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PubMed1999

Brief communication: foramen magnum-carotid foramina relationship: is it useful for species designation?

The anterior placement of the foramen magnum is often used to indicate bipedalism and therefore to distinguish hominid from nonhominid fossils. Often, only fragmentary cranial remains are found, and the placement of the foramen magnum must be determined by its relationship to another landmark. The purpose of this study was to test if hominid crania could be distinguished from nonhominid crania based on the relationship between the foramen magnum and the carotid foramina, and therefore to determine if the carotid foramina can be used to determine the anteriorness of the foramen magnum. The samples consisted of 16 modern human crania and 19 modern chimpanzee (Pan troglodytes) crania. Linear measurements were taken of (1) the distance from the anterior border of the foramen magnum to a chord connecting the carotid foramina and (2) total cranial length. An index of the distance of the foramen magnum from the bicarotid chord as a proportion of total cranial length was calculated to control for differences due to body size. Results indicate that on average, human crania can be distinguished from chimpanzee crania by using either (1) the distance of the foramen magnum from the bicarotid chord as a linear measurement or (2) this linear measurement as a proportion of total cranial length. Both measures are significantly smaller in the human sample; however, there was considerable overlap between species, indicating that the distance of the foramen magnum from the bicarotid chord is not a certain indicator for individual specimens.

Animals↗

PubMed1990

Position and orientation of the foramen magnum in higher primates.

The location of the foramen magnum, with respect to the longitudinal axis of the cranium, and its orientation with respect to the Frankfurt Horizontal, have been studied in a total of 328 modern human and Pan crania. The samples were chosen in order to examine the effect of overall size difference on foramen magnum disposition. Foramen position (expressed as three indices) and inclination are relatively invariant among the modern human samples, but the foramen magnum is consistently, and statistically significantly, more anteriorly located in Pan paniscus than in Pan troglodytes. Sexual dimorphism is virtually non-existent. There is an apparent allometric effect on foramen position, but not on inclination, so that larger crania in the modern human and Pan paniscus samples tend to have more posteriorly situated foramina. The disposition of the foramen is unrelated to cranial base angle or facial prognathism, except that in Pan paniscus its relative anterior location is linked with the more flexed cranial base in that species. These results provide a comparative context for the examination of differences in foramen magnum disposition in fossil hominids. Differences in foramen magnum position and orientation between KNM-ER 1813 and A. africanus are most unlikely to be due to within-taxon variability.

Animals↗

PubMed1992

Significance of left-sided heart disease for the detection of patent foramen ovale by transesophageal contrast echocardiography.

Detection of patent foramen ovale by contrast echocardiography is based on transient inversion (right atrial pressure higher than left atrial pressure) of the interatrial pressure gradient. Therefore, the presence of left-sided heart disease with potential elevation of left atrial pressure might obscure the diagnosis of patent foramen ovale. Accordingly, 150 patients (88 men, 62 women; mean age 51.7 +/- 15.2 years) were evaluated for a patent foramen ovale by transesophageal contrast echocardiography. Additionally, atrial septal motion during normal respiration and during the Valsalva maneuver was analyzed. Patency of the foramen ovale was observed in 20 (27%) of 74 patients without left-sided heart disease and with previous arterial embolism, in none (0%) of 25 patients with left-sided heart disease and embolism, in 7 (39%) of 18 patients without left-sided heart disease and without embolism and in 3 (9%) of 33 patients with left-sided heart disease and without embolism. The detection rate of patent foramen ovale was lower in patients with than without left-sided heart disease (5% vs. 29%, p = 0.0007) but was similar in patients with and without embolism (20% vs. 19.5%, p = NS). Abnormal atrial septal motion was more frequently observed in patients with left-sided heart disease (p = 0.0003) and was inversely correlated to detection of patent foramen ovale (p = 0.0003). Multivariate analysis revealed an independent association between the absence of left-sided heart disease and the detection of patent foramen ovale (p = 0.0003). These data suggest that in patients with left-sided heart disease, patency of the foramen ovale may be missed even by transesophageal contrast echocardiography.

Adult↗

PubMed1993

Transesophageal echocardiographic diagnosis of right to left shunting across the foramen ovale in adults without prior stroke.

OBJECTIVES: The purpose of this study was to estimate the prevalence of potential right to left interatrial shunting and to quantify the morphologic characteristics of the fossa ovalis in adults without a prior history of stroke or systemic embolism. BACKGROUND: Paradoxic embolization through a patent foramen ovale is an important cardiac mechanism for embolic stroke. Although anatomic and physiologic data obtained by transesophageal echocardiography increase the frequency of demonstration of potential cardiac sources of systemic embolism and occasionally can conclusively demonstrate the mechanism for embolic stroke, the prevalence and prognostic implications of these findings in neurologically healthy persons are still being actively investigated. METHODS: Intraoperative transesophageal saline contrast echocardiography was performed on 50 adult patients without prior history of stroke or systemic embolism who were undergoing elective cardiovascular surgery. RESULTS: No patient had a manifest atrial septal defect by right heart oximetric measurements or transesophageal Doppler echocardiographic examination. Eleven of the 50 patients demonstrated right to left atrial passage of saline contrast medium during apnea or after release of 20-cm H2O positive airway pressure, signifying patency of the foramen ovale. These 11 patients with a patent foramen ovale had increased total excursion of the flap valve (septum primum) of the fossa ovalis (1.3 +/- 0.7 cm) compared with findings in the 39 patients without a patent foramen ovale (0.3 +/- 0.5 cm, p < 0.001). All patients with a patent foramen ovale exhibited some mobility of the septum primum and 73% of these patients had > or = 1 cm total excursion of the septum primum. In contrast, 56% of patients without a patent foramen ovale exhibited no motion of the septum primum out of the plane of the atrial septum. The maximal diameter of the fossa ovalis was greater in patients with (1.4 +/- 0.4 cm) than in patients without (1.0 +/- 0.3 cm, p < 0.003) a patent foramen ovale. CONCLUSIONS: Hypermobility of the septum primum and enlargement of the fossa ovalis are morphologic findings that occur in the presence of a patent foramen ovale.

Adult↗

PubMed1995

Identification of patent foramen ovale permitting paradoxic embolism.

OBJECTIVES: We sought to analyze the morphologic and functional characteristics of the patent foramen ovale in patients with different clinical likelihoods for paradoxic embolism. BACKGROUND: The incidence of patent foramen ovale is increased in patients with otherwise unexplained arterial ischemic events. Because signs of venous thrombosis are absent in most patients, the diagnosis of paradoxic embolism is often questioned, even when patent foramen ovale is the only potential explanation for the ischemic event. METHODS: Seventy-eight patients with a patent foramen ovale detected by contrast transesophageal echocardiography were studied: 21 patients with an otherwise unexplained arterial ischemic event and clinical evidence implying paradoxic embolism (group I), 30 patients with an unexplained ischemic event but no clinical evidence for paradoxic embolism (group II) and 27 patients without an ischemic event (group III). RESULTS: During transesophageal contrast echocardiography, patients in group I had more severe right to left shunting (mean +/- SD 52 +/- 16% of the left atrial area filled with contrast medium) and a wider opening of the patent foramen ovale (7.1 +/- 3.6-mm separation between the septum primum and the septum secundum) than did patients in group II (35 +/- 15% and 4.4 +/- 3.2 mm, respectively, p < 0.001) or group III (23 +/- 12% and 3.0 +/- 2.0 mm, respectively, p < 0.001). The incidence of atrial septal aneurysm was similar in the three groups. Severe contrast shunting (> or = 50% of the left atrial area filled with contrast medium) and wide opening of the patent foramen ovale (> or = 5-mm separation) revealed a high sensitivity (71% and 86%, respectively) and high specificity (86% and 96%, respectively) for identification of group I patients. CONCLUSIONS: Right to left contrast shunting is more severe and opening of the patent foramen ovale is larger in patients with ischemic arterial events considered to be due to paradoxic embolism. In patients with a patent foramen ovale as the only potential cause for ischemic events and no signs of venous thrombosis, morphologic and functional variables assessed by transesophageal echocardiography may be helpful in estimating the likelihood of paradoxic embolism.

Adult↗

PubMedDate not supplied

Infraorbital nerve block in children: a computerized tomographic measurement of the location of the infraorbital foramen.

BACKGROUND AND OBJECTIVES: Infraorbital nerve blocks are performed in children undergoing cleft-lip surgery and endoscopic sinus surgery. The nerve exits the maxilla at the level of the infraorbital foramen. A sensory block of the infraorbital nerve can be performed by use of an intraoral route or an extraoral route. The objective of this study was to derive a mathematical formula to determine the position of the infraorbital foramen. METHODS: Computerized tomographic (CT) scans of children who were admitted to our institution for various reasons were evaluated with the assistance of a pediatric neuroradiologist. The distance of the foramen from the midline was determined, and a mixed-effects linear-regression model was used (PROC MIXED in SAS 9.1) to ascertain whether the distance of the infraorbital foramen correlated linearly with the age of the patient. RESULTS: CT scans of 48 pediatric patients were evaluated. The age of the patient accounted for more than half of the variation in this model. Distance of the infraorbital foramen can be predicted by use of the following formula: [Distance of the infraorbital foramen (in mm) from midline = 21.3 + 0.5 x age (in years)]. CONCLUSIONS: Our study found a linear correlation with age to the distance of the infraorbital foramen. This anatomic knowledge of the location of the infraorbital foramen may facilitate correct positioning of the needle. Future studies on the use of this formula with anatomic coordinates should be performed to test the validity of this formula.

Anesthetics, Local↗

PubMed2001

Ultrasound assessment of the fetal foramen ovale.

OBJECTIVES: Based on the assumption that the horizontal area between the fetal foramen ovale valve and the atrial septum (the outlet) represents the limiting structure for the foramen ovale flow, our objective was to determine the normal size of this section during the second half of pregnancy. METHODS: One hundred and thirty-eight women with low-risk singleton pregnancies were examined in a cross-sectional study between 18 and 42 weeks of gestation. Using ultrasound imaging and M-mode, the area and diameter between the foramen ovale valve and the atrial septum were determined in a four-chamber view of the fetal heart above the foramen ovale limbus. The inferior vena cava cross section and right atrial width were also determined. RESULTS: The mean foramen ovale width increased from 3 mm at 18 weeks to 6 mm at term. Correspondingly, the horizontal area grew from 15 to 50 mm2. The mean ratio between this area and the area of the inferior vena cava fell from 1 at 18 weeks to 0.5 at term. The ratio between the transverse width of the foramen ovale and the right atrium remained at average 0.45-0.50 until 32 weeks, when a slight reduction was observed towards term. CONCLUSIONS: Normal values for the horizontal cross section and transverse diameter of the foramen ovale outlet were established for the second half of pregnancy. In particular, the horizontal transverse diameter and its ratio to the right atrial width are easy to determine, and use of these measurements is thus suggested for the assessment of the fetal foramen ovale.

Adult↗

PubMed1994

Endoscopic procedures through the foramen interventriculare of Monro under stereotactical conditions.

The foramen interventriculare of Monro is an anatomical narrowness for the endoscopic access to the third ventricle. The effective mechanical angle to pass the foramen interventriculare from a frontal bore hole depends on the diameter in the plane of entrance, the depth of the foramen, and the diameter of the endoscope. Under the pathological conditions of a hydrocephalus internus the foramen interventriculare is enlarged. By means of stereotactical guidance, it is possible to reach the third ventricle accurately without damaging anatomical structures around the foramen interventriculare. The endoscopic technique under stereotactical guidance using a rigid endoscope is sufficient and safe to perform ventriculostomies in cases of hydrocephalus occlusus. Best clinical results were obtained in patients with benign aqueduct stenosis or with a tumor in this region compressing the aqueduct. In all patients no further shunt operation was necessary. The path through the foramen interventriculare should be considered also for biopsies in the third ventricle. Calculation of the foramen interventriculare trajectory prevents perforation of the roof of the third ventricle containing the main deep veins. Lesions in the foramen interventriculare like colloid cysts can also be approached very accurately by means of stereotactical calculation. However the endoscopic technique with the at present obtainable instruments does not allow removal of the whole lesion. Even so a free passage to the third ventricle can be achieved by reducing the size of the cyst by means of coagulation and sucking off the colloid material.

Adolescent↗

PubMed1999

The enigmatic foramen lacerum.

OBJECTIVE: The microanatomic details of the foramen lacerum and surrounding region are described to clarify the relationship between the internal carotid artery and the foramen lacerum. The terminology related to these structures is reevaluated. Examples of pathological abnormalities restricted to the foramen lacerum region are presented to document the clinical relevance of this region. METHODS: Microanatomic dissections were performed in 12 formalin-fixed cadaveric specimens. Bony landmarks were examined in 50 dry skulls. Microscopic sections of the region were obtained from cadaveric specimens that were formalin-fixed, decalcified, and processed for histological examination. RESULTS: The foramen lacerum is not a true foramen. No significant structures traverse its fibrocartilage. In this region, the bony and fibrous structures surround the internal carotid artery to form an incomplete canal, which serves as the rostral extension of petrous canal. CONCLUSION: The term foramen lacerum should be restricted to that portion of the cranial base at the confluence of the petrous portion of the temporal, basioccipital, and basisphenoid bones that in vivo is filled with fibrocartilage. The region immediately above the foramen lacerum, occupied by the internal carotid artery and traditionally considered the upper portion of the foramen lacerum, should be considered, anatomically and functionally, to be the rostral extension of the petrous canal. We suggest calling this extension the lacerum portion of the carotid canal.

Anatomy, Artistic↗

PubMed1996

Anatomic changes of the spinal canal and intervertebral foramen associated with flexion-extension movement.

STUDY DESIGN: A cadaveric study was done to analyze the dimensional changes in the spinal canal and intervertebral foramen of the lumber spine with flexion and extension movements. OBJECTIVES: To investigate the relationship between flexion and extension movements and morphologic changes in the spinal canal and the intervertebral foramen. SUMMARY OF BACKGROUND DATA: Previous studies have reported that the dimensions of the spinal canal and the intervertebral foramen may change significantly with motion. The purpose of this study was to assess the quantitative changes in the spinal canal and the intervertebral foramen with segmental flexion-extension movements. METHODS: Nineteen fresh cadaveric spines yielding 25 motion segments were used. The lumbar motion segments were frozen and then imaged in axial and sagittal projections by a computed tomography scanner. They were thawed then, and the motion segments were loaded to 5.7 Nm in flexion (13 motion segments) and in extension (12 motion segments) specimens. While in flexion or extension, the specimens again were frozen and imaged by computed tomography scan. The frozen specimens than were sliced using a cryomicrotome in the sagittal plane to study the dimensions of the intervertebral foramen. Eighteen other fresh cadaveric spines were sliced sagittally for study in the neutral position. RESULTS: The axial computed tomography scans showed that extension significantly decreased the canal area, midsagittal diameter, and subarticular sagittal diameter, whereas flexion had the opposite effects. The sagittal computed tomography scans showed that extension decreased all the foraminal dimensions significantly, whereas flexion increased all the foraminal dimensions significantly. The translational changes were associated with the bulging of the disc and the presence of traction spurs. The cryomicrotome sections showed the cross-sectional area of the foramen to be 12% greater for the flexion group and 15% smaller for the extension group than the cross-sectional area of the neutral group. Nerve root compression in the foramen was found to be 21.0% in neutral, 15.4% in flexion, and 33.3% in extension groups. CONCLUSIONS: The study supports the concept of dynamic spinal stenosis. In addition to static anatomic changes, careful dynamic studies may be required to evaluate better the central canal and the foramen.

Adult↗

PubMed2004

On unknown bone bridge and foramen of the atlas.

The atlas of a 52-year-old male Japanese cadaver, which had been removed and macerated, presented a bilateral unknown bone bridge forming a foramen (Case 1). The bone bridge connected the ponticulus lateralis (PL) and posterior (PP) to form an oval foramen between the superior roots of both ponticuli. The atlas of a 69-year-old male Japanese cadaver was found to have similar variations in situ (Case 2). In this case, the right bone bridge connected the superior root of the incomplete PL and the inferior root of the also incomplete PP to form a long ellipsoid foramen opening medially. The medial opening of the foramen was closed by a ligamentous connective tissue in situ. The condylar emissary vein passed this complete foramen to join the cervical epidural venous plexus. The similar bilateral foramen in case 1 was supposed to pass the same vein as in case 2. The bone bridge between the two ponticuli and the resulting foramen mentioned above have not been described previously, as far as we know. We propose that these structures be called the ponticulus interponticularis atlantis and the foramen atlantoideum interponticulare, respectively.

Aged↗

PubMed2006

Ex vivo evaluation of the ability of four different electronic apex locators to determine the working length in teeth with various foramen diameters.

BACKGROUND: The aim of this ex vivo study was to evaluate the accuracy of four electronic apex locators (EALs) to determine the working length in teeth with various foramen diameters. Our previous study revealed that electronically measured canal length was influenced by the root canal diameter. It is not known whether foramen size would interfere with the reading accuracy of an EAL. METHODS: A total of 36 extracted human lower single rooted premolar teeth were divided into four groups of nine teeth each. In groups A, B and C, the root canals were instrumented using #10-80, #10-100 and #10-120 K-files, and the tip of size #80, #100 and #120 K-files were permitted to pass through the apical foramen to a length of 1mm, respectively. In group D, the teeth were instrumented using #10-140 K-files and the tip of #140 K-file was permitted to pass through the apical foramen to a length of 5 mm. Thus, the average apical foramen diameters in groups A, B, C and D were approximately 0.82 mm, 1.02 mm, 1.22mm and 1.5 mm, respectively. The teeth were then mounted in 1% agar and four EALs were used: Root ZX, Foramatron D10, Apex NRG and Apit 7. For electronic measurement, sizes #10 and #80, #10 and #100, #10 and #120, and #10 and #140 K-files were used for groups A, B, C and D, respectively. During electronic measurement the canals were flushed with 6% sodium hypochlorite solution. RESULTS: Three-way ANOVA and Bonferroni test showed that EAL, file size and foramen size all had a significant influence on the measurement error (P<0.0001), with all the interactions between these three factors being significant (P<0.0001). CONCLUSIONS: The four EALs were unreliable to determine the working length of teeth with a wide apical foramen, when using a small size file. The Root ZX and Foramatron D10 showed significantly better scores than the other two EALs and may be more reliable to determine the working length of teeth with a wide apical foramen, if a tight-fit file is used.

Bicuspid↗

PubMed1986

A clinical and anatomical study of the location of the mental foramen in adult Chinese mandibles.

One hundred mandibles of adult Chinese cadavers of both sexes without missing teeth, alveolar bone resorption and malposition of teeth were studied. The anatomical location of each mandibular mental foramen was measured by using a combination of three previous methods. Our results showed that the location of the mental foramen below the apex of the lower second premolar (relation IV: 58.98%) was the most common. On average, the distance between the most anterior portion of the anterior border of the mental foramen and the mandibular symphysis was 28.06 mm, between the most anterior portion of the anterior border of the mental foramen and the posterior border of the ramus 74.14 mm, between the inferior border of the mental foramen and the lower border of the mandibular body 14.70 mm, between the superior border of the mental foramen and the bottom of the lower second premolar socket 2.50 mm. The distance across the mental foramen between the alveolar crest and the lower border of the mandibular body was 30.29 mm. Our results were compared with those of other investigators. The significance of identifying the anatomical location of the mental foramen in dental practice is discussed.

China↗

PubMed2003

Role of the zygomaticofacial foramen in the orbitozygomatic craniotomy: anatomic report.

OBJECTIVE: Elevation of the lateral orbital rim and zygomatic arch during an orbitozygomatic craniotomy requires a bone cut across the zygoma, which commonly extends into the lateral edge of the inferior orbital fissure. The zygomaticofacial foramen has been identified as a superficial landmark for the cut that extends into the inferior orbital fissure. This study examined the usefulness of the zygomaticofacial foramen during orbitozygomatic craniotomy. METHODS: One-hundred two dry hemicrania were used in this study. The zygomaticofacial foramen was considered to be related to the inferior orbital fissure when it was located on the zygoma in the area between lines extending in the medial-to-lateral direction along the long axis of the fissure and crossing the anterior and posterior ends of the lateral edge of the fissure. RESULTS: The zygomaticofacial foramen varied from being absent to representing as many as four small openings. A single foramen was observed in one-half of the specimens. Of the 115 zygomaticofacial foramina, 93 were related to the inferior orbital fissure. Among the 51 specimens with a single foramen, 49 foramina met the criteria for being related to the inferior orbital fissure; in those cases, there would have been no difference in the amount of bone resected using the inferior orbital fissure or the zygomaticofacial foramen as the landmark for the zygomatic cut. CONCLUSION: The zygomaticofacial foramen was a reliable landmark for locating the inferior orbital fissure and making the cut across the zygoma in only 50% of the specimens.

Brain Diseases↗

PubMed1995

The microsurgical anatomy of the jugular foramen.

The microsurgical anatomy of the jugular foramen was studied in 10 fixed cadavers, each cadaver consisting of the whole head and neck. Five of the cadavers were injected with latex. The jugular foraminal region was exposed using the infratemporal fossa type A approach of Fisch and Pillsbury in five cadavers (10 sides) and the combined cervical dissection-mastoidectomy-suboccipital craniectomy approach in five cadavers (10 sides). The right foramen was larger than the left in seven cases (70%), equal in two cases (20%), and smaller in one case (10%). The dura covering the intracranial portal of the foramen had two perforations, a smaller anteromedial perforation through which passed the ninth cranial nerve (CN IX), and a larger posterolateral perforation, through which passed the 10th and 11th cranial nerves (CNs X and XI) and the distal sigmoid sinus. The perforations were separated by a fibrous septum in 16 specimens (80%). After exiting the posterior fossa, CNs IX, X, and XI all lay anteromedial to the superior jugular bulb (SJB) within the jugular foramen. The inferior petrosal sinus (IPS) entered the foramen between CNs IX and X in most cases; however, in 10% of our cases it entered the foramen between CNs X and XI, and in 10% it entered the foramen caudal to CN XI. The IPS terminated in the SJB in 90% of our cases; in 40%, the IPS termination consisted of multiple channels draining into both the SJB and internal jugular vein. This study shows that the arrangement of the neurovascular structures within the jugular foramen does not conform to the hitherto widely accepted notion of discrete compartmentalization into an anteromedial pars nervosa containing CN IX and the IPS and a posterolateral pars venosa containing the SJB, CNs X and XI, and the posterior meningeal artery.

Accessory Nerve↗

PubMed1993

Positive end-expiratory pressure increases the right-to-left shunt in mechanically ventilated patients with patent foramen ovale.

OBJECTIVE: To determine the effect of the presence of a patent foramen ovale on the right-to-left shunt in patients with respiratory failure who receive positive end-expiratory pressure (PEEP). DESIGN: Convenience sample with randomized application of PEEP. SETTING: General intensive care unit of a university teaching hospital. PATIENTS: A total of 46 mechanically ventilated patients with respiratory failure requiring an inspired oxygen concentration of at least 50% and a PEEP of at least 5 cm of H2O. INTERVENTION: Randomized application of PEEP (0 and 10 cm of H2O). MEASUREMENTS: A patent foramen ovale was detected by saline contrast transesophageal echocardiography. The alveolar-to-arterial oxygen difference and the right-to-left shunt were calculated from arterial and venous blood gas sampling. RESULTS: In patients without a patent foramen ovale (n = 39), the alveolar-to-arterial oxygen difference and the shunt fraction decreased (-50 mm Hg [95% CI, -21 to -67] and -0.05 [CI, -0.03 to -0.07], respectively) after adding PEEP (10 cm of H2O). In patients with a patent foramen ovale (n = 7), minimal changes were noted in the alveolar-to-arterial oxygen difference (4 mm Hg, P > 0.2), but the shunt fraction increased (0.05, CI, 0 to 0.09). Adding PEEP (10 cm of H2O) increased the shunt fraction in 6 of 7 (86%) patients with a patent foramen ovale, whereas the shunt increased in only 7 of 39 (18%) patients without a patent foramen ovale (P < 0.007). CONCLUSIONS: A patent foramen ovale was found in 7 of 46 patients (15%; CI, 6% to 29%) with acute respiratory failure. This condition is a common cause of lack of improvement in oxygenation with the addition of PEEP in the mechanically ventilated patient. In patients with a patent foramen ovale, the right-to-left shunt is usually increased by using PEEP.

Acute Disease↗

PubMedDate not supplied

Macroanatomic and radiologic characteristics of the superior genial spinal foramen and its bony canal.

PURPOSE: To determine the incidence, size, location, course, and content of the superior genial spinal foramen and its bony canal. MATERIALS AND METHODS: Three hundred eighty dry human cadaver mandibles were morphometrically analyzed by measuring the distance from the foramen to the mandibular base and the size of the foramen and bony canal. Radiologically, the course of the bony canal and its relation to the mandibular incisive canal were investigated after injecting contrast medium (Omnipaque) in the superior genial spinal foramen and the incisive canal at the level of the mental foramen or by inserting a thin metal wire into the bony canal. Dissection was performed on another 10 intact cadaver mandibles. RESULTS: A distinct foramen was present in 98% of all dry specimens studied. Its general form was round or flattened funnel-shaped. Upon microanatomic dissection, a distinct branch of the lingual artery and the lingual nerve entering the superior genial spinal foramen were found. CONCLUSIONS: The superior genial spinal foramen is present in most human mandibles and appears to be the entrance of a true lingual neurovascular bundle passing into the bone via a well-defined bony canal toward the buccal side. This implies that surgery and more specifically implant placement at the mandibular midline may carry some risk of neurovascular damage.

Cephalometry↗

PubMed1995

The anatomy of the inferior petrosal sinus, glossopharyngeal nerve, vagus nerve, and accessory nerve in the jugular foramen.

PURPOSE: To define the variations of the courses of the cranial nerves and the inferior petrosal sinuses as they enter and traverse the jugular foramen. METHODS: Thirty-nine cadaveric specimens containing the jugular foramen were scanned with 1-mm contiguous axial and coronal CT sections. Each specimen was dissected to evaluate the position of the cranial nerves and inferior petrosal sinus as they entered the jugular foramen. RESULTS: The glossopharyngeal nerve entered the most superior, anterior, and medial aspect of the jugular foramen and descended in the anterior portion of the jugular foramen, often within a groove. The vagus and accessory nerves could not be separated by CT. They entered the jugular foramen most often anterior or anterior and inferior to the jugular spine of the temporal bone and descended in a position ranging from medial to anterior to the jugular vein. The inferior petrosal sinus most often coursed inferior to the horizontal portion of the glossopharyngeal nerve and entered the jugular system in the jugular foramen, at the exocranial opening or below the skull base. A pars nervosa and pars venosa could be identified only at the endocranial opening, where the jugular spine separated the pars nervosa containing the inferior petrosal sinus and three cranial nerves from the pars venosa containing the jugular vein. CONCLUSION: Our evaluation demonstrated anatomic variation in the area of the jugular foramen.

Accessory Nerve↗