Skin reference point for the zygomatic branch of the facial nerve innervating the orbicularis oculi muscle (anatomical study)

Purpose

Direct access to the zygomatic branch of the facial nerve in the parotid is less invasive and more selective than first dissecting the nerve trunk and then finding the branches. The aim of this study was to confirm the point of reference on the skin which would give direct access to the zygomatic branch for the orbicularis oculi muscle. The skin reference point studied was on the intertragic notch/external canthus line, 2.5 cm in front of the intertragic notch.

Methods

Ten fresh cadavers, and thus 20 sides of faces were dissected. The zygomatic branch of the facial nerve innervating the orbicularis oculi muscle was accessed directly. The dissection was extended to temporofacial and cervicofacial branches and then to the trunk of the facial nerve by a retrograde path in the parotid.

Results

Twenty dissections of the parotid area confirmed the validity of the anatomical reference point of the zygomatic branch for the orbicularis oculi muscle considered.

Conclusions

The simplicity and reliability of this landmark is important in clinical practice and has numerous potential applications in surgery for rehabilitation of facial paralysis associated with VII healthy and VII affected neurorraphies, in facial paresis for superneurotizations and in traumatology.     

Transversal craniofacial growth evaluated on children dry skulls using V2 and V3 canal openings as references

Purpose

The aim of this study was to investigate the transversal relationships between two cephalometric landmarks and lines on the face using ovale, rotundum, greater palatine and infra-orbital foramina as references.

Method

Thirty-four children dry skulls, 19 males and 15 females aged 0–6 years, were examined by computed tomography scanning by using constructed tomographic axial and frontal planes. The cephalometric transversal dimensions of the face skull were measured between the right and left landmarks from the orbital lateral wall and from the zygomatic arch. The cephalometric transversal dimensions of the base skull were measured between the right and left ovale, rotundum, greater palatine and infra-orbital foramina.

Results

Statistical analysis using partial correlations, regardless of the age, showed strong relationships (p < 0.05) among transversal measurements with nerve canal openings and transversal distances of skull face.

Conclusion

We showed that the cranial base transversal growth was very strongly related to facial transversal growth from the postnatal period up to 6 years of age.     

Branching patterns of the facial nerve and its communication with the auriculotemporal nerve

This study examines the anatomic relationships and variability of the facial nerve trunk and its branches, with emphasis on the intraparotid connections between the divisions. Microdissections were performed on 30 Korean half-heads, and the facial nerve trunks and branches were exposed. The average depth of the stylomastoid foramen from the skin surface was 21.0±3.1 mm, and the distance between the stylomastoid foramen and the bifurcation of the temporofacial (upper) and cervicofacial (lower) divisions was 13.0±2.8 mm. In 26 of 30 dissections (86.7%), the facial nerve trunk bifurcated into two main divisions, and a trifurcation pattern was seen in the other four cases (13.3%). According to the origin of the buccal branches, we classified the branching patterns of the facial nerve into four categories. In type I (13.8% of cases), the buccal branches arose from the two main divisions of the trunk but not from other branches of the facial nerve. In type II (44.8% of cases), the buccal branches arising from the two main divisions were interconnected with the zygomatic branch. In type III (17.3% of cases), the marginal mandibular branch sent nerve twigs to the buccal branch, which originated from the upper and lower divisions. In type IV (17.3% of cases), the nerve twigs from the zygomatic and marginal mandibular branches merged to the buccal branch arising from the two main divisions. Communications between the facial and auriculotemporal nerve branches, which are known as communicating auriculotemporal nerves, were observed in 28 of the 30 cases (93.3%). Familiarity with these common variations in the facial anatomy provides useful information for the surgeon in careful dissection, preservation of the facial nerve, and complete removal of the tumors in parotidectomies.     

Anatomical basis of transgluteal approach for pudendal neuralgia and operative technique

Background

Pudendal neuralgia is an entrapment syndrome whose both anatomic landmarks and operative technique remain relatively unfamiliar to neurosurgeons.

Objective

To provide an outline of operative steps that is important to correct application of this approach.

Methods

Surgical illustrations are included. The different figures detail the important steps of the operation.

Results

We perform a transmuscular approach leading to the sacrotuberous ligament, which is opened sagittally. The pudendal nerve and internal pudendal artery are found to be enclosed by a fascia sheath. The pudendal nerve swings around the sacrospinous ligament sacrospinous ligament with tension. Both distal branches of the pudendal nerve can be followed, especially the rectal branch running medially. After the section of the sacrospinous ligament, the pudendal nerve can be transposed frontally to the ischial spine within the ischiorectal fat. During this maneuver, significant venous bleeding may be encountered as perineural satellite veins dilatation can accompany or surround the pudendal nerve. It is important to avoid overpacking to limit compression injury to the pudendal nerve using judiciously small pieces of hemostatic device and soft cottonoid with light pressure. Then, the obturator fascia and the membranous falciform process of the sacrotuberous ligament that extend toward the ischioanal fossa must be incised.

Conclusion

Transgluteal approach is a safe technique and we demonstrate that this approach can be performed safely minimizing pain, size of incision, surgical corridor, and trauma to adjacent muscles of buttock.     

Anatomy and surgical landmarks for the ansa pectoralis: application to pectoralis major nerve selective neurotomy

Background

Ansa pectoralis neurotomy is a surgical approach in the treatment of the pectoralis major muscle spasticity causing an attitude in adduction and internal rotation of the shoulder.

Objective

To establish the anatomical landmarks allowing an easier localisation of the ansa pectoralis during neurotomy.

Material and methods

Fifteen adult human cadavers (10 embalmed and 5 fresh) were dissected in order to determine anatomical landmarks allowing an easier localization of the ansa pectoralis during neurotomy.

Results

In all the cadavers, the lateral pectoral nerve arose from the lateral cord of the brachial plexus, 0.2 cm above to 1.5 cm below the inferior border of the clavicle with a mean distance of 0.76 cm for left and right side, whereas the medial pectoral nerve arose from the medial cord of the brachial plexus, 0.7–2.3 cm below the inferior border of the clavicle with a mean distance of 0.61 cm for the left side and 0.68 cm for the right side. We systematically found both the origin of pectoral nerves and the ansa pectoralis at the level of the middle third of the distance between the sternoclavicular and the acromioclavicular joints. Moreover, ansa pectoralis was constantly localized lateral to the thoracoacromial artery. In four cases, the division of the lateral pectoral nerve was not found. In one case, medial pectoral nerve did not exist.

Conclusion

Ansa pectoralis can be found by a curved incision made at the mid-third of the distance between the sternoclavicular and the acromioclavicular joints, the medial point being located just below the lower edge of the clavicle and the lateral point 2 cm below the inferior edge of the clavicle.     

Surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation based on three-dimensional reconstructed temporal bone CT images

Purpose

In this study, we evaluated the surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation (CI).

Materials and methods

Twenty computed tomography (CT) images of the temporal bone from patients aged between 20 and 60 years were selected. The inclusion criterion was a radiologically normal temporal bone CT scan. Three-dimensional (3D) reconstructed images were obtained using high-resolution axial temporal bone CT scans. Eight points were used to evaluate the surgical anatomy of the posterior tympanotomy and cochleostomy. The length of lines between the points and the angles between the lines were measured.

Results

The mean length of line AB (superior-inferior length of the posterior tympanotomy for CI) was 6.48 ± 0.26 mm, while line AC (width of the chorda tympani and facial nerves) was 3.60 ± 0.2 mm. The mean angle of ABC (angle at which the chorda tympani nerve branched from the facial nerve) was 18.40° ± 1.05°. The mean length of line AD (distance from the facial ridge to the point of cochleostomy) was 9.58 ± 0.47 mm.

Conclusions

3D imaging of the facial recess and round window can be used to identify the facial recess before surgery. This may help to avoid injury to the chorda tympani nerve during posterior tympanotomy, and make it easier to insert the electrode array during CI by creating a large enough posterior tympanotomy to avoid injury to the facial nerve, which can cause immediate or delayed facial palsy.     

Surgical anatomy of the styloid muscles and the extracranial glossopharyngeal nerve

Purpose

The purpose of the study was to determine the relationships between the extracranial glossopharyngeal (IX) nerve and the muscles of the styloid diaphragm. In humans, the IX nerve is a hidden retrostyloid nerve which plays a critical role notably in swallowing and has to be preserved during infratemporal fossa and parapharyngeal spaces surgical procedures.

Method

In ten adult heads from cadavers (20 sides) fixed in formalin, dissection of the extracranial IX nerve was performed under operating microscope with special attention given to the relationships between this nerve and the styloid muscles of the styloid diaphragm. The three styloid muscles delimit three triangular intermuscular intervals which were each thoroughly explored. Different osseous landmarks were investigated for easy nerve location.

Results

The styloid process (SP) is the main superior osseous landmark for the three muscles of the styloid diaphragm. The stylohyoid muscle (SHM) is anteromedially located to the posterior belly of the digastric muscle. The styloglossus muscle (SGM) is medial and anterior to the SHM. The stylopharyngeal muscle (SPM) is the most vertical and medial of the three styloid muscles. It courses from the medial surface of the SP in a deep plane hidden between the SHM and the SGM. The extracranial IX nerve turns around the SPM superiorly with a vertical segment posterior to the SPM and inferiorly with a horizontal segment lateral to the SPM. The meeting point of the two segments of the IX nerve is about 10 mm anteriorly located from the transverse process of the atlas. The external carotid artery and some of its branches lie in contact with the lateral side of the IX nerve.

Conclusion

Such relationships between the extracranial IX nerve, the styloid muscles and the transverse process of the atlas should be appreciated by clinician who treats patients with stylohyoid complex syndromes and by the surgeon for the parapharyngeal spaces approach.     

Motor branching patterns of the ulnar nerve in the forearms of fetal cadavers

Purpose

The aim of this study was to investigate the branches of the ulnar nerve given to forearm muscles [flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP)] and typing of ulnar nerve according to distribution of these branches to the muscles.

Methods

From the collection of Anatomy Department Laboratory, Faculty of Medicine, Suleyman Demirel University, 116 upper limbs of fetuses showing no external anomaly and aging between 12th and 40th weeks of pregnancy, were included in this study for anatomical dissection. Parameters about the branching of fetal ulnar nerve were set as follows: branch/branches to FCU muscle and branch/branches to FDP muscle.

Results

Ulnar nerve was typed according to number, sequence, and distribution of motor branches of ulnar nerve. As a result of this typing, eight type branching model of ulnar nerve was confirmed.

Conclusions

Our study is critically important for implementing successful surgical interventions and minimizing complications especially in ulnar nerve and forearm muscles surgery also in nerve replacement on this area.     

Anatomical and CT angiographic study of superior gluteal neurovascular pedicle: implications for hip surgery

Purpose

To identify the site of incision with the lowest risk of injury of the superior gluteal neurovascular pedicle in the total hip arthroplasty with Hardinge’s direct lateral approach.

Methods

Eight fresh donated bodies were dissected and the branches of the superior gluteal nerve (SGN) and superior gluteal artery (SGA) were dissected. The distance between the SGA and the apex of greater trochanter (GT) was also evaluated in vivo in 29 patients by CT angiography.

Results

We observed 12 spray pattern and 4 transverse neural trunk pattern of the SGN. In all cases the nerve runs inferiorly to the artery, with a mean distance of 0.5 cm. At the CT angiography the average distance between the main branch of SGA and the GT was 5.2 cm, indicating a mean distance of 4.7 cm from the SGN to the GT. Terminal branches of SGA are found until 2.7 cm from GT.

Conclusions

This study analyzed the relationships between superior gluteal neurovascular pedicle and the GT in vivo (considering also the muscular tone), showing that during direct lateral access a safe area of 4.7 cm exists from the GT to the SGN and of 3.5 cm to its lower rami.     

面神经分支的表盘定位及临床意义

目的：研究面神经分支的行程和分布及在外科手术中的意义。方法：用表盘在15个（30侧）人头部标本上进行面神经各分支的定位观察。结果：面神经各分支在表盘中位置较固定。左颞支位于11～12点间13例（86．7％），右支10例（66．7％）。左颧支位于10～11点间10例（66．7％），右支9例（60％）。左上颊支位于9～10点间12例（80％），右支14例（93％）。左下颊支位于8～9点间13例（86．7％），右支11例（73％）。左右下颌缘支位于6～7点间各有15例（100％）。结论：利用表盘对面神经各分支进行定位更具有可预见性，其结果对腮腺咬肌区解剖和外科手术寻找面神经分支具有参考价值。     

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.     

Variations in the branching pattern of posterior division of mandibular nerve: a case report

Purpose

Abnormal communications among the branches of mandibular nerve especially the posterior division are significant due to various procedures undertaken in this region. These variations are worth reporting as they pose serious implications in several interventions in this region, and may even lead to false diagnosis.

Methods

During routine dissection, the mandibular nerve and its branches were dissected in the infratemporal fossa. The branches from the posterior division of the mandibular nerve namely the inferior alveolar and auriculotemporal nerves were carefully dissected, and their abnormal branching pattern was noted.

Results

There was a communicating branch between left inferior alveolar and auriculotemporal nerve. There was also a variant recurrent branch from the left inferior alveolar nerve that supplied the lateral pterygoid muscle.

Conclusions

Such variant branches and communications between the branches of mandibular nerve as seen in this case have an embryological basis and are clinically important in this region especially for dental surgeries and anesthesia.     

Is the high submandibular transmasseteric approach to the mandibular condyle safe for the inferior buccal branch?

Purpose  

There are basically 3 main approaches for extra-articular mandibular condyle fractures: low cervical, retromandibular and preauricular. These include a risk of facial palsy affecting the marginal mandibular branch. We use a high submandibular transmasseteric approach featuring masseter section 10–20 mm above the mandibular basilar edge. Our null hypothesis was that both the marginal mandibular and the inferior buccal branches are not more at risk than in other surgical approaches.     

Can palmar creases serve as landmarks for the deeper neuro-vascular structures?

Purpose

The aim of this study was the examination of the superficial anatomy of palmar creases and their relation to deeper neuro-vascular structures.

Methods

Four creases: distal wrist flexion crease, thenar crease, proximal palmar crease and distal palmar crease were evaluated with reference to the following structures: palmar cutaneous branch of median nerve, palmar cutaneous branch of ulnar nerve, the nerve of Henle, transverse palmar branches from ulnar nerve, recurrent motor branch of median nerve, radial proper palmar digital nerve to the index and the ulnar proper palmar digital nerve to the thumb, Berrettini’s communicating branch, ulnar nerve and artery, superficial palmar arch. We performed dissections of 20 cadaveric upper limbs derived from a homogenous Caucasian group. In our study we measured the location of surgically important structures with reference to palmar skin creases.

Results

Among the other observations we noticed that the palmar cutaneous branches of the median and ulnar nerves were located at least 0.5 cm away from the thenar crease. The superficial palmar arch was found between the thenar and proximal palmar crease and never crossed the proximal or distal palmar creases.

Conclusions

These anatomical dissections will provide reference material for further ultrasound studies on the arrangements of neuro-vascular structures in reference to superficial palmar creases.     

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.     

Unique distribution by the peroneal nerves: a case report

Purpose

Among the branches of common peroneal nerve, the superficial peroneal provides cutaneous innervation to major part of the dorsum of the foot and deep peroneal nerve supplies the skin over the first interdigital cleft region.

Methods

The present rare case was observed during routine dissection of leg for undergraduate students, in a 52-year-old male, formalin fixed cadaver.

Results

The superficial peroneal nerve provided solely motor branches to peroneus longus and brevis, whereas cutaneous branches were provided by deep peroneal nerve. In the lower one-third of the leg deep peroneal nerve divided into medial and lateral branches. The medial branch supplied tibialis anterior and the lateral branch supplied skin of medial three and half toes. Moreover, the sural nerve supplied the skin of lateral one and a half toes.

Conclusion

Awareness of this type of variations in the course of nerves helps to alert the surgeons when there are complaints of atypical or unique pain in that particular region.     

Uncommon trajectory variations of the mandibular canal and of the mandibular incisive canal: case report

Purpose

This paper aims to report and discuss a case in which unusual anatomical variations were observed in the mandibular canal (MC) and the mandibular incisive canal (MIC) in a same patient.

Materials and methods

A 49-year-old healthy female was referred for mandibular dental implant placement. Panoramic radiography and cone beam computed tomography (CBCT) were performed. Cross-sections, axial, coronal, panoramic reconstructions and volume rendering were obtained.

Results

The panoramic radiograph did not show any evidence of abnormality. CBCT showed a bifid MC on the right side. It extended to the buccal cortex, exteriorized for 6 mm and returned to its conventional trajectory to reach the mental foramen. On the left side, the MIC initially followed its normal trajectory for 4 mm but, in the canine region, it also extended to the buccal cortex and exteriorized.

Conclusion

The advent of CBCT in Dentistry allowed a greater accuracy in the diagnosis of anatomical variations in the jaws, preventing injury to the neurovascular bundle and enabling an adequate surgical planning in the region.     

Anatomical variations between the sciatic nerve and the piriformis muscle: a contribution to surgical anatomy in piriformis syndrome

Purpose

To detect the variable relationship between sciatic nerve and piriformis muscle and make surgeons aware of certain anatomical features of each variation that may be useful for the surgical treatment of the piriformis syndrome.

Methods

The gluteal region of 147 Caucasian cadavers (294 limbs) was dissected. The anatomical relationship between the sciatic nerve and the piriformis muscle was recorded and classified according to the Beaton and Anson classification. The literature was reviewed to summarize the incidence of each variation.

Results

The sciatic nerve and piriformis muscle relationship followed the typical anatomical pattern in 275 limbs (93.6 %). In 12 limbs (4.1 %) the common peroneal nerve passed through and the tibial nerve below a double piriformis. In one limb (0.3 %) the common peroneal nerve coursed superior and the tibial nerve below the piriformis. In one limb (0.3 %) both nerves penetrated the piriformis. In one limb (0.3 %) both nerves passed above the piriformis. Four limbs (1.4 %) presented non-classified anatomical variations. When a double piriformis muscle was present, two different arrangements of the two heads were observed.

Conclusions

Anatomical variations of the sciatic nerve around the piriformis muscle were present in 6.4 % of the limbs examined. When dissection of the entire piriformis is necessary for adequate sciatic nerve decompression, the surgeon should explore for the possible existence of a second tendon, which may be found either inferior or deep to the first one. Some rare, unclassified variations of the sciatic nerve should be expected during surgical intervention of the region.     

Branching patterns and localization of the common fibular (peroneal) nerve: an anatomical basis for planning safe surgical approaches

Purpose

Given the severity and incidence of injury to the common fibular (peroneal) nerve (CFN), there is a need to further clarify its anatomical location and branching patterns. This project attempts to consolidate current anatomical understanding of this nerve and provide physicians with reproducible measurements regarding the CFN and its branches.

Methods

Dissections were performed on 50 specimens (28 cadavers), both fresh and preserved. The CFN was dissected from its emergence from the fibular tunnel to its anterior tibial recurrent nerve (ATRN), superficial fibular nerve (SFN), and deep fibular nerve (DFN) branches. The CFN branching patterns were assessed and all variations were categorized into four types.

Results

Several significant relationships were identified between observable traits and key anatomical characteristics of the CFN. A significant correlation was found between fibular length and distance from the tip of the fibula to the DFN/ATRN branch, as well as between fibular length and distance from the tibial tuberosity to the SFN/DFN and DFN/ATRN branches. An association was identified between length of exposed sub-cutaneous CFN and height. Thickness of the biceps femoris tendon correlated significantly with BMI.

Conclusions

These findings allow physicians to better assess a patient’s individual CFN anatomy based on correlations with measureable physical traits and will contribute to anatomic education and successful completion of various surgical, anesthetic, and physical therapy procedures.