A color-coded atlas of the cortical surface anatomy of the equine brain.

Objective Overview

• This research aimed to create a detailed, standardized, and color-coded atlas of the surface anatomy of the equine brain cortex, focusing on sulci and gyri, based on established veterinary anatomical terminology.
• The study provides a practical, high-resolution visual reference to aid in clinical, educational, and comparative neuroscience involving horses.

Introduction and Background

• The horse brain is highly gyrencephalic, meaning it has many folds (gyri and sulci), which increases surface area and complexity.
• Despite this complexity, detailed references or atlases describing the surface anatomy of the horse brain are limited.
• Current inconsistencies in terminology complicate comparative studies, clinical diagnosis, and education related to equine neuroanatomy.
• There was a need for a standardized, clear, and detailed anatomical map using the Nomina Anatomica Veterinaria (NAV), a recognized veterinary anatomical nomenclature system.

Methodology

• The study examined brains from ten neurologically normal horses to ensure consistent and healthy anatomical representation.
• Brains were fixed (preserved) and carefully dissected to reveal the sulci (grooves) and gyri (ridges) on various cortical surfaces:
  • Lateral surface (side of brain)
  • Dorsal surface (top)
  • Rostral surface (front)
  • Medial surface (middle side, towards the brain’s longitudinal fissure)
• Each identified sulcus and gyrus was documented and color-coded for clarity.
• All features were labeled using NAV terminology to maintain nomenclature consistency across veterinary and neurological fields.

Findings: Surface Anatomy Description

• Lateral Surface:
  • Dominated by the Sylvian fissure, a major brain groove.
  • An accessory Sylvian fissure noted at the origin of the main Sylvian fissure.
  • A three-limbed ectosylvian sulcus partitioning the ectosylvian gyrus into subdivisions.
  • A continuous suprasylvian sulcus observed above the Sylvian fissure.
  • A distinct oblique sulcus also identified, contributing to the complexity of the lateral surface.
• Dorsal Surface:
  • Coronal, cruciate, and ansate sulci were consistently identified.
  • Presence of a well-developed marginal complex consisting of marginal, ectomarginal, and endomarginal sulci.
• Medial Surface:
  • The genual region differentiated into genual, endogenual, and ectogenual sulci.
  • The callosal and cingulate sulci run parallel to each other.
  • The splenial complex made up of splenial, endosplenial, and ectosplenial sulci was consistently identifiable.
  • Medial rhinal sulcus also consistently present.

Anatomical Variability

• Major sulci and gyri were consistent across all ten equine specimens.
• Variations mainly involved depth differences and branching patterns of sulci, but overall structural layout was stable.
• This indicates a reliable anatomy pattern useful across different horses.

Implications and Applications

• The atlas offers a comprehensive, color-annotated visual guide to equine cortical anatomy, facilitating:
  • Cross-species anatomical comparisons, supporting evolutionary and functional studies.
  • Clinical neuroimaging interpretation helping veterinarians diagnose and treat neurological conditions.
  • Educational purposes for veterinary students and professionals learning equine brain anatomy.
• The specimen-based nature of the atlas provides anatomical accuracy and a solid reference for future research.
• Possible future applications include:
  • Morphometric studies to analyze structural variations quantitatively.
  • Developmental studies to understand how the equine brain grows and organizes.
  • Functional investigations linking structure to neural activity and behavior.

Summary

• This research fills a notable gap in veterinary neuroanatomy by providing a color-coded, standardized surface atlas of the horse brain’s cortical anatomy.
• The detailed documentation and use of consistent terminology pave the way for improved communication among veterinary neurologists, anatomists, and educators.
• The work supports both practical and research needs, enhancing understanding and assessment of the equine brain.