The Nail Unit - Podcast Version TeachMeAnatomy 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The nail unit is a complex structure located on the dorsal surface of the fingers and toes. It has two main functions: Protection – protects the digits from trauma Sensation – assists with tactile sensation In this article, we shall look at the anatomy of the nail unit – its component parts and clinical correlations. Adobe Stock, Licensed to TeachMeSeries Ltd Fig 1Anterior view of the nail unit. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Components of the Nail Unit The nail unit consists of the nail plate and the surrounding soft tissues: Nail plate – outer portion of the nail unit, formed by layers of keratin. It forms a hard, yet flexible, translucent plate. Nail folds – skin that surrounds and protects the proximal and lateral margins of the nail plate Nail bed (sterile matrix) – lies underneath the nail plate, attaching it to the distal phalanx. The nail bed provides a smooth surface for the growing nail plate to slide over (it does not contribute to plate growth itself). Germinal matrix – area of soft tissue proximal to the sterile matrix. Cells within the germinal matrix divide and become keratinised to form the nail plate. Continuous cell division within the matrix ‘pushes’ the nail plate over the bed as it matures. Hyponychium – the area distal to the nail bed, situated underneath the free edge of the nail plate. Eponychium (cuticle) – layer of stratum corneum which extends between the skin of the finger and proximal nail plate. Lunula – white ‘half-moon’ appearance of the germinal matrix through the proximal nail plate. Adobe Stock, Licensed to TeachMeSeries Ltd Fig 2Lateral view of the nail unit. Clinical Relevance Nail Bed Injury A nail bed injury refers to damage to the soft tissue underneath the nail plate – the nail bed and germinal matrix. There are two main mechanisms of injury: Crush – e.g. finger caught in door or direct blow from a hammer Laceration – e.g. circular saw injury An x-ray of the affected finger is required to assess for any bony injury (these injuries are often associated with a fracture of the distal phalanx). In cases where the nail bed is lacerated, surgical repair can be carried out to improve the cosmetic appearance of the new nail growing through. The nail is removed, and the laceration repaired with absorbable sutures. Following a nail bed repair, it takes approximately 6 months for the new nail to fully grow through and the finger can be sensitive to cold during this time. Do you think you’re ready? Take the quiz below Pro Feature - Quiz The Nail Unit Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 1800 More Questions Available Upgrade to TeachMeAnatomy Pro Challenge yourself with over 1800 multiple-choice questions to reinforce learning Learn More Frequent questions What is the nail unit and what are its main functions? The nail unit is a complex structure on the dorsal surface of fingers and toes, primarily serving to protect the digits from trauma and assist with tactile sensation. It consists of the nail plate and surrounding soft tissues, which work together to fulfil these roles. What are the components of the nail unit? The nail unit comprises several key components: the nail plate, nail folds, nail bed, germinal matrix, hyponychium, eponychium, and lunula. Each part plays a specific role in the structure and function of the nail. How does the germinal matrix contribute to nail growth? The germinal matrix is a soft tissue area located proximal to the nail bed, where cells divide and become keratinised to form the nail plate. Continuous cell division in this matrix pushes the nail plate over the nail bed as it matures. What is a nail bed injury and how does it occur? A nail bed injury involves damage to the soft tissue beneath the nail plate, specifically the nail bed and germinal matrix. Common causes include crush injuries, such as getting a finger caught in a door, or lacerations from sharp objects like circular saws. What is the typical treatment for a lacerated nail bed? Treatment for a lacerated nail bed often involves surgical repair to enhance the cosmetic appearance of the new nail. This includes removing the nail, repairing the laceration with absorbable sutures, and allowing approximately six months for the new nail to fully grow through. Rate This Article