Equine Flash Notes - Joint & Nerve Blocks Flashcards
what is a point block?
blocking a specific nerve directly at one site that blocks the nerve & its distal braches
what is a line block?
produced by infiltrating the anesthetic along a line that numbs the nerve branches that cross it
what is a ring block/field block?
achieved by injecting anesthetic in a complete or partial circle around the limb
what nerves are desensitized by a palmar digital block?
palmar/plantar digital nerves that innervate the heel of the foot
where is a PD block performed?
neurovascular bundle on the lateral & medial aspect along the dorsal border of the flexor tendons in the pastern region
what are the boundaries of the injection site of a PD block?
palmar/plantar: flexor tendons, distal: ungual cartilage, & dorsal: digital artery
what conditions are often blocked by a PD block?
shoeing problems, bruising of the sole, thrush, navicular disease/fractures, palmar fractures of P3, digital cushion/bulb lesions & partially blocks coffin joint problems & laminitis - dorsal portion (toe) is unaffected
what does the abaxial sesamoidean block cover?
pastern & entire foot
where is an abaxial sesamoiden block performed?
abaxial sides at distal ends of proximal sesamoids - palpate palmar digital nerve & dorsal branch over the sides of the proximal sesamoids (pop them under your fingers) & move distally to locate the base of the sesamoids - infect in a distal direction
what conditions are often blocked by an abaxial sesamoidien block?
pastern joint, pastern area, coffin joint, toe of foot (bruising, abscesses, canker, laminitis), & heel
what nerves are blocked in a low four point?
medial & lateral palmar nerves, medial & lateral palmar metacarpal nerves, dorsal branch of the ulnar nerve (cutaneous sensation), & musculocutaneous nerve branch (cutaneous sensation)
where is a low 4 point block performed in a forelimb?
palmar nerves: inject anesthetic between the flexor tendons & suspensory ligament on each side (stay in the sub cutis!!!), palmar metacarpal: pass needle under the buttons of splint bones, & cutaneous branches: block by leaving a bleb SQ as the needle is withdrawn after performing the metacarpal nerve block
what are the boundaries of the injection site for a low 4 point block?
palmar nerves between the flexor tendon & suspensory ligament, metacarpal nerves under the buttons on splint bones, & cutaneous nerves as you withdraw the needle after blocking metacarpal nerves
T/F: since 90% of all lamenesses are in the foot, most conditions will be blocked by a PD, abaxial sesamoidean, & low 4 point block
TRUE
what conditions are often blocked by a low 4 point?
fetlock joint, collateral ligament strain/sprain, sesamoiditis, proximal sesamoid fractures, P1 fractures, & condylar fractures (MCIII, cannon bone, most common)
where is a low 4 point block performed in a hindlimb?
plantar nerves: between flexor tendon & suspensory ligament, metatarsal nerves: under the buttons of splint bones, & cutaneous nerves: with a ring block of the dorsal surface of the cannon bone
what is blocked by a high 4 point block?
metacarpal region except the origin of the suspensory ligament, inferior check ligament of deep digital flexor, proximal splint bones, & cannon bone
what is a high palmar block used for?
used to anesthetize superficial metacarpal structures by blocking the medial & lateral palmar nerves at proximal metacarpus
what is a high metacarpal block used for?
anesthetizes the metacarpal nerves, most of the suspensory ligament, & interroseous ligaments of metacarpal bones
what conditions are often blocked by a high 4 point block?
bowed tendon, tenosynovitis, stress fractures of cannon bone, bucked shins, splint bone fractures, middle & low desmitis of suspensory ligament
where is a high 4 point block performed?
palmar nerves: needle inserted above communicating branch through deep fascia to the palmar nerve located between the DDF & suspensory ligament (anesthetizes superficial metacarpal region but not deep structures) & metacarpal nerves: in the junction between the cannon bone & splints deep to the suspensory ligament (blocks deep structures of the metacarpus except for the proximal metacarpus)
what conditions are not blocked with a high 4 point?
high suspensory desmitis, splints, high splint fractures, & the inferior check ligament
what are the main reasons to arthrocentes a joint in a horse?
remove a sample for visualization, administer therapeutic drugs, administer a diagnostic substance for radiograph contrast studies, & to administer an anesthetic
what is arthrocentes?
puncturing & aspiration of a joint
how is a joint block done for a dorsal fetlock/pastern/coffin joint?
same for all three joints - insert the needle proximal to the joint under the common/long digital extensor tendon laterally & pass obliquely into the dorsal pouch
how is a palmar approach to the coffin joint done for a block?
needle is placed slightly above the deepest indentation of the fossa above the bulbs of the heel - needle is directed dorsally & distally toward midpoint between the coronary band & toe of the foot
how is a palmar approach to the fetlock joint performed?
flex the fetlock & palpate the boundaries of the palmar pouch (suspensory ligament & cannon bone just proximal to the joint), insert the needle dorsal to the suspensory ligament & palmar to the cannon bone
what are the boundaries used for a palmar pouches of the fetlock joint?
proximal: button of splint bone, dorsal: cannon bone, distal: proximal sesamoid bone, & palmar: suspensory ligament
what are the boundaries used for a dorsal pouches of the fetlock joint?
proximal to the joint & obliquely under the extensor tendon
