Bearing Surface
Definition
The area of the striking implement that was in contact with the skull at the moment of force transfer; its geometry can sometimes be estimated from the dimensions and shape of the depressed fracture defect.
- Defines
- Contact area of the implement at moment of impact
- Injury type
- Depressed skull fracture
- Inference use
- Estimating weapon geometry from fracture shape
Common questions
How reliable is estimating weapon shape from bearing surface?+
It gives a range of plausible geometries rather than a precise match. Bone elasticity, the angle of impact, and skull thickness variation all distort the defect relative to the implement's true contact profile, so the estimate should be treated as corroborative, not conclusive, evidence.
What distinguishes bearing surface analysis from tool mark comparison?+
Bearing surface analysis works from the fracture pattern in bone to infer a general implement shape and size. Tool mark comparison, by contrast, matches microscopic striations from a specific suspect tool against a mark, which requires a much more direct and individualising point of contact than a skull fracture typically preserves.
Related terms
- Concentric Fracture
- An arc-shaped fracture encircling the impact zone, produced by outer-table bending tension at a distance from the focal impact; always post-dates the...
- Depressed Fracture
- A fracture where the impacted skull segment is driven inward beyond the elastic limit; the geometry of the depression reflects the bearing...
- Diffuse Loading
- Force distributed over a broad contact area (as from a fall onto a flat surface or a broad-surface blow); produces a broader...
- Focal Loading
- Force concentrated on a small contact area of the skull surface (as from a hammerhead, poker, or stone edge); produces a discrete...
- Hering's Principle
- The 1853 observation that a radiating fracture from a subsequent impact is arrested when it reaches a fracture line produced by a...
- Perimortem Fracture
- A fracture produced at or near the time of death while the bone retains green (fleshed) properties; distinguished by sharp fracture margins...
- Radiating Fracture
- A linear fracture extending outward from the impact point, initiated by inner-table tension as the outer table is compressed; propagates until arrested...
- Wedge Fracture
- The three-dimensional fracture geometry described by Berryman and Symes (1998): a conical inner-table failure zone wider than the outer-table defect, produced by...
- Wolff's Law
- The principle that bone is deposited and resorbed in response to mechanical loading history. Cortical thickness and trabecular orientation follow principal stress...