Proprioceptive inputs from the joints and limbs arise from mechanoreceptors in the muscles, ligaments and tendons. The knee joint has a wide range of movements, and proper neuroanatomical organization is critical for knee stability. Four ligaments (the anterior (ACL) and posterior (PCL) cruciate ligaments and the medial (MCL) and lateral (LCL) collateral ligaments) and four tendons (the semitendinosus (STT), gracilis (GT), popliteal (PoT), and patellar (PaT) tendons) from eight fresh frozen cadavers were harvested. Each harvested tissue was divided into its bone insertion side and its tendinous part for immunohistochemical examination using S100 staining. Freeman-Wyke's classification was used to identify the mechanoreceptors. The mechanoreceptors were usually located close to the bone insertion. Free nerve endings followed by Ruffini endings were the most common mechanoreceptors overall. No Pacini corpuscles were observed; free nerve endings and Golgi-like endings were most frequent in the PCL (PCL-PaT: P = 0.0.1, PCL-STT: P = 0.00), and Ruffini endings in the popliteal tendon (PoT-PaT: P = 0.00, Pot-STT: P = 0.00, PoT-LCL: P = 0.00, PoT-GT: P = 0.00, PoT-ACL: P = 0.09). The cruciate ligaments had more mechanoreceptors than the medial structures (MS) or the patellar tendon (CR-Pat: P = 0.000, CR-MS: P = 0.01). The differences in mechanoreceptor distributions between the ligaments and tendons could reflect the different roles of these structures in the dynamic coordination of knee motion. Clin. Anat. 29:789-795, 2016. © 2016 Wiley Periodicals, Inc.

Prognostic study, Level I.

IntroductionSchwannoma is a benign, solitary, and slowly progressive encapsulated tumor originating from the sheath of myelinated nerve fibers. Schwannoma of the salivary gland is a particularly rare form of an extracranial neurogenic tumor. Here, we present an unusual case of a schwannoma of the submandibular gland in a 19-year-old man. Total excision of the submandibular gland resulted in complete resolution of symptoms with no cranial nerve deficits. The details of the histopathologic and immunohistochemical features are presented.Case presentationA 19-year-old Caucasian man was admitted to our clinic with a painless mass on the right side of his neck that he had had for the past four months. A neck examination revealed a smooth-surfaced, mobile, firm, and painless mass, 6cm in its greatest diameter, on the right side of the submandibular region. Fine-needle aspiration cytology was suggestive of a submandibular gland schwannoma. After the initial evaluation, our patient was prepared for surgical evaluation and resection with a presumptive diagnosis of a neurogenic tumor of the submandibular gland. The final diagnosis of schwannoma was verified by microscopic and immunohistochemical studies. At one-year follow-up of the case, there was no evidence of recurrence.ConclusionsSchwannoma of the salivary gland is a particularly rare form of an extracranial neurogenic tumor. Our findings indicate good prognosis in an unusual case of a submandibular gland schwannoma in a 19-year-old man treated by surgical excision with no recurrence within 12 months of follow-up.

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