
What Causes Ankles to Swell? A Vascular & Podiatry Expert Explains
Swollen Ankles: Causes, Warning Signs, and When to See a Specialist in Miami Nearly one in three adults will experience noticeable ankle swelling at
Medically Reviewed by
Dr. Peter Hanna, DPM
Board Certified Podiatrist
Every time you stand, walk, run, or climb stairs, roughly 26 bones, 33 joints, and over 100 muscles, tendons, and ligaments execute a perfectly coordinated sequence of movements beneath you. Most of us never think about foot anatomy until something hurts. But understanding the structure of the foot, especially its tendons and bones, is the first step toward protecting it. Learn more about our comprehensive podiatry services in Miami.
At South Florida Multispecialty Medical Group, our podiatry team in Miami sees patients every week whose foot pain stems from an underlying structural issue they never knew existed. Whether you are dealing with heel pain, ankle instability, or a tendon injury, a clear understanding of your foot’s architecture helps you make better decisions about your care.

The foot is divided into three anatomical regions: the hindfoot, the midfoot, and the forefoot. Each region handles distinct mechanical tasks, and together they form one of the most efficient load-bearing structures in the human body.
The hindfoot is the foundation of the foot. It consists of two bones: the calcaneus (heel bone) and the talus (ankle bone).
The calcaneus is the largest bone in the foot. It absorbs the initial impact of each step, acting like a natural shock absorber. The talus sits on top of the calcaneus and connects the foot to the lower leg bones, the tibia and fibula, forming the ankle joint. Together these two bones create the subtalar joint, which allows the foot to rotate inward and outward, a motion essential for walking on uneven terrain.
The midfoot bridges the hindfoot and forefoot. It consists of five bones: the navicular, cuboid, and three cuneiform bones (medial, intermediate, and lateral). These bones are tightly bound by ligaments and form the arch of the foot. The midfoot absorbs and distributes compressive forces before passing them forward to the toes.
Unlike the hindfoot, the midfoot has very limited mobility. Its primary job is structural, maintaining the integrity of the arch while transferring load during the push-off phase of walking and running.
The forefoot contains the five metatarsal bones and the 14 phalanges (toe bones). The metatarsals form a fan-like array that spreads weight across the ball of the foot. The phalanges allow the toes to grip the ground, balance the body, and provide the final propulsion force when you push off during a stride.
The great toe has two phalanges, proximal and distal, while the remaining four toes each have three. Small sesamoid bones are also found near the base of the great toe, embedded within tendons to reduce friction and absorb pressure.
Tendons are dense, fibrous connective tissues that connect muscles to bones. In the foot and ankle, they act as mechanical cables, transmitting the force generated by muscles in the leg into movement at the foot. Without tendons, even the strongest leg muscles would be useless for walking or running.
Let us look at the four primary motions of the foot and the tendons that drive them.
The Achilles tendon is the largest and most powerful tendon in the human body. It originates from the calf muscles, the gastrocnemius and soleus, and attaches to the back of the calcaneus (heel bone). Its primary function is plantar flexion: pointing the foot downward, which is the motion that drives you forward when you walk, run, or climb stairs.
Because the Achilles tendon absorbs enormous tensile forces, it is also one of the most commonly injured tendons in the body. Achilles tendinitis and Achilles ruptures are conditions we treat frequently at our podiatry clinic in Miami. Explore our tendon injury treatment options. A sudden increase in training load, tight calf muscles, or improper footwear can all push this tendon past its tolerance.
The posterior tibialis tendon runs along the inside of the ankle and connects the posterior tibialis muscle to the bones of the midfoot. Its primary role is inversion, turning the foot inward, and it is the single most important tendon for maintaining the medial arch of the foot.
When this tendon weakens or tears, the arch gradually collapses, leading to adult-acquired flatfoot deformity. This condition causes progressive pain along the inside of the ankle and foot. We see many patients with this issue, often describing a dull, persistent ache that worsens with activity. Learn about our flat foot treatment in Miami.
The peroneal tendons run along the outside of the ankle, just behind the lateral malleolus (outer ankle bone). There are two main peroneal tendons: the peroneus longus and the peroneus brevis. Together, they control eversion, turning the foot outward, and they play a critical role in stabilizing the ankle during lateral movements.
Athletes who participate in sports that involve cutting, jumping, or running on uneven surfaces are particularly vulnerable to peroneal tendon injuries. Peroneal tendon tears or subluxation can mimic lateral ankle sprains, which is why proper imaging and an expert clinical assessment matter. Find out how we treat ligament sprains and tears.
The anterior tibialis tendon runs down the front of the lower leg and crosses the top of the ankle onto the medial side of the foot. It enables dorsiflexion, pulling the foot upward toward the shin, which is the movement that lifts the foot off the ground during the swing phase of walking.
Weakness or rupture of this tendon leads to “foot drop,” a condition where the foot cannot clear the floor during walking, increasing the risk of tripping and falls. In older adults, this is a serious concern that warrants prompt evaluation.
A common source of confusion for patients is the difference between tendons and ligaments. Both are fibrous connective tissues, but they serve different purposes. Tendons connect muscles to bones, enabling movement. Ligaments connect bones to other bones, providing joint stability.
In the foot, both work continuously as a team. For example, when you land from a jump, the Achilles tendon absorbs the pulling force of the calf muscles while the lateral ankle ligaments prevent the foot from rolling too far outward. When either structure fails, the other is placed under increased stress, which is why untreated ligament sprains often lead to tendon overuse injuries over time.

While not technically a tendon, the plantar fascia deserves its own discussion in any guide to foot anatomy. It is the longest ligament in the foot, originating at the calcaneus and running along the bottom of the foot to the base of the toes. It acts like a bowstring, maintaining the arch of the foot and absorbing compressive forces during weight-bearing activity.
Plantar fasciitis, inflammation of this tissue, is one of the most common causes of heel pain we treat. See how our sports podiatrist in Miami can help with heel and arch pain. Patients typically describe a sharp, stabbing pain with the first steps of the morning that gradually improves as the tissue warms up. Left untreated, the condition can become chronic and significantly impact quality of life.

The real engineering marvel of the foot is not any single structure. It is the coordination between all of them. Consider what happens during a single walking stride:
This entire sequence happens in under a second, thousands of times per day. Any disruption, whether a tendon injury, a stress fracture, or structural deformity, can alter the entire chain of movement. According to the U.S. Centers for Disease Control and Prevention (CDC), conditions like diabetes, which affect millions of Americans, can significantly compromise foot structure and function over time, making preventive foot care essential.
Understanding foot anatomy helps explain why so many common conditions develop. Here are some of the most frequent issues our podiatry team in Miami diagnoses and treats:
Inflammation of the plantar fascia, usually caused by repetitive stress, tight calf muscles, or biomechanical imbalances. It accounts for the majority of heel pain cases we evaluate. Learn more about rearfoot disorders and heel pain treatment.
Overuse or degeneration of the Achilles tendon produces pain and stiffness at the back of the heel. Runners and middle-aged active adults are most at risk. Without proper treatment, the tendon can progress to a partial or complete rupture.
When the posterior tibialis tendon weakens, the medial arch collapses. Over time, this shifts load to other structures and can cause knee, hip, and lower back pain in addition to foot pain.
A bunion forms when the metatarsophalangeal joint of the great toe drifts out of alignment. Muscle and tendon imbalances contribute to this bony deformity, which causes progressive pain and difficulty with footwear. Find out about our bunion treatment in Miami.
An imbalance in the tendons and muscles that normally hold the toe straight causes the middle joint of the toe to buckle. Over time the deformity becomes rigid and painful. Read about our hammertoe treatment options.
The plantar plate, a tough fibrocartilaginous structure beneath the metatarsophalangeal joints, can tear from chronic overloading. This causes forefoot pain, toe misalignment, and instability during walking. Learn about plantar plate tear diagnosis and treatment.
Fractures of the tibia, fibula, or talus compromise the ankle joint’s ability to bear weight. Proper alignment during healing is critical to restoring normal biomechanics. See how we treat ankle fractures at SFL Medical Group.
Given the complexity of foot anatomy, prevention is always more effective than treatment. The American Podiatric Medical Association (APMA) notes that 75% of Americans will experience a foot problem at some stage in their lives, reinforcing the importance of proactive care. Here are practical steps to protect your tendons and bones:
If you are experiencing foot or ankle pain in Miami, our podiatry team at South Florida Multispecialty Medical Group is here to help. We offer comprehensive evaluation, advanced imaging, and both conservative and surgical treatment for the full range of foot and ankle conditions. Contact our podiatry team in Miami today.
Dr. Peter Hanna is a board-certified podiatrist and reconstructive foot & ankle surgeon with over 15 years of experience. He serves as Director of Podiatry at South Florida Multispecialty Medical Group, specializing in complex reconstruction, minimally invasive surgery, and diabetic foot care.
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