Equine Distal Limb Flashcards
Define ‘distal limb’
From the level of the carpus/tarsus, to the hoof.
Bony segments of limb
- 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)
Joints of limb
- Metacarpophalangeal / metatarsophalangeal
joint (MCP/MTP; fetlock) - Proximal interphalangeal joint (PIP; pastern
joint) - Distal interphalangeal joint (DIP; coffin joint)
5 parts of hoof dermis
- Perioplic - Coronary - Lamellar - Solar - Frog
3 types of ligaments
- Collateral ligaments
- Palmar ligaments
- Sesamoidean ligaments
collateral ligaments
- MCP
- PIP
- DIP
Palmar ligaments
» Palmar axial and abaxial ligaments
» Annular ligaments
Annular Ligaments
- 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
Proximal Sesamoidean Ligaments
- short
- collateral
- oblique
- cruciate
- intersesamoidean
- straight
- distal (navicular)
Types of tendons in equine distal limb
- Flexor tendons
- Common and lateral digital extensor tendons
Types of tendons in equine distal limb
- Flexor tendons
- Common and lateral digital extensor tendons
Types of flexor tendon
- Suspensory ligament (interosseous muscle)
- Deep Digital flexor tendon
- Superficial digital flexor tendon
Going from deep to superficial
Suspensory ligament
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
DDFT
- 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
SDFT
- Inserts either side of the proximal interphalangeal joint
- Flattens and wraps around the DDFT
Distal check ligament
- Stiffens the DDFT
- attaches the DDFT to the palmar carpal ligament
- Less strain placed on the DDF muscle
Bursae of distal limb
- Navicular bursae; between navicular bone and the DDFT
- definition; A cavity lined with synovial membrane
Tendon sheaths of the distal limb
- 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
The Navicular Apparatus
- Navicular bone
- Collateral sesamoidean (navicular) ligaments
- Distal sesamoidean impar (navicular)
ligaments - Navicular bursa
- Deep digital flexor tendon (DDFT)
- Distal digital annular ligament
Functions of the Navicular Apparatus
- Navicular bone displaces DDFT away from
DIP - Bursa cushions both the DDFT and the nav.
bone
SENSORY INNERVATION OF THE DISTAL LIMB; palmar aspect
- 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
SENSORY INNERVATION OF THE DISTAL LIMB; dorsal aspect
- Dorsal branches of the digital nerves; innervate toe and foot
- Dorsal metatarsal nerves
