Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Anatomic Landmarks”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed2001

Certain anatomical relations and the precise morphometry of the infraorbital foramen--canal and groove: an anatomical and cephalometric study.

OBJECTIVES: To determine and to standardize the certain anatomical relations, and the precise size, course, and location of the infraorbital foramen, canal, and groove for facilitating surgical and invasive procedures. STUDY DESIGN: This anatomical study consisted of two main steps, namely, the examination of skulls and the cephalometric analysis of the skulls. Measurements of the skulls and of the radiograms were performed. METHODS: Thirty-five adult bony heads (70 sides) were studied regarding the localization and dimensions of the infraorbital groove (IOG), infraorbital canal (IOC), and infraorbital foramen (IOF) as well as their relationships with different anatomical landmarks. The cephalometric analysis of the skulls was measured for evaluating the relationships of certain anatomical points and the distances of the skulls in the cephalometric analysis. For this purpose, 13 different distances and two angles were measured on anteroposterior and lateral craniographies. Differences between data of skull and cephalogram measurements were analyzed by the Student t test. The Pearson correlation test was used in the statistical analysis of the 15 values in the cephalogram. RESULTS: Examination of the 70 sides of the 35 bony heads revealed that the shape of the IOF was oval in 34.3%, round in 38.6%, and semilunar in 27.1% of all skulls. The IOF was single in 94.3% and double in 5.7% of the cases. The average distance from the IOF to the infraorbital margin and to the lateral process of the canine tooth in vertical direction and to the lateral nasal border in horizontal direction were 7.19 +/- 1.39 mm, 33.94 +/- 3.15, and 17.23 +/- 2.64 mm, respectively. In cephalometric analysis, when S-N (the distance between the center of the sella turcica and the nasion) and N-ANS (the distance between the nasion and the anterior nasal spine) distances were used as independent parameters for the linear analysis, the correlation of the three values for both independent parameters were statistically significant. CONCLUSION: While the IOF has no statistically significant changes with regard to the size of the skull, expressive changes take place in the course and the length of the IOG and IOC. Meticulous preoperative evaluation of the IOF and the route of the infraorbital nerve are necessary in patients who are candidates for maxillofacial surgery and regional block anesthesia. If these measurements are taken into account, there will be little surgical risk, and this will be helpful in identifying the extent of the operative field.

Adult↗
PubMed2004

Surgical anatomy of the turbinal wall of the ethmoidal labyrinth.

The upper part of the lateral nasal wall is formed by a common structure or conchal lamina that is attached all along the junction between the ethmoidal roof and the cribriform plate. From this continuous conchal lamina, the different ethmoidal turbinates take their origin. All these structures form a well defined wall that encloses the ethmoidal cells medially and that deserves the name of "turbinal wall of the ethmoidal labyrinth". The objectives of this paper were: 1) to precisely define the anatomical landmarks of the turbinal wall of the ethmoidal labyrinth, and 2) to study, from an anatomical point of view, the consequences of the surgical resection of the middle turbinate. We performed an anatomic study on 12 frozen human heads, cut in a median-sagittal plane, and then photographed with a millimetre scale in order to perform several measurements. The surface of the turbinal wall of the ethmoidal labyrinth can range from 6.1 to 11.3 cm2. The resection of the middle turbinate preserves approximately half of the turbinal wall, this being around 4.3 cm2 (range 2.6 to 6.3 cm2). The conchal lamina appears as the noble sensorial element of the turbinal wall. It can be described as a continuous bone plate, grossly rectangular in shape, measuring approximately 1 cm in height and 3.5 cm in length that forms the lateral wall of the olfactory groove. The anatomic study shows that its dimensions can vary from simple to double in different individuals. It seems to us that instead of considering the difference of height between the cribriform plate and the ethmoidal roof (Keros classification), we should consider the vertical height of the conchal lamina as a potential risk factor in ethmoidal surgery.

Adult↗
PubMed2000

Distal end of the atrioventricular nodal artery predicts the risk of atrioventricular block during slow pathway catheter ablation of atrioventricular nodal re-entrant tachycardia.

OBJECTIVE: To search for a reliable anatomical landmark within Koch's triangle to predict the risk of atrioventricular (AV) block during radiofrequency slow pathway catheter ablation of AV nodal re-entrant tachycardia (AVNRT). PATIENTS AND METHODS: To test the hypothesis that the distal end of the AV nodal artery represents the anatomical location of the AV node, and thus could be a useful landmark for predicting the risk of AV block, 128 consecutive patients with AVNRT receiving slow pathway catheter ablation were prospectively studied in two phases. In phase I (77 patients), angiographic demonstration of the AV nodal artery and its ending was performed at the end of the ablation procedure, whereas in the subsequent phase II study (51 patients), the angiography was performed immediately before catheter ablation to assess the value of identifying this new landmark in reducing the risk of AV block. Multiple electrophysiologic and anatomical parameters were analysed. The former included the atrial activation sequence between the His bundle recording site (HBE) and the coronary sinus orifice or the catheter ablation site, either during AVNRT or during sinus rhythm. The latter included the spatial distances between the distal end of the AV nodal artery and the HBE and the final catheter ablation site, and the distance between the HBE and the tricuspid border at the coronary sinus orifice floor. RESULTS: In phase I, nine of the 77 patients had complications of transient (seven patients) or permanent (two patients) complete AV block during stepwise, anatomy guided slow pathway catheter ablation. These nine patients had a wider distance between the HBE and the distal end of the AV nodal artery, and a closer approximation of the catheter ablation site to the distal end of the AV nodal artery, which independently predicted the risk of AV block. In contrast, none of the available electrophysiologic parameters were shown to be reliable. When the distance between the distal end of the AV nodal artery and the ablation target site was more than 2 mm, the complication of AV block virtually never occurred. In phase II, all 51 patients had successful elimination of the slow pathways without complication when the ablation procedure was guided by preceding angiography with identification of the distal end of the AV nodal artery. CONCLUSIONS: The distal end of the AV nodal artery shown by angiography serves as a useful landmark for the prediction of the risk of AV block during slow pathway catheter ablation of AVNRT.

Adolescent↗
PubMed1990

Craniofacial osseous landmark determination from stereo computer tomography reconstructions.

The accurate and reproducible determination of the three dimensional (3D) co-ordinate positions of anatomical landmarks from computer tomography (CT) images has been limited even though potentially the data have been available for several years. This paper describes a method of acquisition of osseous landmark positions using an off-line computing technique based on multiple stereo images of 3D CT reconstructions. The use of stereo pairs greatly enhances the consistent identification of osseous landmarks. Further, the technique is of particular value where access to the CT scanner is restricted due to heavy clinical demand and separate high quality graphics facilities are unavailable. Osseous landmark position data were determined for dried skulls and patients with craniofacial conditions. Accuracies of the order 1.7mm (median) were obtained. These results encourage the use of the technique for acquisition of landmark positions for the study of the craniofacial complex in three dimensions.

Acrocephalosyndactylia↗
PubMed1998

A novel mammalian wnt gene, WNT8B, shows brain-restricted expression in early development, with sharply delimited expression boundaries in the developing forebrain.

Our current knowledge of mammalian forebrain development is meagre. The comparatively few relevant anatomical landmarks are, however, being supplemented by gene expression studies which are able to identify subsets of anatomical structures. We previously described cloning, subchromosomal localization and preliminary structural characterization of the human WNT8B gene, the first mammalian Wnt8b gene to be reported. Wnt genes encode intercellular signalling molecules which play a variety of critical roles in early development, including, in several cases, a presumed role in brain development. In the current report we present the full-length cDNA sequence and genomic organization of the human Wnt8b gene and report studies of expression of the Wnt8b gene in human and mouse embryos. The human and mouse expression patterns appeared identical and were restricted to the developing brain, with the great majority of expression being found in the developing forebrain. In the latter case expression was confined to the germinative neuroepithelium of three sharply delimited regions: the dorsomedial wall of the telencephalic ventricles (which includes the developing hippocampus), a discrete region of the dorsal thalamus and the mammillary and retromammillary regions of the posterior hypothalamus. Expression in the developing hippocampus may suggest a role for WNT8B in patterning of this region and subchromosomal localization of the human gene to 10q24 may suggest it as a candidate gene for partial epilepsy in families where the disease has been linked to markers in this region.

Amino Acid Sequence↗
PubMed1985

Facial nerve identification in children.

A surgical technique utilizing common anatomic landmarks has been developed to aid in the safe identification of the facial nerve in children. Anatomic dissections demonstrated that the facial nerve trunk can be consistently found in a triangle formed by the sternocleidomastoid muscle, posterior belly of the digastric muscle, and cartilaginous ear canal. Because of the superficial course of the facial nerve in infants and the underdevelopment of surrounding structures, the standard techniques for identification of the facial nerve trunk in adults would jeopardize the nerve in children, and an alternative technique for identifying the facial nerve has been developed.

Child↗
PubMed2005

Surgical approaches to the cervico-thoracic junction.

The cervico-thoracic junction (CTJ) extends between the 7th cervical and the 4th thoracic vertebrae and comprehends the inferior portion of the brachial plexus and the parenchymatous, vascular and nervous structures of the upper mediastinum. The posterior surgical approaches, as the laminectomy or the arthro-pediclectomy, fail to expose the anterior spinal elements. Thus, further surgical approaches have been proposed: postero-lateral, antero-lateral (thoracotomies) and purely anterior. The aim of this study was to discuss indications, key anatomical landmarks and risks of the main surgical approaches to the CTJ. Ten fresh cadavers from the Anatomical Laboratory of the University of Nantes (France) were used for the surgical dissection of the CTJ. The postero-lateral and the antero-lateral approaches were performed in 4 cadavers each and the anterior approaches were studied in 2. The postero-lateral extrapleural approach (PLEA) permits an excellent antero-lateral exposure of the T2-T4 segment, preserving the parascapular musculature integrity. The thoracotomies allow the exposure of the antero-lateral portion of the junctional vertebrae, with the limits of the intrapleural approaches. The anterior approaches, including the presternocleidomastoid cervicotomy eventually associated to the sterno-claviculotomy, expose the anterior portion of the cervical and the upper thoracic vertebrae up to T4. We believe that the PLEA performs the greater surgical exposure with minimal risk of vasculo-nervous damage. Among the anterior approaches, the simple cervicotomy is the most indicated procedure in case of patients with certain anatomical conditions.

Cervical Vertebrae↗
PubMedDate not supplied

A comparison of computer-aided surgery registration methods for endoscopic sinus surgery.

BACKGROUND: Stereotactic computer-aided surgery has provided the surgeon with a means to navigate more safely through diseased or surgically altered sinus anatomy. Accurate registration is vital to successful image-guided surgery. This study compared the accuracy and performance of three registration methods: fiducial, anatomic landmarks, and surface registration. METHODS: Ten fixed cadaveric heads underwent endoscopic computed tomography scan followed by middle meatal antrostomy and sphenoidotomy. Each registration method was performed, and the time required and mean registration error were recorded. Five anatomic sites were then identified and compared with the preoperative computed tomography images. The true distances between the known anatomic sites and the crosshair locations on the images were measured. RESULTS: Statistically significant differences were noted for mean registration error and time for registration. The mean +/-SEM time for registration for the fiducial, surface, and landmark methods were 5 minutes 24 seconds +/-27 seconds, 1 minute 1 second +/-5 seconds, and 11 minutes 46 seconds +/-45 seconds, respectively. The mean +/-SEM registration error for the fiducial, surface, and landmark methods were 0.48 +/- 0.21 mm, 1.05 +/- 0.06 mm, and 3.1 +/- 0.25 mm, respectively. When the true accuracy of the three registration methods were compared, no significant difference was found between fiducial and surface registration. However, fiducial registration was significantly more accurate than landmark registration at all points. When compared with landmark registration, surface registration was statistically more accurate at all anatomic sites except for the sella turcica and optic nerve. CONCLUSION: When the true accuracies of these methods were compared in fixed cadaveric specimens,fiducial and surface registration were statistically similar but were found to be significantly more accurate than landmark registration. Furthermore, when time of registration, accuracy, and ease of use were considered, surface registration was found superior.

Analysis of Variance↗
PubMed2001

A stepwise surgical technique using the medial orbital floor as the key landmark in performing endoscopic sinus surgery.

HYPOTHESIS: The medial orbital floor (MOF) and adjacent bony ridge of the antrostomy, when combined with columellar measurements, are easily identifiable and consistent anatomic reference points from which critical orbital and skull base structures can be found during endoscopic sinus surgery. METHODS: Two examiners, with varying endoscopic sinus surgery experience, performed endoscopic and direct measurements from the columnella and medial orbital floor to critical orbital and skull base structures on 11 human cadaver heads (18 sides). The distances to four critical skull base or orbital structures and to the anterior and posterior wall of the sphenoid sinus were measured. The mean, ranges, and standard deviations for all measurements (endoscopic and direct) were calculated and simple regression analysis was performed. RESULTS: The mean and range of values for each of the variables correlated well between examiners, and between endoscopic and direct measurements. There was slightly more variability in measurements when the MOF was used. However, the differences were no more than a few millimeters and did not appear to affect the overall clinical use of these values. CONCLUSIONS: The MOF and adjacent bony ridge of the antrostomy, when combined with columellar measurements, are easily identifiable and consistent anatomic landmarks that are not affected by the presence of significant inflammatory disease or previous surgery. These reference points provide even the most inexperienced surgeon with precise anatomic localization within the paranasal sinuses. They also determine the correct anteroposterior trajectory into the sphenoid sinus, whereby inadvertent intracranial or intraorbital complications may be avoided.

Cephalometry↗
PubMed2004

Identification of the nonrecurrent laryngeal nerve during thyroid surgery: 20-year experience.

The nonrecurrent laryngeal nerve, which is rarely observed during thyroidectomy, is at high risk for damage. During a 20-year period 6000 thyroidectomies were performed at our institution, and during these operations inferior laryngeal nerves were routinely identified in all the patients with a standard procedure based on the usual anatomic landmarks. A nonrecurrent laryngeal nerve was observed on the right side in 31 cases (0.51%), with no anatomic anomalies found on the left side. The nerve anomaly was diagnosed preoperatively in five patients. A vocal cord deficit, caused by a nerve lesion, was observed in four cases (12.9%). Our results suggest that the best way to avoid morbidity is routine identification of the nerve. This can be done by carefully identifying all the thyroid structures and being suspicious of the presence of the abnormality when the inferior laryngeal nerve is not found in a classic position.

Female↗
PubMed2005

Lateral femoral cutaneous nerve: an anatomic study.

The purpose of our study was to determine the location of the lateral femoral cutaneous nerve and its branches at the inguinal ligament and proximal thigh. We think that further defining the location of the nerve and its branches based on certain measurements from known anatomic landmarks would enable us to determine a danger zone that could aid in preventing iatrogenic injury to the lateral femoral cutaneous nerve. The anatomic course of the lateral femoral cutaneous nerve was studied in 29 cadaver specimens and distances from various landmarks were recorded. In addition, the branching pattern of the nerves was recorded. We observed variability in the course and branching patterns of the lateral femoral cutaneous nerve. The lateral femoral cutaneous nerve was found to potentially be at risk as far as 7.3 cm medial to the anterior superior iliac spine along the inguinal ligament and as much as 11.3 cm distal on the sartorius muscle from the anterior superior iliac spine. As many as five branches of the lateral femoral cutaneous nerve were found and in 27.6% of cases the lateral femoral cutaneous nerve branched before traversing the inguinal ligament. We used this information to describe a danger zone, which could be used as a guide to help prevent unnecessary injury during certain procedures.

Adult↗
PubMedDate not supplied

Computer-assisted intraoperative navigation during skull base surgery.

PURPOSE: In patients with diseases of the cranial base, anatomical landmarks are often obliterated by tumor inflammatory diseases or previous surgery. The surgeon may fail to recognize important anatomical structures or tumor margins, increasing the morbidity of the surgery and downgrading the oncological outcome. MATERIALS AND METHODS: The ISG Viewing Wand is an intraoperative navigational device that uses a position-sensing articulated arm linked to a computer that allows the surgeon to correlate the anatomy of the patient with the computerized display of the reformatted images of preoperative computerized tomography or magnetic resonance. We used the ISG system in 20 patients undergoing skull base surgery for the treatment of tumor inflammatory diseases and trauma. RESULTS: The use of the ISG wand translated into a decreased need for the resection of vital structures and provided reliable mapping of the boundaries of the paranasal sinuses and tumor margins. CONCLUSION: Intraoperative navigation is a promising technology that complements the surgeon's interpretation of the surgical field. Further refinements of this technology will ease the incorporation of these intraoperative navigation systems into other surgical procedures.

Decision Making, Computer-Assisted↗
PubMed2006

Using the nerve stimulator for peripheral or plexus nerve blocks.

Conventional methodology for nerve location utilizes anatomical landmarks followed by invasive exploration with a needle to a suitable endpoint. An appropriate endpoint can be either anatomical in nature (e.g. transaterial technique) or functional (paresthesia or motor response to electrical stimulation). Ability to electrically stimulate a peripheral nerve or plexus depends upon many variables, including; 1) conductive area at the electrode, 2) electrical impedance, 3) electrode-to-nerve distance, 4) current flow (amperage), and 5) pulse duration. Electrode conductive area follows the equation R = rhoL/A, where R = electrical resistance, p = tissue resistivity, L = electrode-to-nerve distance, and A = electrode conductive area. Therefore resistance varies to the inverse of the electrode's conductive area. Tissue electrical impedance varies as a function of the tissue composition. In general, tissues with higher lipid content have higher impedances. Modern electrical nerve stimulators are designed to keep current constant, in spite of varying impedance. The electrode-to-nerve distance has the most influence on the ability to elicit a motor response to electrical stimulation. This is governed by Coulomb's law: E = K(Q/r2) where E = required stimulating charge, K= constant, Q = minimal required stimulating current, and r = electrode-to-nerve distance. Therefore, ability to stimulate the nerve at low amperage (e.g. < 0.5 mA), indicates an extremely close position to the nerve. Similarly, increasing current flow (amperage) increases the ability to stimulate the nerve at a distance. Increasing pulse duration increases the flow of electrons during a current pulse at any given amperage. Therefore, reducing pulse duration to very short times (e.g. 0.1 or 0.05 ms) diminishes current dispersion, requiring the needle tip to be extremely close to the nerve to elicit a motor response. The above parameters can be varied optimally to enhance successful nerve location and subsequent blockade. Unlike imaging modalities such as ultrasonography, electrical nerve stimulation depends upon nerve conduction. Similarly, percutaneous electrode guidance (PEG) makes use of the above variables to allow prelocation of the nerve by transcutaneous stimulation.

Electric Stimulation↗
PubMed2006

Using intraoperative pelvic landmarks for acetabular component placement in total hip arthroplasty.

Dislocation after total hip arthroplasty is frequently due to acetabular malpositioning. Positioning of the acetabular component using anatomical landmarks may reduce the incidence of dislocation from improper acetabular orientation. The pelvis provides 3 bony landmarks (ilium, superior pubic ramus, and superior acetabulum), which, when used to define a plane, allows cup orientation in abduction and version. Landmarks evaluated in 24 cadaveric acetabuli allowed slightly increased abduction and anteversion of the cup, compared with native acetabuli. Six hundred seventeen primary total hip arthroplasties were performed between 1996 and 2003 using this technique. Mean cup abduction was 44.4 degrees with 13.2 degrees of anteversion. This technique allows satisfactory reproducible cup orientation based on individual pelvic morphology. Review of patient outcome data suggest high patient satisfaction and lower dislocation rate without additional equipment, time, or cost.

Acetabulum↗
PubMed2005

Prognostic significance of parapharyngeal space venous plexus and marrow involvement: potential landmarks of dissemination for stage I-III nasopharyngeal carcinoma.

PURPOSE: To determine whether the parapharyngeal space venous plexus and marrow of the skull base bones are anatomic landmarks of the potential routes for the spread of disease for Stage I-III (American Joint Commission on Cancer 1997 staging system) nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: A total of 364 patients with NPC were enrolled in this study. The selection criteria were Stage I-III disease and primary radiotherapy at our hospital between 1990 and 2001. All patients had undergone MRI to evaluate the head-and-neck tumors. Patients who had undergone inadequate radiotherapy at a dose of <60 Gy and/or preradiotherapy chemotherapy before the imaging evaluation were excluded from the study. RESULTS: Of the 364 patients treated between 1990 and 2001, 163 (44.8%) had low-risk Stage I-III NPC (without parapharyngeal space extension or T3 disease). The 5-year distant metastasis-free survival rate, with and without adjuvant chemotherapy, was 97% and 96%, respectively. The remaining 201 patients had Stage II-III with parapharyngeal space extension or T3 disease. Their 5-year recurrence-free survival rate, with and without adjuvant chemotherapy, was 76.8% and 53.2% (p = 0.01), respectively. CONCLUSION: Our findings suggest that the risk of distant metastasis in Stage I-III NPC patients without parapharyngeal space extension or T3 disease is extremely low. Invasion into the parapharyngeal space venous plexus and marrow of the skull base bones is associated with distant metastasis, and involvement of these anatomic sites is considered a potential route for hematogenous disease spread in patients with Stage I-III NPC.

Adult↗
PubMed2000

The anatomical base of unilateral external fixation in the upper limb.

Unilateral external fixation requires an anatomically sound implantation of screws into the upper extremity. Detailed knowledge about the anatomical situation in the areas of pin implantation is of great importance. This paper focuses on relevant anatomical landmarks when implanting screws for external fixation in the humerus, the elbow, the forearm and the hand by studying anatomical specimen.

Arm↗
PubMedDate not supplied

The missed inferior alveolar block: a new look at an old problem.

A variation of a previously described technique to obtain mandibular block anesthesia is presented. This technique varies from those previously described in that is uses palpable anatomic landmarks, both extra- and intraoral, to orient the placement of the needle. This technique relies on several readily observed landmarks and the integration of these landmarks. Because palpable landmarks are used, consistent results can be easily obtained even in patients who present with a wide variety of anatomical variances which otherwise make this injection technique difficult and prone to failure.

Anesthesia, Dental↗
PubMed1998

The effect of 10 : 1 compression and soft copy interpretation on the chest radiographs of premature neonates with reference to their possible application in teleradiology.

The aim of the study was to assess the potential application of teleradiology in the neonatal intensive care unit (NICU) by ascertaining whether any decrease in conspicuity of anatomic detail or interventional devices in the chest radiographs of premature infants is caused by picture archiving and communication system (PACS)-based soft copy interpretation of 10 : 1 compressed images. One hundred digital chest radiographs of low-birthweight infants were obtained in the NICU using a storage phosphor system. Laser-printed images were interpreted and the data set for each radiograph was then irreversibly compressed by a 10 : 1 ratio. Four radiologists with extensive PACS experience used a five-point grading system to score laser-printed hard copy images for the visibility of six parameters of anatomic landmarks and interventional devices in the chest. Compressed soft copy images displayed on 2K PACS workstation were subsequently scored using the same approach. Statistical manipulation demonstrated no loss of anatomic detail in five of the six parameters scored, with minimal difference in one landmark, the retrocardiac lung assessment. While further study is required to assess the clinical impact of the variance noted when evaluating lung parameters, the preservation or improvement of information in the remaining parameters following irreversible compression and soft copy interpretation is promising for the potential use of teleradiology in this population.

Data Interpretation, Statistical↗