# External Carotid Artery Position Relative to the Greater Horn of the Hyoid: A Comprehensive Bilateral Analysis of Anatomical Variations

## TL;DR

This study examines the variable positions of the external carotid artery relative to the hyoid bone to help improve surgical planning in the neck.

## Contribution

A new classification system for ECA-GHHB positional types and prevalence data for surgical use.

## Key findings

- Lateral and postero-lateral ECA positions were most common (67.4% combined).
- Bilateral asymmetry was more frequent than symmetry (58.3% vs 41.7%).
- Right-side lateral ECA positions were significantly more common than left-side.

## Abstract

Purpose

The external carotid artery (ECA) exhibits variable relationships with the greater horn of the hyoid bone (GHHB), which is relevant to cervical surgery. We aimed to classify ECA positions relative to the GHHB, describe bilateral patterns, and provide prevalence data for surgical planning.

Methods

A retrospective cross-sectional CTA study was conducted in 115 adults (75 males and 40 females), with a mean age of 58.3 ± 14.2 years. Eleven ECA-GHHB positional types were defined. Positions were recorded bilaterally, combined into symmetry/asymmetry patterns, and analysed with descriptive statistics, Chi-square tests, McNemar tests, binomial tests, and logistic regression (EViews 13.0, Quantitative Micro Software, Irvine, CA, USA).

Results

Eleven ECA positions were identified. Lateral (34.8%) and postero-lateral (32.6%) positions dominated (67.4% combined). Overall, 32 bilateral combinations were recorded. Lateral position showed a strong right-side preference (46.1% right vs 23.5% left; p < 0.0001). Bilateral asymmetry was more frequent than symmetry (58.3% vs 41.7%; p = 0.093). Lateralised ECAs (lateral to the internal carotid artery (ICA)) occurred in 3.5% of sides, mainly on the right, and could not be related to the GHHB. No significant gender differences were found (p > 0.05).

Conclusion

ECA-GHHB relationships are highly variable, with dominant lateral/postero-lateral patterns, a marked right-sided lateral preference, and frequent bilateral asymmetry. The proposed classification and prevalence data support preoperative risk assessment and highlight the need for patient-specific imaging in cervical surgery.