Lecture 10: clinical correlates #3 Lameness and nerve blocks (Wronski)

Question 1

palpable structures in the thoracic limb

Answer 1

interosseous (suspensory) ligament
flexor tendons
palmar digital vein
palmar digital artery
palmar digital nerves

• going from dorsal to palmar on the thoracic limb just think V-A-N. the palmar vein is most dorsal, followed by the artery and finally the nerve.

Question 2

in what general direction do you conduct nerve blocks

Answer 2

distal to proximal

Question 3

palmar digital nerve block: injection site

Answer 3

bilateral inections midway between the fetlock and the coronet, dorsal to the flexor tendons and distal to the ligament of the ergot

Question 4

palmar digital nerve block: areas desensitized

Answer 4

palmar portions of the hoof, 
digital cushion, 
palmar portions of the coffin and pastern joints, 
distal part of the deep flexor tendon 
navicular bursa

Question 5

when nerves are desensitized by the palmar digital nerve block?

Answer 5

medial and lateral palmar digital nerves

Question 6

when is the palmar digital nerve block most commonly done?

Answer 6

to identify the source of lameness exhibiting signs of caudal heel syndrome

Question 7

palmar digital and dorsal branch nerve blocks: injection site

Answer 7

proximal to the ligament of the ergot at a point 1/3 of the distance from the fetlock to the coronet. the needle is then directed dorsally and anesthetic deposited at the extensor slip of the suspensory ligament

a more abaxial approach can also be blocked more proximally by a singl anaesthetic injection at the level of the proximal seamoid bones

Question 8

areas densenstized for a palmar digital and dorsal branch nerve blocks

Answer 8

entire hoof, coffin joint, and palmar aspect of the pastern joint

the abaxial block will desensitize the entire pastern joint and the palmar pouch of the fetlock joint

Question 9

nerves desensitized in a palmar digital and dorsal branch nerve block

Answer 9

dorsal branch of palmar nerve

Question 10

distal metacarpal (low volar/low palmar) block: injection site

Answer 10

blocked in the groove between the suspensory ligament and flexor tendons at the level of the palpable button of hte small metacarpal (splint) bones.

the palmar metacarpal nerves are then blocked immediately distal tot he buttons of the splint bones.

the needle is then directed dorsally to ring block from the buttons of the splint bones to the extensor tendons

Question 11

nerves desensitized in a distal metacarapal (low volar/low palmar) block

Answer 11

the ring block desensitizes the dorsal branch of the ulnar nerve

medial cutaneous antebrachial nerve

medial/lateral palmar nerves

palmar metacarpal nerves

Question 12

areas desensitized in a distal metacarpal (low volar/low palmar block)

Answer 12

entire limb distal to splint bones, ring block (not always used)

Question 13

proximal metacarpal (high volar/high palmar) block: injection site

Answer 13

1: in the groove between the suspensory ligament and the flexor tendons, slightly distal to the carpus.
2: same level axial to splint bones
3: ring block (SQ) from abaxial sides of splint bones dorsally to extensor tendons

Question 14

proximal metacarpal (high volar/high palmar) block: areas desensitized

Answer 14

entire limb distal to the carpus

superficial/deep flexor tendons

digital tendon sheath

(carpometacarpal and midcarpal joint sacs can get anesthesized if there is greater than expected diffusion)

Question 15

proximal metacarpal (high volar/high palmar) block: nerves desensitized

Answer 15

palmar nerves

dorsal branch of ulnar

medial cutaneous antebrachii

Question 16

coffin joint: needle insertion

Answer 16

1 cm proximal to the coronet at the lateral border of the common digital extensor (1.5 cm lateral to dorsal midline of limb). needle needs to be directed distally, caudally and medially

Question 17

fetlock joint

Answer 17

proximal palmar pouch between the suspensory ligament and the 3rd metacarpal bone slightly proximal to the proximal sesamoids bones.

OR

in the dorsal aspect of the fetlock joint slightly medial or lateral to the common digital extensor tendon

Question 18

carpal joint - for the midcarpal and carpo-metacarpal sacs

Answer 18

with carpus flexed, insert into distal dimples med/lat to tendon of extensor carpii radialis

these two joints communicate so anesthetic will diffuse through both joint sacs

Question 19

carpal joint - for the radiocarpal joint sac

Answer 19

carpus flexed - more proximal dimple (3 cm proximal to distal dimples)

Question 20

navicular bursa

Answer 20

insert needle in the digital fossa at the palmar/plantar midline and direct needle dorsally parallel to the sole. it passes through the deep digital flexor tendon and hits the navicular bone. withdrawal slightly to enter bursa between distal sesamoid and deep digital flexor tendon.

Question 21

tibiotarsal joint sac: injection site

Answer 21

insert slightly medial to tendons of tibialis cranialis and peroneus tertius, at level of medial malleolus of tibia

Question 22

tibiotarsal joint sac: areas desensitized

Answer 22

between tibia and talus - swelling here is called bog spavin

medial (cunean) tendon of tibialis cranialis is sometimes rsected to relieve pressure from chronic bog spavin

Question 23

tibiotarsal joint sac: what to avoid

Answer 23

the cranial branch of medial sphaneous vein - its very superficial

Question 24

proximal intertarsal joint sac: injection site

Answer 24

since it communicates with the tibiotarsal joint sac there is no injection necessary (because you will have done the tibiotarsal injection first and it will diffuse into proximal intertarsal)

Question 25

proximal intertarsal joint sac: area desensitized

Answer 25

between talus and calcaneus, proximally and central and 4th tarsal bones distally

Question 26

distal intertarsal joint sac: injection site

Answer 26

inserted at the T-shaped junction of central, 3rd and fused 1st and 2nd tarsal bones on medial aspect of hock, dorsal to cunean tendon.

always on medial side, so you dont puncture the cranial tibial artery

Question 27

distal intertarsal joint sac: area desensitized

Answer 27

between central tarsal, T3 and fused T1 and T2

Question 28

tarsometatarsal joint sac: injection site

Answer 28

on lateroplantar aspect of hock between T4 and metacarpal 4 in a depression slightly proximal to head of metacarpal 4

Question 29

tarsometatarsal joint sac: area desnsitized

Answer 29

between tarsal bones 1, 2, 3, 4 proximally and metacarpal bones distally