Surgical challenges associated with the morphology of the spinal accessory nerve in the posterior cervical triangle: functional or structural?

OBJECT: The spinal accessory nerve (SAN) has been reported to have a distinctly coiled appearance in its course through the posterior cervical triangle of the neck. As this is unusual compared with other peripheral nerves including the cranial nerves, the present histological analysis was performed to further elucidate the reason for this anatomy with potential application in nerve injury and repair. METHODS: Ten adult cadavers underwent dissection of the neck. The SAN was harvested proximally and within the posterior cervical triangle. For comparison with other cranial nerves within the neck, the cervical vagus and hypoglossal nerves were also harvested. All nerves underwent histological analysis. Additionally, 2 human fetuses (11 and 20 weeks' gestation) underwent examination of the SAN in the posterior cervical triangle, and 3 randomly selected specimens were submitted for electromicroscopy. RESULTS: All SANs were found to have a straight gross configuration proximal to the posterior triangle and a coiled appearance within this geometrical area. Histologically, no differences were identified for the SAN in these 2 locations (that is, proximal to and within the posterior cervical triangle). The histology of the SAN both with routine analysis and electron microscopy was similar in both regions and to nerves used as controls (for example, vagus and hypoglossal nerves). Interestingly, both fetal specimens were found to have coiled SANs in the posterior cervical triangle. CONCLUSIONS: Based on this study, it appears that the tortuous course of the SAN in the posterior triangle arises from functional as opposed to structural forces. It is hoped that this analysis will provide some insight into the nature behind the morphology observed in the SAN within the posterior cervical triangle and aid in future investigations regarding its injury. Moreover, such a coiled nature of this nerve may assist the neurosurgeon in identifying it during, for example, neurotization procedures.

Clinical anatomy of the mastoid and occipital emissary veins in a large series.

INTRODUCTION: Detailed descriptions of the mastoid emissary veins (MEVs) and the foramina through which they travel are lacking in the literature. Therefore, the aim of our study was to explore and delineate the morphology, topography and morphometry of the MEV, mastoid foramen (MF) and occipital foramen (OF). One hundred cadaver heads and 100 dried human skulls were grossly examined RESULTS: The MF and OF varied from being absent to having as many as four small openings, each transmitting an emissary vein. The overall prevalence of MEV was 98% on the right and 72% on the left. The overall prevalence of OF was 7% on the right and 4% on the left. The mean length of the MEV from its point of origin to its point of termination was found to be 7.2 cm with a range of 3.8-11.8 cm. The mean diameter of the MEV at the mastoid emissary foramen was 3.5 mm with a range of 1.1-5.6 mm. In the majority of the cadavers (85%) it was observed that mastoid and occipital emissary veins formed a confluent venous system, while in the remaining 15%, they remained as single vessels. CONCLUSIONS: The MEV may be a significant source of bleeding during surgery of the skull base or middle ear, particularly during retrosigmoid and far-lateral approaches and detailed anatomical knowledge may help to prevent these complications. Endovascular treatment of dural arteriovenous fistulas is often extremely difficult due to limited access, however, the use of the MEV represents a unique and potentially valuable technique for accessing an isolated or inaccessible transverse or sigmoid sinus system.

An anatomic investigation of the serratus posterior superior and serratus posterior inferior muscles.

In classical anatomy textbooks the serratus posterior superior muscle was said to elevate the superior four ribs, thus increasing the AP diameter of the thorax and raising the sternum. However, electromyographic and other studies do not support its role in respiration. In order to help resolve this controversy and provide some insight into their possible functionality, the present study aimed at examining the morphology, topography and morphometry of serratus posterior superior and inferior muscles in both normal specimens and those derived from patients with a history of chronic obstructive pulmonary disorder (COPD). These muscles were examined in 50 human cadavers with an age range of 58-82 years. In 18 of the cadavers their histories revealed that they were suffering from COPD. There was no significant difference between right and left sides, race, gender and age and positive COPD history in regard to dimensions and nerves supply of serratus posterior superior and inferior muscles (P > 0.05). Based upon our findings that no morphometric differences exist between the of serratus posterior superior and inferior muscles of COPD patients versus controls, we are suggesting that no respiratory function be attributed to either of the serratus posterior superior and inferior muscles.

Cisterna chyli: a detailed anatomic investigation.

With recent laparoscopic advancements in retroperitoneal and thoracic surgical procedures, familiarity with major lymphatic structures, such as including the cisterna chyli (CC) and thoracic duct (TD), has proven beneficial in avoiding misdiagnosis and iatrogenic intraoperative injury. In this light, the aim of our study was to explore and delineate the topography of the CC, classify the different patterns of lymphatic tributaries, and categorize its varying location with respect to the vertebral bodies. The anatomy of the CC was examined in 120 adult human cadavers. The CC was found in 83.3% of the specimens and both the tributaries of the CC and the location, with respect to vertebral level, demonstrated wide variation. The results were classified into four types. The most common tributary configuration (type I), found in 45% specimens, was a single CC formed by the union of the left lumbar trunk (LT) and the intestinal trunk (IT). In 30% the CC was formed where the IT opened into the TD and the right lumbar trunk (RT), LT, retroaortic nodes (RN) and branches from the intercostal lymphatics (IL) joined variably (type II). In 20% the CC was formed by the junction of the RT and IT (type III), while in 5% there was a variable confluence pattern of lymphatic trunks that could not be classified (type IV). The CC was located at L1-L2 (type A) in 63%, T12-L1 (type B) in 21%, T11-T12 (type C) in 8%, T10-11 (type D) in 5%, and T9-10 (Type E) in 3%, of the specimens. The CC was found in the retrocrural space and, in 75% of the cases, to the right of the abdominal aorta. We hope that the data supplied by this study will provide useful information in the future to anatomists, radiologists and surgeons alike.

Death of memory T-cell subsets in humans: changes during aging.

Aging is characterized by a progressive decline in various T-cell functions that are associated with a deficiency of naive and central memory T-cell subsets and the accumulation of oligoclonal effector memory T-cell subsets. In this article, we briefly review different pathways of death signaling and alterations in apoptotic signaling pathways in order to understand changes in various T cells in human aging.

An unusual innervation of pectoralis minor and major muscles from a branch of the intercostobrachial nerve.

Variations of the branching pattern of the intercostobrachial nerve have been known to complicate dissection during mastectomy and other procedures involving the axilla. We present a unilateral case of a 73-year-old Caucasian female, in which the intercostobrachial nerve gives rise to an additional medial pectoral branch, which partially innervates the pectoralis minor muscle, as well as the abdominal head of pectoralis major muscle. Clinical consequences of such a variation may include motor losses, in addition to the commonly reported sensory losses, resulting from accidental or intentional dissection of the intercostobranchial nerve.

Anatomical and surgical considerations of the sacrotuberous ligament and its relevance in pudendal nerve entrapment syndrome.

In view of the paucity of literature, this study was undertaken to reappraise the gross anatomy of the sacrotuberous ligament (STL), with the objective of providing an accurate anatomical basis for clinical conditions involving the STL. We studied the gross anatomy of the STL in 50 formalin fixed cadavers (100 sides) during the period of 2004-2005. All specimens exhibited an STL with a ligamentous part and (87%) of specimens exhibited a membranous (falciform) segment, which extended towards the ischioanal fossa. The variations of the falciform extensions were classified into three types. In Type I (69%), the falciform process extended towards and along the ischial ramus to terminate at the obturator fascia. In Type II (108%), the falciform process extended along the ischial ramus, fused with the obturator fascia and continued towards the ischioanal fossa. In addition, the medial border of the falciform process descended to fuse with the anococcygeal ligament, forming a continuous membrane. Lastly, in Type III (13%), the falciform process of the STL was absent. The above mentioned data could have an important implication to the understanding of the relationship between the pudendal nerve and the sacrotuberous ligament and their relevance to pudendal nerve entrapment syndrome.