Medial Margin Research Articles

Appropriate hinge position for prevention of unstable lateral hinge fracture in open wedge high tibial osteotomy.

Open wedge high tibial osteotomy (OWHTO) for medial-compartment osteoarthritis of the knee can be complicated by intra-operative lateral hinge fracture (LHF). We aimed to establish the relationship between hinge position and fracture types, and suggest an appropriate hinge position to reduce the risk of this complication. Consecutive patients undergoing OWHTO were evaluated on coronal multiplanar reconstruction CT images. Hinge positions were divided into five zones in our new classification, by their relationship to the proximal tibiofibular joint (PTFJ). Fractures were classified into types I, II, and III according to the Takeuchi classification. Among 111 patients undergoing OWHTOs, 22 sustained lateral hinge fractures. Of the 89 patients without fractures, 70 had hinges in the zone within the PTFJ and lateral to the medial margin of the PTFJ (zone WL), just above the PTFJ. Among the five zones, the relative risk of unstable fracture was significantly lower in zone WL (relative risk 0.24, confidence interval 0.17 to 0.34). Zone WL appears to offer the safest position for the placement of the osteotomy hinge when trying to avoid a fracture at the osteotomy site. Cite this article: Bone Joint J 2017;99B10:1313-18.

Application of guide combined with probing the internal wall of pedicle screw trajectory for subaxial cervical pedicle screw placement

To investigate the skill and evaluate the accuracy for application of guide combined with probing the internal wall of pedicle screw trajectory for subaxial cervical pedicle screw placement. Subaxial cervical pedicle screw was inserted in 11 patients by the guide combined with probing the internal wall of pedicle screw trajectory from January 2014 to October 2016, including 7 males and 4 females with an average age of 48.1 years(ranged 32 to 63 years). There were 4 cases with cervical spondylotic myelopathy, 4 with fracture and dislocation of cervical vertebrae, 1 with cervical cord injury without fracture and dislocation, and 2 with atlantoaxialfracture and dislocation. The target pedicle's diameter, optimal entry point, sagittal angle and cross-sectional angle were measured by CT before operation. During operation, the pedicle screw inserted angle was controlled by a guide with a self-designed protractor and probed the internal wall of pedicle screw trajectory as medial safety margin of insertion screw. The accuracy of cervical pedicle screw was evaluated by CT with classification of four grades and assessed whether there was injury of spine cord or vertebral artery postoperatively. Seventy-one cervical pedicle screws were placed among 11 patients, and no one had been found with clinical manifestations of injury of spine cord (or nerve root) or vertebral artery after operation. According to postoperative CT scan for evaluating the grade of screw position, 52 screws were in grade 0, 13 in grade 1, 4 in grade 2, 2 in grade 3, and 91% (65/71) located in good position. In total, 6 screws were incorreted in placement, and 4 cases of them broke medial wall and 2 cases broke lateral wall. The method of probing the internal wall of pedicle screw trajectory for subaxial cervical pedicle screw placement is safe and reliable, but the studying curve is long. Probing the internal wall of pedicle screw trajectory and controlling the insertion angle by guide with a protractor are key points of this technology.

A new species of Hyalella from the High Andes of Ecuador (Crustacea, Amphipoda, Hyalellidae).

Hyalella cajasi sp. n. is described from high altitude shallow water lakes in southern Ecuador. This is the second representative of the genus recorded in the country after H. meinerti. The new species shares with nine South American species of the genus the display of a smooth, non-processiferous body, a male first uropod with a modified curved robust seta on the endopod, and six pairs of sternal gills. The new taxon can be distinguished from these species based on the presence/absence of eyes; relative length of antenna 1 with respect to antenna 2; presence/absence of short pointed robust seta distally on palp of maxilla 1; number of pappose setae proximally on medial margin of inner lobe of maxilla 2; elongation and curvature of the modified robust seta of endopod of male uropod 1; relative length of ramus of uropod 3 with respect to protopod; and armature and outline of telson, among other features. It seems to be a high-altitude endemic to the Cajas Massif in Azuay Province, being replaced in the same area at lower altitudes by H. meinerti.

Biomechanics of the classic metaphyseal lesion: finite element analysis.

The classic metaphyseal lesion (CML) is strongly associated with infant abuse, but the biomechanics responsible for this injury have not been rigorously studied. Radiologic and CT-pathological correlates show that the distal tibial CML always involves the cortex near the subperiosteal bone collar, with variable extension of the fracture into the medullary cavity. Therefore, it is reasonable to assume that the primary site of bone failure is cortical, rather than intramedullary. This study focuses on the strain patterns generated from finite element modeling to identify loading scenarios and regions of the cortex that are susceptible to bone failure. A geometric model was constructed from a normal 3-month-old infant's distal tibia and fibula. The model's boundary conditions were set to mimic forceful manipulation of the ankle with eight load modalities (tension, compression, internal rotation, external rotation, dorsiflexion, plantar flexion, valgus bending and varus bending). For all modalities except internal and external rotation, simulations showed increased cortical strains near the subperiosteal bone collar. Tension generated the largest magnitude of cortical strain (24%) that was uniformly distributed near the subperiosteal bone collar. Compression generated the same distribution of strain but to a lesser magnitude overall (15%). Dorsiflexion and plantar flexion generated high (22%) and moderate (14%) localized cortical strains, respectively, near the subperiosteal bone collar. Lower cortical strains resulted from valgus bending, varus bending, internal rotation and external rotation (8-10%). The highest valgus and varus bending cortical strains occurred medially. These simulations suggest that the likelihood of the initial cortical bone failure of the CML is higher along the margin of the subperiosteal bone collar when the ankle is under tension, compression, valgus bending, varus bending, dorsiflexion and plantar flexion, but not under internal and external rotation. Focal cortical strains along the medial margins of the subperiosteal bone collar with varus and valgus bending may explain the known tendency for focal distal tibial CMLs to occur medially. Further research is needed to determine the threshold of applied forces required to produce this strong indicator of infant abuse.

Pancreatic adenocarcinoma: A simple CT score for predicting margin-positive resection in patients with resectable disease

BackgroundNegative-margin status is a prognostic indicator for long-term survival following curative intent resection for pancreatic adenocarcinoma. Patients at increased risk for positive-margin resections may benefit from neoadjuvant chemotherapy prior to resection. MethodsWe retrospectively analyzed preoperative computed-tomography (CT) scans in 108 consecutive patients that underwent curative intent resection for a resectable pancreatic ductal adenocarcinoma from 2009 to 2016 in two academic hospitals. Two radiologists independently staged the tumor, including tumor location, size, and tumor-to-superior mesenteric/portal vein (SMV/PV) contact. Uni and multivariate analysis were performed to identify independent predictors of an R1 resection. ResultsTwenty-nine patients had an R1 resection (26.9%). Tumor size, location, and presence of tumor-to-SMV/PV contact were significantly associated with an R1 resection. In multivariate analysis, the independent parameters associated with resection status were: tumor size (R2=9.7), and tumor location (neck R2=6.6; pancreaticoduodenal interface R2=4.4; uncinate process R2=4.1), but not tumor-to-SMV/PV contact (R2=0.1, p=0.7). A simple CT score was built based on tumor size and location. Patients with an R0 resectability score ≥3, i.e. patients with tumor size ≥30mm (except when tumor location is at the pancreatico-duodenal interface) or patients with tumor size ≥20mm AND tumor located in the uncinate process or neck, were at high-risk of an R1 resection (AUC, 0.82; sensitivity, 79%; specificity, 76%). This score also showed good diagnostic performances for predicting an R1 resection involving the medial resection margin only (AUC, 0.85). ConclusionsA simple score based on tumor location and size can accurately predict patients at high-risk of an R1 resection.

Does the approach influence the success rate for ultrasound-guided rectus sheath blocks? An anatomical case series

The anterior cutaneous branches of the thoracolumbar spinal nerves enter the rectus sheath at its lateral border and perforate the muscle after travelling a short distance in the ventral direction. In this anatomical case series, we show that dye injection at the medial margin did not lead to reliable impregnation of the target nerves. The local anesthetic should therefore be injected at the lateral edge of the rectus sheath. Preceding surgical procedures to the ventral abdominal wall may affect the craniocaudal spread of local anesthetic.

Cervical laminectomy of limited width prevents postoperative C5 palsy: a multivariate analysis of 263 muscle-preserving posterior decompression cases.

Between 2006 and 2010, we performed wide laminectomy (wide LAM) alone, with decompression performed between the bilateral medial margin of the zygapophyseal joints, or double-door laminoplasty (DL) combined with wide LAM for cervical compressive myelopathy (CCM). From 2010, instead of wide LAM and DL, we began to perform narrow LAM, where the laminectomy width was no more than 2-3mm wider than the spinal cord width (SW). This study aimed to elucidate the risk factors for C5 palsy by reviewing surgical outcomes. The clinical features and radiological findings of 263 CCM patients with or without C5 palsy were compared. Risk factors for C5 palsy were assessed using logistic regression analysis. The decompression width (DW) was defined as the laminectomy width or the width between the bilateral medial margins of the bony gutters in DL. Narrow LAM reduced the incidence of C5 palsy from 9.2 to 1.2%. DL was performed more frequently in the C5 palsy group. The difference between the DW and the SW (DW-SW) was significantly greater in the C5 palsy group. Posterior spinal cord shift, aging, and the number of consecutive laminae surgically treated were significantly higher in the C5 palsy group. The diameter of the foramen (DF) at C4/5 was significantly smaller in the C5 palsy patients. The logistic regression analysis revealed that DL, DW-SW, DF, and aging were risk factors for C5 palsy. Cervical laminectomy of limited width prevented postoperative C5 palsy without compromising the functional recovery.

Diagnóstico radiográfico e tomográfico de osteocondrose dissecante em tarso de cão

Background: The tarsal joint is the third most commonly joint affected by osteochondrosis in dogs. This joint is affected in 4 to 9% of the cases, and in 50% of these cases the disease is bilateral. Radiological signs include defect in the subchondral bone, sclerotic margin, and fragment of mineralized cartilage. Dorsoplantar in flexion and oblique radiologic images are necessary to show tarsal osteochondrosis. Computed tomography avoid overlap of bone structures and allows better visualization of subchondral lesions, showing the exact location, size and number of fragments. The objective of this study is to report a case of bilateral osteochondrosis dissecans in tarsal joint in Rottweiler.Case: A female Rottweiler was examined and presented a history of pain and difficulty in raising the pelvic limbs. There was pain in the right tibiotarsal joint (RTJ) with evident joint cracking and, after three months, the left pelvic limb started to show the same signs. Radiographic examination of the RTJ showed a small osteochondral fragment in the distal medial border of the medial malleolus of the tibia, subchondral sclerosis with radiolucent area in the medial malleolus of the tibia, and a small lateral periarticular osteophyte in the intertarsal joint. The left tibiotarsal joint (LTJ) showed mild articular incongruity and minor increase in radiological interlinear space, diffuse sclerosis in the medial malleolus and in the subchondral surface of the trochlear crest. This exam also showed a small radiolucent area in the medial malleolus of the tibia, a small fragment of radiopaque adjacent bone, and minor subchondral bone irregularity in the medial margin of the medial trochlea. The radiographic examination of the RTJ was inconclusive. Computed tomography was requested and suggested the diagnosis of medial osteochondritis dissecans in the distal talus. The most important tomographic signs were irregularity of the subchondral bone in the caudal region of the distal talus associated to isolated bone fragment, irregularity of the distal and caudal portion of the medial malleolus of the tibia associated with the presence of free adjacent osteophyte.Discussion: Only 4 to 9% of the dogs that develop osteochondrosis present this lesion in the tarsus. The Rottweiler is the breed most affected by this disease, such as the subject of this case report, and is also the breed most frequently affected in the lateral region of the tarsus. It is a fast-growing large breed, a common characteristic in animals affected by osteochondrosis. Bilateral cases are most common in young dogs, such as the patient of this case report. Clinical manifestation of pain and lameness is frequent in this type of disease, and lameness can occur in only one of the affected limbs. The dog of this study presented lesion in the medial region of the trochlea of the talus, one of the regions that present high incidence of osteochondrosis. Radiographic examination was efficient to suggest lesions in the medial region of the talus. However, only 10% of the dogs with osteochondrosis of the tarsus are diagnosed by this technique. The definitive diagnosis was not provided by radiographic examinations in this patient. Computed tomography has several advantages over conventional radiography, such as eliminating overlap of structures, decreasing image complexity, and increasing the ability to identify specific structures. This examination allowed us to reach the diagnosis of osteochondrosis dissecans in the right talus of this dog. A scan was not performed on the contralateral limb (LTJ), because the lesions observed on radiographic examination were similar to the lesions observed in the right pelvic limb.

Bipolar Bone Loss in Patients With Anterior Shoulder Dislocation: A Comparison of Adolescents Versus Adult Patients

To compare bipolar bone loss by evaluating the degree of glenoid bone loss, Hill-Sachs lesion size, and glenoid track in adolescents and adults with shoulder dislocations. We performed a retrospective review between 2012 and 2016 of surgical and nonsurgical patients with a history of anterior shoulder dislocations (primary or recurrent) who underwent magnetic resonance imaging of the affected shoulder. The exclusion criteria included multidirectional instability, prior surgery, and posterior dislocation. Patients were grouped into 2 groups: adolescents (aged 10-19years) and adults (aged ≥20years). The groups were compared regarding measures of glenoid bone loss (best-fit circle technique) and Hill-Sachs lesion size (medial margin of rotator cuff footprint to medial margin of Hill-Sachs lesion). If the medial margin of a Hill-Sachs lesion was within the glenoid track, it was defined as on track; if it was more medial than the glenoid track, it was defined as off track. We identified 45 adolescents (mean age, 16.1years) and 30 adults (mean age, 28.9years) with anterior shoulder dislocations. There was no significant difference in percentage of bone loss between adolescents (mean, 8.4%) and adults (mean, 9.9%; P= .23). There was no significant difference in Hill-Sachs lesion size between adolescents (mean, 12.7mm) and adults (mean, 9.9mm; P= .12). There were 12 patients with off-track lesions. Off-track lesions were present in 11 of 45 adolescents (24.4%) and 1 of 30 adults (3.3%). Adolescents had an increased risk of having an off-track lesion (odds ratio, 9.38; 95% confidence interval, 1.14-77.1). A subgroup analysis identified multiple dislocations as an independent risk factor for an off-track lesion (odds ratio, 4.15; 95% confidence interval, 0.85-20.23). This study shows that adolescence and a history of multiple dislocations are independent risk factors for a greater likelihood of glenoid off-track lesions. The findings support the use of bipolar assessment of shoulder dislocators, especially in adolescents and multiple dislocators. Level III, retrospective comparative study.

An anatomical investigation of the carotid canal.

The carotid canal (CC) located in the petrous temporal bone transmits the internal carotid artery, internal carotid venous plexus and sympathetic nerve plexus from the neck into the cranial cavity. It is an accessible passage into the cranial cavity and is considered an important anatomical landmark for neurosurgeons. The aim of this study was to investigate the topographical, morphometric and morphological parameters of the CC. An examination of the CC and related adjacent structures in 81 dry skull specimens was performed. Distribution of sample by sex was 34 females and 47 males, and by race 77 African and 4 Caucasian. The mean age was 50 years (range: 14-100 years). The external opening of the CC was found to be round-shaped, oval-shaped and tear-drop-shaped in 28.4%, 49.4% and 22.2% of the specimens, respectively. (1) Mean diameters [mm]: (a) medio-lateral 7.52 mm and (b) antero-posterior 5.41mm. Statistically significant difference in the vertical diameter was recorded in the race groups and laterality of the samples. (2) Mean distances [mm] between: (a) medial margins of external opening of CC was 50.03 mm, (b) lateral margins of external opening of CC was 62.73 mm and (c) external openings of CC and foramen lacerum was 15.6 mm. There was a statistically significant correlation between race and location of the opening of external CC in relation to foramen lacerum (viz. postero-lateral, lateral and diagonal, and lateral). The present study corroborated previous reports on the CC; however, the tear-drop shaped external CC opening was a unique finding. The knowledge of the reference measurements pertaining to the CC and its relationship to adjacent structures may postulate a suitable surgical "safe-zone" range within the CC area.

Posterior Bilateral Intermuscular Approach for Upper Cervical Spine Injuries.

To investigate a novel intermuscular surgical approach for posterior upper cervical spine fixation. Twenty-three healthy volunteers underwent magnetic resonance imaging. By using the magnetic resonance imaging scans in transverse view at the level of lower edge of atlas, the distances from the posterior midline to lateral margin of trapezius, to the medial margin of splenius capitis, and to middle line of semispinalis capitis were recorded. The angle between posterior middle line and the line crossing the lateral margin of trapezius and middle point of ipsilateral pedicles. From October 2009 to May 2013, 12 patients with upper cervical spine injuries were operated via the bilateral intermuscular approach. The time required for surgery, blood loss, and pre- and postoperative visual analogue scale scores were analyzed. The average distance of 0-T was 39.2 ± 7.5 mm, the angle between the approach and posterior middle line was 33.2 ± 8.4°. The surgical time was 78.3 ± 22.5 minutes (45-140 minutes), and the mean intraoperative blood loss was 87.5 ± 44.2 mL (30-200 mL). Preoperative and postoperative visual analogue scale scores were 6.4 ± 0.8 and 1.8 ± 0.7, respectively. The average follow-up time was 19.7± 11.5 months (9-48 months). The posterior bilateral intermuscular approach for upper cervical spine injuries is a valid alternative for Hangmans' fractures type I, type II, and type Ia according to Levine and Edwards classification as well as atlantoaxial subluxation caused by upper cervical spine trauma.

Cranial anatomy of an Eocene notoungulate mammal from northwestern Argentina with special reference on the ear region

A detailed anatomical analysis is here presented focused on a notoungulate skull recovered from sediments of the lower part of the Quebrada de los Colorados Formation (LC I; late middle Eocene), cropping out in Salta Province, Argentina. The material was identified as a Toxodontia, although it does not exhibit information useful enough for its generic or even familiar assignment. The description was mainly focused on the basicranium and the auditory region (especially the petrosal and auditory ossicles) given the better preservation of these parts in the specimen. Additionally, a phylogenetic analysis was conducted based on previous studies dealing with a wide sample of South American Native Ungulates. This specimen exhibits some traits traditionally mentioned for the suborder Toxodontia, such as the horizontal bullar septum, and others recently regarded as synapomorphies of Notoungulata, including the lateral location of the tensor tympani fossa and the expanded medial margin of the petrosal. However, it also shows some unexpected features for that suborder of notoungulates, such as the presence of a strongly curved promontorium. The study of this skull increases our knowledge of the auditory anatomy of Eocene Toxodontia and yields a good opportunity to test current phylogenetic hypothesis, mostly based on Neogene representatives.

A new species of Calanopia (Copepoda, Calanoida, Pontellidae) from the plankton of the central Red Sea

Calanopia tulina sp. nov., a new pontellid copepod, is described from plankton samples collected in Saudi Arabian waters of the Red Sea. The female of the new species differs from other congeners in having the genital operculum located posteroventrally on the genital compound somite and by a slightly asymmetrical leg 5, in which the right leg is slightly shorter than the left one. The male is distinguished by: (1) the presence of a distinct notch on the medial margin of the right prosomal corner; (2) the structure of leg 5, in which the second exopodal segment of the left leg has one medially directed spine and two large laterally directed and curved serrated spines distally; and (3) the first exopodal segment of the right leg has a very small rounded-tip thumb located at the mid-length. The new species is most similar to Calanopia media described from the Red Sea. The presence of the new species in night collection may be due to the diel vertical migration behavior that is known for some species of this genus.

Association Between Years of Experience and Ankle Joint Disorder in Male Student Basketball Players Based on Ultrasonography.

The goal of the study was to survey ankle joint disorder in male senior high school and college student basketball players based on the results of an ultrasonographic medical check-up of the ankle joint. The subjects were 17 senior high school student and 19 college student basketball players. Ultrasonography, evaluation of ATFL injury, and examination of the talocrural joint region were performed. The subjects were grouped based on the presence or absence of old ATFL injury, and subjects with ATFL injury were classified by the injured region: fibular insertion site, parenchyma, and talar insertion site. The talocrural joint region was evaluated based on the areas of the lateral margin, central region, and medial margin, and sites with an irregular bone contour and osteophyte were counted individually. The questionnaire asked about the patients' history of ankle injuries. A questionnaire survey revealed that 70-79% of all subjects had experienced a sprain at least once and 21-29% had frequently sprained the left or right foot 10 or more times in the past. On ultrasonography, there was no significant difference in ligament injury or injured site between the senior high school and college students, but the number of osteochondral findings in the talocrural joint region was significantly higher in the college students. In addition, the number of injured sites significantly increased in those with 10 or more years of playing experience. These results suggest that disorder of the talocrural joint region progresses with an increase in years of experience in student basketball players who do not take specific preventive measures against this injury.

Observations of the Acetabulum and Proximal Femur of the Dire Wolf (Canis dirus, Leidy 1854)

individuals, including 23 ace- tabula and 23 proximal femora. The specimens are curated at the Page Museum, Rancho La Brea, CA USA. We selected specimens for the appearance of subtle pathology because our observation plan was lim- ited to establishing whether features of coxofemoral degenerative joint disease (DJD) would be observed on the acetabular fossa, medial articular margin, articular bone surface, lateral articular margin, and peri-articular structure. Similarly, evaluation of femora included articular surface and margin, peri-articular structure, and joint capsule attachment.

The oblique popliteal ligament: an anatomic and MRI investigation.

Despite being the largest ligament on the posterior aspect of the knee, relatively little is known about the normal morphology of the oblique popliteal ligament (OPL). The aim of this study was to investigate the detailed anatomy of the OPL in cadavers and healthy volunteers. The posterior knee was investigated in 25 cadaver lower limbs (mean age 76 ± 9.5 years; 7 men) by dissection, histology, and serial plastination and in 14 healthy individuals (mean age 23 ± 3.2 years; 11 men) using magnetic resonance (MR) imaging. OPL morphology, attachments sites, ligament length and width, relationship to surrounding structures and histological composition were recorded. Intraobserver reliability was assessed using intraclass correlation coefficients. The OPL is a distinct expansion of the semimembranosus (SM) tendon and sheath, which courses superolaterally to attach to the posterolateral joint capsule or fabella (when present), at the medial margin of the lateral femoral condyle. The ligament blends with the joint capsule medially and laterally, serves as an attachment site for plantaris, and has connections with popliteus. In 70% of dissections, the OPL divided into two bands, separated by small branches of the middle genicular neurovascular bundle that pierced the posterior joint capsule. Differences in mediolateral length were noted between dissection and MR imaging (43.6 ± 6.2 vs. 57.6 ± 4.4mm; p < 0.001). At its medial and lateral attachments, the OPL was 23.2 ± 6.9 and 17.4 ± 8.7mm wide (proximodistal), respectively. The OPL was predominantly composed of transverse collagen layers, with little elastin. While visible on axial MR scans, delineation of its most lateral extent was difficult. Repeatability of selected measurements ranged from good to almost perfect. The OPL is a distinct ligament with identifiable anatomical limits. Based on its morphological characteristics, it appears more tendinous than ligamentous in nature. A better understanding of the OPL may help define its importance in the assessment and treatment of posterior knee injuries.

Amorphometric study of condyloid process of dry human mandible for sexing from its shape

The mandible is having the condyloid process which articulates with the temporal fossa to form the temporomandibular joint, on which all the movements occur during the eating, chewing and even on talking also. It is having the articular facet on its head. This articulating facet is having different shapes and sizes which varies according to sex also. The shapes of condyloid processes are classified into four types i.e. convex, flat, rounded and angular. The size of the articular facet varies mandible to mandible and male to female. In the present study120 condyloid processes are studied and different shapes found were convex (55%), flat (20%), rounded (12.50%) and angled (12.50%). To measure the size of articular facet of the condyloid process of the mandible antero-posterior(AP) dimension from the anterior and posterior margins of the articular facet and medio-lateral(ML) dimension from the medial and lateral margins of the facets are taken with the help of vernier calliper. The mean of(AP) dimension of right and left condyles in male found to be (7.23±1.123)mm and (6.50±0.805)mm in females. The mean of medio-lateral dimension in male is (20.13±1.260)mm and in female it is (17.23±1.74)mm. As there is a difference in the size of condyloid process of male and female so the measurements are also helpful in determining the sex of the mandible. The present study is helpful for forensic dentistry, forensic medicine, orodental surgeons, traumatologists and plastic surgeons in the determination of sex of the mandible through the condyloid process of mandible and diagnosis and treatment of the patients.

Ancestral Variation in Orbital Rim Shape: A Three-Dimensional Pilot Study.

Traditional nonmetric methods of ancestry assessment posit orbital rim shape varies among ancestral groups. This pilot study uses morphometric analysis of 3D orbital variation to test discrimination among individuals of primarily European, African, and Asian ancestry. Although the size and nature of the sample analyzed limit inferences for other samples, principal components analysis suggests ancestry has a significant effect on rim shape (p = 2.93e-04). European orbits display more marked folding of the orbit in the sagittal plane than either African or Asian orbits, while the lateral margin of African orbits lies further posterior relative to the medial margin when compared to Asian orbits. The findings suggest curviplanar relationships are the most ancestrally informative aspect of orbital rim shape; these relationships may be distorted by perspective based on orientation of the skull relative to the viewer in traditional nonmetric analyses. Additional studies on geometric morphometric approaches to ancestry assessment are therefore warranted.

Analysis of Anatomical Characteristics and Morphometric Aspects of Infraorbital and Accessory Infraorbital Foramina.

This study aimed to perform a morphological and morphometric study of the characteristics of the infraorbital foramen (IOF) and accessory infraorbital foramen (AIOF) in Brazilian skulls. A sample calculation determined a total of 94 human skulls to be evaluated by a trained examiner for number, shape, diameters, and location of IOF in relation to anatomical landmarks. Number, size, shape, diameters, location, orientation, position, and distances in relation to anatomical landmarks were evaluated for the AIOF. Descriptive analysis, paired t test, Wilcoxon test, Pearson and Spearman correlations were used. A total of 188 IOFs and 48 AIOFs were found. Circular outline was the predominant shape for both IOFs and AIOFs. Infraorbital foramens presented in left sides had a significantly greater transverse diameter and distance from medial margin of the orbit when compared with IOFs located on the right sides (P <0.001). Accessory infraorbital foramens were most frequently found on the left sides of the skulls and had a superomedial position in relation to the IOFs. Accessory infraorbital foramens located on right sides had a significantly greater distance to anterior nasal spine when compared with AIOFs located on the left sides (P <0.001). The results of this solid methodology-based study can help guide surgeons in accurately locating the IOF and AIOF, and consequently, their neurovascular bundles to perform safe procedures during maxillofacial interventions.

Holding visual attention for 400 million years: A model of tectum and torus longitudinalis in teleost fishes

Only ray-finned fishes possess a torus longitudinalis (TL), a paired, elongated body attached to the medial margins of the optic tectum. Its granule cells project large numbers of fine fibers running laterally over adjacent tectum, synapsing excitatorily on the spiny dendrites of pyramidal cells. Sustained TL activity is evoked visuotopically by dark stimuli; TL bursting is a corollary discharge of saccadic eye movements. To suggest a function for this ancient structure, neural network models were constructed to show that: (1) pyramidal cells could form an attentional locus, selecting one out of several moving objects to track, but rapid image shifts caused by saccades disrupt tracking; (2) TL could supply both the pre-saccade position of a locus, and the shift predicted from a saccade so as to prime pyramidal dendrites at the target location, ensuring the locus stays with the attended object; (3) that the specific pattern of synaptic connections required for such predictive priming could be learned by an unsupervised rule; (4) temporal and spatial filtering of visual pattern input to TL allows learning from a complex scene. The principles thus evinced could apply to trans-saccadic attention and visual stability in other species.