_Insertion._—(1) The eminences on the proximal extremity of the second phalanx behind the lateral ligaments; (2) the distal extremity of the first phalanx, also behind the lateral ligaments. _Action._—To flex the digit and carpus, and to extend the elbow. [Illustration: FIG. 195.—SYNOVIAL SHEATHS AND BURSÆ OF LOWER PART OF RIGHT FORE LIMB OF HORSE, INTERNAL VIEW. _a_, Sheath of extensor carpi obliquus; _b_, sheath of flexor carpi internus; _c_, carpal sheath; _d_, _d′_ _d″_, _d‴_, digital sheath; _e_, bursa under anterior extensor tendon; _f_, capsule of fetlock joint; _1_, extensor carpi radialis; _2_, tendon of extensor carpi obliquus; _3_, flexor carpi internus; _4_, flexor carpi medius; _5_, superficial flexor tendon; _6_, deep flexor tendon; _7_, suspensory ligament; _8_, small metacarpal bone; _9_, large metacarpal bone; _10_, posterior annular ligament of fetlock; _11_, proximal digital annular ligament; _12_, radius; _13_, radio-carpal joint; _14_, fetlock joint; _15_, lateral cartilage; _16_, band from first phalanx to lateral cartilage. (After Ellenberger, in Leisering’s Atlas.) The synovial sheaths (colored yellow) and the joint capsules (colored pink) are injected. ] [Illustration: FIG. 196.—SYNOVIAL SHEATHS AND BURSÆ OF LOWER PART OF RIGHT FORE LIMB OF HORSE, EXTERNAL VIEW. _a_, Sheath of extensor carpi radialis; _b_, sheath of anterior extensor; _c_, sheath of lateral extensor; _d_, sheath of outer tendon of flexor carpi externus; _e_, _e′_, carpal sheath; _f_, _f′_ _f″_, digital sheath; _g_, bursa under anterior extensor tendon; _h_, bursa under lateral extensor tendon; _i_, capsule of fetlock joint; _1_, extensor carpi radialis; _2_, anterior digital extensor; _3_, lateral digital extensor; _4_, flexor carpi externus; _4′_ _4″_, tendons of _4_; _5_, superficial flexor tendon; _6_, deep flexor tendon; _7_, suspensory ligament; _8_, external metacarpal bone; _9_, large metacarpal bone; _10_, posterior annular ligament of fetlock; _11_, digital annular ligament; _12_, fetlock joint; _13_, lateral cartilage; _14_, band from first phalanx to lateral cartilage. (After Ellenberger, in Leisering’s Atlas.) ]