RESUMEN
BACKGROUND: Asterion has been recognized as the external skull landmark for localization of the transverse and sigmoid sinus junction (TSJ). This study aimed to localize the asterion using the intersection of the Frankfurt horizontal plane (FHP) line and a vertical line from the mastoid tip, and to determine its relationship with the transverse and sigmoid sinuses. MATERIALS AND METHODS: Distances from the asterion to the FHP and vertical line were measured on 200 dry skulls (100 males and 100 females). In addition, 48 cadavers (24 males and 24 females) underwent asterion drilling, and the relationship with the transverse and sigmoid sinuses was recorded. RESULTS: In most skulls, the asterion was superior to the FHP line, with average distances of 0.5 ± 0.3 cm on both sides. Distances to the vertical line were 3.7 ± 0.4 cm and 3.9 ± 0.4 cm for the left and right sides, respectively. These distances were statistically significant different between sides but not between sexes. The location of asterion was mainly over the TSJ (54%) and transverse sinus (42%). The accuracy of a predictive method was evaluated in additional 10 cadavers. The predicted positions were located with distances ranging from 0 to 1.3 cm in the horizontal plane (0.4 ± 0.4 cm) and 0 to 0.7 cm in the vertical plane (0.3 ± 0.2 cm) from the asterion. CONCLUSIONS: This study confirms the anatomical relationship between the asterion and TSJ including the transverse sinus. Alternative method for localizing the asterion was also introduced.
RESUMEN
Knowledge of the superficial radial nerve (SRN) relationship and anatomic variations of the first extensor compartment (1st EC) will contribute to a better outcome of de Quervain tenosynovitis treatment. We dissected 87 embalmed cadaveric wrists to determine the relationship of the SRN, the 1st EC length, distance from the proximal and distal 1st EC borders to radial styloid process (RSP), abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendon slip numbers, and the presence of septum. Our results revealed SRN crossing over the 1st EC in 59.5%. The lateral branch of the superficial radial nerve to the 1st EC midline in most cases (61.9%) except for one specimen, where lateral antebrachial cutaneous nerve was the closest. Distances from proximal and distal 1st EC borders to the RSP were 19.7±4.1 mm and 7.6±1.8 mm, respectively. Extensor retinaculum (ER) width over 1st EC (1st EC length) was 14.8±3.2 mm. Complete and incomplete septa were found in 17.2%, and 42.5%, respectively. The most frequent APL tendon slip number in the compartment was two in overall 47 specimens (54.0%). Almost all compartments (85 specimens; 97.7%) contained one EPB tendon slip. We detected bilateral EPB absence in one cadaver. Moreover, we recorded a tendon slip from extensor pollicis longus traveling into 1st EC bilaterally in one cadaver and observed the EPB muscle belly extension into 1st EC in 9 wrists. Awareness of 1st EC anatomic variations would be essential for successful surgical and nonsurgical outcomes.