The anatomic relationship around the horizontal segment of petrous internal carotid artery: a study based on reconstructed computed tomography angiography

Purpose

The anatomic relationship around the horizontal segment of petrous internal carotid artery (ICA) is complicated. Relative researches on human patients using radiographic technique are scarce. It is essential to get adequate anatomic knowledge about this region for performing some bypass procedures.

Methods

Using the independent software Mimics, we prospectively studied the 0.45-mm-thick computed tomography angiography (CTA) images of 29 patients (58 sides). All patients’ middle cranial fossa and related critical anatomic structures were reconstructed in 3D. Some measurements were established on the multiplanar reconstructed images, including the distance from foramen ovale and foramen spinosum to the petrous ICA; the distance from the lumen of cochlea to the edge of trigeminal impression and petrous ICA; and the length of the horizontal segment of petrous ICA.

Results

The horizontal segment of petrous ICA was surrounded by the trigeminal impression, the cochlea and the auditory tube spatially. On the multiplanar reconstructed CTA images, the average distances from foramen ovale and foramen spinosum to the petrous ICA were 4.1?mm and 5.8?mm, respectively; the average distance from the lumen of cochlea to the edge of trigeminal impression and petrous ICA were 8.2?mm and 2.0?mm, respectively; and the mean length of the horizontal segment of petrous ICA was 15.8?mm.

Conclusions

Our results indicate adequate and reliable anatomic information can be obtained using reconstructed CTA on an individualized basis.     

The human locus coeruleus 3-D stereotactic anatomy

Purpose

The main goal of this work was to study the stereotactic anatomy of the human locus coeruleus (LC), important relay of adrenergic and dopaminergic human brainstem (HB) circuitry, to allow its easy localization on MRI and in microsurgical procedures.

Methods

Forty LC were studied from 20 adult HB of both sexes. The melanin pigmentation of its cells was used to identify and localize them and so to define the 2-D and 3-D LC contours. These HB were cut on a cryomicrotome with 3-D referenciation. The slices were coloured with haematoxyline-eosin. On the slices, digitized images of the cells were referenced to the midline, the fourth ventricle floor plane and the pontomedullary junction plane with an appropriate computer program.

Results

The LC revealed to be a symmetric, thin and elongated nucleus, divergent caudally except in its superior part, with a sub-ependymal location on the superior dorsal lateral pons. The main LC dimensions are: length 12.0–17.0 mm (m 14.5); width 2.5 mm; height 2.0 mm. The 3-D references of the LC center are: 3.2 ± 0.3 mm to the midline; 1.1 ± 0.2 mm to the IV ventricle floor and 18.5 ± 1.5 mm to the ponto-medullary junction.

Conclusions

The human LC is a nucleus thinner and longer than previously described (in average 14.5 mm long and 2–2.5 mm thick), localized 1 mm under the IV ventricle, 3 mm apart from the midline and centered 14–21 mm above de ponto-medullary junction. No correlation was found between LC and pons dimensions, the gender or the age.     

Morphometric study of mandibular foramen in macerated skulls to contribute to the development of sagittal split ramus osteotomy (SSRO) technique

Purpose

The aim of this study was to provide morphometric data, obtained from macerated mandibles, which might facilitate the topographic location of the mandibular foramen, considering aspects such as gender, age and ethnicity.

Materials and methods

One hundred and eighty-five macerated mandibles of adult black and white individuals of both sexes were analyzed. Initially, 5 points were established: MF, the lowest point of the mandibular foramen; S, greatest concavity of the mandibular notch; A, anterior margin of the ramus of mandible; P, posterior margin of the ramus of mandible; and Go, gonion. Then the following measurements were performed bilaterally: MF-S, MF-A, MF-P and MF-Go.

Results

The following mean values were found: MF-S: 21.02 mm for white females (WF) and 22.00 mm for black females (BF); 24.40 mm for white males (WM) and 24.35 mm for black males (BM); MF-A: 17.05 mm for WF and 18.09 mm for BF; 17.18 mm for WM and 18.11 mm for BM; MF-P: 11.11 mm for WF and 12.24 mm for BF; 13.10 mm for WM and 14.15 mm for BM; MF-Go: 19.00 mm for WF and 19.44 mm for BF; 23.13 mm for WM and 22.12 mm for BM.

Conclusions

The values found in this study, considering gender, age and ethnic group, can be used as a parameter to carry out the sagittal split ramus osteotomy technique, making it more predictable and with less risk of complications.     

Surgical anatomy of the chorda tympani: a micro-CT study

Purpose

Iatrogenic injury of the chorda tympani is a well-known complication of middle ear surgery, yet few studies have investigated the intraosseous course of the nerve. The aim of this study was to accurately delineate the posterior canaliculus in the temporal bone, particularly its relationship to the tympanic annulus, which is critical during the insertion of subannular ventilation tubes.

Methods

Forty temporal bones from 27 cadavers (15 male, mean age 75?years, 13 bilateral) were scanned using a micro-CT scanner, and standardised 3-D multiplanar reconstructions were generated using a software platform. The posterior canaliculus was measured in relation to reproducible bony landmarks.

Results

In 6 (15%) specimens, the chorda tympani originated from the facial nerve outside the skull and in 34 (85%) from within the facial canal at a mean of 3.2?±?1.8?mm above the stylomastoid foramen. The posterior canaliculus was 12.3?±?3.8?mm long and converged on the tympanic sulcus cranially. It entered the middle ear at 62?±?10% of the height of the tympanic membrane.

Conclusions

This novel micro-CT study defines the precise anatomy of the posterior canaliculus housing the chorda tympani and provides data that may help the otologic surgeon protect the nerve from iatrogenic injury.     

An anatomical study of the pterygospinous bar and foramen of Civinini

Purpose

The pterygospinous ligament extends from the posterior free margin of the lateral pterygoid plate till the spine of the sphenoid. The ligament may ossify partly or completely leading to the formation of the pterygospinous bar. A complete ossification of the ligament results in the formation of the foramen of Civinini. Presence of the complete or incomplete pterygospinous bar may lead to a difficulty in passing the needle during anaesthesia for the trigeminal neuralgia or the bar may also compress the mandibular nerve and its branches to cause lingual numbness, pain and speech impairment.

Method

Presence of the complete or incomplete pterygospinous bar and the foramen of Civinini were studied in 55 dried adult skulls and 20 sphenoid bones.

Results

Partial or complete ossification of the pterygospinous ligament was seen in 17.33 % skulls. One skull showed the presence of bilateral complete pterygospinous bar while another skull had the unilateral complete pterygospinous bar on right side. Two skulls and one sphenoid had bilateral incomplete pterygospinous bar while seven skulls and one sphenoid bone had unilateral incomplete pterygospinous bar. In three cases, the bar was passing just below the foramen ovale.

Conclusion

The pterygospinous bar when present medial to the foramen ovale may not have much clinical significance but when the bar is present just below the foramen ovale, it may cause a compression of the mandibular nerve and its branches and may also obstruct the passage for the transoval approach to the neighbouring regions.

     

Evaluation of location and dimensions of mandibular lingual foramina using cone-beam computed tomography

Objectives

The aim of this study was to assess the regional frequency and anatomical properties of mandibular lingual foramina (MLF) and their bony canals with cone-beam computed tomography (CBCT).

Materials and methods

A retrospective study was conducted by selecting images of the mandible from CBCT examination of 500 patients. MLF were located according to tooth areas and were grouped into midline, paramedian, and posterior foramina. In addition, the frequency of bony canals originating from lingual foramina was calculated, and the course and anastomoses were examined.

Results

In total, 491 areas with lingual foramina were observed. The highest regional frequency was recognized in the midline area (95.2 %), followed by left first premolar (15.1 %) area. The frequency of foramina in the midline was different from the paramedian and posterior (p < 0.01) regions. 95.6 % of lingual vascular canals originating from midline lingual foramina had a perpendicular course into the symphysis, whereas 60.3 % of canals from paramedian foramina and 83.6 % of canals from lateral lingual foramina presented with an anteriorly directed course.

Conclusions

CBCT examination easily demonstrates the presence of the lingual vascular canals. MLF are frequently present in a Turkish population; radiologists and oral surgeons should be aware of this anatomic feature and its possible implications.     

Thoracoscopic anatomy and approaches of the anterior thoracic spine: cadaver study

Propose

In spite of the extensive case studies considering thoracoscopic approaches to the anterior thoracic spine, the literature lacks studies of the thoracoscopic anatomic dissection and approaches. In this article, the authors present their study of thoracoscopic anatomy of the anterior spine with illustrated step-wise dissection and approaches for sympathectomy, discectomy and corpectomy.

Materials and methods

Four adult cadavers with no history of disease, local trauma or surgery were studied and bilateral thoracoscopic anterior spinal approaches were performed. Thoracoscopic dissections were done in the Department of Anatomy, using Karl Storz 30°, 5?mm and 30?cm rod lens rigid endoscope (Karl Storz and Co., Tuttlingen, Germany). As surgical instrumentation, Karl Storz Rosenthal endoscopic surgical set and 15?mm portals were used for all approaches.

Results

For sympathectomy, the cadaver is positioned supine and the port locations are in the third and fifth intercostal spaces in the anterior axillary line. The stellate ganglion is cephalad to the second rib, and the T2 and T3 ganglia are divided just superior to T2 ganglia and inferior to T3. For discectomy, the cadaver is positioned in the lateral decubitus position. The working portal is positioned directly over the affected disc in the posterior axillary line. The camera portal is positioned in the middle axillary line; 2–3 intercostal spaces caudal to the working portal. The rib head is removed and the lateral surface of the pedicle and neural foramen are exposed. The pedicle and the floor of the spinal canal are resected to decompress the ventral aspect of the spinal canal. For corpectomy, the position of the cadaver and ports are as same as for discectomy. The adjacent segmental vessels are divided first, and the discs above and below the targeted corpus are removed. The ipsilateral pedicle is then removed to decompress the anterior spinal cord, followed by median corpectomy.

Conclusions

Thoracoscopic approaches are minimally invasive procedures and they can be used safely in patients who need anterior exposure to the thoracic spine for the treatment of a spectrum of diseases. Knowledge of the normal anatomy and thoracoscopic cadaver dissection are essential steps in improving the learning curve.     

Anatomical landmarks for locating the sphenoid ostium during endoscopic endonasal approach: a cadaveric study

Purpose

The sphenoid ostium (SO) provides a natural portal for entering the sphenoid sinus and beyond up to the skull base. It is not always easy to locate the ostium during the endoscopic approach. The present study was designed to establish readily identifiable anatomical landmarks for locating the sphenoid ostium.

Methods

Cadaveric dissection was performed in 30 hemisections of head and neck and various measurements were taken from fixed anatomical landmarks in the nasal cavity to the sphenoid ostium. The size, shape and position of sphenoid ostium were determined in relation to the anterior wall of the sphenoid sinus and the superior turbinate.

Results

The mean distance from the supero-lateral angle of the posterior choana to the SO was found to be 21.21 ± 6.02 mm. The mean distance of the SO from the midline was 4.85 ± 2.89 mm. In all the specimens, the SO was situated within 1 cm of the midline. The mean distance between the inferior end of the SO and the postero-inferior edge of the superior turbinate was 8.03 ± 3.52 mm. The SO was present on an average distance of 55.1 ± 3.54 mm from the limen nasi. In 93.3 % of the specimens, the SO was situated between 5 and 6 cm of the inferior end of the limen nasi. The angle between the anterior nasal spine and the SO was found to be remarkably constant. In 93.3 % of the specimens, it was from 25° to 30°.

Conclusions

The sphenoid ostium could be localized medial to the superior turbinate between 1.5 and 3 cm above the supero-lateral angle of the posterior choana, within 1 cm of the midline and within 1 cm of the postero-inferior edge of the superior turbinate.     

An anatomic study of the inferior oblique nerve with high-resolution magnetic resonance imaging

Objective

To investigate anatomic features of the inferior oblique nerve (IObN) by high-resolution magnetic resonance (MR) imaging and cadaveric dissection.

Methods

This study enrolled 100 consecutive outpatients, who underwent 3.0 T MR imaging equipped by the 32-channel head coil. The T2-weighted imaging data of IObN were extracted for analysis and compared with the findings of microsurgical dissection in 14 orbits.

Results

50 male and 50 female subjects allotted to the imaging study were aged from 11 to 78 years. In 94 % sides, the IObN was found to separate from the inferior rectus muscle (IRM) at the level just behind to the posterior pole of the bulb. At the midpoint of the IObN part coursing along the orbital floor and above or adjacent to the infraorbital nerve and artery complex, the mean distance from the lateral margin of the IRM was 1.0 mm on the right and 0.9 mm on the left. The IObN showed upward direction change just below the belly of the inferior oblique muscle and innervated to it at the equator level in 78 sides on the right and 89 on the left. Dissected specimens revealed the consistent morphological findings of the IObN.

Conclusions

The IObN seems to be a relatively consistent structure. Anatomic information on the IObN and surrounding structures that are provided by high-resolution MR imaging can be a help for safe surgery.     

The medial head of the triceps brachii. Anatomy and blood supply of a new muscular free flap: the medial triceps free flap

Purpose

The anatomical features of the posterior compartment of the arm seem to provide the basis to raise one of the smallest free muscular flaps, with minimal donor site morbidity: the medial triceps free flap.

Methods

The anatomic study was carried out on 27 fresh cadaver arms: 7 prepared for corrosion cast, 15 for simple dissection and 5 for dissection after latex injection. Morphological data of the muscle, as well as pedicle constancy and size, were recorded.

Results

The mean size of the medial head was 10.7?×?2.5?×?3.3?cm; the mean weight was 30.1?g. We found a constant and unique pedicle supplying the whole medial head of triceps muscle, composed by the middle collateral artery (MCA), two veins and a nerve. The mean length of MCA was 2.9?cm and the ??extended?? pedicle, including the deep brachial artery (DBA), was 8?C12?cm long. At their origin, the mean caliber of MCA was 1.5?mm and the mean caliber of DBA 2.4?mm.

Conclusions

Our findings confirmed the reliability of the MC vessels and their anatomical relationships with the medial head of triceps brachii muscle, which could be harvested as a free flap or as a pedicled flap based on anterograde or retrograde flow. This technique should be safe, yielding mild donor site morbidity, and suitable in regional reconstruction or distant reanimations.     

Evaluation of the relationship between the maxillary posterior teeth and the sinus floor using cone-beam computed tomography

Aim

The aim of this study was to evaluate the relationship between each root of maxillary premolars and molars and the maxillary sinus floor according to sex, sinus position, and age by decade in a Turkish population by using cone-beam computed tomography (CBCT) scanning.

Methodology

We evaluated a database of 5,166 (2,680 maxillary premolars and 2,486 maxillary molars) CBCT scans obtained from 849 patients. The vertical relationship between each root of the molar and premolar teeth to the sinus floor was classified into three types: type 1, the roots penetrated into the sinus floor; type 2, the roots contacted the sinus floor; and type 3, the roots extended below the sinus floor.

Results

The results of the classification of each root in relationship to the sinus floor were as follows: type 3 occurred most frequently in the first (92.4 %) and second (71.6 %) premolar teeth, type 1 (34.2 %) occurred most frequently in the palatinal roots of the first molar teeth, type 3 occurred most frequently in the mesiobuccal (39.9 %) and distobuccal (39.7 %) roots of the first molar teeth, and type 2 (36.7 %) occurred most frequently in the mesiobuccal roots of the second molar teeth. No significant differences were found between the left and right sides, but several differences were found between males and females. The relationship between the posterior teeth and the sinus floor differed according to the age decade interval (p < 0.05).

Conclusions

The maxillary first premolars have no relationship with the maxillary sinus floor, but the maxillary second molars are closer to the sinus floor. Also the second decade and males were most susceptible to undesirable results.     

The prevalence, length and position of the anterior loop of the inferior alveolar nerve in Chinese, assessed by spiral computed tomography

Purpose

This study used spiral computed tomography to identify the anterior loop of the inferior alveolar nerve, and to measure its length and position in Chinese. This information may be useful to safely install endosseous implants in the most distal area of the interforaminal region.

Methods

Sixty-eight Chinese patients were included in this retrospective study. Patients were scanned by 64-slice spiral computed tomography, and the prevalence, length, and position of the anterior loop were assessed using the multiplanar capabilities of software.

Results

An anterior loop could be identified in 83.1 % of the cases, with a mean length of 2.09 mm (range 0–5.31 mm). The mean distance from the superior border of the mental foramen to the alveolar crest was 13.00 mm, and the mean distance from the superior border of the origin of the anterior loop to the alveolar crest was 17.83 mm.

Conclusions

The anterior loop was highly prevalent in Chinese, and the length of the anterior loop was highly variable. Therefore, we recommend that drilling commences from a location approximately 5.5 mm mesially from the mental foramen, when installing implants in the most distal interforaminal area.     

The posterior pedicled inferior turbinate–nasoseptal flap: a potential combined flap for skull base reconstruction

Objectives

To develop a combined pedicled flap comprising the mucoperiosteum and mucoperichondrium of the inferior turbinate, lateral nasal wall, nasal floor, and nasal septum based on the posterior lateral nasal artery, a branch of the sphenopalatine artery, for the reconstruction of skull base defects resulting from endoscopic expanded endonasal approaches.

Methods

Eleven fresh adult cadaver heads were dissected. Arterial distribution patterns of the inferior turbinate, lateral nasal wall, nasal floor, and nasal septum were investigated. The posterior pedicled inferior turbinate–nasoseptal flap was designed, measured, and harvested, and its ability to cover ventral skull base defects was examined.

Results

The inferior turbinate artery and/or posterior lateral nasal artery had 3.19 ± 1.47 (range 2–7) branches [mean outer diameter of largest branch, 0.40 ± 0.10 (range 0.24–0.60) mm] that anastomosed with the nasoseptal artery. These anastomosing arteries allowed the posterior lateral nasal artery to supply arterial blood to the nasoseptal mucoperichondrium and mucoperiosteum. Mean flap length was 100.65 ± 5.61 (range 91.43–109.44) mm, and minimum and maximum widths were 25.21 ± 2.29 (range 22.36–30.23) and 44.53 ± 5.02 (range 36.45–54.10) mm, respectively. Mean flap area was 3090.69 ± 288.08 (range 2612.97–3880.09) mm². The flap covered defects extending from the frontal sinus to the foramen magnum in all specimens.

Conclusions

Harvesting of a posterior pedicled inferior turbinate–nasoseptal flap is feasible. It should be considered a useful option for the reconstruction of large defects involving the anterior skull base, planum sphenoidale, sella turcica, and/or clivus.

     

Morphometric analysis of the infraorbital groove, canal, and foramen on three-dimensional reconstruction of computed tomography scans

Purpose

This study aimed to investigate the anatomy of the infraorbital foramen (IOF), infraorbital canal (IOC), and infraorbital groove (IOG) with regard to surgical and invasive procedures using three-dimensional reconstruction of CT scans.

Methods

The CT scans of 100 patients were evaluated retrospectively. The morphology of the IOF, IOC, and IOG as well as their relationships to different anatomic landmarks was assessed in a three-dimensional model.

Results

The mean length of the IOC and IOG and the angle of the IOC relative to IOG were 11.7 ± 1.9, 16.7 ± 2.4 mm, and 145.5° ± 8.5°, respectively. The mean angles of the IOC relative to vertical and horizontal planes were 13.2° ± 6.4° and 46.7° ± 7.6°, respectively. In the relationships between the IOF and different anatomic landmarks, the mean distances from the IOF to supraorbital notch/foramen, facial midline, and infraorbital rim were 5.6 ± 3.1 mm laterally, 26.5 ± 1.9 mm laterally, and 9.6 ± 1.7 mm inferiorly, respectively. The mean distance from the IOF to anterior nasal spine (ANS) was 35.0 ± 2.6 mm, and the mean angle of the axis that passed the IOF and ANS relative to horizontal plane was 28.8° ± 4.1°. In addition, the mean soft tissue thickness overlying the IOF was 11.4 ± 1.9 mm.

Conclusions

These results provide detailed knowledge of the anatomical characteristics and clinical importance of the IOF. Such knowledge is of paramount importance for surgeons when performing maxillofacial surgery and regional block anesthesia.     

An evaluation of CT-scan to locate the femoral head centre and its implication for hip surgeons

Purpose

The aim of this preliminary study was to determine the accuracy of CT-scan to locate the femoral head centre.

Methods

Eleven dried femurs were included for study. Three techniques were compared to determine femoral head centre (FHC) location: CT-scan, Motion Analysis and Faro-Arm. Markers were stuck on each femur to create a system of coordinates. Femurs lied on their posterior parts (bicondylar plane). Several points around the femoral head were palpated (Motion Analysis and Faro-Arm) or determined (Amira software for CT-scans). By a least-square regression method, the FHC location in 3D was defined for each technique.

Results

The results of the FHC location determined by the CT-scan technique were compared with those measured by the faro-arm and the Motion Analysis techniques. The coordinates (X, Y, Z) of the FHC were compared between the three methods, and no statistical difference was found (p = 0.99). In a 3D plot, this gave a mean difference of 1.3 mm. The mean radius of the femoral head was of 22.5 mm (p = 0.6).

Conclusions

CT-scan is as accurate and reliable as gold-standard techniques (motion and faro-arm). Locating FHC before and after hip arthroplasty would allow hip surgeons to determine and compare 3D orientation of the upper-end of femur: offset, height and anteversion.     

Rotation of the osseous spiral lamina from the hook region along the basal turn of the cochlea: results of a magnetic resonance image anatomical study using high-resolution DRIVE sequences

Purpose

To define the rotational anatomy of the osseous spiral lamina (OSL) at the hook region and along the basal turn of the cochlea and to illustrate the potential utility of high-resolution MRI images to study inner ear ultrastructure.

Methods

Retrospective review of high-resolution temporal bone MRI images in 20 consecutive adult patients referred for imaging unrelated to hearing loss. The main outcome measure utilised images in an oblique sagittal plane to measure the rotation of the OSL relative to the vertical axis in the hook region and along the basal turn of the cochlea.

Results

The right OSL is noted to rotate in a clockwise direction as one proceeds anteriorly; over the same distance, the left OSL rotates in an anti-clockwise direction. The average overall rotation for all subjects as measured over a distance of 1–7?mm from the posterior margin of the round window was 25.95°. Inter-subject variability was noted.

Conclusions

Prominent rotation of the OSL was noted in the hook region, this being most pronounced in the proximity to the round window. This concept may have implications for cochleostomy site selection with implant surgery. The study highlights the feasibility of high-resolution MRI to be used to systematically study variations in intra-cochlear anatomy.     

Wedging of vertebral bodies at the thoracolumbar junction in asymptomatic healthy subjects on magnetic resonance imaging

Purpose

Wedging of the vertebral body on radiological examination is a valuable indicator of a vertebral compression fracture, although it can also be observed in subjects with no history of trauma. The purpose of this study was to elucidate the normative value of vertebral wedging at the thoracolumbar junction in asymptomatic healthy subjects for differential diagnosis of vertebral compression fractures using MRI.

Methods

A total of 115 subjects without back pain at the time of the examination and without history of spinal trauma was included (68 males, 47 females, mean age 49.5?years). They underwent MRI of the thoracic and lumbar spine, and the ratio of anterior vertical height to posterior vertical height of the vertebral body (APR) was determined from T10 to L2 on T2 weighted sagittal images.

Results

APR was 0.92?±?0.08 at T10, 0.92?±?0.08 at T11, 0.90?±?0.06 at T12, 0.89?±?0.06 at L1, and 0.90?±?0.07 at L2, indicating that vertebral bodies at the thoracolumbar junction appear wedge-shaped rather than rectangular. Males, thinner subjects, smokers, and subjects with abnormalities of the endplates such as a Schmorl nodule had a significantly smaller APR than females, fatter subjects, non-smokers, and those without endplate abnormalities.

Conclusion

The normative values of APR obtained in the present study can represent a valuable reference in the diagnosis of vertebral compression fracture to help prevent confusion with physiological vertebral wedging.