The anatomy of the accessory n. is defined in the light of 100 dissections with particular regard to the following aspects: its relations with the internal jugular v.; its participation in the innervation of the sternocleidomastoid m.; its location in relation to the anterior and posterior borders of that muscle and to the anterior border of the trapezius; and its branching and anastomoses in the supraclavicular fossa.

No abstract

An immunohistochemical study was performed on three groups of young cattle (21, 60 and 300 days of age). Tonsils (palatine and pharyngeal) and mucosae (nasal and oral) were removed. Eight monoclonal antibodies (specific for CD3, CD2, CD4, CD8, WC1, cell-surface IgM, cell-surface IgG and MHC class II molecules) and an avidin/biotin complex method on frozen sections were used. The immunological cytoarchitecture of bovine tonsils is similar to that of human tonsils. Nevertheless, these lymphoid tissues are not fully developed during the first weeks of life: T and B dependent areas not well-differentiated, few germinal centres, few intra-epithelial WC1+ T lymphocytes. In contrast, at 2 months, tonsils possess all the elements of a mucosa-associated lymphoid tissue (MALT). Tonsillar or mucosal epithelium is infiltrated by a large number of CD8+, WC1+ T lymphocytes and cells which express MHC class II molecules. Between 21 and 60 days, the number of WC1+ T lymphocytes increase markedly in the tonsillar epithelium. These results accredit the hypothesis that the presence of antigens has an effect on the localization of these lymphocytes at these sites.

Studies on the innervation of the sternocleidomastoid muscle have shown the highly variable arrangement of the nerve fibers originating from the accessory nerve (eleventh cranial pair) and cervical nerves which supply the muscle. The results of 100 dissections described in this study confirmed these variations and led to propose a classification of the innervation of the sternocleidomastoid according to three main types. The classical "anastomotic" type of innervation (also referred to as Maubrac's type of innervation) was the most frequent, although present in only half of all cases. Innervation of the sternocleidomastoids in symmetrical fashion was an exceptional finding. The functional attributes of these anatomical variations are discussed.

60 dissections analysed the variability of three types of nerve loops crossing beneath the subclavian artery : Vieussens' annulus, the anastomotic ansa between the lower laryngeal nerve and the cervical sympathetic, and the anastomotic ansa between the phrenic nerve and the stellate ganglion. The classic disposition of these loops, situated below the artery and present simultaneously, was found in only 10% of the cases. Though Vieussens' annulus was present in most of the dissections, the anastomotic ansa between the cervical sympathetic and both the lower laryngeal nerve and the phrenic nerve corresponds more rarely to the conventional pattern.