📝 STANDARD DESCRIPTION:
Longest, strongest bone of the body. Single bone of the thigh.
Ox Standard:
Proximal end:
- Head: rounded; fits acetabulum; has fovea capitis (pit) for ROUND LIGAMENT.
- Neck: connects head to shaft.
- Greater Trochanter: large lateral process; gluteal muscles attach.
- Lesser Trochanter: medial; iliopsoas inserts.
- Trochanteric Fossa: pit between the two trochanters.
Shaft: Cylindrical, slightly curved.
Distal end:
- Medial & Lateral Condyles: articulate with tibia.
- Trochlea (patellar groove) — V-shaped, on cranial surface; receives PATELLA.
- Medial trochlear ridge HIGHER & LARGER than lateral (especially in horse — basis of stay apparatus).
- Intercondylar fossa: deep notch between condyles.
SPECIAL: Third Trochanter — ONLY in HORSE (lateral side of shaft, for superficial gluteus).
📚 DETAILED DESCRIPTION:
FEMUR — THIGH BONE / OS FEMORIS
The femur is the longest and strongest bone in the body. It transmits body weight from the hip joint to the stifle joint.
PROXIMAL END (HIP END):
• Head: Smooth, ball-like; sits inside the acetabulum. It has a small pit, the fovea capitis, where the ligament of the head of femur (round ligament) attaches.
• Neck: Constricted part below the head. The angle of inclination between neck and shaft is approximately 130-140° in large animals.
• Greater Trochanter: Massive lateral projection; site for attachment of gluteal muscles.
• Lesser Trochanter: Smaller, on caudo-medial aspect; iliopsoas (psoas major + iliacus) inserts here.
• Trochanteric fossa: Pit between the two trochanters.
SHAFT: Cylindrical body. Lateral side carries the third trochanter in HORSE only — a unique flat bony plate to which the superficial gluteal inserts.
DISTAL END (STIFLE END):
• Medial & Lateral Condyles: Two large rounded surfaces for articulation with the tibia.
• Intercondylar fossa: Deep pit between condyles, lodges cruciate ligaments.
• Trochlea (patellar groove): V-shaped groove on the cranial surface of the distal femur in which the patella slides up and down. The medial trochlear ridge is taller and more prominent than the lateral one — this asymmetry is the key to the equine 'stifle lock'.
• Supracondylar fossa on caudal surface — origin of superficial digital flexor.
NUTRIENT FORAMEN: Usually on the caudal surface of mid-shaft.
UG MEMORY: Femur features → 'HEAD-NECK-2 trochanters above, 2 condyles + groove below'.
// COMPARATIVE ANALYSIS
| HORSE |
Third trochanter PRESENT on lateral shaft. Medial trochlear ridge very tall & hooked at top — patella locks over it (stay apparatus). |
| DOG |
No third trochanter. Trochlear ridges nearly equal. Hip dysplasia common. |
| PIG |
Short, robust femur; no third trochanter. |
| FOWL |
Short, light femur; no third trochanter. Held nearly horizontal under body. |
CLINICAL RELEVANCE
Femoral Head Fracture / Capital Femoral Fracture: Common in puppies/calves after road accidents.
Upward Fixation of Patella (Horse): The medial patellar ligament catches over the tall medial trochlear ridge → leg is locked in extension; the horse drags the toe.
