The subdiaphragmatic part of the phrenic nerve - morphometry and connections to autonomic ganglia.

Few anatomical textbooks offer much information concerning the anatomy and distribution of the phrenic nerve inferior to the diaphragm. The aim of this study was to identify the subdiaphragmatic distribution of the phrenic nerve, the presence of phrenic ganglia, and possible connections to the celiac plexus. One hundred and thirty formalin-fixed adult cadavers were studied. The right phrenic nerve was found inferior to the diaphragm in 98% with 49.1% displaying a right phrenic ganglion. In 22.8% there was an additional smaller ganglion (right accessory phrenic ganglion). The remaining 50.9% had no grossly identifiable right phrenic ganglion. Most (65.5% of specimens) exhibited plexiform communications with the celiac ganglion, aorticorenal ganglion, and suprarenal gland. The left phrenic nerve inferior to the diaphragm was observed in 60% of specimens with 19% containing a left phrenic ganglion. No accessory left phrenic ganglia were observed. The left phrenic ganglion exhibited plexiform communications to several ganglia in 71.4% of specimens. Histologically, the right phrenic and left phrenic ganglia contained large soma concentrated in their peripheries. Both phrenic nerves and ganglia were closely related to the diaphragmatic crura. Surgically, sutures to approximate the crura for repair of hiatal hernias must be placed above the ganglia in order to avoid iatrogenic injuries to the autonomic supply to the diaphragm and abdomen. These findings could also provide a better understanding of the anatomy and distribution of the fibers of that autonomic supply.

The tori of the mouth and ear: a review.

There is a great deal of literature regarding the tori of the mouth and ear. However, there is controversy regarding the etiology and prevalence of each. The torus palatinus is generally agreed to be the most common oral exostosis and is more frequently found in females. The torus mandibularis is also quite common, is more prevalent in males, and occurs bilaterally in 80% of cases. Far less data have been presented regarding the torus maxillaries primarily due to the lack of consensus regarding its nomenclature and classification. These oral tori are thought to be inherited in an autosomal dominant manner with a relatively high penetrance; however, environmental and functional factors have been postulated that may account for a more complex etiology than simply genetics. The torus auditivus is rarely acknowledged in clinical papers and most data are found in anthropological journals. Although there is an abundance of literature that addresses these traits individually, there is a lack of research that collectively acknowledges these. Therefore, the aim of this study was to present a composite review of the tori with regards to their anatomical features, prevalence, etiology and clinical relevance.

Anatomy of the ilioinguinal and iliohypogastric nerves with observations of their spinal nerve contributions.

Proper anesthesia and knowledge of the anatomical location of the iliohypogastric and ilioinguinal nerves is important during hernia repair and other surgical procedures. Surgical complications have also implicated these nerves, emphasizing the importance of the development of a clear topographical map for use in their identification. The aim of this study was to explore anatomical variations in the iliohypogastric and ilioinguinal nerves and relate this information to clinical situations. One hundred adult formalin fixed cadavers were dissected resulting in 200 iliohypogastric and ilioinguinal nerve specimens. Each nerve was analyzed for spinal nerve contribution and classified accordingly. All nerves were documented where they entered the abdominal wall with this point being measured in relation to the anterior superior iliac spine (ASIS). The linear course of each nerve was followed, and its lateral distance from the midline at termination was measured. The ilioinguinal nerve originated from L1 in 130 specimens (65%), from T12 and L1 in 28 (14%), from L1 and L2 in 22 (11%), and from L2 and L3 in 20 (10%). The nerve entered the abdominal wall 2.8 ± 1.1 cm medial and 4 ± 1.2 cm inferior to the ASIS and terminated 3 ± 0.5 cm lateral to the midline. The iliohypogastric nerve originated from T12 on 14 sides (7%), from T12 and L1 in 28 (14%), from L1 in 20 (10%), and from T11 and T12 in 12 (6%). The nerve entered the abdominal wall 2.8 ± 1.3 cm medial and 1.4 ± 1.2 cm inferior to the ASIS and terminated 4 ± 1.3 cm lateral to the midline. For both nerves, the distance between the ASIS and the midline was 12.2 ± 1.1 cm. To reduce nerve damage and provide sufficient anesthetic for nerve block during surgical procedures, the precise anatomical location and spinal nerve contributions of the iliohypogastric and ilioinguinal nerves need to be considered.

A rare case of a complete left inferior vena cava associated with the symptoms of Dunbar syndrome.

We report a case of an 82-year-old female with an anomalous left inferior vena cava. The left inferior vena cava ascends parallel and to the left of the descending abdominal aorta. At the level of the celiac trunk, the inferior vena cava courses anteriorly and to the right to reach the posterior surface of the liver. The patient also suffers from chronic mild postprandial abdominal pain. It is possible that position of inferior vena cava anterior to the aorta, at the level of the celiac trunk, may lead to intermittent celiac artery compression syndrome (Dunbar syndrome).

Peripheral facial nerve communications and their clinical implications.

The facial nerve (CN VII) nerve follows a torturous and complex path from its emergence at the pontomedullary junction to its various destinations. It exhibits a highly variable and complicated branching pattern and forms communications with several other cranial nerves. The facial nerve forms most of these neural intercommunications with branches of all three divisions of the trigeminal nerve (CN V), including branches of the auriculotemporal, buccal, mental, lingual, infraorbital, zygomatic, and ophthalmic nerves. Furthermore, CN VII also communicates with branches of the vestibulocochlear nerve (CN VIII), glossopharyngeal nerve (CN IX), and vagus nerve (CN X) as well as with branches of the cervical plexus such as the great auricular, greater, and lesser occipital, and transverse cervical nerves. This review intends to explore the many communications between the facial nerve and other nerves along its course from the brainstem to its peripheral branches on the human face. Such connections may have importance during clinical examination and surgical procedures of the facial nerve. Knowledge of the anatomy of these neural connections may be particularly important in facial reconstructive surgery, neck dissection, and various nerve transfer procedures as well as for understanding the pathophysiology of various cranial, skull base, and neck disorders.

Temporary reduction of distortion product otoacoustic emissions (DPOAEs) immediately following auditory brainstem response (ABR).

The hearing status of an experimental animal is typically assessed in the laboratory setting by the combined use of auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs), carried out in succession, with the former assay preceding the latter. This study reports a cautionary finding that the use of this accepted regimen yields a reduced DPOAE response. When the DPOAEs were performed after ABR testing, transient reduction of the DPOAE amplitudes was observed at all frequencies in both the inbred, C57/B6 and FVB/N, and the outbred, SW mouse strains. DPOAEs were reduced post-ABR in multiple mouse strains which suggests that this finding is not strain-specific but a general consequence of the preceding ABR analysis. The reduction in DPOAE was temporary: when re-tested at one hour, DPOAE amplitudes recovered to pre-ABR levels. In contrast to the ABR's impact on DPOAE response, ABR thresholds were not altered or reduced when preceded immediately by DPOAE measurements. The molecular alterations underlying the ABR-induced transient reduction of DPOAE remain to be determined. To investigate the potential role of reactive oxygen species in post-ABR DPOAE reduction, transgenic mice over-expressing SOD1, the cytoplasmic enzyme critical for removal of superoxide radicals were subjected to the same auditory testing regimen. Similar to their wild type littermates, the SOD1 transgenic mice also demonstrated post-ABR DPOAE reduction, and thus do not support a role for superoxide radicals in transient reduction of DPOAE. While toxic noise exposure is known to negatively impact OAE, transient decrease in DPOAE levels following standard ABR assay has not been previously described. A practical outcome from this study is a recommendation for reversal of the traditional order for carrying out auditory tests, with the OAE measurements preceding ABR assessment, thus ensuring that the DPOAE response is unaffected.

A review of the gross anatomy, functions, pathology, and clinical uses of the buccal fat pad.

The buccal fat pad is a trigone-shaped adipose tissue located in the cheek that assumes numerous functional and aesthetic clinical uses. It has been studied extensively within the past four decades, and its use in repairing common and debilitating oral defects is the motive for continued research on this topic. It is vital to understand the etiology of any oral defect or of a lesion of the buccal fat pad, for a misdiagnosis can prevent effective treatment of the underlying problem. In this review, we describe the embryology and anatomy of the buccal fat and its association with clinical condition and clinical procedures.

The clinical anatomy of the sinutubular junction.

Specific sites of atherosclerotic processes due to hemodynamic changes and resultant stress, including how these normal anatomical structures become problematic in certain individuals, have yet to be acknowledged. One of these areas of the cardiovascular system occurs at the sinutubular junction (SJ), causing altercation in an otherwise normal flow status. The anatomy of the SJ was examined in 100 adult human hearts during the gross anatomy course at St George's University, during the years 2006-2007. All hearts were examined in situ, using a General Electric model 3200S ultrasound machine with a 5 MHz linear probe. The aforementioned cadavers were also examined using a Stryker laparoscopic unit. Serial transverse histological sections were made through the SJ perpendicular to its axis, and stained with eosin-hematoxylin, van Gieson, Masson trichrome, and Orcein methods. In addition, an immunohistochemical analysis was performed for the detection of positive smooth muscle cells stained areas. During gross and endoscopic examination we were able to identify the SJ in all adult heart specimens. Neonatal and fetal hearts did not exhibit any gross evident SJ; however, a SJ was evident histologically. Ultrasonographically we were able to identify the SJ in all adult heart specimens examined, and a sinutubular ridge in 62%. A significant association was present between the thickness of the ridge and the age of the specimens. The SJ was found to exhibit atherosclerotic changes and plaque formation in an age-related manner. In older subjects, the SJ was marked with local calcification and hemorrhages. In contrast, the SJ of neonatal hearts appeared to have intimal thickening with focal fragmentation and absent or duplicate internal elastic lamina. Intuitively speaking, the presence of a sinutubular ridge, an inevitable fate in humans based on the results of this study, provides an irreversible atherosclerotic process as there is no evidence that the promoting ridge regresses. This is an alarming situation in those individuals who will eventually develop cardiovascular risk factors, whether through inevitable genetic manifestations or by means of exogenous environmental causes.

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.

Arcuate line of the rectus sheath: clinical approach.

The rectus sheath has been extensively described in gross anatomic studies but there is very little information available regarding the arcuate line (AL). The aim of the present study therefore was to explore and delineate the morphology, topography and morphometry of the arcuate line and provide a comprehensive picture of its anatomy across a broad range of specimens. The AL was present in all specimens examined. In addition, the AL was found to be located at a mean of 70.2% (67.3-75.2%) of the distance between the pubic symphysis and the umbilicus, and at 33.9% (30.2-35.4%) of the distance between the pubic symphysis and the xiphoid process. This location was found to be at a mean of 2.1 +/- 2.3 cm superior to the level of the anterior superior iliac spines. Furthermore, there were three distinct types of AL morphology. In type I (65%), the fibers of the posterior rectus sheath (PRS) gradually disappeared over the transversalis fascia, creating an incomplete demarcation of the actual location of the AL. In type II (25%) the termination of the fibers of the PRS was acutely demarcated over the transversalis fascia, creating a clear border with the AL. In type III (10%) the fibers of the PRS created a double and thickened aponeurotic line. In these cases a double AL was observed. Better preoperative knowledge of the location of the AL may, in some cases, help preoperative planning to facilitate primary fascial repair, which can then be supported with on-lay mesh, depending on the clinical situation.

Histopathological basis for neurogenic thoracic outlet syndrome. Laboratory investigation.

OBJECT: To the best of the authors' knowledge, no report exists that has demonstrated the histopathological changes of neural elements within the brachial plexus as a result of cervical rib compression. METHODS: Four hundred seventy-five consecutive human cadavers were evaluated for the presence of cervical ribs. From this cohort, 2 male specimens (0.42%) were identified that harbored cervical ribs. One of the cadavers was found to have bilateral cervical ribs and the other a single right cervical rib. Following gross observations of the brachial plexus and, specifically, the lower trunk and its relationship to these anomalous ribs, the lower trunks were submitted for immunohistochemical analysis. Specimens were compared with two age-matched controls that did not have cervical ribs. RESULTS: The compressed plexus trunks were largely unremarkable proximal to the areas of compression by cervical ribs, where they demonstrated epi- and perineurial fibrosis, vascular hyalinization, mucinous degeneration, and frequent intraneural collagenous nodules. These histological findings were not seen in the nerve specimens in control cadavers. The epineurium was thickened with intersecting fibrous bands, and the perineurium appeared fibrotic. Many of the blood vessels were hyalinized. The nerve fascicles contained frequent intraneural collagenous nodules in this area, and focal mucinous degeneration was identified. CONCLUSIONS: Cervical ribs found incidentally may cause histological changes in the lower trunk of the brachial plexus. The clinician may wish to observe or perform further evaluation in such patients.

Right ventricular false tendons, a cadaveric approach.

Left ventricular false tendons (LFTs) have been extensively described and recognized by gross anatomic studies. However, there is very little information available regarding right ventricular false tendons (RFTs). The aim of our study, therefore, was to explore and delineate the morphology, topography and morphometry of the RFTs, and provide a comprehensive picture of their anatomy across a broad range of specimens. We identified 35/100 heart specimens containing right ventricular RFTs and classified them into five types. In Type I (21, 47.7%) the RFTs, was located between the ventricular septum and the anterior papillary muscle; in Type II (11, 22.9%) between ventricular septum and the posterior papillary muscle; in Type III (7, 14.5%) between the anterior leaflet of the tricuspid valve and the right ventricular free wall; in Type IV (5, 10.4%) between the posterior papillary muscle and the ventricular free wall; and lastly, in Type V (4, 8.3%) between the anterior papillary muscle and ventricular free wall. The mean length of the RFTs was 18 +/- 7 mm with a mean diameter of 1.4 +/- 05 mm. Histologic examination with Masson trichrome and PAS revealed that 20 (41.6%) of the 48 RFTs carried conduction tissue fibers. The presence of conduction tissue fibers within the RFTs was limited to Types I, III, and IV. In Types II and V the RFTs resembled fibrous structures in contrast with Type I, II and IV, which were composed more of muscular fibers, including conduction tissue fibers. RFTs containing conduction tissue fibers were identified, which may implicate them in the appearance of arrhythmias.

Suprascapular nerve as a donor for extracranial facial nerve reanimation procedures: a cadaveric feasibility study.

OBJECTIVES: Facial nerve injury with resultant facial muscle paralysis is disfiguring and disabling. To the authors' knowledge, neurotization of the facial nerve using a branch of the brachial plexus has not been previously performed. METHODS: In an attempt to identify an additional nerve donor candidate for facial nerve neurotization, 5 fresh adult human cadavers (10 sides) underwent dissection of the suprascapular nerve distal to the suprascapular notch where it was transected. The facial nerve was localized from the stylomastoid foramen onto the face, and the cut end of the suprascapular nerve was tunneled to this location. Measurements were made of the length and diameter of the supra-scapular nerve. In 2 of these specimens prior to transection of the nerve, a nerve-splitting technique was used. RESULTS: All specimens were found to have a suprascapular nerve with enough length to be tunneled, tension free, superiorly to the extracranial facial nerve. Connections remained tensionless with left and right head rotation of up to 45 degrees . The mean length of this part of the suprascapular nerve was 12.5 cm (range 11.5-14 cm). The mean diameter of this nerve was 3 mm. A nerve-splitting technique was also easily performed. No gross evidence of injury to surrounding neurovascular structures was identified. CONCLUSIONS: To the authors' knowledge, the suprascapular nerve has not been previously explored as a donor nerve for facial nerve reanimation procedures. Based on the results of this cadaveric study, the authors believe that use of the suprascapular nerve may be considered for surgical maneuvers.

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.

The clinical anatomy of the communications between the radial and ulnar nerves on the dorsal surface of the hand.

Sensations of the dorsal surface of the hand are supplied by the radial and ulnar nerves with the boundary between these two nerves classically being the midline of the fourth digit. Overlap and variations of this division exist and a communicating branch (RUCB) between the radial and ulnar nerves could potentially explain variations in the sensory examination of the dorsal hand. The aim of this study was to examine the origin and distribution of the RUCB thereby providing information that may potentially decrease iatrogenic injury to this connection. We grossly examined 200 formalin-fixed adult human hands. A RUCB was found to be present in 120 hands (60%). Of the specimens with RUCBs, we were able to identify four notable types. Type I (71, 59.1%) originated proximally from the radial nerve and proceeded distally to join the ulnar nerve. Type II (23, 19.1%) originated proximally from the ulnar nerve and proceeded distally to join the radial nerve. Type III (4, 3.3%) traveled perpendicularly between the radial and ulnar nerves so that it was not possible to determine which nerve served as its point of origin. Type IV (18.3%) had multiple RUCBs arising from both the radial and ulnar nerves. With the continual development of new surgical techniques and the ongoing effort to decrease postoperative complications, it is hoped that this study will provide useful information to both anatomists and surgeons.

The velum interpositum revisited and redefined.

INTRODUCTION: Descriptions of the velum interpositum (VI) are typically brief and lacking detail in most neuroanatomical and neurosurgical texts. As this structure may be involved clinically or encountered surgically, the present study seemed warranted. MATERIALS AND METHODS: Twenty-adult (10 male and 10 female) formalin fixed and fresh cadaveric brains underwent a detailed dissection of the VI via an interhemispheric transcollosal approach. Observations were made of the attachment sites and continuation of the VI. Measurements were made of its length and width at its anterior, midportion, and posterior parts. RESULTS: The VI extended laterally over the thalami to become continuous with the choroid plexus of the lateral ventricles. At a point along the thalami where the choroid plexus was found, the VI became "tacked" down and thus continuous with the choroid plexus subependymally. No specimen exhibited a separate choroid plexus of the third ventricle. In each, the choroid plexus of the lateral and third ventricles were the same tissue layer, all arising from the VI. This structure was adherent to but not fused to the deep surface of the fornix. The VI was also not fused to the pineal gland or habenula commissure but simply covered these structures. This membrane was confluent with the pia/arachnoid over the cerebellum and from the inferior surface of the parietal/occipital lobes and extended laterally into the choroid fissure. CONCLUSIONS: To our knowledge, the extent of the VI as described herein has not been reported earlier. The supratentorial choroid plexus is simply a vascular extension of the VI. There is no separate choroid plexus of the third ventricle as often described. Clear planes exist between the VI and surrounding structures such as the pineal gland. Such data may be useful to neurosurgeons who operate in this region and to clinicians who interpret imaging in the area of the VI.

Use of the clavicle in anterior cervical discectomy/corpectomy fusion procedures: cadaveric feasibility study.

INTRODUCTION: Graft sources for cervical fusion procedures include synthetic materials, donor grafts, and autologous bones such as the iliac crest. Considering the data that autologous bone grafts seem to generate the best results for fusion, the next logical step is to seek alternative donor sites so as to attempt to reduce the morbidity associated with these procedures. To our knowledge, autologous clavicle has not been explored as a potential source for cervical fusion. Therefore, the following study was performed to verify the utility of this bone for these procedures. MATERIALS AND METHODS: Seven adult cadavers were used for this study. In the supine position, a standard surgical approach and dissection to the anterior cervical spine were performed. Specimens underwent a standard discectomy or corpectomy with placement of harvested ipsilateral clavicle previously dissected. An anterior cervical plating system was next placed over these sites using standard techniques. Measurements of the harvested clavicle were made. RESULTS: The results of our morphometric analysis were as follows: An average of 5 cm of bone was easily removed from the middle one third of the clavicle. No gross injury was found to vicinal neurovascular structures. The middle one third of the clavicle offered sufficient bone for the one to two segments fused in our study with remaining bone for at least two additional segments. The mean diameter of this part of the clavicle was 1.2 cm. CONCLUSIONS: Based on our cadaveric study, such a bony substitute as autologous clavicle might be a reasonable alternative to the iliac crest for use in anterior cervical fusion procedures.

Intra-abdominal laparoscopic pudendal canal decompression - a feasibility study.

BACKGROUND: Pudendal canal syndrome (PCS) is induced by the compression or the stretching of the pudendal nerve within Alcock's canal. METHODS: Considering the difficulty and possible complications involved in exposing the pudendal canal and nerve by either transperineal, transgluteal or transischiorectal approaches, an intra-abdominal laparoscopic pudendal canal decompression (ILPCD) was employed. For this technique, 30 male adult human cadavers were examined. RESULTS: Measurements revealed an adequate working space in 16 (80%) of the 20 cadavers, while in four specimens the ischiococcygeus muscle was too large to be mobilized sufficiently. The mean working space was 24 mm with a range of 18 to 31 mm. It was considered that a working space of less than 20 mm would not be sufficient for manipulation of the instruments. With regards to pudendal nerve compression, it was observed that 7 (35%) of the 20 cadavers exhibited anatomic signs of PCS. In five (25%) specimens, the compression was observed between the sacrospinous and sacrotuberous ligaments, while the other two (10%) exhibited a broader compression, by the falciform portion of the sacrotuberous ligament. Under the guidance of a laparoscope, the peritoneum was cut laterally to the bladder, and fascia pelvis was identified. The latter was split and the internal iliac vein was traced to the opening of the pudendal canal allowing clear visualization of its contents. Subsequently, either the sacrospinous or sacrotuberous ligament was cut. CONCLUSIONS: Considering that none of the surgical procedures currently used are known to completely improve all the symptoms of PCS, ILPCD could theoretically reduce stretching of the pudendal nerve.