Redefining the surface anatomy of the saphenofemoral junction in vivo.

The surface anatomy of the saphenofemoral junction (SFJ) is especially relevant to surgeons. It is variably described in contemporary anatomy and clinical texts but is usually stated to lie 2.5-4 cm below and lateral to the pubic tubercle. The aim of this study was to map the SFJ accurately in healthy adults using ultrasound. One hundred healthy adults (mean age 27 years; 64 men) were scanned by an experienced sonographer using a 13-5 MHz linear probe. The center of the SFJ was recorded bilaterally in relation to the most superficial point of the pubic tubercle. The SFJ was readily identified in all participants. Its center was a mean of 2.4 ± 0.6 cm lateral (range 1-4.5 cm) and 1 ± 0.9 cm inferior to the pubic tubercle (range 2.5 above to 4 cm caudal to it). The junction was inferior to the pubic tubercle in 90% of lower limbs and at or above that level in 10%. In men, the SFJ was a mean of 2.6 cm lateral to the pubic tubercle and 1.2 cm inferior to it, compared with 2.2 and 0.6 cm, respectively, in women (P < 0.001). The SFJ was also slightly nearer the pubic tubercle in younger and thinner participants (P < 0.01). The center of the SFJ lies in a square extending 1-4 cm lateral and up to 3 cm below the pubic tubercle in >90% of adults. The junction is slightly closer to the pubic tubercle in women. These results provide a more robust guide to the surface anatomy of the normal SFJ.

Redefining the surface anatomy of the parotid duct: an in vivo ultrasound study.

BACKGROUND: The surface anatomy of the parotid duct is important when assessing facial lacerations and in facial rejuvenation surgery but is inconsistently described in reference texts. The aim of this study was to map the surface anatomy of the adult parotid duct using ultrasound. METHODS: Fifty healthy adults (31 women; mean age, 33 years) were scanned by an experienced sonographer using a 13-5 MHz linear probe and a Siemens Sonoline Antares ultrasound machine. The caliber, length, and course of the parotid duct were recorded bilaterally. RESULTS: The parotid duct was identified bilaterally in all participants. One subject had a double duct bilaterally. In the remaining 49 individuals (98 ducts), the duct had a mean maximum internal caliber of 0.6 ± 0.2 mm and length 42 ± 7.5 mm. Ninety-two (94 percent) ducts were below the most popular surface marking, which is reported as a line between the lower border of the tragus and mid philtrum. In 93 percent of individuals, the duct was within 1.5 cm of the middle half of a line between the lower border of the tragus and cheilion. CONCLUSION: A more accurate description of the surface anatomy of the parotid duct should assist with early diagnosis of parotid duct injuries and avoidance of iatrogenic injury. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, IV.

Ultrasound visualization of the spinal accessory nerve in vivo.

BACKGROUND: Inadvertent injury of the spinal accessory nerve during surgical procedures is a cause of significant morbidity with medicolegal repercussions. Surface anatomy is an unreliable guide to the nerve's location. We suggest that ultrasound can be used to map the course of the nerve in the posterior triangle of the neck. MATERIALS AND METHODS: Fifty healthy subjects (28 females, mean age 37 y) were scanned using a VF13-5 linear probe and a Siemens Sonoline Antares ultrasound machine (Siemens Medical Solutions USA Inc., Malvern, PA). The caliber, course, and distribution of the nerve in the posterior triangle of the neck were recorded. RESULTS: The nerve was visualized bilaterally in all subjects, running superficially across the posterior triangle with either a straight (56%) or tortuous (44%) course at a depth of about 3 mm beneath the skin surface. It had a mean caliber of 0.76 ± 0.12 mm. It exited the posterior border of sternocleidomastoid at a mean of 6.7 (4.0-9.4) cm below the mastoid process and 1.1 (0.1-2.1) cm above the great auricular point and penetrated the anterior border of trapezius 5.4 (2.1-9.2) cm above the clavicle. Importantly, 58% of nerves divided into 2-4 branches before penetrating trapezius; the nerve branched on at least one side in 49 of 50 individuals. CONCLUSIONS: The spinal accessory nerve and its anatomical variants can be consistently and reliably demonstrated by ultrasound in normal individuals. Surface anatomical landmarks are not a reliable guide to the position and course of the nerve in the posterior triangle. Preoperative mapping of the nerve with ultrasound may reduce the risk of iatrogenic injury.