Endoscopic Orientation of Juxta-pituitary Carotid in Transsphenoidal Approaches: Critical Considerations for Clinical Applications

Abstract Introduction In sphenoid sinuses with ill-defined carotid bony landmarks, accidental injury of the internal carotid artery (ICA) remains one of the most challenging complications, which is particularly reported in the endoscopic endonasal transsphenoidal approaches (EETAs). Objectives To describe an anatomical model for the endoscopic orientation of the juxta-pituitary segment of the ICA in relation to the lateral opticocarotid recess (OCR) as a nearby bony landmark. Methods Dissection was performed progressively, simulating the EETA, in twenty fresh adult cadavers. After reducing the posterior and lateral walls of the sphenoid sinuses, various measurements were taken from both lateral OCRs to "contact points" on the juxta-pituitary segment of the ICA and lateral margins of the pituitary gland. Results The current results have enabled us to divide the region between the lateral OCRs into 3 compartments: 2 lateral parasellar compartments contain juxta-pituitary segments of the ICA with a mean width of 8 mm and a narrow range from 7 mm to 10 mm; and a central intercarotid sellar compartment represents the safe region for bone drilling, showing widely variable widths ranging from 9 mm to 20 mm. In all specimens, the variation in the width of the intercarotid compartment correlated with the distance between both lateral OCRs. Conclusion The present study improves surgeon awareness of the variations in the course of the ICA through the EETA along sphenoid sinuses with ill-defined bony landmarks. An appreciation of the measurements taken in the present study can help in operative training, and can also provide a base for future studies to confirm ICA courses associated with a higher risk of injury.

Lower Four Cranial Nerves in the Management of Glomus Jugulare: Anatomical Study

Abstract Introduction The surgical management that achieves minimal morbidity and mortality for patients with glomus and non-glomus tumors involving the jugular foramen (JF) region requires a comprehensive understanding of the complex anatomy, anatomic variability, and pathological anatomy of this region. Objective The aim of this study is to propose a rational guideline to expose and preserve the lower cranial nerves (CNs) in the lateral approach of the JF. Methods The technique utilized is the gross and microdissection of 4 fixed cadaveric heads to revise the JF's surgical anatomy and high part of the carotid sheath compared with surgical cases to understand and preserve the integrity of lower CNs. The method involves radical mastoidectomy, microdissection of the JF, facial nerve, and high neck just below the carotid canal and the JF. The CNs IX, X, XI, and XII are microscopically dissected and kept in sight up to the JF. Results This study realized well the surgical and applied anatomy of the lower CNs with relation to the facial nerve and JF. Conclusions The JF anatomy is complicated, and the key to safely operate on it and preserving the lower CNs is to find the posterior belly of the digastric muscle, to skeletonize the facial nerve, to remove the mastoid tip preserving the stylomastoid foramen, to skeletonize the sigmoid sinus and posterior fossa dura not only anterior but also posteroinferior to reach and drill the jugular tubercle.

The effect of the minimum effective volume for suprainguinal fascia iliaca block in fresh cadavers / El efecto del volumen efectivo mínimo para el bloqueo de la fascia ilíaca suprainguinal en cadáveres frescos

SUMMARY: The goal of ultrasound-guided suprainguinal fascia iliaca block (USG-SFIB) is anesthetic spread to three nerves, which are lateral femoral cutaneous nerve (LFCN), femoral nerve (FN), and obturator nerve (ON). The 90 % minimum effective volume (MEV90) for USG-SFIB is each result of studied showed the successful block and effect in various volume for block. So, Thus, the study purposes to demonstrate the efficiency of the effective volume (MEV90,62.5 ml) for USG-SFIB and confirm the staining of dye in connective tissue of nerve (nerve layer) that focused on the obturator nerve by histological examination in cadavers. The histological result showed the dye staining on the nerve layer of the ON in epineurium (100 %) and un-staining perineurium & endoneurium. Therefore, the minimal effective volume (MEV) is effective for USG-SFIB. Moreover, dye stain at the epineurium of stained obturator nerve only.

RESUMEN: El objetivo del bloqueo de la fascia ilíaca suprainguinal guiado por ecografía (USG-SFIB) es la propagación anestésica a tres nervios, cutáneo femoral lateral, femoral y obturador. El volumen efectivo mínimo del 90 % (MEV90) para USG-SFIB en cada uno de los resultados mostró el bloqueo exitoso y el efecto en varios volúmenes por bloqueo. Por lo tanto, el estudio tuvo como objetivo demostrar la eficiencia del volumen efectivo (MEV90,62.5 ml) para USG-SFIB y confirmar la tinción de tinte en el tejido conectivo del nervio, el cual se centró en el nervio obturador a través del examen histológico en cadáveres. El resultado histológico mostró tinción de colorante en el epineuro (100 %) del nervio obturador, sin embargo no hubo tinción del perineuro y endoneuro. Por lo tanto, el volumen efectivo mínimo (MEV) es efectivo para USG-SFIB.

Distribution of various volumes of methylene blue injection in suprainguinal fascia iliaca block under ultrasound guidance: a cadaveric study / Distribución de varios volúmenes de inyección de azul de metileno en el bloque suprainguinal de la fascia ilíaca bajo guía por ultrasonido: un estudio cadavérico

SUMMARY: The local anesthetic volume for a single-shot suprainguinal fascia iliaca block (SFIB) is a key factor of a block success because the courses of the three target nerves from the lumbar plexus (LP), the lateral femoral cutaneous nerve (LFCN), femoral nerve (FN), and obturator nerve (ON), at the inguinal area are isolated and within striking distance. Thus, this cadaveric study aims to demonstrate the distribution of dye staining on the LFCN, FN, ON, and LP following the ultrasound-guided SFIB using 15-50 ml of methylene blue. A total of 40 USG-SFIBs were performed on 20 fresh adult cadavers using 15, 20, 25, 30, 35, 40, 45, and 50 ml of methylene blue. After the injections, the pelvic and inguinal regions were dissected to directly visualize the dye stained on the LFCN, FN, ON, and LP. All FN and LFCN were stained heavily when the 15-50 ml of dye was injected. Higher volumes of dye (40-50 ml) spread more medially and stained on the ON and LP in 60 % of cases. To increase the possibility of dye spreading to all three target nerves and LP of the SFIB, a high volume (≥40 ml) of anesthetic is recommended. If only a blockade of the FN and LFCN is required, a low volume (15-25 ml) of anesthetic is sufficient.

RESUMEN: El volumen de anestésico local para un bloqueo de la fascia ilíaca suprainguinal (FISI) de una sola inyección es un factor clave para el éxito del bloqueo, debido a que los cursos de los tres nervios objetivo del plexo lumbar (PL), el nervio cutáneo femoral lateral (NCFL), femoral (NF) y el nervio obturador (NO), en el área inguinal están aislados y dentro de la distancia de abordaje. Por lo tanto, este estudio cadavérico tiene como objetivo demostrar la distribución de la tinción de tinte en NCFL, NF, NO y PL siguiendo el FISI guiado por ultrasonido usando 15-50 ml de azul de metileno. Se realizaron un total de 40 USG-FISI en 20 cadáveres adultos frescos utilizando 15, 20, 25, 30, 35, 40, 45 y 50 ml de azul de metileno. Después de las inyecciones, se disecaron las regiones pélvica e inguinal para visualizar directamente el tinte teñido en NCFL, NF, NO y PL. Todos los NF y NCFL se tiñeron intensamente cuando se inyectaron los 15- 50 ml de colorante. Volúmenes mayores de colorante (40-50 ml) se esparcen más medialmente y tiñen el NO y la PL en el 60 % de los casos. Para aumentar la posibilidad de que el colorante se propague a los tres nervios objetivo y al PL del FISI, se recomienda un volumen elevado (≥40 ml) de anestésico. Si solo se requiere un bloqueo de NF y NCFL, un volumen bajo (15-25 ml) de anestésico es suficiente.

Accuracy of sonographic identification of suprascapular nerve at supraclavicular fossa: a cadaveric study / Precisión de la identificación ecográfica del nervio supraescapular en la fosa supraclavicular: un estudio cadavérico

SUMMARY: Sonographic identification of suprascapular nerve (SSN) is essential for diagnosis of suprascapular neuropathy and ultrasound-guided suprascapular nerve block. This study aims to demonstrate the accuracy of identification of SSN at supraclavicular region by ultrasonography in fresh cadavers. Ninety-three posterior cervical triangles were examined. With ultrasonography, SSN emerging from the upper trunk of brachial plexus was identified and followed until it passed underneath the inferior belly of omohyoid muscle. Sonographic visualization of SSN in supraclavicular fossa was recorded. Then, cadaveric dissection was performed to determine the presence or absence of SSN. An agreement between sonographic identification and direct visualization was specified and categorized the following three patterns: "correctly identified" (pattern I), "incorrectly identified" (pattern II), and "unidentified" (pattern III). The identification of SSN using sonography was correct in almost 90 %. The diameter of SSN with pattern I was the largest compared to those of other two patterns. In pattern I, SSN ran laterally from the upper trunk of brachial plexus and passed underneath the inferior belly of omohyoid muscle. Therefore, SSN was easily identified under ultrasonography. In pattern II, nerve identified by ultrasonography was literally the dorsal scapular nerve. In pattern III, SSN was unable to be identified because of its anatomical variation. The accuracy of ultrasonographic identification of SSN at supraclavicular fossa is high and the key sonoanatomical landmarks are the lateral margin of brachial plexus and the inferior belly of omohyoid muscle. The anatomical variants of SSN are reasons of incorrect or unable identification of SSN under ultrasonography.

RESUMEN: La identificación ecográfica del nervio supraescapular (NSE) es esencial para el diagnóstico de neuropatía supraescapular y bloqueo del nervio supraescapular mediante la ecografía. Este estudio tiene como objetivo demostrar la precisión de la identificación de NSE en la región supraclavicular por ecografía en cadáveres frescos. Se examinaron noventa y tres triángulos cervicales posteriores. Se identificó el NSE emergente de la parte superior del tronco del plexo braquial con la ecografía, y se siguió hasta su trayecto por debajo del vientre inferior del músculo omohioideo. Se registró la visualización ecográfica del NSE en la fosa supraclavicular. Luego, se realizó disección cadavérica para determinar la presencia o ausencia de NSE. Se especificó un acuerdo entre la identificación ecográfica y la visualización directa y se categorizaron los siguientes tres patrones: "identificado correctamente" (patrón I), "identificado incorrectamente" (patrón II) y "no identificado" (patrón III). La identificación de NSE mediante ecografía fue correcta en casi el 90 %. El diámetro del NSE con el patrón I fue el más grande en comparación con los de los otros dos patrones. En el patrón I, NSE corría lateralmente desde la parte superior del tronco del plexo braquial y pasaba por debajo del vientre inferior del músculo omohioideo. Por lo tanto, el NSE se identificó fácilmente mediante ecografía. En el patrón II, el nervio identificado por ecografía era literalmente el nervio escapular dorsal; en el patrón III, el NSE no pudo ser identificado debido a su variación anatómica. La precisión de la identificación ecográfica del NSE en la fosa supraclavicular es alta y los puntos de referencia sonoanatómicos clave son el borde lateral del plexo braquial y el vientre inferior del músculo omohioideo. Las variantes anatómicas de NSE son razones de identificación incorrecta o incapaz de NSE bajo ecografía.

A Study On Anatomical Variations In The Formation Of Brachial Plexus And Its Branches

Background: The variable course of the nerves may be the cause of many neuralgic pains of the superior extremity.The knowledge of percentage of variations may help the surgeons in treating the cases of trauma & entrapmentneuropathies.Materials and Methods: The present study in 70 upper limbs of 35 human cadavers over a period 1year at thedepartment of Anatomy at Siddhartha medical college and surrounding medical colleges around Vijayawada.The detailed examination of the following nerves that is musculocutaneous, median, ulnar, radial and axillarynerves was done in the arm and following variations were observed.Results: Communication between musculocutaneous and median nerves in eleven limbs. Musculocutaneousnerve was absent in our limbs. Median nerve supplied muscles of front of arm where musculocutaneous nervewas absent in one limb. Musculocutaneous nerve did not pierce coracobrachialis muscle in seven limbs. TheCommunication between radial and ulnar nerve in one limb.Conclusion: Lesions of communicating nerve may give rise to pattern of weakness that may impose difficulty indiagnosis. So it is important to be aware of the variations that are observed and discussed in our study. Knowledgeof these variations is important for neurologists, orthopaedicians and traumatologists as these may give rise tovariable clinical picture depending upon the variations present.

Prevalence Of Patency Of Accessory Pancreatic Duct At Minor Papilla In South Indian Population: A Cadaveric Study

The accessory pancreatic duct is the smaller and less constant pancreatic duct in comparison with the mainpancreatic duct. We investigated the patency of the accessory pancreatic duct and its role in pancreaticpathophysiology. The present study was carried out in the department of Anatomy and forensic medicine, ACSRGovt. medical college, Nellore, Andhra Pradesh, India and in the department of Anatomy, RIMS, Ongole, AndhraPradesh, India. With 96 human cadavers (64 males and 32 females) with 30 to 80 years age group have beenstudied after obtained of ethical committee permission. The dissection method was followed to obtain specimenof pancreas along with C-loop of duodenum, papillae were identified ad dye was injected into APD to see itspatency at MIP. 93.75% specimens present MIP. The prevalence of patency of APD at MIP in population understudy was 38.89%; this is more in males was 43.33%, when compared to the females was 30% but this differencewas not significant statistically. It observed that out of 35 patent APD cases, 33 cases had inter papillarydistance either 2cm or more than 2cm. I t indicates 94.29% of patent APD cases had inter-papillary distancee”2cm. So there is strong relationship between APD patency and inter papillary distance in population understudy. The means inter-papillary distance in patent APD cases was 2.29 ± 0.2cm and non-patent APD cases was1.85 ± 0.25 cm. This difference was statistically significant.

Risk of Axillary Nerve Injury in Standard Anterolateral Approach of Shoulder: Cadaveric Study

@#Introduction:The anterolateral acromion approach of the shoulder is popular for minimally invasive plate osteosynthesis (MIPO) technique. However, there are literatures describing the specific risks of injury of the axillary nerve using this approach. Nevertheless, most of the studies were done with Caucasian cadavers. So, the purpose of this study was to evaluate the risk of iatrogenic axillary nerve injury from using the anterolateral shoulder approach and further investigate the location of the axillary nerve, associated with its location and arm length in the Asian population that have shorter arm length compared to the Caucasian population. Materials and Methods:Seventy-nine shoulders in fourtytwo embalmed cadavers were evaluated. The bony landmarks were drawn, and a vertical straight incision was made 5cm from tip of the acromion (anterolateral approach), to the bone. The iatrogenic nerve injury status and the distance between the anterolateral edge of the acromion to the axillary nerve was measured and recorded. Results: In ten of the seventy-nine shoulders, the axillary nerve were iatrogenically injured. The average anterior distance was 6.4cm and the average arm length was 30.2cm. The anterior distance and arm length ratio was 0.2. Conclusion: Our results demonstrated that the recommended safe zone at 5cm from tip of acromion was not suitable with Asian population due to shorter arm length, compared to Caucasian population. The location of axillary nerve could be predicted by 20% of the total arm-length.

A descriptive study on formation and branching of brachial plexus in adult human cadavers of West Bengal

Variation in anatomy of brachial plexus is important for surgeons working in the upper limb area. It is equally important for anaesthetists performing brachial plexus block as well as neurologists assessing neuronal pathology. The present study was conducted to find the anatomical variations in formation and branching of brachial plexus in adult human cadavers of West Bengal. A total of 54 upper limbs in 27 cadavers were included in this study and were assessed for its course from its formation in cervical region to its termination into branches in the upper extremity. Four plexus were prefixed in origin. Middle and lower trunk were fused in one limb. Lateral cord variations included absence of musculocutaneous nerve in three limbs and extra lateral root of median nerve in one case. Posterior cord variation included two thoracodorsal nerves in two cases. Communicating branch between musculocutaneous nerve was found in three limbs and between radial and ulnar nerve in one limb. In one case, high division of radial nerve was seen. The present study indicated that there are variations in anatomy of brachial plexus and awareness of its pattern is important for those dealing with procedures involving brachial plexus.

Arthroscopic Mumford Procedure Utilizing the Anteromedial and Neviaser Portals – A Pilot Cadaveric Study on Neurovascular Structures at Risk

Introduction: Degenerative disorder involving the acromioclavicular joint (ACJ) is quite common especially in the elderly. One of the surgical modalities of treatment of this disorder is the Mumford Procedure. Arthroscopic approach is preferred due to its reduced morbidity and faster post-operative recovery. One method utilizes the anteromedial and Neviaser portals, which allow direct and better visualization of the ACJ from the subacromial space. However, the dangers that may arise from incision and insertion of instruments through these portals are not fully understood. This cadaveric study was carried out to investigate the dangers that can arise from utilization of these portals and which structures are at risk during this procedure. Materials and Methods: Arthroscopic Mumford procedures were performed on 5 cadaver shoulders by a single surgeon utilizing the anteromedial and Neviaser portals. After marking each portals with methylene blue, dissection of nearby structures were carried out immediately after each procedure was completed. Important structures (subclavian artery as well as brachial plexus and its branches) were identified and the nearest measurements were made from each portal edges to these structures. Results: The anteromedial portal was noted to be closest to the suprascapular nerve (SSN) at 2.91 cm, while the Neviaser portal was noted to be closest also to the SSN at 1.60 cm. The suprascapular nerve was the structure most at risk during the Mumford procedure. The anteromedial portal was noted to be the most risky portal to utilize compared to the Neviaser portal. Conclusion: Extra precaution needs to be given to the anteromedial portal while performing an arthroscopic distal clavicle resection in view of the risk of injuring the suprascapular nerve of the affected limb.

Anatomical considerations of the superior thyroid artery: its origins, variations, and position relative to the hyoid bone and thyroid cartilage / 대한해부학회지

The aim of this study was to provide accurate anatomical descriptions of the overall anatomy of the superior thyroid artery (STA), its relationship to other structures, and its driving patterns. Detailed dissection was performed on thirty specimens of adult's cadaveric neck specimens and each dissected specimen was carefully measured the following patterns and distances using digital and ruler. The superior thyroid, lingual, and facial arteries arise independently from the external carotid artery (ECA), but can also arise together, as the thyrolingual or linguofacial trunk. We observed that 83.3% of STAs arose independently from the major artery, while 16.7% of the cases arose from thyrolingual or linguofacial trunk. We also measured the distance of STA from its major artery. The origin of the STA from the ECA was 0.9±0.4 mm below the hyoid bone. The STA was 4.4±0.5 mm distal to the midline at the level of the laryngeal prominence and 3.1±0.6 mm distal to the midline at the level of the inferior border of thyroid cartilage. The distance between STA and the midline was similar at the level of the hyoid bone and the thyroid cartilage. Also, when the STA is near the inferior border of the thyroid cartilage, it travels at a steep angle to the midline. This latter point may be particularly important in thyroidectomies. We hope that anatomical information provided here will enhance the success of, and minimize complications in, surgeries that involve STA.

Effect of Device Rigidity and Physiological Loading on Spinal Kinematics after Dynamic Stabilization : An In-Vitro Biomechanical Study

OBJECTIVE: To investigate the effects of posterior implant rigidity on spinal kinematics at adjacent levels by utilizing a cadaveric spine model with simulated physiological loading. METHODS: Five human lumbar spinal specimens (L3 to S1) were obtained and checked for abnormalities. The fresh specimens were stripped of muscle tissue, with care taken to preserve the spinal ligaments and facet joints. Pedicle screws were implanted in the L4 and L5 vertebrae of each specimen. Specimens were tested under 0 N and 400 N axial loading. Five different posterior rods of various elastic moduli (intact, rubber, low-density polyethylene, aluminum, and titanium) were tested. Segmental range of motion (ROM), center of rotation (COR) and intervertebral disc pressure were investigated. RESULTS: As the rigidity of the posterior rods increased, both the segmental ROM and disc pressure at L4-5 decreased, while those values increased at adjacent levels. Implant stiffness saturation was evident, as the ROM and disc pressure were only marginally increased beyond an implant stiffness of aluminum. Since the disc pressures of adjacent levels were increased by the axial loading, it was shown that the rigidity of the implants influenced the load sharing between the implant and the spinal column. The segmental CORs at the adjacent disc levels translated anteriorly and inferiorly as rigidity of the device increased. CONCLUSION: These biomechanical findings indicate that the rigidity of the dynamic stabilization implant and physiological loading play significant roles on spinal kinematics at adjacent disc levels, and will aid in further device development.

Abnormal origin of right subclavian artery – A cadaveric study.

Background: During early embryonic life, the aortic arch undergoes complex development and normally results in the formation of a left aortic arch from which three arteries arise: (1) the brachiocephalic artery, which divides into the right common carotid and right subclavian arteries, (2) the left common carotid artery and (3) the left subclavian artery. In the present study we found an aberrant right subclavian artery arising from the arch of aorta distal to the left common carotid artery. Aims & Objective: Abnormalities of branches of arch of aorta are not uncommon and they have been identified more frequently with increasing use of imaging studies. However, the clinician should be aware of the wide range of anomalies that occur in the arch & the great vessels. This could help in adequately managing these variations in emergency approaches to the arch & the great vessels when imaging studies are not available. Our aim is to report the occurrence of the abnormal origin of right subclavian artery in a sample of western Indian population. Material and Methods: Present study was conducted on embalmed cadavers in Anatomy Department at various medical colleges in Gujarat. Branches of arch of aorta were dissected & observed for any variation. Results: A total of 70 cadavers were dissected. In one cadaver we found abnormal origin of right subclavian artery from the arch of aorta. The anomalous artery was passing behind the oesophagus. (1.43%, n = 70) Conclusion: An aberrant right subclavian artery is a rare vascular anomaly & it is also an unusual cause of problems with the passage of solid food through the oesophagus. Recently it has been suggested that it occurs more frequently in patients with Down syndrome. Knowledge of this anomaly is important while evaluating feeding difficulties in patients with Down syndrome as well as in preventing vascular complications in patients with aberrant right subclavian artery.

Systematic Review of Cadaveric Studies on Anatomic Posterior Cruciate Ligament Reconstruction: The Landmarks in Anatomic Posterior Cruciate Ligament Reconstruction

Recently, several new techniques for anatomic posterior cruciate ligament reconstruction (PCLR) have emerged and are believed to restore the normal anatomy of the posterior cruciate ligament more accurately. Despite the latest trend, the optimal methods for anatomic PCLR remain controversial. The purpose of this research is to review surgical techniques for PCLR in cadaver studies and suggest consistent and reproducible technical criteria. For the review of the literature, MEDLINE and EMBASE were screened for articles on anatomic PCLR. Only basic science studies on PCLR performed on human cadavers and written in English were included. Seventeen studies were included in this systematic review. Only the tunnel positions, graft types, and surgical techniques were reported in the majority of the studies. There were many variations of the reported tunnel positions, graft types, and surgical techniques among the studies. In most studies, surgical techniques for consistent and reproducible anatomic PCLR were not explained clearly. Therefore, high level medical research should be encouraged in order to establish standard surgical techniques for anatomic PCLR.

Morphometric Relationship between the Cervicothoracic Cord Segments and Vertebral Bodies

OBJECTIVE: The objective of this study was to investigate the morphologic characteristics between the vertebral body and the regions of the cervical and thoracic spinal cords where each rootlets branch out. METHODS: Sixteen adult cadavers (12 males and 4 females) with a mean age of 57.9 (range of 33 to 70 years old) were used in this study. The anatomical relationship between the exit points of the nerve roots from the posterior root entry zone at each spinal cord segment and their corresponding relevant vertebral bodies were also analyzed. RESULTS: Vertical span of the posterior root entry zone between the upper and lower rootlet originating from each spinal segment ranged from 10-12 mm. The lengths of the rootlets from their point of origin at the spinal cord to their entrance into the intervertebral foramen were 5.9 mm at the third cervical nerve root and increased to 14.5 mm at the eighth cervical nerve root. At the lower segments of the nerve roots (T3 to T12), the posterior root entry zone of the relevant nerve roots had a corresponding anatomical relationship with the vertebral body that is two segments above. The posterior root entry zones of the sixth (94%) and seventh (81%) cervical nerve roots were located at a vertebral body a segment above from relevant segment. CONCLUSION: Through these investigations, a more accurate diagnosis, the establishment of a better therapeutic plan, and a decrease in surgical complications can be expected when pathologic lesions occur in the spinal cord or vertebral body.

Free Hand Pedicle Screw Placement in the Thoracic Spine without Any Radiographic Guidance : Technical Note, a Cadaveric Study

Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic deficit. Methods to aid the surgeon in appropriate screw placement have included the use of intraoperative fluoroscopy and/or radiography as well as image-guided techniques. We describe our technique for free hand pedicle screw placement in the thoracic spine without any radiographic guidance and present the results of pedicle screw placement analyzed by computed tomographic scan in two human cadavers. This free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.

Morphometric Study of the Nerve Roots Around the Lateral Mass for Posterior Foraminotomy

OBJECTIVE: Morphometric data on dorsal cervical anatomy were examined in an effort to protect the nerve root near the lateral mass during posterior foraminotomy. METHODS: Using 25 adult formalin-fixed cadaveric cervical spines, measurements were taken at the lateral mass from C3 to C7 via a total laminectomy and a medial one-half facetectomy. The morphometric relationship between the nerve roots and structures of the lateral mass was investigated. Results from both genders were compared. RESULTS: Following the total laminectomy, from C3 to C7, the mean of the vertical distance from the medial point of the facet (MPF) of the lateral mass to the axilla of the root origin was 3.2-4.7 mm. The whole length of the exposed root had a mean of 4.2-5.8 mm. Following a medial one-half facetectomy, from C3 to C7, the mean of the vertical distance to the axilla of the root origin was 2.1-3.4 mm, based on the MPF. Mean vertical distances from the MPF to the medial point of the root that crossed the inferior margin of the intervertebral disc were 1.2-2.7 mm. The mean distance of the exposed root was 8.2-9.0 mm, and the mean angle between the dura and the nerve root was significantly different between males and females, at 53.4-68.4degrees. CONCLUSION: These data will aid in reducing root injuries during posterior cervical foraminotomy.

Anatomical Investigation of Sural Nerve and Its Contributing Nerves

OBJECTIVE: To identify the location and formation of the sural nerve and its contributing nerves. METHOD: Fourteen lower limbs of 7 adult cadavers were anatomically dissected. The location and formation of the sural nerve (SN) in relation to the medial sural cutaneous nerve (MSCN) and the lateral sural cutaneous nerve (LSCN) were investigated. The length and diameter of the SN and contributing nerves were measured and the differences of the results were analyzed. RESULTS: Twelve SNs were formed by the union of the MSCNs and LSCNs, and 2 SNs were direct extensions of the MSCNs. The point of formation of the SN by union of the MSCN and LSCN was found in the middle third of the legs in 66.7% of SNs examined. The union sites of the SNs were located at 40.58+/-13.97% of the length of lower leg from the tip of lateral malleolus and 55.84+/-6.48% of the calf width from the medial border of the calf. There were significant statistical differences of diameter among nerves (p<0.05) and no significant difference of length between MSCN and LSCN. CONCLUSION: The results of this cadaveric study would increase the accuracy of the sural nerve conduction study and provide the locational information for precise surgical approach.

The Safety of Entrance Reference Line in Endoscopic Carpal Tunnel Release: A Cadaveric Anatomical Evaluation

OBJECTIVE: The purpose of this study is to investigate the anatomic relationship between the neurovasular structures and transverse carpal ligment(TCL) to avoid complications during endoscopic carpal tunnel release. METHODS: Sixteen fresh cadaver hands from 3 men and 5 women(age range, 58~74 years) were used. Neurovascular structures around the TCL were meticulously dissected under a loupe magnification and several morphometric indices were calculated. RESULTS: We found an average length of TCL is 41mm and average distance between the TCL distal margin and superficial palmar arch along the flexor tendon of the ring finger is 9.2mm. In 3 hands, the looped ulnar artery, coursed 1 to 4mm radial to hook of hamate, continuing to the superficial palmar arch. During radial-to-ulnar flexion of the wrist, the looped ulnar artery beyond the hook of hamate shifts more radially (2 to 7mm) with proximal carpal bone. We also noted a Berretini branch located adjacent to the edge of the distal TCL. CONCLUSION: It is appropriate to transect the ligament at least 4mm radial from the radial margin of the hook of hamate or transect the proximal ligament in the radially deviated hand position to protect ulnar neurovascular structure. The proximal portal could be made just ulnar to the palmaris longus tendon to avoid the vascular injury in the proximal portion of the TCL.

Surgical Anatomy of Lateral Extracavitary Approach to the Thoracolumar Spine: Cadaveric Study

OBJECTIVE: The lateral extracavitary approach(LECA) to the thoracolumbar spine is known as one of procedure which allows not only direct vision of pathologic lesion, but also ventral decompression, and dorsal fixation of the spine through the same incision. However, some drawbacks of LECA, including the technically- demanding, time-consuming, unfamiliar surgical anatomy and excessive blood loss, make surgeons to hesitate to use this approach. This study is to provide the surgical anatomy of LECA using cadavers, for detailed informations when LECA is considered for the surgery. METHODS: We performed the 10 cadaveric studies, 7 male and 3 female, and careful dissection was carried out on right side of thoracolumbar region, except one for thoracic region. The photographs with micro-lens were taken to depict the close-up findings and for demonstrating detailed anatomy. RESULTS: The photographs and hand-drawings demonstrated the relationships among the musculature, segmental vessels and nerve roots seen during each dissection plane. The lateral branches of dorsal rami of spinal nerve and the transverse process were confirmed to be the most important landmark of this approach. CONCLUSION: We concluded that detailed anatomical findings for LECA through this step-by-step dissection would be useful during operative intervention to reduce the intraoperative complications in LECA.