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Purpose The palatopharyngeus is one of the longitudinal pharyngeal muscles which contributes to swallowing. It is reported that the palatopharyngeus has muscle bundles in various directions and with attachment sites, and each muscle bundle has a specific function. Although previous reports suggest that the palatopharyngeus is partly interlaced with some parts of the inferior constrictor, the precise relationship remains unclear. The purpose of this study was to examine the precise manner of the connection between the palatopharyngeus and inferior constrictor, and to examine the histological characteristics of this connection. Methods We examined 15 halves of nine heads from Japanese cadavers (average age: 76.1 years); 12 halves, macroscopically, and three halves, histologically. Results Our observation suggests that the palatopharyngeus spreads radially on the inner aspect of the pharyngeal wall. The most inferior portion of the palatopharyngeus extended to the inner surface of the cricopharyngeal part of the inferior constrictor. Histological analysis showed that the inferior end of the palatopharyngeus continued into the dense connective tissue located at the level of the cricoid cartilage. The dense connective tissue not only covered the inner surface of the inferior constrictor but also entered its muscle bundles and enveloped them. Conclusion Therefore, the palatopharyngeus interlaced the cricopharyngeal part of the inferior constrictor through the dense connective tissues. The findings of this study show that the palatopharyngeus may act on the upper esophageal sphincter directly and help in its opening with the aid of the pulling forces in the superolateral direction.

The medial patellofemoral ligament (MPFL) has been recognized as the primary restraint against lateral dislocation of the patella. Biomechanical studies have shown that the MPFL contributes around 60 % of the medial stabilizing strength of the patella [2]. Therefore, restoration of medial stabilizing structure of the patella including MPFL is crucial after lateral patellar dislocation. Although conservative treatment or primary repair is normally performed as a first treatment for an initial lateral patellar dislocation, MPFL reconstruction has been widely accepted for the treatment of chronic patellar instability caused by dysfunction of medial stabilizing structure.

There has been some disagreement concerning the size and location of the femoral attachment of ACL. Namely, some original studies reported that ACL is attached to a relatively narrow oval area on the lateral condyle [2, 4, 15, 16]. In contrast, other recent studies have described that ACL is attached to a wide area on the lateral condyle; as a consequence the posterior attachment margin comes into contact with the articular cartilage margin [3, 6, 9, 10, 17]. Therefore, we performed a series of anatomic studies to clarify this discrepancy [5, 8]. In those studies, the femoral attachment of ACL fibers was found to be composed of two different shapes of fibers. One shape is the main attachment of the mid-substance of ACL fibers, and the other is the attachment of the thin fibrous tissue which extends from the mid-substance fibers and broadly spreads out like a fan on the posterior condyle. These fibers were termed “fanlike extension fibers” [8]. In addition, all fascicles which make up the mid-substance of ACL were observed to attach to the relatively narrow oval area on the lateral condyle [5].