Nail Anatomy
Nail Anatomy
Overview
The human fingernail is a hard, keratinous structure at the tip of each finger. It protects the fingertip, helps with tactile sensation and precision tasks, and plays an important aesthetic role. For manicure and nail extension work, several parts of the nail unit are especially relevant.
Growth, Health & Structural Features
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Growth rate: Fingernails grow about 2–4 mm per month (varies by finger, individual, age) depending on health, nutrition, season. Cleveland Clinic+1
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Keratin structure: The nail plate is made of compact keratinocytes (dead cells) with many disulfide cross-links, giving hardness and rigidity. Its layers (dorsal, intermediate, ventral) differ in orientation and properties. NCBI+1
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Attachment & vascularization: The nail bed is richly vascularized (good blood supply), which gives the nail its pinkish colour under the plate. Proper adhesion and maintenance depend on healthy blood supply.
Anatomy Parts
| Part | Location / Description | Function / Relevance for Manicure & Extensions |
|---|---|---|
| Nail Plate | This is the hard visible part of the nail. Made of layers of keratin. | All polish, gels, acrylics, etc. are applied to the nail plate. It must be clean, smooth, and healthy for good adhesion. Shape and thickness affect how well enhancements sit. |
| Nail Matrix (including germinal matrix and sterile matrix) | Located under the skin behind (proximal) the visible nail base; partly under the proximal nail fold. The matrix is where new nail cells are generated. PubMed+3Healthline+3Medscape+3 | Damage to the matrix can permanently affect nail growth and shape. In extensions, over-filing or aggressive removal near the matrix can cause harm. Understanding where the matrix is helps avoid injury. |
| Lunula | The whitish, half-moon shaped visible part at the base of the nail plate above the matrix, in many (but not all) nails. Altmeyers Encyclopedia+3Wikipedia+3Encyclopedia Britannica+3 | Important marker: helps locate the matrix, useful for manicure/builder gel work to see where to place forms/extension tips without harming sensitive tissue. |
| Nail Bed | The skin (epithelium) just under the nail plate (on its underside), extending from the matrix to where the free edge begins. NCBI+3PubMed+3Medscape+3 | The nail plate adheres to the nail bed. If adhesive or product gets under the plate, it can cause lifting or fungal/bacterial risk. Also, damage here can lead to sensitivity or irregular growth. |
| Proximal Nail Fold | The fold of skin at the base of the nail, covering the early part of the nail (including matrix). Medscape+2PubMed+2 | Protects the matrix. Care when pushing back, trimming (if trimming), or applying product near this fold matters. Over-aggressive action can injure live tissue. |
| Cuticle / Eponychium | “Cuticle” often refers to the thin layer of dead skin at the tooth-edge of the proximal nail fold / nail plate. “Eponychium” is the living skin of the proximal fold. PubMed+2Altmeyers Encyclopedia+2 | For manicure, pushing back or gentle removal of dead cuticle improves look and adhesion. But cutting living eponychium is risky because of infection, bleeding, or damage to the matrix. |
| Lateral Nail Folds | The skin on the sides of the nail plate. NCBI+1 | They frame and protect the nail plate edges. When applying side-extensions or tips, edges must align; product should seal edges to prevent lifting. Also risk of skin irritation here. |
| Hyponychium | The thickened layer of epithelium under the free edge of the nail plate (just under where the nail ends). Sometimes called “the quick.” Wikipedia+2Altmeyers Encyclopedia+2 | Protects the tissue under the free edge. Extensions that extend too far can stress or injure this region; cleaning/lifting issues may trap moisture here. |
| Free Edge | The part of the nail plate that extends beyond the fingertip. | This is what is trimmed or shaped. Extensions will replace or extend this. It needs to be shaped well and sealed to avoid breakage or snagging. |
