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The joint is a synovial joint, comprising a common outer fibrous capsule and three inner synovial pouches, one for each joint. '''Collateral ligaments''' extend from the radius to the metacarpal bones on the medial and lateral aspect of the carpus. The '''carpal canal''' houses both the superficial and deep digital flexor tendon within a common synovial sheath.

The joint is a synovial joint, comprising a common outer fibrous capsule and three inner synovial pouches, one for each joint. '''Collateral ligaments''' extend from the radius to the metacarpal bones on the medial and lateral aspect of the carpus. The '''carpal canal''' houses both the superficial and deep digital flexor tendon within a common synovial sheath.

====Metacarpophalangeal (Fetlock) Joint====

===Metacarpophalangeal (Fetlock) Joint===

The fetlock joint allows flexion and extension movements. This joint is associated with a pair of sesamoid bones on the palmar surface. Between the sesamoids in a groove lies articular cartilage which articulates with the sagittal ridge of metacarpal III. The joint capsule runs between all bones in the joint and  attaches to the articular cartilage of the sesamoids. It has an extensive pouch under the extensor tendon continuing a quarter the length up the cannon bone. The '''collateral ligaments''' bind the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone. The '''palmar/intersesamoidean ligament''' is a mass of fibrocartilage that embed the sesamoid bones. The palmar aspect of it forms a groove for the deep flexor tendon to run in. The '''collateral sesamoid ligaments''' connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the cannon bone. The '''distal sesamoid ligaments''' are a collection of ligaments that are very marked in the horse and connect the distal surface of the sesamoids to the palmar aspect of the phalanx. These ligaments include the '''short ligaments''', '''cruciate ligaments''', '''oblique ligament''', '''straight ligament''' and the '''palmer annular ligament'''. The '''short ligaments''' connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments. The '''cruciate ligaments''' are paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments. The '''oblique ligament''' is a triangular shaped ligament, the base of which attaches to the sesamoids and their interconnecting ligament and the point attaches to the rough palmar aspect of the proximal phalanx. It is superficial to the cruciates. The '''straight ligament'''  proximally attaches like the oblique but attaches as a flat band to the edge of the complementary fibrocartilage of the proximal end of the middle phalanx. Finally, the '''palmar annular ligament''' wraps around the sesamoids, flexor tendons and their associated sheaths.

The fetlock joint allows flexion and extension movements. This joint is associated with a pair of sesamoid bones on the palmar surface. Between the sesamoids in a groove lies articular cartilage which articulates with the sagittal ridge of metacarpal III. The joint capsule runs between all bones in the joint and  attaches to the articular cartilage of the sesamoids. It has an extensive pouch under the extensor tendon continuing a quarter the length up the cannon bone. The '''collateral ligaments''' bind the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone. The '''palmar/intersesamoidean ligament''' is a mass of fibrocartilage that embed the sesamoid bones. The palmar aspect of it forms a groove for the deep flexor tendon to run in. The '''collateral sesamoid ligaments''' connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the cannon bone. The '''distal sesamoid ligaments''' are a collection of ligaments that are very marked in the horse and connect the distal surface of the sesamoids to the palmar aspect of the phalanx. These ligaments include the '''short ligaments''', '''cruciate ligaments''', '''oblique ligament''', '''straight ligament''' and the '''palmer annular ligament'''. The '''short ligaments''' connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments. The '''cruciate ligaments''' are paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments. The '''oblique ligament''' is a triangular shaped ligament, the base of which attaches to the sesamoids and their interconnecting ligament and the point attaches to the rough palmar aspect of the proximal phalanx. It is superficial to the cruciates. The '''straight ligament'''  proximally attaches like the oblique but attaches as a flat band to the edge of the complementary fibrocartilage of the proximal end of the middle phalanx. Finally, the '''palmar annular ligament''' wraps around the sesamoids, flexor tendons and their associated sheaths.

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====Proximal Interphalangeal (Pastern) Joint====

===Proximal Interphalangeal (Pastern) Joint===

The pastern joint allows flexion and extension movements. The palmar border of the middle phalanx has a complementary fibrocartilage that extends the proximal articular surface of the middle phalanx. It is sometimes called the middle scutum as it provides a gliding surface for the deep digital flexor. The joint capsule is simple and attaches by the articular margins of the two phalanges. The  '''collateral ligaments''' connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis. The fibres of the '''collateral sesamoid ligaments''' of the distal interphalangeal joint run with it, attach to the middle phalanx and then continue on to their distal attachments. The '''palmar ligaments''' connect the palmar aspect of the distal half of the proximal phalanx to the complementary fibrocartilage of the middle phalanx. These restrict dorsiflexion of the joint. A '''proximal digital annular ligament''' wraps around the superficial surface of the flexor tendons and their sheaths at the level of the proximal phalanx. There is a distal one also exists that is attached to the proximal phalanx, it is superficially associated with the digital cushion and is connected to the ergot by the thin fibrous '''ligament of the ergot'''.

The pastern joint allows flexion and extension movements. The palmar border of the middle phalanx has a complementary fibrocartilage that extends the proximal articular surface of the middle phalanx. It is sometimes called the middle scutum as it provides a gliding surface for the deep digital flexor. The joint capsule is simple and attaches by the articular margins of the two phalanges. The  '''collateral ligaments''' connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis. The fibres of the '''collateral sesamoid ligaments''' of the distal interphalangeal joint run with it, attach to the middle phalanx and then continue on to their distal attachments. The '''palmar ligaments''' connect the palmar aspect of the distal half of the proximal phalanx to the complementary fibrocartilage of the middle phalanx. These restrict dorsiflexion of the joint. A '''proximal digital annular ligament''' wraps around the superficial surface of the flexor tendons and their sheaths at the level of the proximal phalanx. There is a distal one also exists that is attached to the proximal phalanx, it is superficially associated with the digital cushion and is connected to the ergot by the thin fibrous '''ligament of the ergot'''.

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====Distal Interphalangeal (Coffin) Joint====

===Distal Interphalangeal (Coffin) Joint===

The coffin joint allows extension and slight flexion movements. The '''navicular bursa''' lies between the navicular bone and the deep flexor tendon. The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx. It dips between the distal phalanx and sesamoid and bulges laterally where it is related to the collateral ligaments. The '''collateral ligaments''' connect the distal part of the middle phalanx to the sides of the proximal distal phalanx. The '''distal sesamoid ligaments''' connect the distal border of the navicular bone to the flexor surface of the distal phalanx. The '''collateral sesamoid ligaments''' are fibroelastic ligaments that attach to the proximal phalanx with the collateral ligaments of the pastern joint and insert to the proximal border of the navicular bone. The ungual/lateral cartilages have a series of ligaments going to the medial/lateral surfaces of the three phalanges and distal sesamoid. There is also a fibrous band connecting the inner surfaces of the cartilages by crossing the superficial aspect of the deep digital flexor tendon.

The coffin joint allows extension and slight flexion movements. The '''navicular bursa''' lies between the navicular bone and the deep flexor tendon. The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx. It dips between the distal phalanx and sesamoid and bulges laterally where it is related to the collateral ligaments. The '''collateral ligaments''' connect the distal part of the middle phalanx to the sides of the proximal distal phalanx. The '''distal sesamoid ligaments''' connect the distal border of the navicular bone to the flexor surface of the distal phalanx. The '''collateral sesamoid ligaments''' are fibroelastic ligaments that attach to the proximal phalanx with the collateral ligaments of the pastern joint and insert to the proximal border of the navicular bone. The ungual/lateral cartilages have a series of ligaments going to the medial/lateral surfaces of the three phalanges and distal sesamoid. There is also a fibrous band connecting the inner surfaces of the cartilages by crossing the superficial aspect of the deep digital flexor tendon.