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Fibers of the facial muscles occasionally extend, cross the midline, and connect to surrounding structures on the contralateral side, perhaps enabling the mouth to make more delicate movements and generate more facial expressions. This case report describes a variant in which the extended fibers of the mentalis crossed the midline and indicates the relationship of these fibers to the surrounding structures. Some of the deepest fibers of the mentalis descended inferomedially and crossed transversely just below the chin prominence to attach to the periosteum of the mandible on the contralateral side. The variation presented in this study shed light on the interactions of the mentalis with the surrounding muscles.

Lower third molar removal is the most commonly performed dental surgical procedure. Nevertheless, it is difficult to ensure that all the informed consent forms given to patients are based on the best evidence as many newer publications could change the conclusions of previous research. Therefore, the goal of this review article is to cover existing meta-analyses, randomized control trials, and related articles in order to collect data for improved and more current informed consent.

While palsy of the L5 nerve root due to stretch injury is a known complication in complex lumbosacral spine surgery, the underlying pathophysiology remains unclear. The goal of this cadaveric study was to quantify movement of the L5 nerve root during flexion/extension of the hip and lower lumbar spine. Five fresh-frozen human cadavers were dissected on both sides to expose the lumbar vertebral bodies and the L5 nerve roots. Movement of the L5 nerve root was tested during flexion and extension of the hip and lower lumbar spine. Four steps were undertaken to characterize these movements: (1) removal of the bilateral psoas muscles, (2) removal of the lumbar vertebral bodies including the transforaminal ligaments from L3 to L5, (3) opening and removing the dura mater laterally to visualize the rootlets, and (4) removal of remaining soft tissue surrounding the L5 nerve root. Two metal bars were inserted into the sacral body at the level of S1 as fixed landmarks. The tips of these bars were connected to make a line for the ruler that was used to measure movement of the L5 nerve roots. Movement was regarded as measurable when there was an L5 nerve excursion of at least 1 mm. The mean age at death was 86.6 years (range 68–89 years). None of the four steps revealed any measurable movement after flexion/extension of the hip and lower lumbar spine on either side (

The facial muscles have significant roles for vocalization, feeding, and facial expression in both human and non-human primates. Of these, the anatomy of the incisivus labii superioris (ILS) and incisivus labii inferioris (ILI), which are considered as the accessory bundle of the orbicularis oris (OO) in humans, has rarely been documented in the literature. Our current understanding of the function of the ILS and ILI is that they probably retract the upper and lower lips. Also, there is no account of these muscles in non-human primates in the current literature. The aim of this study was to reveal the ILS and ILI in non-human primates. Five Macaca fascicularis, one Macaca fuscata, one Macaca fuscata yakui, and one Pan troglodytes were dissected. Seven formalin-fixed cadavers and one fresh cadaver were included. Both the ILS and ILI were observed in all specimens. The ILS originated from the incisive fossa of the maxilla and inserted into the OO. The mentalis (MT) and ILI arose from the incisive fossa of the mandible and inserted into the OO and the skin of the chin area. The MT and ILI in the P. troglodytes examined were thicker than in the other three non-human species, and the ILS and ILI in the three macaques were similar in shape to those of humans. The difference of these muscles may result in different functions of the lip such as during vocalization, feeding, and facial expression.

The ansa cervicalis is an important nerve of the cervical plexus. Knowledge of its anatomy can prevent patient complications.

Study Design: In vitro biomechanical study. Objective: The transverse ligament is the strongest ligament of the craniocervical junction and plays a critical role in atlanto-axial stability. The goal of this cadaveric study, and the subsequent study (part II), was to reevaluate the force required for the transverse ligament and alar ligament to fail in a more physiological biomechanical model in elderly specimens. Methods: Twelve C1-2 specimens were harvested from fresh-frozen Caucasian cadavers with a mean age at death of 81 years (range 68-89 years). Only the transverse ligament was preserved, and the bony C1-2 complex was left intact. The dens was pulled away from the anterior arch of C1 using a strength test machine that applies controlled increasing force. After testing, the axis was split in half to check for hidden pathologies and osteoporosis. The differences in the failure force between sex and age groups (group 1: 80 years) were compared. Results: The mean force required for the transverse ligament to fail was 236.2 ± 66 N (range 132-326 N). All but 2 specimens had significant osteoporotic loss of trabecular bone. No significant differences between sex and age groups were found. Conclusions: The transverse ligament’s failure in elderly specimens occurred at an average force of 236 N, which was lower than that reported in the previous literature. The ligament’s failure force in younger patients differs and may be similar to the findings published to date.

The mental artery is a terminal branch of the inferior alveolar artery arising from the maxillary artery. It often communicates with the submental and inferior labial arteries branching off the facial artery. To our knowledge, few reports have described its anatomy and clinical significance in detail. The aim of this paper was to clarify the anatomy of the mental artery. Ten sides from five embalmed Caucasian cadaveric heads were used. The facial artery was identified at the point passing through a notch for the facial vessels and was traced medially. The mental artery and its anastomoses with other arteries were observed in detail. It was detected on all sides. Fourteen anastomoses were found, eight with the inferior labial artery and six with the submental artery. On one side, the mental artery directly supplied the lower lip with no anastomosis. The inferior labial artery tended to anastomose with the mental artery superior to the mental foramen and was likely to anastomose with the submental artery anterior to the mental foramen. We clarified the detailed anatomy of the mental artery. Our results could provide dentists with information that will help them to make oral surgery safer and more successful.

The ansa cervicalis is a neural loop in the neck formed by connecting the superior root from the cervical spinal nerves (C1-2) and the inferior root descending from C2-C3. It has various anatomical variations and can be an important acknowledgment in specific operations of the neck region. This is a review the anatomy, variations, pathology and clinical applications of the ansa cervicalis.

The frontal nerve is the largest branch of the ophthalmic nerve. This nerve gives rise to two terminal branches, the supraorbital (SON) and supratrochlear nerves (STN). To the best of our knowledge, there are no reports describing the detailed proximal course of these nerves while inside the orbit. Therefore, the goal of this study was to clarify the anatomy of the SON and STN inside and at their exit from the orbit. Twenty sides from ten fresh-frozen cadavers were used in this study. Intra and extra orbital dissections were performed to observe the course of the SON and STN. Additionally, measurements of the nerves were made at these locations. The course of the SON and STN inside the orbit was classified into three groups depending on the STN branching pattern from the SON. The group without any branch from the SON and STN inside the orbit was the most common. The exit points of these nerves were via the supraorbital notch, foramen, or neither a notch nor foramen. A distinct fibrous band was consistently found tethering the nerve except in specimens with nerves traversing a bony foramen. The mean diameters of the SON and STN were 1.3 ± 0.2 and 0.7 ± 0.1 mm, respectively. The results of this study further our knowledge of the course and morphology of the SON and STN and might be useful for better understanding and potentially treating some forms of migraine headache due to SON or STN compression/entrapment. Clin. Anat. 33:332-337, 2020. © 2019 Wiley Periodicals, Inc.

The condylar canal and its associated emissary vein serve as vital landmarks during surgical interventions involving skull base surgery. The condylar canal serves to function as a bridge of communication from the intracranial to extracranial space. Variations of the condylar canal are extremely prevalent and can present as either bilateral, unilateral, or completely absent. Anatomical variations of the condylar canal pose as a potential risk to surgeons and radiologist during diagnosis as it could be misinterpreted for a glomus jugular tumor and require surgical intervention when one is not needed. Few literature reviews have articulated the condylar canal and its associated emissary vein through extensive imaging. This present paper aims to further the knowledge of anatomical variations and surgical anatomy involving the condylar canal through high-quality computed tomography (CT) images with cadaveric and dry bone specimens that have been injected with latex to highlight emissary veins arising from the condylar canal.

The genitofemoral nerve is a branch of the lumbar plexus originating from the ventral rami of the first and second lumbar spinal nerves. During routine dissections of this nerve, we have occasionally observed that the genital branch of the genitofemoral nerve gave rise to the femoral branch, and the femoral branch of the genitofemoral nerve gave rise to the genital branch. Therefore, this study aimed to investigate the aforementioned distributions of the genitofemoral nerve in a large number of cadaveric specimens. Twenty-four sides from fourteen fresh-frozen cadavers derived from nine males and five females were used in this study. For proximal branches of the genitofemoral nerve, that is, as they first arise from the genitofemoral nerve, the terms "medial branch" and "lateral branch" were used. For the final distribution, the terms "genital branch" and "femoral branch" were used. On eight sides (33.3%) with nine branches, one or two branch(s) from either the medial or lateral branch became coursed as the femoral or genital branches (five became femoral and four became genital branches). Our study revealed that the distribution of the genitofemoral nerve is more complicated than previously described. The "medial branch" and "lateral branch" that we have used in the present study for describing the proximal branches of the genitofemoral nerve are more practical terms to describe the genitofemoral nerve. Clin. Anat. 32:458-463, 2019. © 2019 Wiley Periodicals, Inc.

Air insufflation has been used for various surgical procedures such as during laparoscopy. We hypothesized that the use of pressurized air might enable cadaveric dissection to differentiate smaller veins better than traditional dissection techniques. In three fresh-frozen cadavers, the inferior vena cava (IVC) and right or left femoral veins were exposed just distal to the inguinal ligament and a needle placed into one of them. Pressurized air was then placed into the cannulated femoral vein using an air compressor. In all specimens, the IVC and most of its tributaries, both left and right sides, were clearly insufflated. When the IVC was traced superiorly by resecting the diaphragm through the caval foramen, the right atrium and ventricle were also found to be dilated. Additionally, venous variants that would have not been obvious without dilatation of the IVC were identified. Air dissection of the venous system in fresh-frozen cadavers aids in anatomical dissection. Such a model might also serve as a surgical training model and teaching tool as it better mimics life-like anatomy and physiology. We term this technique "cadaveric air dissection." Clin. Anat. 32:566-572, 2019. © 2019 Wiley Periodicals, Inc.

Introduction: The superficial anterior atlanto-occipital ligament (SAAOL) is a narrowband located anterior to the anterior atlanto-occipital membrane. Nearly forgotten, it has not been well described in older anatomical textbooks and is missing in the current anatomical literature. As all of the binding structures of the craniocervical junction (CCJ) are important in maintaining stability, this study aims to clarify the anatomy and potential function of the SAAOL. Materials and Methods: The CCJ from ten fresh-frozen cadavers was studied. These specimens were derived from three males and seven females, and the age at death ranged from 57 to 91 years (mean, 79.8 years). The length, width, and thickness of the SAAOL were measured. In five specimens, the force to failure was recorded. Results: The SAAOL was found between the anterior tubercle of the atlas and the occiput and located as central thick fibers in front of the anterior atlanto-occipital membrane in 9 (90%) specimens. In one specimen, the vertical band to the occipital bone did not attach to the anterior tubercle of the atlas, but extended to the anterior aspect of the axis. The mean length, width, and thickness of the SAAOL were 19.8, 6.2, and 0.6 mm, respectively. The force to failure for the ligament was 38.8 N. Conclusion: The SAAOL was a constant structure of the anterior atlanto-occipital joint. This ligament seems to be a secondary stabilizer of the CCJ by limiting the extension of CCJ. Knowledge of this ligament may help in further understanding of craniocervical stability.

The retromolar canal (RMC) and foramen (RMF) are anatomic variants in the retromolar area of the mandible. The purpose of this study was to clarify the relationship between the RMC and RMF and related complications, and to reveal how the RMC could impact the mandibular anatomy using cone-beam computed tomography (CBCT) and panoramic images (PAN). CBCT and PAN images of 50 patients were retrospectively analyzed to investigate the morphology of the RMC and RMF, and their impact on impacted third molar surgery and orthognathic surgery. In PAN images, neither the RMC nor RMF was detected. In CBCT images, the RMCs were detected in 26% (13/50) of the patients. A double RMC was detected on one side of one patient. The diameter of the RMC ranged from 0.8 to 2.9 mm (mean; 1.5 ± 0.6 mm), and the RMF ranged from 0.6 to 2.3 mm (mean; 1.1 ± 0.5 mm). No patients experienced unexpected bleeding. Unilateral postoperative hypoesthesia of the buccal gingiva in the molar region was reported in 6.7% of patients with the RMC. Hypoesthesia of the buccal gingiva in the lower molar region may be the main complication when the RMC is damaged.

The great auricular nerve (GAN) has been used for trigeminal and facial nerve repair and the inferior alveolar nerve (IAN) are often sacrificed during segmental mandibulectomy. To our knowledge, only 1 case report has discussed IAN repair using GAN after segmental mandibulectomy. The goal of this study is to clarify the feasibility of using GAN for IAN repair. Eleven sides from 6 fresh frozen Caucasian cadavers were used for this study. The mean age at the time of death was 82.3 years. A submandibular skin incision was made 2 finger breadths below and parallel to the inferior border of the mandible. The GAN was identified and then the mental foramen was found via extraoral dissection. The buccal cortical bone was removed 5 mm posterior to the mental foramen to the wisdom tooth area. Next, the anteroposterior length of the window was measured. The diameter of the IAN at the first molar tooth area was measured. Finally, the GAN was cut with maximum available length to compare to the length of the window in the mandible. The anteroposterior length of the window and diameter of the IAN ranged from 23.1 to 31.2 mm and 1.2 to 2.1 mm, respectively. The length of the available GAN was longer than the ipsilateral bony window of the mandible on all sides. This study might encourage surgeons to consider a new way to treat patients who undergo segmental resection of the mandible with surgical neck dissection with injury to their IAN.

The Stafne bone cavity (SBC), also called the static bone cavity, salivary inclusion cyst, latent cyst, and lingual bone defect is an asymptomatic bony defect that is commonly located inferior to the mandibular canal and slightly above the inferior border of the mandible. It is rare to see the actual bony defect in the cadaver because of its relatively low incidence of 0.1% to 6.06%. We report a unilateral SBC found in a 76-year-old at death male Caucasian cadaver and involving the right mandible. The SBC was oval in shape with a smooth surface and measured 10.8×6.0 mm. The SBC was continuous with the right mylohyoid groove. Since actual photographs of the SBC are lacking in the literature, this report might provide additional insight for better understanding the SBC.

The femoral nerve is the largest branch of the lumbar plexus. It is normally composed of the ventral rami of spinal nerves L2 to L4. The psoas major has proximal attachments onto the T12 to L5 vertebrae and related intervertebral discs, fuses with the iliacus deep to the inguinal ligament and then attaches onto the lesser trochanter of the femur. Normally, the anatomical relationship is that the femoral nerve is located between the iliacus and psoas major. Herein, we report a case of the psoas quartus muscle related to several splits of the femoral nerve within the pelvis. Although the embryology for this is unclear, surgeons and physicians should be aware of such anatomical variants in order to better understand pain and entrapment syndromes and during surgical maneuvers in this region such as lateral transpsoas approaches to the lumbar spine.

The lingual nerve (LN) is a branch of the mandibular division of the trigeminal nerve, and its injury is one of the major complications during oral surgery. This study aims to investigate the anatomy of the LN in the lower third molar area. Twenty sides from ten fresh-frozen adult cadaveric Caucasian heads were examined to measure the diameter of the LN. The mean diameter of the LN was 2.20±0.37 mm (range, 1.61-2.95 mm). There were no statistically significant differences in the measurements between sexes, sides, or tooth status (dentulous or edentulous). Understanding the anatomical features of the LN is essential for performing any surgical procedure in the oral region.

Background Ligaments of the craniocervical junction play a critical role in stabilizing this region. Gerber's ligament has more or less been forgotten and, to our knowledge, never studied. Methods Dissection of the craniocervical junction was performed in 15 fresh frozen cadavers. In the prone position, the posterior elements of the upper cervical vertebrae and occiput were removed. After removing the contents of the spinal canal and posterior cranial fossa, the dura mater and tectorial membrane were reflected. The superior band of the cruciform ligament was reflected. When Gerber's ligament was identified, its attachments and morphometry were recorded. Lastly, Gerber's ligament was observed while range of motion of the craniocervical junction was performed. Results Gerber's ligament was identified in 7 specimens (46.7%). This structure arose anteriorly from the junction of the superior band and transverse part of the cruciform ligament. Gerber's ligament was always found to be just deep to the superior band of the cruciform ligament but traveled more anteriorly to attach onto the posterior aspect of the dens approaching, but not attaching onto, its apex. Mean length was 11 mm, and mean width was 7 mm. Thickness of the ligament was 0.5–1.1 mm. The ligament was found to become taut with minimal rotation of the atlantoaxial joint and extension of the craniocervical junction. Conclusions A good understanding of all ligaments of the craniocervical junction is important to surgeons and physicians treating patients with injury to the upper cervical spine.

Cone-beam computed tomography gives us much useful morphological information about the mandibular bone. Many studies of the mandible include findings from this technique. However, there have been no endoscopic studies of the mandible. Sixteen sides of eight dry mandibles resected from cadavers (age range 38-83 years) were examined by endoscopy. The head of the endoscope was 2.0 mm in diameter. We examined the mandibular foramen, lingula, mylohyoid groove, and mandibular canal. The mylohyoid grooves showed variations such as double grooves and canals. The mandibular lingula was located superior or medial to the the mandibular foramen. In a single case, the medial wall inside the mandibular canal showed a porous surface. The retromolar canal was observed in three sides. None of the images in the present study have been seen in other studies. Observation of the retromolar canal from the mandibular canal in particular can help dental students as well as oral and maxillofacial surgeons to understand its morphology. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1875-1880, 2017. © 2017 Wiley Periodicals, Inc.

The depressor septi nasi is a facial muscle with many different descriptions of its anatomy. Therefore, the aim of this study was to clarify the relationship of the depressor septi nasi, incisivus labii superioris, and surrounding structures.Twenty sides from 10 fresh-frozen cadaveric heads were used in this study. The depressor septi nasi and incisivus labii superioris were dissected intraorally and extraorally, and the relationship with surrounding structures was observed.Eighteen of 20 sides had a depressor septi nasi. When present, the depressor septi nasi originated from the orbicularis oris above the central incisor and the medial portion of the inferior part of the incisivus labii superioris and inserted into the base of the medial crus of the major alar cartilage and nasal septum. These three muscles were three-dimensionally fused at the insertion point of the depressor septi nasi. There was no specimen where the depressor septi nasi originated directly from the maxilla. The depressor septi nasi runs obliquely from the nasal septum and the base of the medial crus of the major alar cartilage to the orbicularis oris and inferior part of the incisivus labii superioris.A better understanding of the depressor septi nasi, incisivus labii superioris, and surrounding structures might be important during various surgical techniques, especially rhinoplasty.

Purpose Neurosensory disturbance of the infraorbital nerve is one of the many complications of the Le Fort osteotomy. An accessory infraorbital foramen (AIOF) can be one reason for such complications. Therefore, the purpose of the present study was to elucidate the distribution of the accessory infraorbital nerve (AION) arising from the AIOF. Materials and Methods We dissected 60 sides from 30 fresh-frozen cadaveric heads. Results An AIOF was found in 36.7% of the heads examined. When an AIOF was detected, the nerve was traced distally and proximally. The mean horizontal and vertical diameters of the AIOF were 1.64 ± 0.88 and 1.75 ± 0.87 mm, respectively. The largest AIOF was 3.42 × 3.79 mm. All AIOFs were located medial to the infraorbital foramen. Most of the AIONs (87.5%) had branches to the external nose. Conclusions The AION should always be remembered by surgeons to allow for improved outcomes and better understanding of the complications such as those occurring after Le Fort osteotomy.

Objective The sacral dorsal rami form the posterior sacrococcygeal plexus (PSCP), which has been scantly studied. This study's goal was to clarify the PSCP s detailed anatomy and discuss its clinical relevance. Methods Ten sides of 5 fresh-frozen cadavers were dissected for this research. After the muscles covering the sacrum were removed, the PSCP was identified and traced under the operating microscope until the entire plexus was exposed. The contributions to this plexus and its relations to surrounding anatomic structures were recorded. Results The PSCP was found on all sides and was composed of a medial trunk (MT), communicating branches, and a lateral trunk. Each sacral dorsal ramus's MT formed a series of loops created by adjacent sacral dorsal rami placed between the transverse tubercles and the posterior sacral foramina. The MT, communicating branches, and lateral trunk demonstrated potential entrapment sites. Conclusions To our knowledge, this is the first anatomic study that provides detailed images that indicate 3 potential sites where surrounding structures could entrap the PSCP. Knowledge of its detailed anatomy might help in better understanding low-back pain, targeting pain sources and guide spine surgeons for avoiding injury to these nerves.

The posterior auricular nerve (PAN) is the first branch of the facial nerve after it leaves the stylomastoid foramen. The literature describing the anatomy of the PAN is very sparse. Therefore, the purpose of this study was to clarify the detailed anatomical features of the PAN and consider its clinical and surgical applications. The authors examined 10 sides from 6 fresh frozen adult cadaveric Caucasian heads. The PAN was observed as the first branch of the facial nerve in all specimens. During the dissection of the PAN, the posterior auricular artery was constantly near the PAN. Moreover, the PAN was located under the investing layer of deep cervical facia covering the sternocleidomastoid and mastoid process in all specimens. The diameter of the PAN was 0.82 ± 0.21 mm (range from 0.55 to 1.21). The distance from the stylomastoid foramen to where the PAN branched from the facial nerve was 0.40 ± 1.25 mm (range from 0 to 4.35). The distance from the location of this branching point of the PAN to the entering point of the PAN to any muscles was 28.03 ± 5.51 mm (range from 19.71 to 38.75). Understanding the anatomical features of the PAN is essential for performing surgical procedures in this region.

Neurotrophic keratitis is a rare corneal disease that is challenging to treat. Corneal neurotization (CN) is among the developing treatments that uses the supraorbital (SON) or supratrochlear (STN) nerve as a donor. Therefore, the goal of this study was to provide the detailed anatomy of these nerves and clarify their feasibility as donors for ipsilateral CN. Both sides of 10 fresh-frozen cadavers were used in this study, and the SON and STN were dissected using a microscope intra- and extraorbitally. The topographic data between the exit points of these nerves and the medial and lateral angle of the orbit were measured, and nerve rotation of these nerves toward the ipsilateral cornea were attempted. The SON and STN were found on 19 of 20 sides. The vertical and horizontal distances between the exit point of the SON and that of the STN, were 7.3±2.1 mm (vertical) and 4.5±2.3 mm, respectively. The mean linear distances between the medial angle and the exit points of each were 22.2±3.0 mm and 14.5±1.9 mm, respectively, and the mean linear distances between the lateral angle and the exit points of the SON and STN were 34.0±2.7 mm and 36.9±2.5 mm, respectively. These nerves rotated ipsilaterally toward the center of the orbit easily. A better understanding of the anatomy of these nerves can contribute to the development and improvement of ipsilateral CN.

An accessory foramen around the mandibular foramen is called an accessory mandibular foramen (AMF). The clinical anatomy of the AMF has not been well described. The aim of this study was to reveal the clinical anatomy of the AMF for a better understanding of its implication during ramus surgeries. Twenty-two sides fresh-frozen cadaveric heads with a mean age of 76.2 ± 14.4 years at death underwent dissection. The neurovascular bundles passing through the AMF were observed. Additionally, a hemi-face of a latex injected embalmed cadaver was dissected medially to laterally and the neurovascular bundles of the AMF investigated. A unilateral foramen, bilateral foramina, and absence of foramina were found in 45.4%, 18.2%, and 36.4%, respectively. The origin of the neurovascular bundle entering the AMF was a branch of the maxillary artery in 20% and a tributary of the inferior alveolar vein in 80%. In the latex embalmed cadaver, the AMF was found to contain a branch from the maxillary artery and a tributary of the maxillary vein. Given the practical meaning of the specific AMF located in the operative field of the ramus osteotomy, we suggest these be named “foramina for ramus osteotomy.”

The ansa cervicalis is located around the carotid sheath and forms a neural loop, which consists of superior and inferior roots. It innervates the infrahyoid muscles. Anatomical variations of the superior root of the ansa cervicalis are uncommon. Herein, we present an extremely rare case of the superior root of the ansa cervicalis arising both from the hypoglossal and vagus nerves.

In the original publication, the given name and family name of the last author was incorrectly published. The correct given name and family name should be "R. Shane" and "Tubbs".

The carotid sinus nerve branches off the glossopharyngeal nerve just after its appearance from the jugular foramen, descends along the internal carotid artery, and enters the carotid sinus. There have been many studies of the pathway and the course of the carotid sinus nerve and its communications with surrounding nerves. The intercommunication is exceedingly complicated. Acknowledgment of its anatomic diversity can be important in specific operations dealing with this area. Herein we review the anatomy, variations, pathology, and clinical applications of the carotid sinus nerve.

Objectives The current study aims to increase awareness of the falciform ligament and its anatomical and surgical relationships, for the benefit of the neurosurgeon. Patinents and Methods Twenty-four sides from twelve Caucasian cadaveric heads (all fresh-frozen) were used in this study. The length and thickness of the falciform ligament were recorded. The relationship of the falciform ligament to the optic nerve was also observed and documented. Finally, the force needed to avulse the falciform ligament was recorded. Results In all specimens, the ligament was identified as a continuation of the outer dural layer, forming a roof at the entrance of the optic canal. The mean medial-to-lateral length, anteroposterior length, and thickness of the falciform ligament were 7.97 mm, 2.12 mm, and 0.26 mm, respectively. The mean distance from the medial attachment of the ligament to the midline was 5.54 mm. For the undersurface of the falciform ligament, the optic nerve occupied the middle third in 50.0 %, the lateral third in 44.4 %, and the medial third in 5.6 % of sides. The mean optic nerve diameter at the entrance of the optic canal was 4.20 mm. The mean failure force was 2.47 N. Conclusion The anatomical measurements and relationships provided in this description of the falciform ligament serve as a tool for surgery selection and planning, as well as an aid to improving microsurgical techniques, with the final goal being better patient outcomes.

Objective The middle cluneal nerves (MCNs) are stated to arise from the sacral dorsal rami of S1 to S3 and supply the gluteal skin, but their detailed anatomy is unclear and often variably depicted and described. Therefore, the goal of this study was to revisit the anatomy of the MCNs and provide a clearer picture of their morphology. Methods Five fresh-frozen Caucasian cadavers (10 sides) (2 men and 3 women) were dissected for this study. The sacral dorsal rami from each posterior sacral foramen were identified and traced laterally to identify the MCNs. The contribution, pathway, and distribution of the MCNs were investigated. Results Each sacral dorsal ramus joined to form the posterior sacrococcygeal plexus. A total of 25 MCNs were identified. The MCNs were formed by the sacral dorsal rami of S1-2 in 48% (12/25), S1-3 in 4% (1/25), S1-4 in 20% (5/25), S2-3 in 8% (2/25), and S2-4 in 20% (5/25). The MCNs pierced the gluteus maximus by 2 different pathways and supplied the gluteal skin or the gluteus maximus muscle. Conclusions We clarified the anatomy and variations of the MCNs and revisited its current nomenclature. Such knowledge might improve diagnoses and invasive procedure outcomes in patients with pathology in the region of the MCNs.

Most of the studies of the mandible's anatomical variations have presented the authors' speculations, and only a limited number has provided evidence that demonstrated the actual complications injury to the variant structures caused. To our knowledge, no study has evaluated the risks associated with these variant anatomical structures' injury. We reviewed articles that described clinical cases of the injury to, and anatomical studies of, three anatomical variants of the mandible-the accessory mental, lingual, and retromolar foramina-with which dentists are relatively familiar and that are mentioned often in the context of implant and third molar surgeries, to describe risk assessment methods with which to evaluate potential complications preoperatively. Only a limited number of the clinical reports of injury to the mandible's accessory foramina were available. The potential severe complication of injury of the accessory mental foramen (AMF) is sensory disturbance of the lower lip. Risk of neurosensory disturbance of lower lip can be assessed by AMF/MF ratio and positional relations to the MF. Potential severe complication of injury of the lingual foramen is bleeding and hemorrhage in the oral cavity's floor. Risk of bleeding can be assessed by diameter and positional relation between the mental spine/mylohyoid line. A risk assessment of the retromolar foramen could not be made because of inadequate data. We hope the risk assessments suggested will encourage dentists to predict intraoperative/postoperative complications caused by damaging the mandible's accessory foramina. Clin. Anat. 32:672-677, 2019. © 2019 Wiley Periodicals, Inc.

Objective Nerve repair and repositioning are procedures for treating and avoiding injury to the inferior alveolar nerve during oral and maxillofacial surgery. The present study aimed to examine how the mobility of the inferior alveolar neurovascular bundle (IAB) changes with or without removing the bone around the mental foramen (MF). Study Design Six fresh-frozen cadavers (11 sides) were dissected in this study. Osteotomy in the buccal cortical bone was performed from 5 mm posterior to the MF to the distal edge of the second molar with a high-speed drill and osteotome. Next, the distance from the lateral surface of the buccal cortical bone to the retracted IAB was measured with and without removing the bone around the MF. Results The distance from the lateral surface of the buccal cortical bone to the retracted IAB without removing the bone around the MF was 0 mm on all sides. After removing the bone, the mean distance changed by 4.71 ± 1.41 mm (range 2.83–7.90). There was no statistically significant difference between the right and left sides. Conclusions The results of this study support removing the bone around the MF for increased mobility of the IAB.

Purpose The digastric branch is the second branch of the facial nerve after emerging from the stylomastoid foramen. To the best of our knowledge, few detailed anatomic studies of the digastric branch have been performed. Moreover, the use of the digastric branch for facial nerve reanimation has not been explored. Materials and Methods Nine sides of 5 fresh frozen cadavers were dissected for anatomic observation of the digastric branch and exploration of the feasibility of the digastric branch as a donor for facial nerve reanimation. The facial nerve trunk (FNT) and digastric branch were readily found by dissection using the tragal cartilage and tragal pointer as landmarks. The length and diameter of the digastric branch were measured, and the digastric branch was repositioned anterior to the FNT and the 2 major extracranial divisions of the FNT. Results On all sides, the digastric branch existed as a single branch and innervated only the posterior belly of the digastric muscle. The available length of the digastric branch was 13.28 ± 2.47 mm (range, 8.87 to 16.38 mm), and the mean diameter was 0.98 ± 0.31 mm (range, 0.64 to 1.64 mm). The digastric branch reached the FNT and its 2 major divisions without tension. Conclusions The results of the present study have clarified the anatomic findings of the digastric branch in detail and the feasibility of using the digastric branch as a potential donor for facial nerve reanimation. The surgeon might consider the use of the digastric branch as a feasible donor for facial nerve reanimation based on the findings from our cadaveric study.

The retromolar region is a triangular area bounded by temporal crest on the medial side, anterior border of ramus on the lateral side, and the posterior portion of the third molar area. The deeper fibers of the temporalis muscle attach to the upper two-thirds of the medial boundary of the retromolar fossa. The superficial fibers of the temporalis muscle attach to the upper one-third of the lateral boundary of the retromolar triangle. The buccal nerve and artery cross the middle portion of the medial border, while the lingual nerve crosses the inferior portion. The retromolar foramen also consists of clinically relevant vessels and nerves. The posterior portion of the third molar attaches to the pterygomandibular raphe, where the buccinator and superior pharyngeal constrictor muscle attach anteriorly and posteriorly. It is implicated clinically in procedures such as third molar extractions, periodontal distal wedge procedures, and sagittal split osteotomy. Furthermore, the retromolar trigone marks an aggressive type of oral cancer.

The tongue is dynamically related to various oral functions such as speech, breathing, swallowing, and breastfeeding. It is guided forward by the lingual frenum during growth. The frenum is a single fold that tenses between the sublingual surface and the lingual alveolar mucosa and consists of connective tissue covered by the mucosa without major nerves or vessels. Structural disorders and abnormal attachment of the lingual frenum can result in ankyloglossia, a congenital oral anomaly commonly known as “tongue-tie.” Severe ankyloglossia can entail various functional disorders of the tongue. The sublingual glands located in the sublingual space sometimes induce mucoceles. In this chapter, the normal anatomy and variations of the lingual frenum and sublingual surface are reviewed and their clinical relevance is discussed.

We present a rare anatomical variation in which an additional incisive canal was observed during the routine dissection of the palatal region in a cadaver. The diameter of the incisive and additional incisive canals measured 4.59 mm and 0.91 mm, respectively. Even though this variation is rare, oral surgeons should be aware of such anatomical variations for a better understanding.

The lingual nerve is a branch of the mandibular division of the trigeminal nerve. It descends medial and anterior to the inferior alveolar nerve through the pterygomandibular space, runs by the lingual plate and lingual crest at the lower third molar closely, and supplies sensory fibers to the anterior two-thirds of the tongue. Therefore, injury of this nerve is occasionally induced by wisdom tooth extraction and could lead to paralysis of the tongue. The inferior alveolar nerve gives rise to the nerve to mylohyoid just before entering the mandibular foramen, which supplies the mylohyoid and anterior belly of the digastric muscle. We present an extremely rare anatomical variation where the nerve to mylohyoid arose from the lingual nerve near the submandibular duct during routine oral dissection.

The inferior alveolar nerve block (IANB) procedure delivers anesthetics to the pterygomandibular space through which the lingual nerve (LN) and inferior alveolar nerve (IAN) travel. Injury to the LN has been reported more often than injury to the IAN. However, the number of anatomical studies of LN injury is limited. We aimed to establish evidence by investigating LN and IAN anatomy at the level of the mandibular foramen (MF). Forty-four sides from 22 Caucasian cadaveric heads (16 fresh-frozen and six formalin-fixed cadavers) were used in this study. The LN and IAN were laterally dissected, and the diameter and the distance between the two nerves were measured at the level of the MF. The mean diameters of the LN and IAN were 2.57 mm and 2.53 mm in fresh-frozen specimens and 2.97 mm and 2.93 mm in formalin-fixed specimens, respectively. The mean diameters of the LN and IAN in all the specimens were 2.65 mm and 2.64 mm. The distance between the posterior edge of the LN and anterior edge of the IAN at the level of the MF ranged from 1.62 to 8.36 mm with a mean of 5.33 ± 1.88 mm. These findings could elucidate the risk of LN injury during the IANB procedure.

During routine dissection of the anterior craniocervical junction (CCJ), a variant ligament just anterior to the articular capsule of the atlantooccipital joint was observed. To our knowledge, no literature has previously described this ligament. Therefore, the aim of this study was to clarify the anatomy, incidence, and biomechanics of this undescribed structure of the anterior atlantooccipital joint. Twenty-six sides from 13 fresh-frozen adult cadavers were used for this study and the morphology of the variant ligament examined. When present, its length, width, thickness, and the angle from the midline of the CCJ were measured. The variant ligament identified, when present, is distinct and located anterior to the atlantooccipital joint capsule traveling between the occipital bone and the transverse process of the atlas. The ligament was found on 12 of 26 sides (46.2%). The mean length of the ligament was 32.0 ± 5.5 mm. The ligament became taut with contralateral lateral flexion and the ipsilateral rotation of the atlantooccipital joint. We propose that this ligament may be termed the lateral oblique atlantooccipital ligament. To date, this structure has not been described in any textbooks or reports in the extant medical literature. Although its function is not clear, based on its course and connections, it might function as a secondary stabilizer of the atlantooccipital joint. As the stability of the craniocervical junction is of paramount importance, knowledge of normal and variant anatomical structures in this region is important for the surgeon treating patients with pathology of this region. These slides can be retrieved under Electronic Supplementary Material.

Isolated cleft palate without cleft lip is a rare deformity. Cleft lip and cleft palate can sometimes develop in combination with a syndrome due to genetic causes. Affected patients have morbidity through life from birth and experience comprehensive treatment for such clefts including surgery. It is extremely rare that the untreated clefts are found during routine cadaveric dissection, since many patients have treatment for clefts in developed countries. Herein, we present a case of an untreated incomplete isolated cleft palate on the right side of the maxilla. An oronasal fistula was found in the same location as the missing right maxillary lateral incisor, and the soft palate was considerably intruding into the hard palate but without penetration into the nasal cavity. The right incisivus labii superioris muscle forming the oral vestibule was incompletely torn with two fistulae. An incomplete bony defect was found on the right maxilla without oronasal or oroantral fistula. This paper may contribute to evaluating the disturbed site of the incomplete isolated cleft palate with no treatment.

The incisive canal, also known as the nasopalatine canal, is an interosseous conduit through the anterior maxilla connecting the oral and nasal cavities. Within this canal lies the nasopalatine nerve and the vascular anastomosis between the greater palatine and sphenopalatine arteries. The embryology of the canal has led to interesting theories explaining its function. Efforts have been made to describe the morphometrics of the incisive canal by radiologic evaluation across sex and ethnicities. This paper aims to review the current literature on the embryology, anatomy, and clinical relevance of the incisive canal.

Supratrochlear nerve (STN) is a terminal branch of the frontal nerve arising from the ophthalmic nerve (V1). Compression of the STN by adjacent structures might result in migraine headaches. The aim of this study was to explore the relationship of the STN and trochlea for a better understanding of potential entrapment of the STN. Nineteen orbits from ten fresh-frozen cadaveric heads were dissected. The relationship of the STN and the trochlea was classified into three types: In type I, the STN passed lateral to the trochlea; In type II, the STN passed through the trochlea; In type III, the STN passed medial to the trochlea. Type I was found in 52.6% (10/19 sides), type II was found in 42.1% (8/19 sides), and type III was seen in 3.4% (1/19 sides). In type III, both the STN and infratrochlear nerve were identified as separate branches. The authors propose a new classification of the pathway of the STN based on its relationship with the trochlea. This study might shed light on headaches emanating from this region.

Knowledge of the anatomy and variations of the nerves of the oral cavity is important to surgeons who operate this region. Herein, we report a rare case of a buccal nerve with two distinct roots. The anatomy of this case and its clinical applications is discussed.

A 27-year-old female was referred to our hospital with a chief complaint of removal of an impacted right mandibular third molar. Panoramic radiography showed two small circular radiolucencies on the right mandibular ramus. Computed tomography revealed that one of the radiolucencies was an accessory foramen located lateral to the mandibular ramus, and the other radiolucency was an accessory foramen located medial to the ramus; it was also connected to the mylohyoid groove. Continuity with the mandibular canal was confirmed for both accessory foramina. After explaining the risks of extraction, the patient decided against surgery and the impacted tooth was left in situ. Most patients have at least one or more accessory foramina in the mandible; however, accessory foramina of the lateral aspect of the mandibular ramus have not been reported. The high resolution of cone-beam computed tomography and three-dimensional reconstructed images enable improved detection of accessory foramina. Therefore, additional accessory foramina that are similar to those found in the present case could be found in the future using such imaging modalities.

Introduction The accessory foramina could not be identified on some imaging modalities such as surface-rendered images. The purpose of this study was to investigate the ability of surface-rendered images in detecting these foramina. Materials and methods We analyzed 20 accessory mental foramina (AMF) in nine mandibles removed from cadavers with cone-beam computed tomography (CBCT) and assessed in surface-rendered images. All AMF were divided into three groups depending on their visibility. Results Group 1 included AMF that were clearly visible as foramina, Group 2 were not clearly visible but could be recognized with concave parts, and Group 3 were not visible and the smooth surface of the bone was observed. Group 1 ranged from 1.3 to 5.1 mm2, Group 2 from 0.3 to 3.8 mm2, and Group 3 from 0.2 to 1.1 mm2. A statistically significant difference in the mean size between Groups 1 and 3 was observed. Even if the AMF are smaller (e.g., 1 mm in diameter), they should still be avoided to prevent injury. Conclusions The clinician should be aware that smaller foramina might not be detected on these images.

Purpose Facial nerve paralysis can result in critical complications, including those to the visual, respiratory, and digestive systems. The facial nerve has been reanimated using various nerves, but the posterior auricular nerve (PAN) branching off the facial nerve has not been explored for this purpose. Materials and Methods Ten sides from 6 fresh-frozen adult cadavers were used for dissection of the PAN to explore its potential as a donor for facial nerve reanimation. The facial nerve trunk (FNT) and PAN were consistently and readily identified by deep dissection using the tragal cartilage and tragal pointer as landmarks. The PAN was transected at the point of insertion of its innervated muscles. Its length and diameter were measured, and it was transposed anteriorly to the FNT and its 2 major extracranial divisions. Results The PAN was observed on all sides. Its available length was 27.11 ± 5.02 mm and its mean diameter was 0.85 ± 0.20 mm. In all specimens, the PAN readily reached the FNT and its 2 major divisions without tension. Conclusion No previous study has explored the use of the PAN as a donor for facial nerve reanimation. Based on the present cadaveric study, surgeons might consider it for this purpose.