## Overview Adductor strain is an injury to the muscles that pull the hind limb toward the midline (primarily the adductor, gracilis, and pectineus muscles). In horses it commonly occurs when a horse slips or splays the hind limbs on poor footing. The injury ranges from mild muscle fiber disruption to complete tear. Sport horses that perform sharp turns or rapid starts and stops are also at elevated risk, but slipping on wet grass, mud, or ice is a frequent trigger. ## Causes Sudden abduction of the hind limb against active adduction, as occurs when a foot slips laterally, produces eccentric overload of the adductor group. Fatigue, poor footing, previous groin injury, and lack of conditioning increase susceptibility. The injury is analogous to a human groin strain. ## Diagnosis Clinical signs include acute hind-limb lameness or reluctance to move the limb inward, pain on palpation of the medial thigh, and sometimes heat or swelling. Grade 1 strains may show little lameness until after exercise; grade 2 and 3 strains produce more obvious pain and gait abnormality. Ultrasound can confirm muscle tearing or hematoma. Thermography may highlight the affected area. ## Treatment Initial treatment follows the principles of rest, cold therapy, and anti-inflammatory medication. Controlled walking is introduced once acute pain subsides, followed by progressive strengthening. Premature return to work commonly leads to reinjury. Severe tears may benefit from regenerative therapies, although evidence in horses is limited. ## Recovery and Prognosis Mild strains often resolve in 2 to 6 weeks. Moderate to severe strains may require 8 to 16 weeks or longer. Prognosis is generally good if the horse is given adequate rest and a structured rehabilitation program. Recurrent injury is common when rest is insufficient. ## Prevention Good footing management, progressive conditioning of the hindquarter musculature, and avoidance of slippery surfaces reduce risk. Warm-up before intense work is also beneficial. Signs include: hindlimb lameness or shortened stride; pain on palpation of the medial thigh; reluctance to adduct the limb; heat or swelling in the groin region; stiffness after rest
What are the clinical concerns for the Adductor?
Obturator nerve paralysis (post-partum) produces characteristic splay-legged stance, inability to adduct, and risk of secondary myopathy or pelvic fracture. Diagnosis is clinical; electromyography or nerve conduction studies are rarely practical. Treatment: anti-inflammatories, sling support, deep bedding, and time; many mares recover over days to weeks. Adductor strain or partial tear: medial swelling, pain on palpation or forced adduction, elevated muscle enzymes. Ultrasound confirms fiber disruption. Rest, controlled exercise, and physical therapy are mainstays. Differential diagnoses include pelvic fracture, sacroiliac pain, and other medial thigh muscle injuries.
What should horse owners know about the Adductor?
After foaling, watch for a mare that cannot keep her hind legs under her or that stands with legs spread wide. Provide deep, non-slip bedding and assist her to rise if necessary; call the veterinarian immediately; early anti-inflammatory treatment and sling support improve recovery. During winter, avoid icy surfaces that can cause sudden medial-thigh strains.
Explore This Structure in 3D
See the Adductor on our interactive 3D horse model. Open 3D Model