Lingual nerve revisited-A comprehensive review Part I: Anatomy and variations.

The lingual nerve (LN) is a branch of the mandibular division of the fifth cranial nerve, the trigeminal. It primarily carries sensory fibers from the lingual gingiva, mucous membranes of the floor of the mouth, sublingual gland, and the anterior two-thirds of the tongue. Recent studies have explored and reclassified the five branches of the LN as branches to the isthmus of the fauces, lingual branches, sublingual nerves, posterior branch to the submandibular ganglion, and branches to the sublingual ganglion. The knowledge of the LN anatomy and its variants is clinically relevant to avoid its injury during oral procedures. The objective of this paper is to review the literature on the LN and to describe the anatomy, its course, and its functions.

Radiological assessment of the dissection area in supraomohyoid neck dissection.

PURPOSE: The current supraomohyoid neck dissection (SOHND) is performed above the omohyoid muscle to dissect levels I, II, and III in the levels of cervical lymph nodes. However, the anatomical boundary between levels III and IV is the inferior border of the cricoid cartilage. We investigated the anatomical relationship between the omohyoid muscle and cricoid cartilage using contrast-enhanced CT (CE-CT) images to assess the validity of the current SOHND. METHODS: CE-CT images of the head and neck regions in patients were reviewed. The patients were divided into two groups: "malignant tumors" and "others". The vertebral levels corresponding to the positions of anatomical structures such as the intersection of the omohyoid muscle and internal jugular vein (OM-IJ), and the inferior border of the cricoid cartilage (CC), were recorded. RESULTS: The OM-IJ was located around the seventh cervical to the first thoracic vertebra. There was a significant difference between the malignant tumor and others groups in females (p = 0.036). The CC was located around the sixth to seventh cervical vertebrae. There was a significant sex difference in each group (malignant tumor: p < 0.0001; others: p = 0.008). Both sexes tended to have lower OM-IJ than CC, and females had significantly lower OM-IJ than males. CONCLUSION: This study provides clear anatomical evidence showing the difference between the SOHND dissection area and levels I, II, and III. It could be considered that in most cases SOHND invades level IV, not just levels I, II, and III, especially in female patients.

Lingual nerve revisited-A comprehensive review Part II: Surgery and radiology.

The lingual nerve (LN) is a branch of the mandibular division of the fifth cranial nerve, the trigeminal nerve, arising in the infratemporal fossa. It provides sensory fibers to the mucous membranes of the floor of the mouth, the lingual gingiva, and the anterior two-thirds of the tongue. Although the LN should rarely be encountered during routine and basic oral surgical procedures in daily dental practice, its anatomical location occasionally poses the risk of iatrogenic injury. The purpose of this section is to consider this potential LN injury risk and to educate readers about the anatomy of this nerve and how to treat it.

Revisiting morphology of xiphoid process of the sternum in human: a comprehensive anatomical study.

BACKGROUND: The xiphoid process (XP) in animals such as sheep and rats are well known to have cartilage called xiphoidal cartilage (XC). In humans, the cartilage in the xiphoid process is considered an anatomical variant and is not well understood. The aim of this study was to investigate the morphology of the XP. METHODS: A total of twenty embalmed European descendant cadaveric sterna (aged 52 to 98 years) were used. Transilluminated XPs and midsagittal sections of XPs were used to examine the bone and cartilage. Subsequently, a sagittally-sectioned XP was harvested for histology and stained with Masson's trichrome. The results of the transillumination and histological examinations were compared qualitatively. RESULTS: The dark area visible in transilluminated XPs was consistent with the bony part in the midsagittal XP sections, which contained bone marrow; the bright area was consistent with the cartilage part in the midsagittal XP sections. This was all demonstrated histologically. Most of the XPs (85%) had some portion of cartilage. The XP was classified into four types based on its proportions of bone and cartilage: Type I, no ossification (< 1/3 ossification) 45%; Type II, minor ossification (1/3 - 1/2 ossification) 20%; Type III, major ossification (1/2-2/3 ossification) 20%; Type IV, complete ossification (> 2/3 ossification) 15%. Most of the XPs (85%) had bone and cartilage, which could have been overlooked in studies using skeletons or CT. CONCLUSION: Previous studies probably underestimated or overestimated the size of the XP. The XC needs to be considered as normal anatomy.

The use of diffusion tensor imaging in spinal pathology: a comprehensive literature review.

STUDY DESIGN: We reviewed the available literature systematically without meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. OBJECTIVE: To evaluate contemporary literature on use of spinal diffusion tensor imaging(sDTI) in spinal pathology. BACKGROUND: sDTI reveals the location and functional state of critical long tracts and is a potentially useful adjunct in disease management. METHODS: Studies were included if they presented or discussed data from investigative or therapeutic procedures involving sDTI on human subjects in the setting of surgically amenable spinal pathology. Studies were excluded if they were (1) restricted to computational models investigating parameters using data not obtained clinically, (2) about cranial DTI methods, (3) about spinal pathology data not related to surgical management, (4) discussions or overviews of methods/techniques with minimal inclusion of objective experimental or clinical data. RESULTS: Degenerative pathologies of interest were restricted to either cervical myelopathy (22/29,75.9%) or lumbar spondylosis 7/29,24.1%). Mass-occupying lesions included intradural pathology and discussed preoperative (7/9,77.8%) and intraoperative imaging(2/9,22.2%) as an adjunct to surgery 22.2%. Traumatic pathology focused on spinal cord injury prognosis and severity grading. CONCLUSIONS: sDTI seems useful in surgical decision making and outcome measurements and in establishing clinical prognoses over a wide range of surgical pathologies. Further research is warranted with longer follow-up and larger population sizes in a prospective and controlled protocol.

An accessory head of the extensor indicis: a rare case report.

PURPOSE: A deep knowledge of the variations of the posterior forearm musculature is crucial for assessing and diagnosing conditions in this region. Extensor indicis (EI) is one of the muscles in this region, which exhibits diverse anatomical variations. This report documents an extremely unusual form of the EI with an accessory head on the dorsum of the hand. METHODS: During routine dissection, an extremely rare presentation of the EI was found in the left forearm of a 94-year-old female cadaver. RESULTS: This unusual EI consisted of two muscle bellies. The traditional belly originated from the distal two-thirds of the ulna. The muscle became tendinous around the carpal area, distal to the extensor retinaculum. The tendon was subsequently joined by an accessory muscle belly originating from the distal radioulnar ligament. The EI tendon inserted onto the dorsal expansion of the index finger, ulnar to that of the extensor digitorum. The posterior interosseous nerve innervated the muscle. CONCLUSION: Herein, we report an extremely rare form of the EI. To our knowledge, EI with an accessory head has only been reported rarely over the past 200 years. Moreover, our report appears to be the first case with photographic details of this anatomical variation. Clinicians should be aware of this variation for proper diagnosis and treatment.

An anatomical study of the nasal foramina.

PURPOSE: The nasal foramen is located in the nasal bone and for vessels passage to supply the nasal area. This project aimed to establish reliable references for the nasal foramina for future clinical applications. METHODS: The 72 dried skulls, 46 from the Division of Anatomy, University of Phayao, Thailand, and 26 from the Tulane University School of Medicine, USA, were collected and examined. The location, number, and sizes of nasal foramina were noted. The distances from each nasal foramen to the internasal suture, frontonasal suture, nasomaxillary suture, nasion, and rhinion were also recorded and used in the statistical analytical programs. RESULTS: The most common type of nasal foramen in all skulls was type II (one external opening) at 65.97%, followed by type I (no foramen opening) at 20.83%, type III (two external openings) at 11.11% and type IV at 2.08% (three external openings). Nasal foramen subtypes in many of the Thai and American skulls were type IIb and type IIa. The diameter of a connecting nasal foramen was significantly larger than that of a non-connecting. Results from embalmed confirmed the passage of the external nasal artery through the nasal cavity. CONCLUSION: The study shows no significant difference in nasal foramen morphometry between Thai and American. It illustrates recent data on type and subtype classifications and the location of a vascular passage through the nasal foramen. This is the first study of NF variations and their respective classifications.

Newly revealed anatomy of the bucinator muscle: An anatomical and histological study.

BACKGROUND: Current anatomical knowledge of the origin of the bucinator muscle (BM), i.e., long thin attachments on the maxilla and mandible and the pterygomandibular raphe (PMR), is not supported by anatomical dissection of this muscle. The aim of this study was therefore to investigate the detailed morphology of the BM and associated structures and to discuss its function. METHODS: The anatomy of the BM and related structures was investigated in 15 cadaveric heads using a surgical microscope and histological analysis. RESULTS: The inferior fibers of the BM originated from a small retromolar area (internal oblique line), which shared a common tendon with the deep tendon of the temporalis. The superior fibers of the BM originated from the maxillary tuberosity. The middle fibers originated the pterygoid hamulus. No PMR was identified in any of the specimens, but the border between the BM and superior pharyngeal constrictor muscle (SC) was clear because the muscle fibers followed different directions. Some horizontal fibers were continuous between the BM and SC. CONCLUSIONS: Our results suggest the need to revise established accounts of the origins of the bucinator (the maxillary tuberosity, conjoint tendon of the temporalis, and pterygoid hamulus without a pterygomandibular raphe. It also needs to be noted that some of its fibers merge directly with the SC.

Anatomy of mamillo-accessory foramen and prevalence of ossified mamillo-accessory ligament in lumbar vertebrae related to age.

PURPOSE: Ossification of the mamillo-accessory ligament (MAL) results in the formation of a mamillo-accessory foramen (MAF), which is associated with aging. The MAL tethers the medial branches of the lumbar dorsal rami to the lumbar vertebrae. A MAL ossified at the lumbar vertebrae can cause low back pain by compressing the medial branch of a dorsal ramus. Age ranges related to ossification of the MAL have not been reported in previous studies. The objective of the present study was to determine the prevalence of ossification of the MAL in the lumbar column and its relationship to aging, and to measure the newly formed MAF at each level of the lumbar vertebrae. METHODS: This study examined 935 dried lumbar vertebrae from 187 donors at Khon Kaen University, Thailand, consisting of 93 females and 94 males. The research focused on ossification patterns of the MAL, categorizing them into three patterns. RESULTS: We found that over 50% of ossified MAL occurred in the 30-45-year-old range and the frequency increased with age. The prevalence of ossified lumbar MAL was 72.73%, especially in L5 on the left side in females (76.92%). The width of the MAF did not differ significantly between the sexes, but it was greater on the left side (2.46 ± 1.08; n = 76) than the right (2.05 ± 0.95; n = 72) (p = 0.016). CONCLUSION: Ossification of the MAL into the MAF progresses with age, leading to low back pain from nerve compression. Physicians should be aware of the MAF during anesthesia block to treat low back pain.

Anatomy of the Buccal Space: Surgical and Radiological Perspectives.

Among the anatomical spaces in the head and neck area, the buccal space has often been studied in dental/oral surgery and cosmetic surgery because it contains the facial vessels, mandibular and facial nerves, and adipose tissue called the buccal fat pad. In addition, as the space can communicate with other spaces, it can be significant in infections. Although the anatomy of the buccal space has been reported in several studies, there have been discrepancies concerning its boundaries, and its communications have often been overlooked. The aim of this review is to examine the anatomy of buccal space including its boundaries, contents, continuity with adjacent spaces, and clinical significance. A literature review was performed on Google Scholar and PubMed. The literature has depicted the anterior, medial, and lateral boundaries more or less consistently, but descriptions of the posterior, superior, and inferior borders are controversial. The buccal space includes the facial arteries, veins, facial nerves, parotid duct, and lymph nodes, which can be described differently depending on definitions and the extent of the space. As it communicates with other anatomical spaces including the masticatory space, it can be a reservoir and a channel for infections and tumors. Buccal fat pads have various clinical applications, from a candidate for flap reconstruction to a target for removal for cosmetic purposes. This review will help understand the anatomy of the buccal space including its boundaries, residing structures, and communication with other spaces from surgical and radiological perspectives.

Anatomical evaluation of the superficial medial collateral ligament distal tibial attachment of the knee.

This study aimed to evaluate the superficial medial collateral ligament distal tibial attachment (sMCL-dTA) morphologically and morphometrically. Seventeen unpaired formalin-fixed cadaveric knees were used. The sMCL was divided into anterior and posterior sections in the paracoronal plane along the midline of the sMCL. The distance from the medial edge of the tibial plateau and the joint line to the proximal margin, center, and distal margin of the sMCL-dTA and the length of the sMCL-dTA were measured in the anterior section, respectively. The sMCL-dTA was histologically observed in the posterior section with hematoxylin and eosin and Masson's trichrome staining. The distance from the medial edge of the tibial plateauto the proximal margin, center, and distal margin of the sMCL-dTA were 38.1 ± 4.2, 49.7 ± 4.4, and 61.5 ± 5.1 mm, respectively. The perpendicular distance from the joint line to the proximal margin, center, and distal margin of the sMCL-dTA were 36.1 ± 4.0, 47.4 ± 4.2, and 59.1 ± 4.8 mm, respectively. The length of the sMCL-dTA was 23.6 ± 3.2 mm. Histologically, the sMCL-dTA was formed by two layers of collagen fibers: the unidirectional fibrous layer and the multidirectional fibrous layer. The respective thicknesses of the two layers both decreased distally. The anatomical location, the length, and the attachment morphology of sMCL-dTA have been clarified using human cadaveric knees. Anatomical data in the present study contribute to the quality of surgery associated with sMCL-dTA.

Intrafacet Spacer Placement as a Mobility-Sparing Bailout Option in Atlantoaxial Fusion Construct Salvage.

Background: Salvage revisions of atlantoaxial (AA) joint complex posterior segmental instrumented fusion constructs require careful individualized planning to prevent occipital extension. In this case report, we describe the use of bilateral intrafacet spacer placement as a mobility-sparing bailout option for the revision surgery. Case Report: A 64-year-old male with a history of diffuse idiopathic skeletal hyperostosis, extremely limited baseline cervical mobility, and prior AA posterior segmental instrumented fusion presented with increasing pain at his 6-month follow-up. Imaging showed fusion and hardware failures and dynamic instability. To prevent occipitocervical fixation, AA intra-articular fusion via a DTRAX spinal system (Providence Medical Technology, Inc) was used as an adjunct to a navigated C1 lateral mass and C2 pars screw posterior segmental instrumented fusion construct. The patient had an uneventful postoperative course and was discharged with resolution of symptoms. Three-month postoperative follow-up confirmed persistent resolution of symptoms and absence of complaints, along with successful arthrodesis on imaging. Conclusion: AA posterior segmental instrumented fusion revision is technically challenging, particularly when partial preservation of craniovertebral junction mobility is required. Bilateral intra-articular cages may be used as an adjunct to hardware revision in construct salvage when sturdy arthrodesis is desired without occipital extension and may represent a major potential strength of intra-articular cages.

The importance of the palatine bone for endoscopic endonasal skull base surgery.

Endoscopic endonasal skull base surgery is increasingly prevalent, with its scope expanding from pathogens in the midline region to those in the paramedian region. Maximizing anterior sphenoidectomy is important for the median approach, and lateralizing the pterygopalatine fossa is crucial for the paramedian approach. Maximizing the surgical corridor in the nasal cavity and minimizing damage to neurovascular structures are vital for establishing a surgical field with minimal bleeding, ensuring safe, precise, and gentle procedures. However, the relationship between the maxillofacial and skull base bones in endoscopic endonasal skull base surgery is difficult to understand because these bones are intricately articulated, making it challenging to visualize each bone's outline. Understanding important bones and their related neurovascular structures is essential for all skull base surgeons to maximize the surgical corridor and minimize iatrogenic injury to neurovascular structures. This study aimed to elucidate the role of the palatine bone from a microsurgical anatomical perspective. Three dry skulls were used to demonstrate the structure of the palatine bone and its relationship with surrounding bones. A formalin-perfused cadaveric head was dissected to show the related neurovascular structures. The arteries and veins of the cadaveric heads were injected with red- and blue-colored silicon. Dissection was performed using a surgical microscope and endoscope. In addition, the utilization of the palatine bone as a landmark to identify neurovascular structures, which aids in creating a wider surgical field with less bleeding, was shown in two representative cases. The palatine bone consists of unique complex structures, including the sphenoidal process, ethmoidal crest, pterygopalatine canal, and sphenopalatine notch, which are closely related to the sphenopalatine artery, maxillary nerve, and its branches. The ethmoidal crest of the palatine bone is a well-known structure that is useful for identifying the sphenopalatine foramen, controlling the sphenopalatine artery and nerve, and safely opening the pterygopalatine fossa. The sphenoidal process of the palatine bone is a valuable landmark for identifying the palatovaginal artery, which is a landmark used to safely and efficiently expose the vidian canal. The sphenoidal process is easily cracked with an osteotome and removed to expose the palatovaginal artery, which runs along the pharyngeal groove, just medial to the vidian canal. By opening the pterygopalatine canal (also known as the greater palatine canal), further lateralization of the periosteum-covered pterygopalatine fossa contents can be achieved. Overall, the sphenoidal process and ethmoidal crest can be used as important landmarks to maximize the surgical corridor and minimize unnecessary injury to neurovascular structures.

Novel Muscle in Infraspinous Fossa.

The infraspinatus muscle (IS) makes a minor contribution to lateral rotation of the arm but mainly serves to stabilize the glenohumeral (GH) joint as part of the rotator cuff. Although reports of variations in the rotator cuff muscles have been documented previously, specific discussions of IS variants are lacking. In this report, we present a novel case of an accessory muscle in the infraspinous fossa and its relationship to the IS, which was normally located. We describe the observed physical features of the muscles and their innervation patterns.

The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study.

OBJECTIVE: Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. METHODS: The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. RESULTS: The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. CONCLUSIONS: Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.