title: Clinically relevant variations of the superior thyroid cornu.
abstract: OBJECTIVE
  The superior thyroid cornu (STC) of the thyroid cartilage is a variable structure that maybe associated with different clinical symptoms. This study evaluates the three-dimensional anatomy of the STC.
  
  
  METHODS
  Measurements were conducted on 97 CT scans (45 male and 52 female). The protocol models a vector from the base to the tip of the STC and references the cornu to the midline. From these data, the length (C), the rotation angle (γ), the inclination angle (β), and the deviation of STC base (X2) and tip (X3) from the midline were measured. An additional measure of the medial inclination quotient (Q = X3/X2) was calculated.
  
  
  RESULTS
  The STC has a mean length of 13.9 ± 3.26 mm. The male STC is more bent inwards (rotation angle (γ) 60.95° vs. 12.15°; p < 0.001), and the female STC is more steep (inclination angle (β) 75.44° vs. 73.44°; p < 0.001). The mean Q in men was significantly lower (0.85 ± 0.15 vs. 0.97 ± 0.15; p < 0.001). An extreme medial deformation was found in 13.4 % of the patients. This variation is associated with Q ≤ 0.7, most of the time unilateral and more common in men (86.7 vs. 13.3 %). Furthermore, we can describe STC variations with close proximity to the common carotid artery or the cervical spine.
  
  
  CONCLUSIONS
  The clinically most relevant variation of the STC seems to be the extreme medial deviation, which may lead to symptoms described with the superior thyroid cornu syndrome. The evaluation of Q in axial CT scans is easily done and may propose a helpful tool for clinical diagnostics.
authors: Institute of Clinical Anatomy and Cell Analysis, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 8, 72076, Tübingen, Germany. thomas.shiozawa@uni-tuebingen.de.
authors: Thomas
authors: T
authors: Shiozawa
authors: Institute of Clinical Anatomy and Cell Analysis, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 8, 72076, Tübingen, Germany.
authors: P
authors: P
authors: Epe
authors: Institute of Clinical Anatomy and Cell Analysis, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 8, 72076, Tübingen, Germany.
authors: S
authors: S
authors: Herlan
authors: Department of Otolaryngology, Head and Neck Surgery, University Hospital Tuebingen, Tübingen, Germany.
authors: M
authors: M
authors: Müller
authors: Department of Otolaryngology, Head and Neck Surgery, University Hospital Tuebingen, Tübingen, Germany.
authors: A
authors: A
authors: Tropitzsch
authors: Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tübingen, Germany.
authors: I
authors: I
authors: Tsiflikas
authors: Institute of Clinical Anatomy and Cell Analysis, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 8, 72076, Tübingen, Germany.
authors: B
authors: B
authors: Hirt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D063405:Anatomic Variation; D002339:Carotid Arteries / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D003680:Deglutition Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009139:Musculoskeletal Abnormalities / Q000150:complications* / Q000000981:diagnostic imaging; D010865:Pilot Projects; D012399:Rotation; D012737:Sex Factors; D013957:Thyroid Cartilage / Q000002:abnormalities* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
keywords: Anatomical variations; Dysphagia; Superior thyroid cornu; Superior thyroid cornu syndrome