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PubMed2003

Brain afferents to the lateral caudal ventrolateral medulla: a retrograde and anterograde tracing study in the rat.

The ventrolateral medulla (VLM) modulates autonomic functions, motor reactions and pain responses. The lateralmost part of the caudal VLM (VLMlat) was recently shown to be the VLM area responsible for pain modulation. In the present study, the brain sources of VLMlat afferent fibers were determined by tract-tracing techniques. Following injection of cholera toxin subunit B into the VLMlat, retrogradely labeled neurons in the forebrain occurred at the somatosensory, insular, motor, limbic and infralimbic cortices, and at the central amygdaloid nucleus. Retrogradely labeled neurons in diencephalic regions were observed in the lateral hypothalamus, posterior hypothalamus and paraventricular nucleus. In the brainstem, retrograde labeling occurred at the periaqueductal gray, red nucleus, parabrachial area, nucleus raphe magnus, nucleus tractus solitarii, lateral reticular nucleus and dorsal and ventral medullary reticular formation. In the cerebellum, retrogradely labeled neurons occurred at the lateral nucleus. Following injections of the anterograde tracer biotinylated dextran amine (BDA) into the lateral hypothalamus or paraventricular nucleus, anterogradely labeled fibers were mainly observed in the VLMlat. Injections of BDA into the periaqueductal gray, red nucleus or lateral nucleus of the cerebellum resulted in anterograde labeling in the VLMlat and lateral reticular nucleus. The present study gives an account of the brain regions putatively involved in triggering the modulatory actions elicited from the VLMlat. These include areas committed to somatosensory processing, autonomic control, somatic and visceral motor activity and affective reactions. The findings suggest that the VLMlat may play a major homeostatic role in the integration of nociception with other brain functions.

Adjuvants, Immunologic↗
PubMed1997

Lateral nucleus of the rat amygdala is reciprocally connected with basal and accessory basal nuclei: a light and electron microscopic study.

Information flow within the intra-amygdaloid circuitry has been generally believed to be unidirectional rather than reciprocal, in which case sensory inputs entering the amygdala via the lateral nucleus would not be modulated by inputs from other amygdaloid regions. In the present study we extend our earlier findings which indicated that the lateral nucleus of the rat amygdala is reciprocally connected with the basal and accessory basal nuclei. The type of synaptic contacts made by these connections is also characterized at the ultrastructural level. An anterograde tracer, Phaseolus vulgaris leucoagglutinin, was injected into the basal (n=22) or accessory basal nuclei (n=12) of the rat amygdala. The results demonstrate that the ventrolateral division of the lateral nucleus receives projections from the basal nucleus, while the medial division receives projections from the accessory basal nucleus. Electron microscopic analyses revealed that axons projecting from the basal nucleus formed both asymmetric and symmetric contacts within the ventrolateral division of the lateral nucleus, whereas axons projecting from the accessory basal nucleus to the medial division of the lateral nucleus formed only asymmetric synapses with their targets. These findings suggest that the lateral nucleus receives both inhibitory and excitatory intra-amygdaloid projections and indicate that information flow within the amygdala is not unidirectional as previously thought. The results of this study provide evidence that the early phase of sensory processing within the amygdala is already modified by inputs from other amygdaloid nuclei.

Amygdala↗
PubMed1998

Projections from the superior olive and lateral lemniscus to tonotopic regions of the rat's inferior colliculus.

The projections to physiologically defined tonotopic regions of the central nucleus of the inferior colliculus (ICC) from the adult rat's superior olivary complex (SOC) and lateral lemniscus were investigated using retrograde tract tracing methods. Iontophoretic injections of the retrograde tracers, Fluoro-Gold (FG) or horseradish peroxidase (HRP), were made into the ICC through a glass micropipette, which also served as a recording electrode to determine the frequency response at the injection site. Injections were made into frequency-specific regions based on the best responses of neurons to contralaterally presented tones between 2 25 kHz. In the dorsal nucleus of the lateral lemniscus (DNLL) neurons were labeled both ipsilaterally and contralaterally to the injection site with a larger proportion projecting to the contralateral side. The distribution of labeled cells was concentric, with high frequencies represented along the outer margin and low frequencies represented centrally within DNLL. The lateral superior olive (LSO) was labeled bilaterally, with high frequencies represented medially and low frequencies laterally along the nuclear axis. The projection from the medial superior olive (MSO) was ipsilateral, with high frequencies represented ventrally and low frequencies dorsally. The projection from the superior paraolivary nucleus (SPN) was also largely ipsilateral, with high frequencies represented medially and low frequencies laterally. The intermediate and ventral nuclei of the lateral lemniscus (INLL and VNLL) were also labeled ipsilaterally and exhibited a distribution of tracer that depended on the frequency of the injection site: the low frequency projection was banded but the high frequency projection was more evenly distributed.

Animals↗
PubMed1999

Salicylate induced changes in outer hair cell lateral wall stiffness.

Micropipette aspiration was used to study the lateral wall stiffness of isolated guinea pig outer hair cells (OHCs) perfused with a sodium salicylate solution. Salicylate treatment significantly decreased lateral wall stiffness as measured by a stiffness parameter (S) compared to cells perfused with a standard bathing solution (S = 0.68 +/- 0.26 vs. S= 1.09 +/- 0.25, P < 0.05). The effect was reversible cells treated with salicylate and then with bathing solution exhibited a lateral wall stiffness similar to control cells (S = 1.10 +/- 0.40. P=0.94). Salicylate perfusion diminishes electromotile responses in isolated OHCs and physiologic doses of salicylate produce hearing loss and tinnitus in human subjects. The OHC lateral wall, the locus of electromotility, consists of three concentric layers: (1) an outermost plasma membrane, (2) a cytoskeletal network of actin and spectrin called the cortical lattice and (3) an innermost collection of flattened membranes called the subsurface cisternae (SSC). Ultrastructural studies have shown that salicylate treatment dilates and vesiculates the lateral wall subsurface cisternae (SSC) in guinea pig OHCs. In addition, salicylate causes an outward curvature of plasma membranes in human erythrocytes. The reversible, salicylate induced increase in lateral wall compliance may result from a direct action on the SSC and/or the plasma membrane.

Animals↗
PubMed1984

Electrocardiographic changes of acute lateral wall myocardial infarction: a reappraisal based on scintigraphic localization of the infarct.

To determine how often acute lateral myocardial infarcts may be electrocardiographically "silent," a new approach was utilized in which subjects were selected by admission thallium scintigraphy. Thirty-one patients with their first infarction were identified with moderate to severe perfusion defects of the lateral and posterolateral walls, persistent over 7 days and associated with severe wall motion abnormalities. Patients with involvement of the anterior, septal or "inferior" regions were not included. In nine patients, the perfusion defect extended to the anterolateral wall: all developed ST elevation and Q waves in at least one of the "lateral" leads (I, aVL or V6) but none showed changes in the "inferior" leads (II, III or aVF). In the other 22 patients, the perfusion defect was limited to the lateral and posterolateral walls: only 12 showed ST elevations (inferior leads only in 7, lateral leads only in 2, both leads in 3) and only 9 developed Q waves (inferior in all). In 8 of these 22 patients, the infarct was silent in the sense that no ST segment elevation or Q waves were seen, although ST depressions or T wave inversions, or both, in all but one patient were compatible with subendocardial infarction. The results indicate that the standard electrocardiogram is insensitive to changes in the lateral and posterolateral regions. Additional diagnostic studies are needed for proper localization and sizing of acute myocardial infarcts.

Adult↗
PubMed2003

Biomechanical effects of medial-lateral tibial tunnel placement in posterior cruciate ligament reconstruction.

With most posterior cruciate (PCL) reconstruction techniques, the distal end of the graft is fixed within a tibial bone tunnel. Although a surgical goal is to locate this tunnel at the center of the PCL's tibial footprint, errors in medial-lateral tunnel placement of the tibial drill guide are possible because the position of the tip of the guide relative to the PCL's tibial footprint can be difficult to visualize from the standard arthroscopy portals. This study was designed to measure changes in knee laxity and graft forces resulting from mal-position of the tibial tunnel medial and lateral to the center of the PCL's tibial insertion. Bone-patellar tendon-bone allografts were inserted into three separate tibial tunnels drilled into each of 10 fresh-frozen knee specimens. Drilling the tibial tunnel 5 mm medial or lateral to the center of the PCL's tibial footprint had no significant effect on knee laxities; the graft pretension necessary to restore normal laxity at 90 degrees of knee flexion (laxity match pretension) with the medial tunnel was 13.8 N (29%) greater than with the central tunnel. During passive knee flexion-extension, graft forces with the medial tibial tunnel were significantly higher than those with the central tunnel for flexion angles greater than 65 degrees while graft forces with the central tibial tunnel were not significantly different than those with the lateral tibial tunnel. Graft forces with medial and lateral tunnels were not significantly different from those with a central tunnel for 100 N applied posterior tibial force, 5 Nm applied varus and valgus moment, and 5 Nm applied internal and external tibial torque. With the exception of slightly higher graft forces recorded with the medial tunnel beyond 65 degrees of passive knee flexion, errors in medial-lateral placement of the tibial tunnel would not appear to have important effects on the biomechanical characteristics of the reconstructed knee.

Adult↗
PubMed2003

The level of compressive load affects conclusions from statistical analyses to determine whether a lateral meniscal autograft restores tibial contact pressure to normal: a study in human cadaveric knees.

This study addressed the question of whether the level of compressive load would affect the conclusions from statistical analyses aimed at determining how well a lateral meniscal autograft restores tibial contact (as indicated by the maximum contact pressure, mean pressure, and contact area) to that of the intact knee. If statistical analyses indicated that normal tibial contact was not restored with a higher, more physiologic load, then a secondary question was whether an autograft surgically implanted with bone plugs would improve tibial contact compared to that in a meniscectomized knee. Nine, fresh-frozen human cadaveric knees were subjected to a low, non-physiologic compressive load of 400 N and a higher, more physiologic compressive load of 1200 N under three conditions (lateral meniscus intact, lateral meniscus removed and reimplanted as an autograft, and lateral meniscus removed). Contact pressure on the lateral plateau was measured with pressure sensitive film at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of flexion. At 400 N, p-values from statistical analyses indicated that both the maximum and mean pressures with the autograft were comparable to those of the intact knee (p> or =0.685). However, at 1200 N, p-values from statistical analyses indicated that both the maximum and mean pressures with the autograft were significantly greater than those of the intact knee (p< or =0.0001). Therefore studies designed to evaluate tibial contact pressure for a meniscal transplant should use a higher, more physiologic compressive load, because lower loads overestimate the transplant's effectiveness. Although none of the contact variables was restored to normal when the compressive load was increased to 1200 N, all of the contact variables were more normal than those of the meniscectomized knee. Thus, lateral meniscal allografts implanted using bone plugs can significantly improve contact pressure relative to a meniscectomized knee at the time of implantation.

Adult↗
PubMed1999

Arthroscopic release for lateral epicondylitis: a cadaveric model.

At least 10 different surgical approaches to refractory lateral epicondylitis have been described, including an arthroscopic release of the extensor carpi radialis brevis tendon. The advantages of an arthroscopic approach include an opportunity to examine the joint for associated pathology, no disruption of the extensor mechanism, and a rapid return to premorbid activities with possibly fewer complications. A cadaveric study was performed to determine the safety of this procedure. Ten fresh-frozen cadaveric upper extremities underwent arthroscopic visualization of the extensor tendon and release of the extensor carpi radialis brevis tendon. The specimens were randomized with regard to the use of either a 2.7-mm or a 4.0-mm 30 degree arthroscope through modified medial and lateral portals. Following this, the arthroscope remained in the joint, and the portal, cannula track, and surgical release site were dissected to determine the distance between the cannula and the radial, median, ulnar, lateral antebrachial, and posterior antebrachial nerves, and the brachial artery and the ulnar collateral ligament. No direct lacerations of neurovascular structures were identified; however, the varying course of the lateral and posterior antebrachial nerves place these superficial sensory nerves at risk during portal placement. As in previous reports, the radial nerve was consistently in close proximity to the proximal lateral portal (3 to 10 mm: mean, 5.4 mm). The ulnar collateral ligament was not destabilized. Arthroscopic release of the extensor carpi radialis brevis tendon appears to be a safe, reliable, and reproducible procedure for refractory lateral epicondylitis. Cadaveric dissection confirms these findings.

Arthroscopy↗
PubMed2000

Laparoscopic adrenalectomy: lateral transabdominal approach vs posterior retroperitoneal approach.

Laparoscopic adrenalectomy has been used to remove a wide variety of adrenal neoplasms. Although several laparoscopic approaches to the adrenal gland have been described, the lateral transabdominal approach has several advantages when compared with other approaches for laparoscopic adrenalectomy. From October 1995 to July 1999, we performed laparoscopic adrenalectomies on 16 patients, including eight posterior retroperitoneal approaches and eight lateral transabdominal approaches. Sixteen patients, ranging in age from 23 to 69 years, were treated for the following conditions: non-functioning adenoma, four patients; aldosteronoma, seven patients; pheochromocytoma, three patients; Cushing's adenoma, two patients. The average tumor size was 2.5 +/- 0.5 cm (1.8-3.0 cm, median 2.4 cm) in the lateral transabdominal approach, 1.2 +/- 0.8 cm (0.8-3.2 cm, median 1.75 cm) in the posterior retroperitoneal approach. Average operative time of lateral transabdominal approach was significantly shorter than that of the posterior retroperitoneal approaches (mean 129 min vs 269 min, P = 0.0005). Conversion to laparotomy was required in one patient in the posterior approach. Postoperative complication occurred in one pneumothorax in the lateral transabdominal approach and two subcutaneous emphysemas in the posterior retroperitoneal approach. There was no statistical difference in blood loss during the operation in the two groups. There was no mortality in either group. The lateral transabdominal approach is a safe and efficient technique for the removal of the adrenal neoplasms. Compared with other approaches, this technique has a wider working space and also good exposure for removing the adrenal gland.

Abdomen↗
PubMed1991

Routine use of a lateral approach to cataract extraction to achieve rapid and sustained stabilization of postoperative astigmatism.

After observing that lateral under-riding scleral pocket incisions and closures decayed very little and required full correction on the table to achieve the desired reduction in astigmatism, I began performing routine lateral approaches to planned extracapsular cataract extraction (ECCE). The result was an improvement in early and prolonged stabilization of keratometric astigmatism. This improvement was statistically significant when compared with the identical surgery performed in the vertical meridian. Using a 6.5 mm scleral pocket incision and the same suture material and closure technique, I found that the results of phacoemulsification via vertical and lateral approaches were not statistically different from the planned ECCE via lateral approach. Scleral pocket incisions and modified shoelace closures with 11-0 polyester suture were used in all cases; no suture removal was performed. The early visual recovery with planned ECCE via lateral approach was equivalent to that with phacoemulsification but did not require the expensive instrumentation or the "phaco learning curve." The minimal and stable postoperative astigmatism, along with early and sustained visual recovery possible with ECCE via lateral approach, may reduce the potential benefit of mini-incision and foldable intraocular lens surgery.

Aged↗
PubMed2002

Semiology of temporal lobe epilepsy in children and adolescents. Value in lateralizing the seizure onset zone [corrected].

PURPOSE: To determine the frequency and lateralizing value of clinical seizure symptoms in children and adolescents with drug-resistant temporal lobe epilepsy (TLE). METHODS: Patients enrolled had to be <18 years of age and seizure free at follow-up for at least 12 months after epilepsy surgery. Patients were assigned to two age groups, children (age<12 years) and adolescents (age>12 and <18 years). Video-tapes were reviewed blinded to patients' demographic data and results of additional investigations by two independent raters. Clinical signs of known lateralizing significance in adults and additional clinical signs without lateralizing value were assessed. RESULTS: 14 patients (eight boys; 2-18 years) fulfilled the inclusion criteria. Inter-observer agreement was excellent (kappa coefficient: 0.82). Compared with adult series, no differences were found concerning overall occurrence of lateralizing signs and lateralizing accuracy. There were age-related differences, however, concerning the occurrence of individual signs: secondary generalization, complex automatisms and version were less frequent in children than in adolescents. CONCLUSIONS: Clinical signs of lateralizing value can also be found in children and adolescents, provided that the evaluation protocols used consider developmental aspects.

Adolescent↗
PubMed2001

Language lateralization in schizophrenia, an fMRI study.

Anatomical studies have shown that cerebral asymmetry is reduced in schizophrenia. Functional asymmetry appears to be reduced also, as was shown with dichotic listening studies. These studies, however, have not revealed whether reduced lateralization is the result of decreased language activity of the left hemisphere or whether it is the consequence of increased language-related activity in the right hemisphere. To elucidate this, we examined hemispheric dominance for language processing by means of functional MRI. Twelve schizophrenic patients and twelve healthy controls were scanned while they were engaged in a verb-generation and a semantic decision task. Activation was measured bilaterally in the frontal, temporal and temporo-parietal language areas, and a laterality index was derived from activity in these regions of interest in the left and the right hemispheres. Clinical symptoms were rated at the time of scanning. The results indicate that language processing is less lateralized in patients than in controls (a mean laterality index of 0.35 versus 0.63, respectively, difference p<0.01). Analysis of variance of the extent of activity, i.e. numbers of active voxels, revealed a significant hemisphere by group interaction (F(1,22)=11.2, p<0.001), which was due to increased activation in the right hemisphere of the patients (post hoc t-test p<0.05). We found no evidence of reduced activity in the left hemisphere. Further analysis of clinical symptoms rated prior to scanning revealed that decreased language lateralization was associated with more severe hallucinations (r=-0.54, p<0.05). We postulate that decreased language lateralization in schizophrenia may result from failure to inhibit the right hemisphere.

Adult↗
PubMed2006

Transforniceal lateral deep bone decompression--a modified technique to prevent postoperative diplopia in patients with disfiguring exophthalmos due to dysthyroid orbitopathy.

BACKGROUND/PURPOSE: Postoperative diplopia remains a significant complication of orbital decompression in dysthyroid orbitopathy. This study evaluated the results of orbital decompression treatment using a transforniceal approach to sculpt the lateral orbital deep bone area. METHODS: The two areas of bone in the deep lateral orbit (the basin of the inferior orbital fissure and the sphenoid door jamb) were exposed using a transforniceal swinging eyelid approach. An electric drill was used to sculpt these deep bone areas of the lateral orbit, and approximately 1 mL intraconal fat was removed simultaneously. Between October 1999 and March 2003, transforniceal lateral deep bone decompression was performed in 35 consecutive patients (62 orbits) with disfiguring dysthyroid orbitopathy. Data on proptosis reduction effect, new-onset diplopia and other complications of lateral wall decompression were analyzed. RESULTS: The average preoperative Hertel value was 21.2 +/- 1.3 mm (range, 18-23 mm) and decreased to 17.4 +/- 1.2 mm (range, 15-19.5 mm) postoperatively. The mean decrease in proptosis 3 months postoperatively was 3.8 +/- 0.91 mm (range, 1.5-4.6 mm). New-onset downgaze diplopia occurred in two (5.7%) of the 35 patients. Persistent trigeminal paresthesia was noted in one patient (2.8%). No cerebrospinal fluid leak, globe injury or vision deterioration was noted during 9.5 +/- 1.7 months of follow-up. The cosmetic appearance was improved in all patients after surgery. CONCLUSION: Transforniceal lateral deep bone decompression produces less new-onset, persistent diplopia than traditional inferomedial wall decompression, and provides good cosmesis by using a hidden small incisional wound. This approach appears to be a safe and effective procedure for patients with disfiguring exophthalmos, especially for Asian patients without crease fold.

Adult↗
PubMed2001

Influence of memory demand and contra lateral activity on muscle activity.

Computer mouse work often includes memory demands and contra lateral activity. This study simulated video display unit (VDU) mouse-work and the focus was on forearm muscle activity as a result of standardised postural loads, memory demands and contra lateral activity. Surface and intramuscular electromyography (EMG) were recorded from the right forearm muscles during finger elevation and rest with and without memory demands and with and without contra lateral activity i.e. activity of the left hand. In most situations, memory demand increased activity in the m. extensor carpi radialis brevis and m. flexor digitalis superficialis. Also contra lateral activity increased activity in situations with and without memory demands. While surface EMG level of the m. extensor digitorum communis did not increase during memory demands, intramuscular EMG level increased when memory demands and contra lateral activity was combined. Influence of memory demands and contra lateral activity were most pronounced, in situations where activity levels were small. We presume that it is not only prolonged time of active computer mouse use that is a risk for development of musculoskeletal disorders, but also the time when people interact with the computer mentally or with the 'non-mouse hand', while resting their 'mouse-hand' on the mouse.

Adult↗
PubMed2003

Quantitative fMRI assessment of the differences in lateralization of language-related brain activation in patients with temporal lobe epilepsy.

Defining language lateralization is important to minimize morbidity in patients treated surgically for temporal lobe epilepsy (TLE). Functional magnetic resonance imaging (fMRI) offers a promising, noninvasive, alternative strategy to the Wada test. Here we have used fMRI to study healthy controls and patients with TLE in order to (i) define language-related activation patterns and their reproducibility; (ii) compare lateralization determined by fMRI with those from of the Wada test; and (iii) contrast different methods of assessing fMRI lateralization. Twelve healthy right-handed controls and 19 right-handed preoperative patients with TLE (12 left- and seven right-TLE) were studied at 3T using fMRI and a verbal fluency paradigm. A Wada test also was performed on each of the patients. Greater activation was found in several areas in the right hemisphere for the left-TLE group relative to controls or right-TLE patients. Relative hemispheric activations calculated based on either the extent or the mean signal change gave consistent results showing a more bihemispheric language representation in the left-TLE patients. There was good agreement between the Wada and fMRI results, although the latter were more sensitive to involvement of the nondominant right hemisphere. The reproducibility of the fMRI values was lowest for the more bihemispherically represented left-TLE patients. Overall, our results further demonstrate that noninvasive fMRI measures of language-related lateralization may provide a practical and reliable alternative to invasive testing for presurgical language lateralization in patients with TLE. The high proportion (33%) of left-TLE patients showing bilateral or right hemispheric language-related lateralization suggests that there is considerable plasticity of language representation in the brains of patients with intractable TLE.

Adolescent↗
PubMedDate not supplied

Lateral tennis elbow: "Is there any science out there?".

As orthopaedic surgeons, we are besieged by myths that guide our treatment of lateral epicondylitis, or "tennis elbow." This extends from the term used to describe the condition to the nonoperative and operative treatments as well. The term epicondylitis suggests an inflammatory cause; however, in all but 1 publication examining pathologic specimens of patients operated on for this condition, no evidence of acute or chronic inflammation is found. Numerous nonoperative modalities have been described for the treatment of lateral tennis elbow. Most are lacking in sound scientific rationale. This has led to a therapeutic nihilism with respect to the nonoperative management of this condition. An examination of the literature can only lead us to believe that most, if not all, common nonoperative therapeutic modalities used for the treatment of tennis elbow are unproven at best or costly and time-consuming at worst. Most of the published literature on the nonoperative treatment of patients with lateral tennis elbow consists of poorly designed trials. The selection criteria are nebulous, the control group is questionably designed, and the number of patients is often too low to avoid a serious loss of study power. These studies therefore have a high beta error, implying an inability to detect a difference between groups, even if one truly existed. If clinical signs and symptoms persist beyond the limit of acceptability of both patient and surgeon, then an array of surgical options are available. These range from a 10-minute office procedure (the percutaneous release of the extensor origin with the patient under local anesthetic) to an extensive joint denervation, in which all radial nerve branches ramifying to the lateral epicondyle are directly or indirectly divided. How is the surgeon to choose, given the fact that most of the published surgical studies are case series of one type of operation or another, consisting of patients operated on and evaluated by the same surgeon, who has a vested interest in his or her own patients' successful outcome? The orthopaedic surgeon therefore has very little on which to "hang his hat" when it comes to objective data to guide treatment of patients with lateral tennis elbow syndrome. In the final analysis we are guided simply by our own subjective viewpoint and clinical experience. In 1999, to have such a common clinical condition have such a paucity of peer-reviewed published data of acceptable scientific quality is disappointing. In this review article we will examine the "myths" of tennis elbow: the name, the salient features on history and physical examination, the diagnostic modalities, the pathology of the "lesion," the anatomy of the lateral elbow and extensor origin and why it has led to such confusion in differential diagnosis, the nonoperative and operative treatment of tennis elbow, and finally the various studies that have been carried out on elbow biomechanics as it relates to the pathoetiology of true "tennis elbow." It is our hope that the reader will emerge with a clearer picture of the pathoetiology of the condition and the scientific rationale (or lack thereof) of the various operative and nonoperative treatment modalities.

Acupuncture Therapy↗
PubMed1996

Lateral pterygoid muscle and its relationship to the meniscus of the temporomandibular joint.

OBJECTIVE: The theory of internal derangement of the temporomandibular joint involves the anterior displacement of the meniscus, which is thought to be the result of hyperactivity of the lateral pterygoid muscle. There is, however, a great deal of confusion with respect to the attachment of this muscle to the meniscus. This anatomic study reexamines the meniscal attachment of the lateral pterygoid muscle, in particular, the upper head of this muscle. STUDY DESIGN: The anatomic relationship between the lateral pterygoid muscle and the meniscus was examined in the postmortem specimens of 25 males and 15 females between the ages of 7 to 85 years. RESULTS: In 65% of specimens, the upper head of the lateral pterygoid muscle was attached to the medial aspect of the capsule, meniscus, and to the pterygoid fovea of the condyle. In 27.5% of specimens, the upper head was attached solely to the condyle; in the remaining 7.5% of cases, there were other types of attachments of the lateral pterygoid muscle to the meniscus. CONCLUSION: This study confirms that the lateral pterygoid muscle has a variable attachment to the meniscus. The role of this muscle in the displacement of the meniscus is still unknown and further research into temporomandibular disorders should involve the investigation of other structures in the craniomandibular complex.

Adolescent↗
PubMed2003

Lateral line pore diameters correlate with the development of gas bubble trauma signs in several Columbia River fishes.

Gas bubble trauma (GBT) caused by gas supersaturation of river water continues to be a problem in the Columbia River Basin. A common indicator of GBT is the percent of the lateral line occluded with gas bubbles; however, this effect has never been examined in relation to lateral line morphology. The effects of 115, 125 and 130% total dissolved gas levels were evaluated on five fish species common to the upper Columbia River. Trunk lateral line pore diameters differed significantly (P<0.0001) among species (longnose sucker>largescale sucker>northern pikeminnow>/=chinook salmon>/=redside shiner). At all supersaturation levels evaluated, percent of lateral line occlusion exhibited an inverse correlation to pore size but was not generally related to total dissolved gas level or time of exposure. This study suggests that the differences in lateral line pore diameters between species should be considered when using lateral line occlusion as an indicator of gas bubble trauma.

Animals↗