Related Experiment Video
Updated: Aug 22, 2026

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact
Published on: September 21, 2017
Quantitative representation of the upper surface of the human head
1Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118.
Abstract:
A three dimensional digitizer was used to locate 62 positions on an electrode cap placed on the heads of nine subjects. Nonlinear regression methods were used to obtain the best fit sphere, ellipsoid, and perturbed ellipsoid. RMS errors varied from approximately 1 cm to 2 mm, depending on subject and surface chosen. The spherical coordinates of the standard 10/20 electrodes on best fit spheres were obtained. A method to estimate ellipsoid axes using only three standard EEG head dimensions with an ordinary tape measure is derived from the data. The results have at least two potential applications: the forward/inverse problem in EEG and MEG, and the estimation of surface Laplacians from EEG data.
Related Concept Videos
Cranial Bones: Superior and Posterior View
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
Cranial Bones: Lateral View
The temporal bone forms the lower lateral side of the skull. The temporal bone is subdivided into several regions. The flattened upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch. Posteriorly is the mastoid portion of the temporal bone. Projecting...
Area of a Surface of Revolution
Quadric Surfaces
Interpretations of Partial Derivatives
Parametric Surfaces

