Radioanatomical relationships of the carotid arteries to the superior cornu of the thyroid cartilage

PURPOSES: The carotid arteries demonstrate variable relationships with adjacent laryngeal structures. Although thyroid cartilage (TC) is commonly used as a surgical landmark, the relationship between the carotid arteries and the superior cornu of the thyroid cartilage (SCTC) remains insufficiently quantified. Previous clinical reports have suggested that close proximity between the vessel and cartilage may have anatomical significance in selected cases of vascular compression. This study aimed to evaluate these relationships and propose a classification system. METHODS: A retrospective analysis of 214 head and neck computed tomography angiography (CTA) scans (153 males, 61 females; mean age 63.07 years) was performed. The level of the carotid bifurcation (CB) relative to the SCTC, spatial relationships, and minimum distances between vessels and the SCTC were recorded. SCTC morphology, length, and angulation were also assessed. RESULTS: The CB was suprathyroid in 89% of sides and infrathyroid in 11%. The CCA was lateral to the SCTC in 73.4% of sides, whereas the ECA and ICA were lateral in 19.6% and 11%, respectively. Medial configurations were uncommon. Mean distances increased from the CCA (2.33 ± 1.82 mm) to the ECA (4.38 ± 3.07 mm) and ICA (6.18 ± 3.67 mm). SCTC length demonstrated a moderate positive correlation with ECA distance (R = 0.401), while coronal angulation showed weak negative correlations with ECA and ICA distances. Eleven relationship types were identified, with Type 1 (CCA lateral) representing the predominant configuration (64.5%). CONCLUSIONS: A consistent proximity pattern was observed, with the CCA located closest to the SCTC, followed by the ECA and ICA. SCTC morphology modestly contributed to carotid artery positioning. The proposed classification system captures the variability of these anatomical relationships and may facilitate standardized radiological description and preoperative anatomical assessment. Further studies incorporating dynamic imaging and clinical correlation are required to determine the potential pathological significance of these configurations.