Equine Distal Limb

Question 1

Define ‘distal limb’

Answer 1

From the level of the carpus/tarsus, to the hoof.

Question 2

Bony segments of limb

Answer 2

• Metacarpal/metatarsal bone III (canon bone)
• Proximal sesamoid bones
• Proximal phalanx (long pastern)
• Middle phalanx (short pastern)
• Distal sesamoid bone (navicular)
• Distal phalanx (pedal bone; coffin)

Question 3

Joints of limb

Answer 3

• Metacarpophalangeal / metatarsophalangeal
  joint (MCP/MTP; fetlock)
• Proximal interphalangeal joint (PIP; pastern
  joint)
• Distal interphalangeal joint (DIP; coffin joint)

Question 4

5 parts of hoof dermis

Answer 4

• Perioplic - Coronary - Lamellar - Solar - Frog

Question 5

3 types of ligaments

Answer 5

• Collateral ligaments
• Palmar ligaments
• Sesamoidean ligaments

Question 6

collateral ligaments

Answer 6

• MCP
• PIP
• DIP

Question 7

Palmar ligaments

Answer 7

» Palmar axial and abaxial ligaments
» Annular ligaments

Question 8

Annular Ligaments

Answer 8

• Keep flexor tendons in place
• Tendon sheaths pass deep to the annular ligaments* Palmar (PAL) over MCP
• Proximal over prox P1
• Distal over distal P1

Question 9

Proximal Sesamoidean Ligaments

Answer 9

• short
• collateral
• oblique
• cruciate
• intersesamoidean
• straight
• distal (navicular)

Question 10

Types of tendons in equine distal limb

Answer 10

• Flexor tendons
• Common and lateral digital extensor tendons

Question 11

Types of tendons in equine distal limb

Answer 11

• Flexor tendons
• Common and lateral digital extensor tendons

Question 12

Types of flexor tendon

Answer 12

• Suspensory ligament (interosseous muscle)
• Deep Digital flexor tendon
• Superficial digital flexor tendon
  Going from deep to superficial

Question 13

Suspensory ligament

Answer 13

Originates from the distal row of carpal bones
Inserts upon the abaxial aspect of the proximal sesamoids
The extensor branches connect with the common digital extensor

Question 14

DDFT

Answer 14

• Inserts upon the palmar aspect of the distal phalanx
• Pass over the palmar aspect of the navicular bone
• Distal ‘check’ ligament connects to the proximal MC bone

Question 15

SDFT

Answer 15

• Inserts either side of the proximal interphalangeal joint
• Flattens and wraps around the DDFT

Question 16

Distal check ligament

Answer 16

• Stiffens the DDFT
• attaches the DDFT to the palmar carpal ligament
• Less strain placed on the DDF muscle

Question 17

Bursae of distal limb

Answer 17

• Navicular bursae; between navicular bone and the DDFT
• definition; A cavity lined with synovial membrane

Question 18

Tendon sheaths of the distal limb

Answer 18

• DDFT and the SDFT share the same tendon sheath; the digital tendon sheath
• the digital tendon sheath begins proximal to the MCP and terminates mid-level of the middle phalanx
• Lubricate passage of tendons as they slide against
  neighbouring structures and against each other
• Site of potential damage and infection

Question 19

The Navicular Apparatus

Answer 19

• Navicular bone
• Collateral sesamoidean (navicular) ligaments
• Distal sesamoidean impar (navicular)
  ligaments
• Navicular bursa
• Deep digital flexor tendon (DDFT)
• Distal digital annular ligament

Question 20

Functions of the Navicular Apparatus

Answer 20

• Navicular bone displaces DDFT away from
  DIP
• Bursa cushions both the DDFT and the nav.
  bone

Question 21

SENSORY INNERVATION OF THE DISTAL LIMB; palmar aspect

Answer 21

• Palmar aspect; medial and lateral palmar nerves alongside the SDFT; branch at the MCP into dorsal branches and palmar digital nerves
• Palmar metacarpal nerves
• Palmar digital nerves; innervates the heel of the foot

Question 22

SENSORY INNERVATION OF THE DISTAL LIMB; dorsal aspect

Answer 22

• Dorsal branches of the digital nerves; innervate toe and foot
• Dorsal metatarsal nerves