Heel

The heel is the posterior part of the foot, forming the base of the foot’s rear section. It is primarily composed of the calcaneus (heel bone), which is the largest tarsal bone, along with surrounding soft tissues, muscles, and tendons.^[1] The heel provides a supportive and cushioning structure for standing, walking, and running. The thick layer of fat under the calcaneus acts as a natural shock absorber.

Location

The heel is located at the back of the foot, below the ankle joint and behind the arch. It is positioned between the posterior end of the calcaneus and the Achilles tendon, connecting to the leg.

Anatomy

The heel is a complex structure composed of bones, muscles, tendons, ligaments, and fat pads that provide support and stability to the foot. Below is a detailed description of the anatomy of the heel:

Bones of the Heel

The heel’s skeletal framework is formed primarily by the calcaneus, the largest tarsal bone:

Calcaneus (Heel Bone)

Structure:

A roughly rectangular bone situated at the rear of the foot.

Articulations:

• Superior: Articulates with the talus at the subtalar joint, allowing for inversion and eversion.
• Anterior: Articulates with the cuboid bone at the calcaneocuboid joint, forming part of the midfoot.^[4]

Surfaces:

• Posterior: Provides attachment for the Achilles tendon.^[6]
• Inferior: Contains the calcaneal tuberosity, which bears weight during standing and walking.

Soft Tissues of the Heel

The soft tissues around the heel provide cushioning, support, and flexibility:

Plantar Fat Pad

• A thick layer of fat beneath the calcaneus.
• Functions as a shock absorber, reducing impact forces during weight-bearing activities.

Skin

• The skin of the heel is thick and hairless, designed to withstand friction and pressure.
• Contains sweat glands for thermoregulation.

Muscles of the Heel

The muscles associated with the heel are involved in foot and toe movements:

Intrinsic Muscles

• Abductor Hallucis: Located medially, responsible for abducting the big toe.
• Flexor Digitorum Brevis: Located centrally, flexing the middle toes.
• Abductor Digiti Minimi: Located laterally, abducting the little toe.^[8]

Extrinsic Muscles

• The gastrocnemius and soleus muscles form the calf and attach to the heel via the Achilles tendon.
• Flexor Hallucis Longus and Flexor Digitorum Longus pass through the heel region to insert on the toes, enabling flexion.

Tendons of the Heel

Achilles Tendon

• The strongest and largest tendon in the body.
• Connects the gastrocnemius and soleus muscles to the posterior calcaneus.
• Facilitates plantarflexion of the foot.

Plantar Fascia

• A thick connective tissue band running from the calcaneal tuberosity to the metatarsal heads.
• Supports the arch and absorbs stress during walking or running.

Ligaments of the Heel

Several ligaments stabilize the heel and connect it to adjacent bones:

Plantar Calcaneonavicular (Spring) Ligament

• Runs from the calcaneus to the navicular bone.
• Supports the medial arch of the foot.

Long Plantar Ligament

• Extends from the calcaneus to the cuboid and metatarsals.
• Helps maintain the lateral longitudinal arch.

Calcaneocuboid Ligament

Stabilizes the calcaneocuboid joint.

Nerves of the Heel

The heel is innervated by branches of the tibial nerve:

• Medial Calcaneal Nerve: Provides sensory innervation to the skin over the medial and plantar aspects of the heel.
• Lateral Calcaneal Nerve: Innervates the lateral side of the heel.^[7]

Blood Supply

The heel’s blood supply is derived from branches of the posterior tibial artery:

• Medial Plantar Artery: Supplies the medial plantar aspect of the heel.
• Lateral Plantar Artery: Supplies the lateral plantar aspect.
• Venous Drainage: Blood is drained through the accompanying veins into the posterior tibial vein.

Fascia and Compartments

• Plantar Fascia:A strong band of connective tissue providing support to the plantar aspect of the heel.
• Deep Fascia:Divides the plantar structures into compartments, separating muscles and tendons.

Function of the Heel

The heel serves as a critical structure in the biomechanics of the lower limb, facilitating support, stability, and movement. Its functions are derived from its unique anatomy, including the calcaneus, surrounding soft tissues, and associated muscles and tendons. Below is a detailed explanation of the heel’s functions:

Weight-Bearing Support

• The heel is the primary point of contact between the body and the ground during standing, walking, or running.^[5]
• The calcaneal tuberosity bears the majority of the body’s weight, distributing it to the foot’s arches and other regions.
• The heel’s wide surface area provides a stable base for weight-bearing activities.

Shock Absorption

• The plantar fat pad beneath the calcaneus cushions the impact forces generated during activities such as walking, running, and jumping.
• The calcaneus and surrounding ligaments work together to dissipate these forces, protecting the bones, joints, and soft tissues of the foot and leg.

Force Transmission

The heel plays a vital role in transmitting forces from the ground to the rest of the body during movement:

• During the heel strike phase of walking or running, the calcaneus absorbs the initial ground reaction forces.
• These forces are then distributed through the arches of the foot and up the leg.

Stability and Balance

• The heel provides a stable foundation for maintaining balance during standing and locomotion.
• The Achilles tendon and surrounding musculature stabilize the heel, enabling precise control over foot movements.

Lever for Locomotion

The heel acts as a fulcrum for the foot during the gait cycle:

• In the push-off phase, the heel rises as the Achilles tendon and calf muscles contract, transferring energy to propel the body forward.
• This lever mechanism is essential for efficient walking, running, and jumping.

Adaptation to Terrain

The heel, along with the subtalar joint, allows the foot to adapt to uneven surfaces:

• Inversion and eversion movements of the calcaneus help stabilize the body on sloped or irregular terrain.
• This adaptability reduces the risk of falls or injuries during movement.

Arch Support

The heel supports the longitudinal arches of the foot:

• The medial longitudinal arch relies on the calcaneus and the spring ligament for structure and flexibility.
• The lateral longitudinal arch depends on the calcaneus and the long plantar ligament for stability.

Energy Storage and Release

• The Achilles tendon and plantar fascia store elastic energy during the loading phase of walking or running.^[3]
• This energy is released during push-off, improving efficiency and reducing muscular effort.

Facilitation of Foot Movements

The heel works in conjunction with the forefoot and toes to perform complex movements:

• It acts as a pivot point during heel-to-toe rolling motion in walking and running.
• Facilitates precise adjustments for turning, pivoting, or stopping.

Sensory Feedback

The heel is rich in sensory nerves, providing critical feedback about pressure, texture, and balance:

• This information helps the brain coordinate movement and maintain posture.
• Reflexes involving the heel (e.g., withdrawal from pain) protect the foot from injury.

Clinical Significance

The heel is a crucial structure in weight-bearing and movement, making it susceptible to various injuries and conditions. Its clinical significance includes:

Injuries

• Calcaneal Fractures: Often result from high-impact trauma, such as falls, leading to pain and limited mobility.
• Achilles Tendon Disorders: Tendinitis or ruptures can impair plantarflexion and overall foot function.

Plantar Fasciitis

Inflammation of the plantar fascia, a common cause of heel pain, especially in athletes and individuals with prolonged standing jobs.

Heel Spurs

Bony growths on the calcaneus that may cause discomfort during walking or standing.

Fat Pad Atrophy

Loss of the cushioning fat layer under the heel, resulting in increased pressure and pain during weight-bearing activities.

Nerve Issues

Tarsal Tunnel Syndrome: Compression of the tibial nerve can lead to radiating pain or numbness in the heel.^[2]

Skin Conditions

Calluses, blisters, or cracking of the thick skin over the heel can result from friction or excessive pressure.