A unique variation with five branches of the aortic arch.

Here, we present a unique case with 5 branches of the aortic arch (AA), namely the right common carotid artery, left common carotid artery, left thyrocervical trunk, left subclavian artery and right subclavian artery (RSA), from right to left. We found that the left thyrocervical trunk originated directly from the AA rather than the left subclavian artery. In addition, the RSA arose dorsally as the last branch of the AA and passed posteriorly to the oesophagus to supply the right upper limb. In addition, the right vertebral artery originated from the right common carotid artery instead of the RSA. Despite numerous studies on AA variations, to our knowledge, this is the first case of the left thyrocervical trunk originating directly from the AA and the RSA arising dorsally as the last branch of a 5-branch AA. Our case provides useful information to anatomists, radiologists and neck and thoracic surgeons.

[Anatomic observation of annular distribution of perirectal fascia and space around the mesorectum].

OBJECTIVE: To explore the regional anatomy of the rectum including the perirectal fasciae and spaces. METHODS: Twenty-one cadavers (15 males and 6 females) were embalmed and their vessels were visualized by injection with color dye. From the cadavers, 30 hemipelvis and 6 three-quarter pelvis were harvested. The perirectal fasciae and spaces and the pelvic autonomic nerves were dissected and examined. RESULTS: Three tissue layers were dissected from the inside to the periphery including the proper rectal fascia enveloping the mesorectum, the presacral fascia, and the piriformis fascia fused with the sacral periosteum. The mesorectum comprised 2 parts with the classical posterolateral fat covered by the proper rectal fascia posteriorly and the anterior fat covered by the posterior layer of Denonvilliers fascia anteriorly. Extending anteriorly to the anterior layer of Denonvilliers fascia, the presacral fascia bisected the space between the mesorectum and the piriformis fascia into the retrorectal space and the presacral space. The retrorectal space extended cranially to the left retrocolic space, anterior to the space between the 2 layers of Denonvilliers fascia(prerectal space). CONCLUSIONS: From the inside to the periphery, the proper rectal fascia, the presacral fascia, and the muscular fascia are distributed in an annular pattern around the mesorectum. The presacral fascia divides the perirectal space into 2 annular parts, the central retrorectal space and the peripheral presacral space. The retrorectal space is the ideal surgical plane for total mesorectal excision.