Equine Hind Limb

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Equine Hind Limb

• Vessels and Nerves
• Tarsal Radiographs
• Paragraphs 294-305
• March 29, 2000 Dr. Provo

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Sacrosciatic Ligament - Nerves (S363)
greater sciatic foramen
lesser sciatic foramen
caudal gluteal nerve
caudal rectal nerve
pudendal nerve
caudal cutaneous femoral nerve
sciatic nerve
cranial gluteal nerve
ischiatic spine
greater trochanter
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Vessels Associated with Sacrosciatic Ligament
(S683)
Lateral view
cranial gluteal
caudal gluteal
internal pudendal
anastomotic branch of obturator vein
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Motor Nerves of the Lumbosacral Plexus Going to
the Hind Limb
Nerve
Muscles Supplied
semimembranosus, semitendinosus, biceps femoris,
rotator muscles of hip
Sciatic
sublumbar muscles, quadriceps femoris, sartorius
(saphenous nerve)
Femoral
Obturator
pectineus, gracilis, adductor, external obturator
Cr. Gluteal
tensor fascia lata, gluteal muscles
Cd. Gluteal
superficial and middle gluteal, vertebral head of
biceps femoris and semitendinosus
Common Peroneal
biceps femoris, flexors of hock, extensors of
digit
Tibial
extensors of hock, flexors of digit
Reminder REVIEW flexion and extension in the
rear limb!
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flexion
flexion
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Thinking ahead to 2002-2003

• A horse has a bump in this location
• What joint is in this area?
• This is a common injection site
• What muscles are involved?
• There is a swelling here
• What structure could be involved?

sacroiliac
biceps femoris and semitendinosus
popliteal lymph node
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Gluteal Muscles Organization, and Insertion
Points
Superficial
Middle
Deep
Third trochanter
Convexity of greater trochanter
Superficial part
Deep part (accessory head)
main part
piriformis
Crest distal to convexity
Summit of greater trochanter
Intertrochanteric crest and third trochanter
Trochanteric bursa
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Greater Trochanter
Summit (insertion of main part of superficial
part of middle gluteal)
Area of bursa
Convexity (deep gluteal inserts on medial side)
Intertrochanteric crest between greater and third
trochanters (insertion of piriformis of
superficial part of middle gluteal)
Roughened area for insertion of deep part of
middle gluteal
third trochanter (insertion of superficial
gluteal and of piriformis)
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Leg Muscles
long digital ext.
lat. dig. extensor
deep dig. flexor
extensor retinacula proximal middle distal latera
l
S685
S445, lateral view
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Extensor Retinacula
S447

• Peroneus tertius (yellow)
• Cranial tibial (blue)
• Long Digital Extensor (green)
• Lateral Digital Extensor (red)
• Extensor Retinacula (orange)
• proximal
• lateral (not shown)
• middle
• distal
• Emergence of the cranial tibial tendon from
  bifurcation of the peroneus tertius

M
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Cutaneous Innervation some general notes

• Three nerves supply the sensory innervation from
  mid-crus distally
• Saphenous (a branch of the femoral) tibial
  common peroneal (the last two are branches of the
  sciatic)
• There is a lot of overlap between branches of
  common peroneal and tibial nerves.
• General distribution
• Common peroneal to dorsal and dorsolateral
  surface of hock and metatarsus
• Tibial to plantar and plantaromedial surface of
  hock and metatarsus.
• Overlap in the digit and plantarolateral surface
  of metatarsus.

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Cutaneous Innervation
12 branch of common or superficial peroneal 13
branch of tibial 12a. lat. cut. sural 11.
saphenous 13. caudal cutan. sural 12b. sup.
peroneal 12a. med. or lat. dorsal metatarsal
n. 13. dorsal br. of digital n.
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Example Quiz Questions

• What is the action of these muscles on the hock?
• What nerve innervates these muscles?

flexion
common peroneal
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Sensory Nerve Supply to Distal Limb Summary
sciatic
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Schematic of Common Peroneal and Tibial Nerves

• Sciatic divides
• Common peroneal
• Tibial
• Common peroneal divides
• Superficial branch
• Deep branch
• stays with cranial tibial artery
• Tibial divides
• Medial plantar
• Lateral plantar
• Note that the rear digit has both plantar and
  dorsal nerves.

From the Mediclip image bank
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Tibial Nerve, Plantar View branching identical
to pattern in forelimb
Tib.
F
M
L
tibial nerve
T
C
medial plantar nerve
lateral plantar nerve
c
4
12
3
medial plantar metatarsal nerve
2
3
4
lateral plantar metatarsal nerve
communicating branch
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Deep Branch of Peroneal Nerve (Dorsal View)
L
M
peroneal nerve, deep branch
lateral dorsal metatarsal nerve
medial dorsal metatarsal nerve
(both dorsal metatarsals exchange fibers with
plantar metatarsal nerves)
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Digital and Metatarsal Nerves, Medial View
medial dorsal metatarsal n. (from deep peroneal)
medial plantar (from tibial)
medial plantar metatarsal (from tibial)
medial dorsal digital nerve (from peroneal and
tibial)
medial plantar digital nerve
dorsal branch of medial plantar digital nerve
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Arterial Supply to Distal Limb Overview
external iliac
saphenous
caudal femoral
caudal tibial
anastomosis (at hock)
perforating tarsal (prox. perf. branch)
plantar arteries
deep plantar arch
plantar metatarsal arteries
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Example Quiz Question

• What branch of the sciatic nerve supplies the
  plantar nerves?
• The cranial tibial artery continues across the
  dorsal aspect of the tarsus as the artery.

tibial
dorsal pedal
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Schematic of Major Arterial Supply
From the Mediclip image bank
ext. iliac femoral popliteal cr.
tibial dors. pedal d. metatars. III dist.
perf. branch digital aa.
palpable
medial view (Sack and Habel p. 104)
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Origin of (Plantar) Digital Vessels
main blood supply from dorsal metatarsal
III (great metatarsal a.)
crosses between MT III IV (as distal
perforating br.)
divides into medial and lateral digital arteries
medial and lateral plantar (and plantar
metatarsal, not shown) arteries join plantar
digitals at fetlock
lateral
plantar
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Cross Section - Metatarsus
long digital extensor dorsal
metatarsal artery III and lat. dorsal metatarsal
nerve lat. plantar metatarsal artery and
nerve lat. plantar vein, artery, nerve
medial dorsal metatarsal nerve plantar mt.
v. med. plantar mt. artery and nerve dorsal
common dig v. II med. plantar vein, artery,
nerve
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General Comments about Digital Vessels and Nerves
of the Rear Digit

• The arrangement of the digital vessels is
  essentially identical in the rear digit to that
  in the thoracic digit.
• However, the rear digital vessels have more
  collateral circulation contributing to their
  formation than in the forelimb.
• The arrangement of the plantar digital nerves is
  essentially identical to that of the palmar
  digital nerves.
• The rear limb also has dorsal digital nerves.
• Remember this when you do a nerve block in the
  rear digit.

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Example Quiz Question

• 1. Breed?
• 2. What nerve can be palpated here?
• 3. What artery can be used to take a pulse here?

thoroughbred
tibial
dorsal MT III
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Thinking Ahead to 2002-2003

• Which radiographic projection of the tarsus would
  be the best to demonstrate each of the following
  lesions?
• Fracture of the lateral trochlear ridge (hint
  this is on the dorsolateral aspect of the
  tarsus)
• Separation of MT II and III
• Chip fracture of the lateral aspect of tarsal
  bone 4

plantarolateral dorsomedial oblique
plantarolateral dorsomedial oblique
dorsoplantar
Left tarsus
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Dorsoplantar (DPl) Tarsal Radiographs
left dorsal
right plantar
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Lateromedial (LM) Tarsal Radiographs
left lateral
right medial
(slightly oblique)
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Oblique Tarsal Radiographs
Dorsolateral-Plantaromedial Oblique (DLPM-O) of
Left Tarsus
Plantarolateral Dorsomedial Oblique (DMPL-O) of
Left Tarsus

• Usually called a DMPL-O, even though the x-rays
  went the opposite direction. (They usually dont
  put the head of the machine under the horse.)

Areas best visualized
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Dorsolateral-Plantaromedial Oblique (DLPM-O) of
Left Tarsus
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Dorsomedial-Plantarolateral Oblique (DMPL-O) of
Left Tarsus
Notice the deep notch on the lateral trochlear
ridge.
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Example Quiz Question

• 1. Name the radiographic projection shown.
• 2. Which aspect of the tarsus is this?

Dorsolateral-plantaromedial oblique
Plantarolateral (hint you can see the calcaneus
on the free edge)
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The End