onychology

Onychology is the study of nails, including their anatomy, growth, physiology, and diseases in humans, with comparative references to nails in other animals. The term derives from Greek onyx (onykh) meaning nail or claw. In clinical use, it is often considered a subspecialty area within dermatology and podiatry rather than a standalone discipline.

The nail unit comprises the nail plate, nail bed, nail matrix, proximal and lateral nail folds, the cuticle, hyponychium, and the lunula. The matrix generates the nail plate; growth proceeds outward from the matrix. Fingernails grow roughly 3 millimeters per month, while toenails grow about 1 to 1.5 millimeters per month. Blood supply, keratinization, and loading conditions influence color and texture.

Common nail disorders include onychomycosis (fungal infection of the nail plate or bed), paronychia (infection of the periungual folds), nail psoriasis, nail dystrophy due to trauma, and subungual hematoma. Additional conditions include clubbing, koilonychia, pterygium, and tumors. Diagnosis relies on clinical examination, dermoscopy, microscopy, fungal culture, and histopathology in selected cases. Imaging or biopsy may be used for suspicious lesions.

Management varies by condition and may include topical or systemic antifungals for onychomycosis, anti-inflammatory or immunomodulatory therapies for psoriasis, wound care and surgical or chemical avulsion for dystrophy or tumors, and preventive measures such as avoiding nail trauma and maintaining moisture.

The field intersects with dermatology, podiatry, microbiology, and pathology.