"A comprehensive study of the potential compression points of the third occipital nerve and its possible clinical interests".

BACKGROUND: The anatomical features of the third occipital nerve (TON) are the least studied among the occipital nerves. This study aimed to analyze the anatomical features and potential compression points of the TON. METHODS: The posterior neck and scalp of 39 cadavers were dissected. The TON was carefully followed from the emerging point from C2-C3 vertebrae distally. Its muscular investments were detected. The determined points were marked superficially and measured according to external occipital protuberance with the Image J Software program. RESULTS: The TON revealed 4 different potential entrapment points along its course. The most proximal point was between the C2-C3 vertebrae. The second and third points were at their piercing points of semispinalis capitis and splenius capitis muscles, respectively. The final point was at its penetrating point of the trapezius muscle. Additionally, TON did not pierce the semispinalis capitis muscle on 6 sides and pierced this muscle from 3 different points by splitting into 3 branches on 1 side. Moreover, on 5 sides, the TON split into two branches and perforated the splenius capitis muscle from two different points. CONCLUSION: There were 4 potential compression points regarding the TON. These entrapment points and variations of TON in this study may play a significant role in understanding the reason for TON-related headaches and the treatment of headaches caused by TON.

Anatomical evaluation of P1 segment of posterior cerebral artery and posterior communicanting artery in 340 human hemispheres: a proposal for morphological classification.

PURPOSE: The aim of our study is to examine the morphometry of the P1 segment of the posterior cerebral artery (P1) and the posterior communicating artery (PcomA) and to present a descriptive classification according to morphometric findings. METHODS: 340 hemispheres from 170 cadavers were included. The outer diameters of P1 and PcomA were measured with ImageJ software. Then, the configurations of the posterior cerebral artery were revealed as fetal, adult and transitional. The findings were correlated with the demographic information of the cadavers such as gender, body mass index (BMI), age. RESULTS: According to the morphometric findings, 83.75%, 13.85% and 2.40% of the posterior cerebral arteries were found to be adult, fetal and transitional, respectively. The fetal type was more common in cadavers aged 60 years and older (13.73%) compared to the 18-39 and 40-59 age groups. In addition, P1 and PcomA diameters also increased with age. Fetal and transtional types showed a similar low distribution in people with low (< 18.5), normal (18.5-24.9), overweight (25-29.9) and obese (> 30) BMI, whereas adult type was found in cadavers with a normal BMI of 140/303. CONCLUSION: We believe that the findings of our study will contribute to the planning of neurointerventional procedures, the development of endovascular devices, the success of invasive procedures and the reduction of complications.

Morphological and morphometric anatomy of the lesser occipital nerve and its possible clinical relevance.

The lesser occipital nerve (LON) has one of the most variations among occipital nerves. We aimed to investigate morphological and morphometric features of LON. A total of 24 cadavers, 14 males (58%) and 10 females (42%), were dissected bilaterally. LON was classified into 3 types. The number of branches and the perpendicular distances of the point where LON emerged from the posterior border of sternocleidomastoid muscle to vertical and transverse lines passing through external occipital protuberance were determined. The shortest distance between LON and great auricular nerve (GAN), and linear distance of LON to its branching point were measured. The most common variant was Type 1 (30 sides, 62.5%), followed by Type 2 (12 sides, 25%) and Type 3 (6 sides, 12.5%), respectively. In males, Type 1 (22 sides, 78.6%) was the most common, while Type 1 (8 sides, 40%) and Type 2 (8 sides, 40%) were equally common and the most common in females. On 48 sides, 2-9 branches of LON were observed. The perpendicular distance of said point to vertical and transverse lines was meanly 63.69 ± 11.28 mm and 78.83 ± 17.21 mm, respectively. The shortest distance between LON and GAN was meanly 16.62 ± 10.59 mm. The linear distance of LON to its branching point was meanly 31.24 ± 15.95 mm. The findings reported in this paper may help clinicians in estimating the location of the nerve and/or its branches for block or decompression surgery as well as preservation of LON during related procedures.

Morphometric and morphological evaluation of the nasolacrimal groove in 150 dry bones in the Anatolian population.

PUPOSE: In this study, we aimed to evaluate the anatomical features of the nasolacrimal groove in detail by providing a morphological classification based on morphometric evaluations of the nasolacrimal groove. METHODS: A total of 150 sagittal dry bones in the Department of Anatomy, Faculty of Medicine, Istanbul University were evaluated. The length and the width at different points of the nasolacrimal canal were calculated. According to the widths of the nasolacrimal canal ten different morphological types were revealed. RESULTS: The length of the canal was found as mean 13.62 ± 2.42 mm on the right and 12.44 ± 2.68 mm on the left side. The entrance, the base, the upper and the lower thirds of nasolacrimal canal were 6.22 ± 1.19 mm, 7.95 ± 1.85 mm, 5.85 ± 1.06 mm, 6.60 ± 1.54 mm, on the right and 6.08 ± 1.16 mm, 7.24 ± 1.64 mm, 5.45 ± 1.29 mm, 6.23 ± 1.48 mm, on the left side, respectively. The width of the entrance of the nasolacrimal canal was the narrowest width compared to the base, upper and lower thirds in 7/10 types of 71/150 cranial bones. CONCLUSION: This comprehensive morphological classification of the nasolacrimal groove sheds new light on its complex variations. We support that the finding of this study has the potential to improve the precision of diagnostic assessments and guide specific therapeutic interventions for patients with lacrimal drainage disorders.

The triangular area between the greater, lesser, and third occipital nerves and its possible clinical significance.

PURPOSE: Occipital Neuralgia (ON) is defined as a unilateral or bilateral pain in the posterior area of the scalp occurring in the distribution area or areas of the greater occipital nerve (GON), lesser occipital nerve (LON), and/or third occipital nerve (TON). In the present study, the purpose was to show the possible importance of the triangular area (TA) in nerve block applied in ON by measuring the TA between GON, TON, and LON. METHODS: A total of 24 cadavers (14 males, 10 females) were used in the present study. The suboccipital region was dissected, revealing the points where the GON and TON pierced the trapezius muscle and superficial area, and the point where the LON left the sternocleidomastoid muscle from its posterior edge and was photographed. The area of the triangle between the superficial points of these three nerves and the center of gravity of the triangle (CGT) were determined by using the Image J Software and the results were analyzed statistically. RESULTS: The mean TA values were 952.82 ± 313.36 mm2 and 667.55 ± 273.82 mm2, respectively in male and female cadavers. Although no statistically significant differences were detected between the sides (p > 0.05), a statistically significant difference was detected between the genders (p < 0.05). The mean CGT value was located approximately 5 cm below and 3-3.5 cm laterally from the external occipital protuberance in both genders and sides. CONCLUSION: In ON that has more than one occipital nerve involvement, all occipital nerves can be blocked by targeting TA with a single occipital nerve block, and thus, the side effects that may arise from additional blocks can be reduced. The fact that there was a statistically significant difference according to the genders in the TA suggests that different block amounts can be applied according to gender.

Anatomical Features of Posterior Cerebral Arteries and Basilar Artery in 170 Anatolian Fresh Cadavers: Implications for Surgical Planning and Intervention.

BACKGROUND: The posterior cerebral arteries (PCAs) are terminal branches of the basilar artery (BA) and are responsible for the primary supply of the occipital lobe. Saccular aneurysm is most commonly seen close to the bifurcation of the BA. Various surgical interventions are performed for aneurysms. Therefore, the anatomy and localization of the BA and PCA are crucial. The aim of this study was to determine the characteristics of these arteries in a large Anatolian population. METHODS: The study included 170 Anatolian fresh cadavers. The diameters of the BA and PCA were measured. Correlations according to sex and age groups were analyzed. The Q1, Q2, and Q3 angles between the right and left PCA, between the right PCA and BA, and between the left PCA and BA, respectively, were measured. The location of the PCA relative to the sulcus pontocruralis (pontocrural groove) was also evaluated. RESULTS: The diameter of the artery increased with age and was higher in males than in females. Q1 and Q2 diameters were larger in males, while the Q3 diameter was larger in females. The Q1 angle between the right and left PCAs was found to be higher in age range 40-59 years with a mean of 87.33 ± 17.91 mm. Finally, the bifurcation point of the PCA was most frequently located above the sulcus pontocruralis (pontocrural groove) and least frequently located on the sulcus pontocruralis (pontocrural groove). CONCLUSIONS: The findings of our study will contribute to the planning of surgical approaches, the development of endovascular devices, the success of invasive procedures, and the reduction of complications.

Morphological features of the greater occipital nerve and its possible importance for interventional procedures.

Being one of the most prevalent neurological symptoms, headaches are burdensome and costly. Blocks and decompression surgeries of the greater occipital nerve (GON) have been frequently used for migraine, cervicogenic headache, and occipital neuralgia which are classified under headache by International Headache Society. Knowledge of complex anatomy of GON is crucial for its decompression surgery and block. This study was performed to elucidate anatomical features of this nerve in detail. Forty-one cadavers were dissected bilaterally. According to its morphological features, GON was classified into four main types that included 18 subtypes. Moreover, potential compression points of the nerve were defined. The number of branches of the GON up to semispinalis capitis muscle and the number of its branches that were sent to this muscle were recorded. The most common variant was that the GON pierced the aponeurosis of the trapezius muscle, curved around the lower edge of the obliquus capitis inferior muscle, and was loosely attached to the obliquus capitis inferior muscle (Type 2; 61 sides, 74.4%). In the subtypes, the most common form was Type 2-A (44 sides, 53.6%), in which the GON pierced the aponeurosis of each of the trapezius muscle and fibers of semispinalis muscle at one point and there was a single crossing of the GON and occipital artery. Six potential compression points of the GON were detected. The first point was where the nerve crossed the lower border of the obliquus capitis inferior muscle. The second and third points were at its piercing of the semispinalis capitis muscle and the muscle fibers/aponeurosis of the trapezius, respectively. Fourth, fifth, and sixth compression points of GON were located where the GON and occipital artery crossed each other for the first, second, and third times, respectively. On 69 sides, 1-4 branches of the GON up to the semispinalis capitis muscle were observed (median = 1), while 1-4 branches of GON were sent to the semispinalis capitis muscle on 67 sides (median = 1). The novel anatomical findings described in this study may play a significant role in increasing the success rate of invasive interventions related with the GON.

Anatomical variations of the zygomaticofacial foramen and its related canal through the zygomatico-orbital and zygomaticotemporal foramina in dry human skulls.

PURPOSE: The aim of this study is to reveal the location of the zygomaticofacial foramina, the variations of their numbers, and their connections between the zygomatico-orbital and zygomaticotemporal foramina. METHODS: Ethics committee approval of our study was received by the Istanbul Medical Faculty Clinical Research Ethics Committee (date:30.07.2021, number:358356). 171 zygomatic bones of unknown gender from the Department of Anatomy, Istanbul University, were included in this study. The number of zygomaticofacial foramina and their connections with the zygomatico-orbital foramen and the zygomaticotemporal foramina were examined. Also, the morphometric distances between the zygomaticofacial foramen were calculated. Evaluation of the data was done with SPPS v.21. RESULTS: The number of zygomaticofacial foramina was found as 299. It was found single, double, three, four, five and six foramina, in 52 (30.4%), 52 (30.4%), 24 (14.03%), 10 (5.85%), 5 (2.93%), 1 (0.58%) zygomatic bone, respectively. Zygomaticofacial foramen was absent in 27 (15.8%) bones. Of these 299 foramina, 129 were found to be connected with zygomatico-orbital foramen and 23 with zygomaticotemporal foramen. It was noted that 147 zygomaticofacial foramina had no connection with any foramina. The distances between the zygomaticofacial foramen and the frontozygomatic suture, temporal process, maxillary process, the lowest point of the zygomatic bone, and orbital rim were found as 25.30 ± 2.81mm, 18.74 ± 3.56mm, 21.56 ± 4.16mm, 18.72 ± 2.57mm, 6.67 ± 3.27mm, respectively. CONCLUSION: Consequently, the location and variations of ZFF are of great importance for maxillofacial surgery and regional block anesthesia. Knowing its location and variations will help prevent complications during any surgical intervention in this region.

Accessory Muscles Associated With the Levator Palpebrae Superioris Muscle in 100 Cadavers.

PURPOSE: This study aimed to determine the variations of the levator palpebrae superioris muscle and to reveal its morphological features. METHODS: This study conducted on 100 adult orbit cadavers in the Department of Anatomy, Istanbul University, used an exploratory, descriptive research design. The anatomical and morphological variations of the levator palpebrae superioris muscle and its relationship with the superior ophthalmic vein were evaluated. RESULTS: Variations of levator palpebrae superioris muscle were discovered in 11 of 100 orbits. Single (9%), double (1%), and triple (1%) accessory muscle slips were observed. The origin of accessory muscle slips showed variation as the accessory muscle slips originated either from the proximal or distal half of the levator palpebrae superioris muscle. Also, the insertions of accessory muscle slips were variable, as they were inserted into levator aponeurosis, trochlea, lacrimal gland, lateral orbital wall, or the fascia of the superior ophthalmic vein. CONCLUSIONS: Accessory muscles associated with levator aponeurosis were found in a significant proportion of cadavers. These muscles may cause confusion in orbital surgery and should be taken into account during surgical planning and orientation in the superior orbit.

Topographic and morphometric anatomy of the proximal part of the dorsal scapular nerve.

The dorsal scapular nerve (DSN) entrapment neuropathy has recently been recognized as a common cause of circumscapular pain and cases of winged scapula. Course of the nerve is important because the middle scalene muscle is frequently accessed for surgical treatments. Studies in the literature have not focused on the morphometric relationship of the DSN with the scalene muscles and its relationship with the long thoracic nerve (LTN). The neck regions of 13 adult cadavers were dissected bilaterally. The relationship of DSN with scalene muscles and LTN was evaluated. Cervical spinal nerves involved in the formation of the DSN were identified. Three types of DSN were observed based on the cervical spinal nerves from which it originates, five types of DSN from its relationship with the scalene muscles, and two types of DSN from its relationship with the LTN. The distance from where the nerve pierces the scalene muscle to the mastoid process was found to be greater in DSNs originating from C4 and C5 (93.85 ± 4.11 mm, p = 0.033). In DSNs not connected with LTN, the distance from where the nerve pierces the scalene muscle to the superior trunk/C5 (12.74 ± 7.73 mm, p = 0.008) and the length of the nerve within the scalene muscle (14.94 ± 5.5 mm, p = 0.029) were found to be statistically significantly greater. The topographic and morphometric anatomy of the proximal part of the DSN is important, especially for scalene muscles-focused surgical treatments and interscalene nerve blocks. We believe our results may guide clinical approaches and surgery.

Variations in the course of the externalbranch of the superior laryngeal nerveand their importance in surgicalprocedures: an experimental cadaveric study.

<br><b>Introduction:</b> Injury of the external branch of the superior laryngeal nerve can cause a hoarse or weak voice due to the functional loss (dysergia) of the cricothyroid muscle. Defining the anatomical variations of the external branch of the superior laryngeal nerve and estimating their frequency are crucial for surgical interventions.</br> <br><b>Aim:</b> To reveal the topography of the external branch in the Anatolian population, to prevent injury of it during the surgical intervention in the anterior neck region.</br> <br><b>Material and methods:</b> 26 bilateral hemilarynges (4 females, 22 males) were dissected. The morphometric and morphological features of the external branch were examined. The obtained results were compared statistically, left and right.</br> <br><b>Results:</b> Landmarks such as the thyroid gland and laryngeal prominence were determined for the detection of the external branch. The variations of the course of the external branch and the points of piercing the cricothyroid muscle or inferior pharyngeal constrictor muscle were evaluated.</br> <br><b>Discussion:</b> Although safe approaches have been described for nerve protection during neck surgeries, injuries may occur during preliminary surgery as the mentioned nerve is thinner and more superficial than other branches of the vagus nerve. However, it can be detected more easily and safely by knowing the defined anatomical landmarks and morphological variations of the external branch.</br> <br><b>Conclusion:</b> The anatomical variations described can be a safe and important guide in surgeries of the anterior neck region.</br>.

Frequency Morphologic and Morphometric Properties and Osseous Relationships of Whitnall's Tubercle.

Whitnall tubercle (WT) of the zygomatic bone is used as an anatomical landmark in some surgical approaches to the orbit. The authors aimed to determine the localization of WT by using some palpable bony landmarks and to reveal its morphological and morphometric features. Three hundred twenty-two zygomatic bones (167 right and 155 left) belonging to adults of unknown sex, were examined. An acetate prepared by drawing a clock with a dial on it was used to determine the localization of WT according to marginal tubercle and zygomatic arch. Distances between WT and frontozygomatic suture and lateral margin of the orbital rim were measured with digital calipers. One zygomatic bone had double tubercles, thus 321 bones were taken into consideration. Whitnall tubercle was determined in 284 of 321 zygomatic bones. 181 were classified as small, 10 as medium, and 93 as large. The position of the WT according to the marginal tubercle was at the 8, 9, and 10 o'clock positions on the left, and at 2, 3, and 4 o'clock on the right. The position of the WT according to the zygomatic arch was at the 9,10 and 11 o'clock positions on the left, and at the 1 and 2 o'clock positions on the right. Distances between the WT and lateral margin of the orbital rim and the frontozygomatic suture were measured meanly as 1.94±0.31 mm and 8.17±5.82 mm, respectively. The authors believe that the data obtained regarding WT will contribute to anatomy and surgical procedures of the related region.

Variations of the external branch of the superior laryngeal nerve during its course and its importance in surgical approaches: an experimental cadaveric study.

INTRODUCTION: Injury of the external branch of the superior laryngeal nerve can cause a hoarse or weak voice due to the functional loss (dysergia) of the cricothyroid muscle. Defining the anatomical variations of the external branch of the superior laryngeal nerve and estimating the frequency of it, it makes crucial for surgical interventions. AIM: To reveal the topography of the external branch in the Anatolian population, to prevent injury of it during the surgical intervention in the anterior neck region. MATERIALS AND METHODS: Twenty-six bilateral hemilarynges (4 females, 22 males) were dissected. The morphometric and morphological features of the external branch were examined. The obtained results were compared statistically left and right. RESULTS: Landmarks such as the thyroid gland and laryngeal prominence were determined for the detection of the external branch. The variations of the course of the external branch and the points of piercing the cricothyroid muscle or inferior constrictor pharyngeal muscle were evaluated. DISCUSSION: Although safe approaches have been described for nerve protection during neck surgeries, it can expose injuries during preliminary surgery approaches as the nerve is thinner and more superficial than other branches of the vagus nerve. However, it can be detected more easily and safely during the surgical approach by knowing the defined anatomical landmarks and morphological variations of the external branch. CONCLUSION: The anatomical variations described can be a safe and important guide in surgical approaches to be applied in the anterior neck region.

The life of the prince of anatomists Jean Riolan, Jr. (the Younger) (1577-1657).

For the first time in the history of anatomy, the important French anatomist Jean Riolan, Jr., clarifies several conditions that anatomy adepts should accomplish during their preparation in his work Anthropographia. Anatomists should be physically, mentally, culturally, and ethically ready for their work. The anatomy teacher should consider three rules: have experience in anatomical dissection, have the essential knowledge and approach to dissection, and use a suitable teaching method.

Anatomical Landmarks of the Beard Region.

BACKGROUND: With recent advancements in hair restoration techniques, hair can be transplanted into nonscalp areas, such as the beard region, and the result looks natural. Although scalp zones and landmarks have been available for planning and designing the hairline, landmarks that will determine the beard lines are yet to be presented and made known for clinical practice. OBJECTIVE: This study aimed to determine and analyze the beard lines and anatomical boundaries of the beard area to provide a more natural restoration/reconstruction appearance. MATERIALS AND METHODS: The soft-tissue landmarks of the face that will enable physicians to create natural-looking beard lines were determined. Based on these important points, beard lines were analyzed with anthropometric methods by using the photographs of 32 male volunteers. RESULTS: The ideal upper and lower beard lines and the anatomical boundaries of the beard area were determined using these landmarks. CONCLUSION: These lines ensure that beard restoration/reconstruction provides a more natural appearance.