Musculus interosseous medius
The suspensory ligament (interosseous medius) originates from the proximocaudal aspect of the cannon bone (MC3 or MT3) and the distal row of carpal or tarsal bones. It inserts on the abaxial surfaces of the proximal sesamoid bones, with extensor branches that pass around the proximal phalanx to join the common digital extensor tendon. Its primary action is to support the fetlock joint and prevent hyperextension during weight bearing. It contains little muscular tissue in the adult (though it is fairly muscular in the foal). It is the principal component of the suspensory apparatus. It has vestigial innervation from the deep branch of the lateral palmar or plantar nerve.
Origin: Proximal palmar/plantar MC3/MT3 (cannon bone) and distal row of carpal/tarsal bones
Insertion: Abaxial surfaces of the proximal sesamoid bones; extensor branches join the common digital extensor tendon
Action: Supports the fetlock joint; prevents hyperextension of the fetlock during weight bearing
Innervation: Deep branch of the lateral palmar/plantar nerve (vestigial innervation)
Suspensory ligament desmitis and branch injuries are common causes of lameness in performance horses. Proximal suspensory desmitis is particularly common in the hindlimbs of sport horses. Diagnosis uses clinical examination, nerve blocks, and ultrasound. Management is usually medical with rest and controlled rehabilitation. Severe injuries can affect fetlock support.
## Overview Proximal suspensory desmitis is inflammation or tearing at the origin of the suspensory ligament high in the cannon bone. It is a very common cause of lameness in sport horses, affecting
## Overview Suspensory branch injuries are tears of the medial or lateral branches where they insert on the sesamoid bones. They are very common in racehorses and eventers. Acute lameness, localized
## Overview A suspensory body lesion is damage to the mid-body of the suspensory ligament in the cannon region. Swelling may be obvious in the forelimb but subtle in the hind limb where the ligament
## Overview Degenerative suspensory ligament desmitis (DSLD) is a progressive, systemic disorder of connective tissue that leads to bilateral breakdown of the suspensory ligaments. It is most recogni
## Overview Sesamoiditis is chronic inflammation and remodeling of the proximal sesamoid bones from repetitive loading and suspensory ligament traction. It is common in young racehorses and sport hor
Sudden swelling or heat along the back of the cannon bone or fetlock after work should be evaluated. Early diagnosis and appropriate rest improve outcomes. Protective boots can help reduce risk in some disciplines.
## Overview Proximal suspensory desmitis is inflammation or tearing at the origin of the suspensory ligament high in the cannon bone. It is a very common cause of lameness in sport horses, affecting both forelimbs and hind limbs. Onset is often gradual. Lameness is worse on soft footing and circles, and bilateral cases may appear as stiffness rather than obvious lameness. Forelimb cases respond well to rest; hind-limb cases are more challenging. ## Causes Repetitive overload. ## Diagnosis Diagnostic analgesia, ultrasound, and sometimes magnetic resonance imaging. ## Treatment Rest and controlled rehabilitation (often 3 to 6 months). Shock wave, regenerative therapies, or surgery (neurectomy and fasciotomy) for refractory hind-limb cases. ## Recovery and Prognosis Excellent (around 90 percent) for acute forelimb cases with adequate rest. Guarded to fair for hind-limb proximal suspensory desmitis. ## Prevention Progressive conditioning and appropriate surfaces. Signs include: gradual-onset lameness; worse on soft footing; may appear as stiffness if bilateral; pain on palpation of proximal cannon; positive to diagnostic analgesia
## Overview Suspensory branch injuries are tears of the medial or lateral branches where they insert on the sesamoid bones. They are very common in racehorses and eventers. Acute lameness, localized swelling, heat, and pain are typical. Ultrasound confirms the fiber damage. ## Causes Hyperextension overload. ## Diagnosis Ultrasound. ## Treatment Rest, controlled rehabilitation, foot balancing, and adjunct therapies as indicated. ## Recovery and Prognosis Fair to good with adequate time. ## Prevention Foot balance and training management. Signs include: acute lameness; swelling over the affected branch; heat; pain on palpation; ultrasound fiber disruption
## Overview A suspensory body lesion is damage to the mid-body of the suspensory ligament in the cannon region. Swelling may be obvious in the forelimb but subtle in the hind limb where the ligament is deeper. Lameness is worse at the trot, and ultrasound confirms fiber disruption. ## Causes Overload. ## Diagnosis Ultrasound. ## Treatment Prolonged rest and controlled rehabilitation. Regenerative therapies are sometimes used. ## Recovery and Prognosis Fair to good depending on lesion size. ## Prevention Appropriate conditioning and footing. Signs include: swelling in the mid-cannon (subtle in the hind limb); lameness worse at trot; pain on palpation; ultrasound confirmation
## Overview Degenerative suspensory ligament desmitis (DSLD) is a progressive, systemic disorder of connective tissue that leads to bilateral breakdown of the suspensory ligaments. It is most recognized in Peruvian Pasos but occurs in other breeds. Affected horses develop dropped fetlocks that worsen over time. There is no cure. ## Causes Genetic factors affecting connective-tissue homeostasis are strongly implicated. The condition is not caused by a single traumatic event. ## Diagnosis Clinical appearance of progressive bilateral fetlock dropping, ultrasound showing diffuse suspensory enlargement and fiber disruption in multiple limbs, and exclusion of traumatic injury. ## Treatment Supportive only: controlled exercise or rest during flares, anti-inflammatories, and hoof care. No treatment halts progression. ## Recovery and Prognosis Poor for athletic use. The disease progresses over months to years. Many horses are eventually euthanized for welfare reasons when they can no longer stand comfortably. ## Prevention Avoid breeding affected horses. No other preventive measures are known. Signs include: bilateral fetlock dropping; progressive over months to years; pasterns become horizontal; pain and reluctance to move; no response to rest
## Overview Sesamoiditis is chronic inflammation and remodeling of the proximal sesamoid bones from repetitive loading and suspensory ligament traction. It is common in young racehorses and sport horses. Signs include low-grade forelimb lameness, pain on palpation of the sesamoids, a positive flexion test, and enlarged, remodeled sesamoids on radiographs. ## Causes Repetitive strain at the suspensory insertion. ## Diagnosis Radiographs showing sesamoid changes, correlated with clinical signs. Ultrasound or scintigraphy may add information. ## Treatment Rest, anti-inflammatories, and gradual return to work. Shock wave or regenerative therapies are sometimes used. Prognosis for high-level performance is often guarded. ## Recovery and Prognosis Guarded for return to previous athletic level in many cases. ## Prevention Careful training of young horses and early management of suspensory soreness. Signs include: chronic low-grade forelimb lameness; pain on sesamoid palpation; positive flexion test; enlarged remodeled sesamoids on radiographs
Suspensory ligament desmitis and branch injuries are common causes of lameness in performance horses. Proximal suspensory desmitis is particularly common in the hindlimbs of sport horses. Diagnosis uses clinical examination, nerve blocks, and ultrasound. Management is usually medical with rest and controlled rehabilitation. Severe injuries can affect fetlock support.
Sudden swelling or heat along the back of the cannon bone or fetlock after work should be evaluated. Early diagnosis and appropriate rest improve outcomes. Protective boots can help reduce risk in some disciplines.
See the Suspensory Ligament (Interosseous Medius) on our interactive 3D horse model. Open 3D Model