Aysun Uz

Thoracic pedicle: surgical anatomic evaluation and relations.

This anatomic study investigated the thoracic pedicle and its relations. The objective was to emphasize the importance of the thoracic pedicle for transpedicular screw fixation to avoid complications during surgery. Twenty cadavers were used to observe the cervical pedicle and its relations. The isthmus of the pedicle was exposed after removal of whole-posterior bony elements, including spinous processes, laminas, lateral masses, and the inferior and superior facets. The pedicle width and height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, root exit angle, and nerve root diameter were measured. There was no distance between the pedicle and dural sac in eight specimens. There was, however, a short distance in 12 remaining specimens in the upper and lower thoracic regions. The distances between the thoracic pedicle and the adjacent nerve roots ranged from 1.5 to 6.7 mm and 0.8 to 6.0 mm superiorly and inferiorly at all levels. The mean pedicle height and width at T1-T12 ranged from 2.9 to 11.4 mm and 6.2 to 21.3 mm, respectively. The interpedicular distance decreased gradually from T1 to T5 and then increased gradually to T12. The mean root exit angle decreased consistently from 104 degrees to 60 degrees. The nerve root diameter was between 2.3 and 2.5 mm at the T1-T5 level and then increased consistently from 2.5 to 3.7 mm. All significant differences were noted at p < 0.05 and p < 0.01. The following suggestions are made based on these results. 1) More care should be taken when a transpedicular screw is placed in the horizontal plane. 2) Improper medial placement of the pedicle screw, especially in the middle thoracic spine, should be avoided, and the anatomic variations between individuals should be considered. 3) Because of substantial variations in the size of thoracic pedicles, utmost attention should be given to the findings of a computed tomographic evaluation before thoracic transpedicular fixation is begun.

Surgical Anatomic Evaluation of the Cervical Pedicle and Adjacent Neural Structures

OBJECTIVEAlthough several clinical applications of transpedicular screw fixation in the cervical spine have been documented recently, few anatomic studies concerning the cervical pedicle are available. This study was designed to evaluate the anatomy and adjacent neural relationships of the middle and lower cervical pedicle (C3–C7). The main objective is to provide accurate information for transpedicular screw fixation in the cervical region and to minimize complications by providing a three-dimensional orientation. METHODSTwenty cadavers were used to observe the cervical pedicle and its relationships. After removal of the posterior bony elements, including spinous processes, laminae, lateral masses, and inferior and superior facets, the isthmus of the pedicle was exposed. Pedicle width, pedicle height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, medial pedicle-dural sac distance, mean angle of the pedicle, root exit angle, and nerve root diameter were measured. RESULTSThe results indicate that there was no distance between the pedicle and the superior nerve root and between the pedicle and the dural sac in 16 specimens, whereas there was a slight distance in the lower cervical region in the 4 other specimens. The mean distance between the pedicle and the inferior nerve root for all specimens ranged from 1.0 to 2.5 mm. The mean distance between the medial pedicle and the dural sac increased consistently from 2.4 to 3.1 mm. At C3–C7, the mean pedicle height ranged from 5.2 to 8.5 mm, and the mean pedicle width ranged from 3.7 to 6.5 mm. Interpedicular distance ranged from 21.2 to 23.2 mm. The mean root exit angle ranged from 69 to 104 degrees, with the largest angle at C3 and the smallest at C6. The mean angle of the pedicle ranged from 38 to 48 degrees. The nerve root diameter increased consistently from 2.7 mm at C3 to 3.8 mm at C6 and then decreased to 3.7 mm at the C7 level. Differences in measurements were considered statistically significant at levels ranging from P < 0.05 to P < 0.01. CONCLUSIONThis study indicates that improper placement of the pedicle screw medially and superiorly in the middle and lower cervical spine should be avoided and that the anatomic variations between individuals should be established by measurement.

Regional anatomic structures of the elbow that may potentially compress the ulnar nerve

HYPOTHESIS Traumatic injuries to the ulnar nerve at the elbow are a frequent problem as it is vulnerable to stretching and compression with motion of the upper limb. The aim of the present study was to explore the course of the ulnar nerve at the elbow and forearm and to determine possible anatomical structures that may cause compression of this structure. MATERIALS AND METHODS We examined 12 upper limbs from cadavers. The length of any fibrous bands, and if present, their distance to the medial epicondyle was recorded. RESULTS On 5 sides a fibrous band originating from the medial intermuscular septum was observed to cross over the ulnar nerve. The average length of the fibrous band was 5.7 cm, and it attached to the medial epicondyle. The mean length of the ulnar nerve as it coursed in the cubital tunnel was 3.8 cm. In 4 of the cases, the ulnar nerve was covered by muscle fibers originating from the flexor digitorum superficialis and extending to the flexor carpi ulnaris. On 5 sides we observed fibrous thickenings, and on 8 sides vascular structures were found crossing over the ulnar nerve. DISCUSSION The cubital tunnel is the most common site of compression of the ulnar nerve. Numerous surgical procedures are recommended for cubital tunnel syndrome. Simple decompression is used most commonly. Although surgical procedures are reported to provide efficient pain relief and functional recovery, residual or recurrent symptoms have been reported. Reasons for such recurrences may be more proximal or distal compression of the ulnar nerve as seen in our study. CONCLUSION Knowledge of possible compression sites of the ulnar nerve is important to the surgeon so that complications are avoided and postoperative recurrence is decreased. LEVEL OF EVIDENCE Basic science study.

The phrenico-esophageal ligament: an anatomical study

The phrenico-esophageal ligament (PEL), which is claimed by some to be an important anti-reflux barrier, has been accepted as an important structure by some surgeons dealing with the surgical treatment of hiatal hernias. However, the characteristics of its anatomical structure and the physiological importance of this ligament is still a subject of discussion. The aim of this study was to define this anatomic structure and to point out the clinical importance of the PEL. This study has been carried out on samples taken from 2 fresh and 12 fixed cadavers. The PEL was observed to be derived from the transversalis and endothoracic fascia attaching the esophagus to the diaphragmatic crura at the region of the esophageal hiatus. While the transversalis fascia covered the inferior surface of the diaphragm, it was observed to divide into upper and lower leaflets when it approached the esophageal hiatus. The endothoracic fascia turned superiorly at the level of esophageal hiatus and attached on to the esophagus by uniting with the upper leaflet of the transversalis fascia in 11 of the specimens. In three of the specimens, it attached on the esophagus at a higher level than the transversalis fascia. The histologic sections of our study revealed that the PEL is formed by collagen and elastic fibers composed of fibroblasts and blood vessels. Since the PEL is a strong structure that firmly attached to the esophageal wall and surrounded the upper part of the distal esophagus like a skirt, it is reasonable that it may play an important role in the gastroesophageal sphincteric mechanism. Histological evidence for decrease in collagen fibers with age and the loose arrangement of the elastic fibers due to this decrement might decrease the resistance and the elasticity of the PEL. This situation may explain the predisposition to hiatal hernias seen with increased in age.

Variations in the origin of the thalamoperforating arteries.

The anatomy of the thalamoperforating arteries located in the interpeduncular fossa must be well understood by surgeons to enable safe surgical treatment of basilar and posterior cerebral artery aneurysms. Therefore, we studied 30 posterior cerebral arteries obtained from 15 fresh adult cadaver brains. By filling the vertebral and internal carotid arteries of the brains with coloured latex, we found thalamoperforating arteries in 97% of the brains studied. The average number of arteries was two (range 0-5). Thalamoperforating arteries were classified into four different types according to their origin at the P1 segment: type I (bilateral multiple), 20%; type II (unilateral multiple, unilateral single), 33%; type III (bilateral single), 40%; type IV (one side multiple, the other side with no branches), 7%. In conclusion, it is important to bear in mind that these arteries can be the unilateral single type, and that they may be absent on the other side. Unilateral single arteries are very significant for surgical technique.

Extraforaminal lumbar arterial anatomy

BACKGROUND There are few studies carried out to reveal lumbar arterial anatomy. The studies of vascular anatomy of the lumbar zone are usually based on the angiographic imaging methods and barium injected radiographic sections of human specimens. METHODS Upon the recent breakthroughs in the microscopic anatomic dissections, the vascular structure of this zone is examined in 16 cadavers. Arterial anatomies of the extraforaminal zones of 80 lumbar vertebral objects were studied. RESULTS In each segment, lumbar artery, extraforaminal branches of the lumbar artery and the spinal (foraminal) branch were described. The spinal branch is originated from lumbar artery and extends as the dorsal branch. The dorsal branch is divided into 4 branches: ganglionic, transverse, ascending, and descending. Diameters of the lumbar artery, spinal, dorsal, and ganglionic branches were measured at each stage. The mean diameter of the lumbar artery was 2.7 mm, the dorsal branch was 2.0 mm, the foraminal branch was 1.9 mm, and the ganglionic branch was 1.0 mm, respectively. CONCLUSION Knowledge of lumbar arterial anatomy is needed for carrying out a successful surgical operation and reducing complications.

Is the asterion a reliable landmark for the lateral approach to posterior fossa

An anatomical study was conducted to gain orientation regarding the posterolateral approaches. The asterion is defined as the junction of the lambdoid, parietomastoid, and occipitomastoid sutures. This anatomical point has been widely used as a landmark in lateral approaches to posterior fossa. Although there are many common practices in posterolateral approaches, studies providing accurate anatomical knowledge as to what is the correct point to start a craniotomy are limited in number. Therefore, this study was conducted in an attempt to determine the reliability of the asterion for the posterolateral approaches as surgical landmark.

Surface landmarks of brachial plexus: ultrasound and magnetic resonance imaging for supraclavicular approach with anatomical correlation

The present study is able to describe a certain line, under which brachial plexus (BP) lies underneath in the supraclavicular region. A line drawn between midpoint of the sternocleidomastoid muscle to the midpoint of the clavicle was considered for BP. Surface landmarks were evaluated by applying ultrasound (US) on 30 volunteers (15 female, 15 male). Axial and sagittal views of BP were taken and distances between skin and BP were measured. Coronal magnetic resonance (MR) sections were taken from 7 volunteers according to the second line after applying two fat capsules on each line. The sonographic views were seen at the same line. Mean distances from skin were found as 16.5+/-0.7 mm for male and 14.5+/-0.5 mm for female volunteers. MR images were obtained bilaterally, which were parallel and posterior from sonographic lines. Surface landmarks, as presented in this study, are simple to accomplish and are not dependent on structural variations as external jugular vein.

Relationship between the posterior cerebral artery and the cisternal segment of the oculomotor nerve.

The aim of this study was to evaluate the relationship between the cisternal segment of the oculomotor nerve and the posterior cerebral artery and its branches. The oculomotor nerve and the posterior cerebral artery of 15 cadaver brains (30 hemispheres) were examined using a surgical microscope. The dorsal portion of the cisternal segment of the oculomotor nerve had a close relationship with the P(1) and P(2) segments of the posterior cerebral artery in 100% of cases, the thalamoperforating arteries in 97%, the collicular arteries in 97%, the short circumferential arteries in 33% and the posterior medial choroidal arteries in 20%. The proximal portion of the nerve had a close relationship with the P(1) segment of the posterior cerebral artery, the thalamoperforating arteries, the collicular arteries and the short circumferential arteries, whereas the distal portion had a close relationship with the P(2) segment of the posterior cerebral artery and the posterior medial choroidal arteries. The oculomotor nerve was perforated by various arteries in different portions. These arteries were the thalamoperforating arteries in 10% of the hemispheres, the collicular arteries in 16% and the short circumferential arteries in 11%. It can be concluded that the dorsal portion of the cisternal segment of the oculomotor nerve has a close relationship with the branches arising from the P(1) and P(2) segments of the posterior cerebral artery. These arteries supply the cisternal segment of the oculomotor nerve.

Anatomical study of the lateral wall of the cavernous sinus, emphasizing dural construction and neural relations

Abstract This study aims to determine the microscopic anatomy of the layers of the lateral wall of the cavernous sinus (CS) and, in particular, intends to examine the location and relations of the dural openings on the deep layer. Forty sides of 20 formalin-fixed and fresh cadavers were dissected and their CS examined. In 12 cases we found an opening on the deep dural layer; however, in four of them the inferolateral trunk of the internal carotid artery (ICA) was identified through these dural openings. We noticed the trochlear nerve making a curve (5% of cases) or lying close to the ophthalmic nerve (12.5%) on the lateral wall. In one case, the triangular area described by Parkinson could not be exposed surgically. Our findings indicate the importance of the heterogeneous courses of the cranial nerves lying on the lateral wall and point to the significance of the dural openings, which can influence the etiology of neoplastic invasions originating from the CS.