1. First Year Anatomy Nicholas Urbanek, BVMS, MRCVS
The Fetlock and Foot
First Year Anatomy
Nicholas Urbanek, BVMS, MRCVS

2. What is the Fetlock?
Fetlock is the common name for the metacarpophalangeal and metatarsophalangeal joints (MCPJ and MTPJ) of the horses.
It is formed by the junction of the third metacarpal (forelimb) or metatarsal (hindlimb) bones (cannon bones) proximally and the proximal phalanx (pastern bone) distally.
Paired proximal sesamoid bones articulate with the palmar or plantar distal surface of the third metacarpal or metatarsal bones and are rigidly fixed to the proximo-palmar /-plantar edge of the proximal phalanx.

3. Common Views
Lateral
Lateral
DMPLO DP
DLPMO

4. Lateral View A: Third MC/MT bone B: Proximal phalanx (P1)
1: Sagittal ridge
3: Palmar process of proximal phalanx
4: Condyles of third metacarpal bone
5: Proximal sesamoid bones

5. Dorso-palmer/-plantar (DP)
A: Third MC/MT bone
B: Proximal phalanx
C: Medial proximal sesamoid bone
D: Lateral proximal sesamoid bone
E: Metacarpo(tarso)-phalangeal joint
J: Depression for medial collateral ligament attachment
1: Sagittal ridge

6. Obliques – A Review The view is named for the projection of the beam.
Typically taken at 45 degree angles off the sagittal axis of the limb.
Markers must be in place, otherwise unable to distinguish medial from lateral side.
Dorsomedial-palmarolateral (plantar)oblique (DMPLO)
Dorsolateral-palmaromedial (plantar)oblique (DLPMO)

7. DLPMO A: Third MC/MT bone B: Proximal phalanx
C: Medial proximal sesamoid bone
D: Lateral proximal sesamoid bone
E: Metacarpo(tarso)-phalangeal joint
1: Sagittal ridge
3: Palmar process of proximal phalanx/Lateral
palmar tubercle (eminence)
6: Medial condyle of third MC/MT bone
DLPMO
Dorsal
Palmar/Pl
Medial
Lateral

8. DMPLO A: Third MC/MT bone B: Proximal phalanx
C: Medial proximal sesamoid bone
D: Lateral proximal sesamoid bone
E: Metacarpo(tarso)-phalangeal joint
1: Sagittal ridge
2: Lateral condyle of third metacarpal/tarsal bone
3: Palmar process of proximal phalanx
DMPLO
Dorsal
Palmar/Pl
Medial
Lateral

9. Fetlock Forelimb vs Hindlimb Bulging 
The MT is convex at its distal aspect
DP view - Hindlimb
DP view - Forelimb
The proximal sesamoid bones
are higher
The proximal sesamoid bones
are more triangular

10. Foot or Distal Limb Composed of four bones Multiple views obtained
Proximal, middle, distal (first, second, and third) phalanx
Navicular bone
Multiple views obtained
Lateral
Dorsopalmar(plantar) view
Dorsoproximal-palmar(plantar)odistal oblique
“Upright Pedal” or “High coronary”
Palmar(plantar)oproximal-palmar(plantar)odistal
“Skyline Novicular”
Other oblique views
The foot should have no shoe, be trimmed, and sulci should be packed with Play-Doh
Marker always to the lateral side…can not tell laterality otherwise

11. Lateral view A: Middle phalanx B: Third phalanx C: Navicular bone
1: Proximal interphalangeal joint
2: Distal interphalangeal joint
3: Extensor process
4: Dorsal surface
5: Palmar process

12. Dorsopalmar(plantar) view
A: Middle phalanx
B: Distal phalanx
C: Navicular bone
6: Proximal interphalangeal joint
7: Distal interphalangeal joint R 6 A 7 C B

13. Dorsoproximal-palmar(pl)odistal oblique view6 5 2 7 B A
A: Middle phalanx
B: Third phalanx
C: Navicular bone
1: Proximal interphalangeal joint
2: Distal interphalangeal joint
3: Extensor process
4: Dorsal surface
5: Palmar process
6: Vascular channel
7: Solar margin R
“Upright pedal”
“High coronary”
Dorsoproximal-palmar(plantar)odistal oblique view

14. Palmaro(plantar)oproximal-palmar(plantar)odistal oblique view “Skyline Novicular”
C: Navicular bone
3: Articular surface
8: Palmar aspect of middle phalanx
9: Nutrient foramen
10: Sagittal ridge
11: Articulation between navicular bone
and middle phalanx