Horse Leg Anatomy: Bones, Joints & Tendons Explained

The horse leg has no muscles below the knee. That single fact explains almost everything about why leg injuries happen and why leg soundness is the foundation of every horse's career and comfort.

Quick Answer: The horse leg is a complex system of bones, joints, tendons, and ligaments designed for speed and endurance, with no muscles below the knee. Understanding this anatomy helps you catch injuries early and keep your horse sound.

From the fetlock down, everything runs on tendons and ligaments. These rope-like structures transmit force from the muscles higher up, absorb shock, stabilize joints, and store elastic energy for efficient movement. They do incredible work. They also operate near their physical limits during fast exercise, which is why tendon and ligament injuries rank among the most common problems in athletic horses.

You don't need a veterinary degree to benefit from understanding leg anatomy. Knowing what's inside those legs changes how you evaluate swelling, how you talk to your vet, and how you make decisions about conditioning, footing, and daily care.

Why Should Every Horse Owner Understand Leg Anatomy?

A single front leg absorbs roughly 60 to 65 percent of the horse's body weight with every stride. At a gallop, each leg handles forces two to three times the horse's total body weight. That's over a ton of force slamming through structures thinner than your wrist.

The lower leg manages all of this without a single muscle fiber. Just bones, tendons, ligaments, and specialized connective tissue. This design is brilliantly efficient for covering ground, but it creates vulnerability. There's no muscular cushion to absorb excess force. Every overload goes straight to tendon and ligament fibers.

When you know the anatomy, you catch problems earlier. You feel heat in a tendon and understand what it means. You spot subtle swelling around a fetlock and know it matters. You describe findings to your vet in terms they can act on immediately. That kind of knowledge pays for itself many times over.

The Bones of the Horse Leg

Bones provide the rigid framework. Everything else attaches to them, wraps around them, or passes between them.

The Forelimb (Front Leg)

The front leg starts at the scapula (shoulder blade), which meets the humerus (upper arm) at the shoulder joint. The humerus connects to the radius and ulna at the elbow. In horses, the ulna is mostly fused to the radius and forms the point of the elbow.

Below the elbow, the radius runs down to the knee. The equine "knee" is technically the carpus, and it's actually equivalent to your wrist, not your knee. It contains seven or eight small carpal bones arranged in two rows, a design that provides flexion while distributing concussive forces across multiple joints.

Below the carpus sits the cannon bone (third metacarpal), a long, strong bone running to the fetlock joint. Flanking it are two splint bones (second and fourth metacarpals), small, tapering remnants of toes that horses lost millions of years ago during evolution. They serve as attachment points and occasionally cause problems, but they're mostly leftover hardware.

The Hindlimb (Back Leg)

The hind leg starts at the pelvis, connects through the femur to the stifle joint (equivalent to the human knee and the largest joint in the horse's body), then runs through the tibia and fibula down to the hock. The hock is a complex joint equivalent to the human ankle. It's built from six bones and generates the propulsive power for every stride the horse takes.

Below the hock, the structure mirrors the front leg: cannon bone, splint bones, fetlock, pasterns, and coffin bone.

The Lower Leg (Front and Hind)

From the fetlock down, both legs share the same architecture:

• Long pastern bone (P1): First phalanx, running from fetlock to pastern joint.
• Short pastern bone (P2): Second phalanx, a shorter bone between the pastern and coffin joints.
• Coffin bone (P3): Third phalanx, sitting entirely within the hoof capsule. This is the bone that rotates or sinks in laminitis.
• Navicular bone: A small, shuttle-shaped bone behind the coffin joint that acts as a pulley for the deep digital flexor tendon. Navicular disease is one of the most common causes of chronic front-leg lameness.
• Sesamoid bones: Two small bones at the back of the fetlock joint, forming a pulley system for the tendons running down the back of the leg.

Joints of the Horse Leg

Joints let the leg flex, extend, and absorb shock. Each one is wrapped in a joint capsule filled with synovial fluid, which lubricates the surfaces and feeds the cartilage.

High-Motion Joints

These joints are built to move:

• Shoulder joint: Ball-and-socket design allowing significant range of motion for stride length.
• Elbow: Hinge joint for flexing and extending the forearm.
• Stifle: The most complex joint in the horse. Contains menisci, cruciate ligaments, and a patella, just like a human knee.
• Fetlock: A high-motion hinge joint that hyperextends (drops toward the ground) with every stride, absorbing enormous force. It's under constant stress.

Low-Motion Joints

These joints prioritize stability and shock absorption over range of motion:

• Carpus (knee): Flexes significantly, but its main job is distributing concussion through its multiple small bones.
• Hock: Most movement happens in the upper portion. The lower hock joints barely move at all and are prime locations for arthritis (bone spavin).
• Pastern joint: Limited motion. Contributes to shock absorption.
• Coffin joint: Sits inside the hoof with small but critical range of motion.

Healthy joints require good cartilage, adequate synovial fluid production, and balanced forces across the joint surface. When any of these break down, you get arthritis, swelling, and pain. Regular exercise, proper trimming and shoeing, appropriate footing, and targeted joint support all play a role in keeping joints functional long-term.

Tendons: The Power Transmitters

Tendons connect muscle to bone. In the lower leg, they do all the work because there are no muscles down there to share the load.

The Superficial Digital Flexor Tendon (SDFT)

This tendon runs down the back of the leg and is probably the most commonly injured structure in athletic horses. It originates from muscles above the knee, crosses behind the fetlock, and attaches to the pastern bones.

The SDFT functions like an elastic band, storing energy during the weight-bearing phase of each stride and releasing it for propulsion. This makes horses incredibly efficient movers. It also means the tendon routinely operates at 90% or more of its breaking strain during fast work. There's very little margin for error. When it fails, you get a bowed tendon, which can end a competitive career if severe.

The Deep Digital Flexor Tendon (DDFT)

The DDFT runs deeper than the SDFT and continues all the way to the coffin bone inside the hoof, passing over the navicular bone along the way. It stabilizes the coffin joint and controls hoof placement. DDFT problems are closely linked to navicular syndrome.

The Common Digital Extensor Tendon

Runs down the front of the leg and extends (straightens) the lower limb during each stride. Less commonly injured than the flexor tendons but can suffer direct trauma.

Caring for Tendons

Run your hands down your horse's legs every day. Feel the tendon area behind the cannon bone. Compare left to right. You're checking for heat, swelling, thickening, or pain on pressure. Any change from normal deserves rest and a vet visit.

Tendons heal slowly because their blood supply is limited. Prevention through proper conditioning, appropriate footing, and adequate warm-up before intense work always beats treatment after the damage is done.

Ligaments: The Stabilizers

Ligaments connect bone to bone and keep joints from moving where they shouldn't.

The Suspensory Ligament

This is arguably the most important structure in the lower leg. It's technically a modified muscle (the interosseous muscle) that evolved to function almost entirely as a ligament in modern horses.

It starts at the back of the cannon bone just below the knee (or hock in the hind leg), runs down between the splint bones, then splits into two branches that attach to the sesamoid bones at the back of the fetlock. From there, extensor branches continue forward and merge with the common digital extensor tendon.

Its job? Supporting the fetlock joint and preventing it from dropping too far toward the ground during weight-bearing. Suspensory ligament injuries are extremely common in sport horses. They can occur in the body, at the origin, or in either branch. These injuries often produce subtle, intermittent lameness that's frustratingly difficult to diagnose without ultrasound or MRI.

The Collateral Ligaments

Every joint has medial (inside) and lateral (outside) collateral ligaments that prevent side-to-side movement. They're critical for stability. Less commonly injured than the suspensory, but when they do fail, the joint instability is significant.

The Inferior Check Ligament

This ligament connects the back of the knee to the deep digital flexor tendon, supporting the DDFT and helping distribute forces. Check ligament injuries are fairly common and generally respond well to rest and controlled rehab.

The Distal Sesamoidean Ligaments

These connect the sesamoid bones to the pastern bones below and are part of the suspensory apparatus. Damage here can cause a "dropped fetlock" appearance where the joint sinks abnormally close to the ground.

The Hoof: Where It All Comes Together

The hoof is not just a hard shell. It's a dynamic, living structure that absorbs shock, assists circulation, and protects the delicate internal anatomy. Inside the hoof capsule, you'll find the coffin bone, the navicular bone, the digital cushion (a fibro-fatty pad for shock absorption), the laminae (tissue layers that bond the hoof wall to the coffin bone), and an extensive blood supply supporting constant hoof growth.

Hoof balance directly affects everything above it. An unbalanced hoof places uneven stress on joints, tendons, and ligaments all the way up the leg. This is why regular farrier care matters so much, and why the farrier-vet partnership is essential when managing leg problems. For a deeper look at hoof structure, explore our 3D Explorer.

What Are the Most Common Horse Leg Problems and Warning Signs?

With the anatomy in mind, here are the problems you're most likely to encounter.

Tendon and Ligament Injuries

Heat, swelling, or pain along the back of the cannon bone or around the fetlock. The horse may or may not be obviously lame. Chronic tendon injuries can produce a visible "bow" in the tendon profile. Ultrasound is the gold standard for diagnosis and monitoring.

Joint Problems

Arthritis hits the hock, fetlock, and coffin joints most often. Look for stiffness after rest, reduced range of motion, joint effusion (puffy joint capsule), and progressive lameness. X-rays and diagnostic nerve blocks help pinpoint the source.

Splints

Inflammation or a small fracture where the splint bone meets the cannon bone, creating a hard bony lump on the inside of the cannon, usually in the upper third. Most common in young horses. Usually resolves with rest, though the bump may be permanent.

Stress Fractures

Tiny bone cracks from repetitive loading during intense training. May not show on initial X-rays and may require bone scan or MRI. Signs include localized pain, mild lameness, and sometimes subtle swelling.

Windpuffs

Soft, fluid-filled swellings around the fetlock or tendon sheath. Extremely common in mature working horses. Most are cosmetic and painless, but new or sudden swelling always deserves investigation.

Daily Leg Care: Your Routine

All the anatomy knowledge in the world means nothing if you're not putting your hands on your horse's legs regularly. Here's the daily routine that every horse owner should build into habit:

• Run your hands down all four legs every day. Feel for heat, swelling, bumps, or tenderness. Compare one leg to the other. Know your horse's normal baseline.
• Check the digital pulse at the back of the pastern. It should be faint and even. A strong, bounding digital pulse means something is wrong inside the hoof.
• Watch your horse move on a flat, hard surface. Head bobbing indicates front-leg pain. Hip hiking indicates hind-leg pain. Uneven strides tell a story.
• Keep legs clean and dry when possible. Chronic moisture invites scratches (pastern dermatitis) that can progress to deeper infections if neglected.
• Maintain a regular farrier schedule for balanced hooves and proper support through the entire limb.

Use the Symptom Advisor if you notice something unusual and want guidance on whether it warrants a vet call. Track changes over time using the My Horse journal.

Supporting Long-Term Leg Health

Beyond daily checks, these management strategies support soundness over the long haul:

• Build fitness gradually. Tendons and ligaments adapt much slower than muscles or cardiovascular fitness. Ramping up workload too fast invites injury.
• Choose appropriate footing. Too hard means excessive concussion. Too deep strains tendons. Uneven ground risks twisting injuries. Good footing has some give without being mushy.
• Warm up and cool down. Walk before asking for faster gaits to increase blood flow to tendons and ligaments. Cool down gradually after hard work.
• Use leg protection wisely. Boots and wraps can help during exercise, but they must fit correctly. Poorly fitted boots trap heat or create pressure points, causing more harm than good.
• Prioritize turnout. Free movement promotes circulation, joint health, and natural limb conditioning. Stall-bound horses are more prone to stocking up and stiffness.
• Feed for structural support. Adequate protein, copper, zinc, and balanced vitamins build strong bone, tendon, and ligament tissue. Consult your vet or nutritionist if you're unsure about your horse's diet.

When to Call the Vet

Call your veterinarian if you see any of these:

• Sudden or severe lameness
• Significant swelling, heat, or pain in any leg structure
• Any wound near a joint or tendon sheath (these are emergencies due to infection risk)
• Lameness that doesn't improve with a day or two of rest
• A leg the horse won't bear weight on
• Changes in fetlock angle or shape (potential ligament or bone failure)

Don't wait and see with leg problems. The structures are too important and too vulnerable for delayed treatment. Early intervention almost always produces better outcomes.

Frequently Asked Questions

Why are there no muscles below a horse's knee?

Horses evolved for speed and endurance. Moving muscle mass higher up the leg and using long tendons to transmit force to the lower limb reduces the weight that has to swing with each stride. Lighter lower legs mean faster, more efficient movement. The tradeoff is that the lower leg relies entirely on tendons and ligaments, which are more vulnerable to strain than muscle tissue.

What does a bowed tendon look like?

A bowed tendon creates a visible outward curve in the tendon profile behind the cannon bone, where it should normally be flat and tight. The area feels warm, may be swollen, and is often painful to pressure. Some bows are subtle and only detectable by running your hands down the leg. Ultrasound confirms the diagnosis and reveals the severity.

How can I tell if my horse's leg swelling is serious?

Swelling with heat and pain, or swelling that accompanies lameness, is always worth a vet call. Swelling in both hind legs after standing in a stall overnight (stocking up) is common and usually resolves with movement. Swelling in a single leg, swelling that doesn't resolve with exercise, or sudden new swelling should be evaluated promptly.

How often should my farrier trim or shoe my horse?

Most horses need farrier visits every 5 to 8 weeks, depending on hoof growth rate, shoe wear, and individual needs. Going too long between trims allows the hoof to grow out of balance, putting uneven stress on joints and soft tissue structures up the leg. Your farrier can help determine the ideal schedule for your horse.

For more on specific conditions, visit the Horse Encyclopedia for detailed entries on tendon injuries, joint disease, laminitis, and more.

Last reviewed: March 2026

The leg ends at the hoof, and that structure is a world of its own. Read our hoof anatomy deep dive and stifle anatomy guide for the joints that drive everything.

Sources

• Texas A&M College of Veterinary Medicine & Biomedical Sciences. "Equine Anatomy." vetmed.tamu.edu
• Dyce, K.M., Sack, W.O., & Wensing, C.J.G. Textbook of Veterinary Anatomy, 4th Edition. Saunders, 2009.
• AAEP. "Lameness: The Basics." aaep.org
• Merck Veterinary Manual. "Musculoskeletal System of Horses." merckvetmanual.com
• UC Davis School of Veterinary Medicine. "Equine Sports Medicine." vetmed.ucdavis.edu