Toe

A toe is one of the five digits of the human foot, essential for maintaining balance, providing support, and aiding in locomotion.^[4] Each toe consists of small bones called phalanges, covered by soft tissue, and supported by muscles, tendons, and ligaments. The toes are highly mobile structures that adjust to various terrains and activities. The big toe, known as the hallux, is the largest and strongest, playing a primary role in push-off during walking and running.

Location

The toes are located at the distal end of the foot, extending from the metatarsophalangeal (MTP) joints to the tips. They are positioned anterior to the arch and heel of the foot.^[6]

Anatomy

The toes are intricate structures that consist of bones, joints, muscles, tendons, ligaments, nerves, and blood vessels. These components work together to provide flexibility, strength, and adaptability. Below is a detailed description of the anatomy of the toes:

Bones of the Toes

Each toe is composed of small bones known as phalanges, supported by the metatarsal bones at the base:

Phalanges

Proximal Phalanges:

The first segment of each toe, connecting to the metatarsal bones via the metatarsophalangeal (MTP) joints.^[1]

Middle Phalanges:

Found in the second to fifth toes. The big toe (hallux) does not have a middle phalanx.

Distal Phalanges:

The terminal segment of each toe, forming the tips.

Metatarsal Bones:

• The long bones in the midfoot that connect to the proximal phalanges via the MTP joints.
• Provide structural support to the toes.

Joints of the Toes

The toes have multiple joints that allow for movement and flexibility:

Metatarsophalangeal (MTP) Joints

• Connect the metatarsals to the proximal phalanges.
• Permit flexion, extension, abduction, and adduction.

Proximal Interphalangeal (PIP) Joints

• Located between the proximal and middle phalanges.
• Allow flexion and extension.

Distal Interphalangeal (DIP) Joints

• Found between the middle and distal phalanges.
• Allow flexion and extension.
• The big toe has only one interphalangeal (IP) joint since it lacks a middle phalanx.

Muscles of the Toes

The toes are controlled by a combination of intrinsic and extrinsic muscles:

Intrinsic Muscles

• Located entirely within the foot, these muscles provide fine control and stabilization.
• Plantar Group (Sole of the Foot):
• Flexor Digitorum Brevis: Flexes the proximal phalanges of the second to fifth toes.
• Abductor Hallucis: Abducts the big toe.
• Abductor Digiti Minimi: Abducts the fifth toe.
• Quadratus Plantae: Assists the flexor digitorum longus in flexing the toes.
• Lumbricals: Flex the MTP joints and extend the IP joints.
• Interossei:
• Dorsal Interossei: Abduct the toes.
• Plantar Interossei: Adduct the toes.
• Dorsal Group (Top of the Foot):
• Extensor Digitorum Brevis: Extends the second to fourth toes.^[8]
• Extensor Hallucis Brevis: Extends the big toe.

Extrinsic Muscles

• Originate in the lower leg and insert on the toes, providing powerful movements.
• Flexor Hallucis Longus: Flexes the big toe.
• Flexor Digitorum Longus: Flexes the second to fifth toes.
• Extensor Hallucis Longus: Extends the big toe.
• Extensor Digitorum Longus: Extends the second to fifth toes.

Tendons

Tendons connect the muscles to the bones, transmitting forces to move the toes:

Flexor Tendons

• Flexor Hallucis Longus Tendon: Inserts into the distal phalanx of the big toe.
• Flexor Digitorum Longus Tendons: Insert into the distal phalanges of the second to fifth toes.

Extensor Tendons

• Extensor Hallucis Longus Tendon: Inserts into the distal phalanx of the big toe.
• Extensor Digitorum Longus Tendons: Insert into the middle and distal phalanges of the second to fifth toes.

Plantar Aponeurosis

A thick band of connective tissue that supports the arch and helps flex the toes.

Ligaments

Ligaments provide stability to the toe joints:

Collateral Ligaments

• Located on either side of the MTP, PIP, and DIP joints.
• Prevent lateral displacement of the joints.

Plantar Ligaments

Reinforce the sole side of the toe joints, preventing hyperextension.

Deep Transverse Metatarsal Ligament

Connects the heads of the metatarsal bones, maintaining their alignment.

Nerves of the Toes

The toes are innervated by branches of the tibial nerve and the common fibular nerve:

• Medial Plantar Nerve: Supplies the big toe, second, third, and part of the fourth toes.
• Lateral Plantar Nerve: Supplies the fifth toe and part of the fourth toe.
• Deep Fibular Nerve: Provides sensation to the web space between the big toe and second toe.

Blood Supply

The toes receive blood from the plantar and dorsal arteries:

• Dorsalis Pedis Artery: Supplies the dorsal surface of the toes through the dorsal digital arteries.
• Posterior Tibial Artery: Supplies the plantar surface through the medial and lateral plantar arteries.^[7]
• Venous Drainage: Superficial and deep veins drain blood from the toes into the venous system of the foot.

Skin and Soft Tissue

Skin:

• The plantar skin of the toes is thick and hairless, providing protection and traction.
• The dorsal skin is thinner and more elastic.

Fat Pads:

Cushion the distal phalanges, absorbing impact during walking and running.

Function

The toes play a vital role in balance, locomotion, and adapting to different terrains. Their coordinated movements and structural integrity enable efficient walking, running, and other physical activities. Below is a detailed explanation of the functions of the toes:

Balance and Stability

• The toes provide a broad base of support, helping to maintain balance in both static and dynamic activities.
• Big Toe (Hallux): The hallux contributes significantly to balance by bearing a substantial portion of body weight during standing and movement.
• Lateral Toes: The smaller toes (second to fifth) distribute weight across the forefoot, preventing instability.

Propulsion During Locomotion

The toes play a critical role in generating forward motion during walking, running, and jumping:

• During the toe-off phase of the gait cycle, the toes push against the ground to propel the body forward.^[5]
• The big toe provides the majority of the propulsion force, acting as a lever.

 Adaptation to Terrain

The toes adjust to uneven surfaces, ensuring stability and grip:

• Flexion and extension of the toes allow the foot to contour to the ground.
• Toe splaying increases surface area, improving stability on slippery or rough terrain.

Absorption and Distribution of Force

The toes help absorb and redistribute the forces exerted on the foot during activities like walking, running, or jumping:

• The arches of the foot, supported by the toes, distribute forces evenly across the foot.
• The fat pads under the distal phalanges cushion the toes, reducing impact stress.

Fine Motor Movements

The toes perform precise adjustments to improve foot placement and grip:

• The flexor muscles allow the toes to grip surfaces or objects, enhancing traction.
• The intrinsic muscles provide fine control for stabilization during complex movements like dancing or climbing.

Arch Support

The toes assist in maintaining the structural integrity of the foot’s arches:

The plantar fascia and tendons of the flexor muscles link the toes to the arch, preventing it from collapsing under body weight.

Coordination in the Gait Cycle

The toes contribute to the smooth progression of walking and running:

• At the heel-off phase, the toes stabilize the foot as it transitions into toe-off.
• The extensors lift the toes to clear the ground during the swing phase.

Role in Energy Efficiency

• The elastic structures associated with the toes, such as the plantar fascia and tendons, store energy during the stance phase of walking or running.
• This energy is released during toe-off, improving efficiency and reducing muscular effort.

Weight Distribution

The toes help distribute body weight across the forefoot:

• The big toe bears the largest load, supporting the foot’s medial arch.^[3]
• The lateral toes contribute to lateral arch stability and help prevent excessive pressure on the big toe.

Reflexive Actions

The toes play a role in reflexive movements that protect the foot:

• Withdrawal Reflex: The toes curl away from harmful stimuli, such as sharp objects.
• Stretch Reflex: Prevents overstretching of the tendons during sudden movements.

Clinical Significance

The toes play a critical role in balance, movement, and weight distribution, making them prone to various injuries and medical conditions. Their clinical significance includes:

Injuries

• Fractures: Common in the phalanges due to trauma or stubbing.
• Dislocations: Can occur at the metatarsophalangeal (MTP) or interphalangeal (IP) joints from excessive force.

Deformities

• Hammer Toe: Abnormal bending of the middle joint of the toe, often caused by ill-fitting shoes or muscle imbalances.
• Bunion (Hallux Valgus): Deviation of the big toe, causing a bony bump at the MTP joint.

Inflammatory Conditions

• Gout: Affects the big toe joint, causing pain, swelling, and redness due to uric acid crystal deposition.
• Arthritis: Osteoarthritis or rheumatoid arthritis can lead to joint pain and deformities.

Infections

• Ingrown Toenail: Occurs when the nail grows into the surrounding skin, causing pain and potential infection.^[2]
• Fungal Infections: Common in the toenails, leading to discoloration and thickening.

Circulatory Issues

• Peripheral Neuropathy: Often associated with diabetes, causing numbness or tingling in the toes.
• Raynaud’s Disease: Reduced blood flow to the toes, causing discoloration and pain.