Reappraising the surface anatomy of the pterion and its relationship to the middle meningeal artery

Despite its clinical importance, the surface anatomy of the pterion is inconsistently reported. This study reappraises the surface marking of the pterion and its relationship to the middle meningeal artery (MMA). The position and morphology of the pterion were analyzed in the Frankfurt plane in 76 adult skulls and 50 adult cranial cone beam CT scans. Relationship to the anterior branch of the MMA was examined in the skulls. Measurement reproducibility was assessed in a 20% randomly selected sample. In the skulls, the majority of pteria were sphenoparietal (78%), followed by epipteric (16%) and frontotemporal (5%). The center of the pterion was a mean of 26 ± 4 mm behind and 11 ± 4 mm above the posterolateral margin of the frontozygomatic suture; measurements were reproducible and consistent between sides and genders. Distances from the frontozygomatic suture were slightly greater (29 and 16 mm, respectively) in cranial CTs. A one centimeter circle centered on the midpoint of the pterion overlapped the anterior branch of the MMA in 68% of skulls; the artery was a few millimeters posterior in the remainder. Mean skull thickness at the midpoint of the pterion was 4.4 mm compared to 1 mm at its thinnest point in the squamous temporal bone. In conclusion, in most adults, the pterion lies within a one centimeter diameter circle 2.6 cm behind and 1.3 cm above the posterolateral margin of the frontozygomatic suture (which is easily palpable in vivo). This region overlaps the anterior branch of the MMA in two-thirds of cases.     

Morphological variability of pterion in the human skull

The pterion is one of the most interesting bone meeting points in craniofacial osteology and its complex morphology derives from the fact that is the contact point of the facial skeletal elements, skull base and calvarium. Knowledge of its peculiar morphology is mandatory for the pterional approach used in microsurgery and surgery. The Authors studied 506 adult, human skulls where the pterion was accurately reconstructed on polyethylene sheets. They report their data on the morphological analysis and classify the forms. They focussed their attention on the presence of wormian bones at the level of the sphenoparietal suture, on the peculiar existing morphology and reviewed the literature on these classifications. The Authors also evaluated the length of the sphenoparietal suture, the minimum gap between the frontal and temporal, the influence of pteric bones on pterion variability and any correlations between measurements and cranial indexes.     

翼点形态特征及其相关径线的应用解剖学观测

目的 观察和描述翼点的解剖学特征,为临床神经外科翼点手术入路精确定位提供参考数据。方法 选取我国吉林地区出土成人完整颅骨50例(100侧),观察和描述各颅骨双侧翼点骨缝形态,测量翼点宽度、翼点中点距颧弓上缘垂直距离、翼点中点与额骨颧突连线距离,对测量数据做统计学分析。结果 颅骨翼点骨缝形态可分为蝶顶缝型、颞额缝型、K型、翼上骨型四种。50例(100侧)颅骨中,蝶顶缝型46例84侧(84%),其中宽H型45例80侧(80%)、窄H型2例2侧(2%)、N型2例2侧(2%);颞额缝型2例2侧(2%);K型2例2侧(2%);翼上骨型10例12侧(12%)。翼点宽度:左侧宽度(11.31±3.00)mm,右侧宽度(12.12±4.79)mm,两侧比较差异无统计学意义(P>0.05);翼点距颧弓上缘垂直距离:左侧(40.12±3.95)mm、右侧(41.94±4.31)mm,左、右侧比较差异有统计学意义(t=3.141, P<0.05);翼点中心距额骨颧突连线距离:左侧(32.13±4.25)mm,右侧(33.71±5.19)mm,左、右侧比较差异有统计学意义(t=2.692, P<0.05)。结论 通过研究吉林地区国人翼点的形态特征及相关数据资料,为翼点手术入路提供相关参考数值。     

Inheritance of sutural pattern at the pterion in Rhesus monkey skulls

Five of the bones that characteristically comprise the cranial vault articulate on the lateral aspect of the skull at or near the cephalometric landmark referred to as the pterion. The pattern of articulation in the sutures associated with these bones varies among and within primate species and has been used as a criterion for classification in taxonomic studies, as well as in archeological and forensic studies. Within species, the sutural patterns found within the region of the pterion have remarkable consistency, which lead to the hypothesis that these patterns have a genetic basis. Sutural pattern variations were investigated at the pterion in 422 skulls from 66 rhesus monkey families with known genealogies from the long-standing colony on Cayo Santiago. Four specific types of articulation patterns were recorded. The results demonstrated that the most common suture pattern at the pterion of Cayo Santiago rhesus monkeys (86%; similar to that seen in some other anthropoid species but not humans and some apes) was characterized by an articulation between the temporal bone and parietal bone. Articulation between the sphenoid and parietal bones (type SP) accounted for 14% of the specimens and was concentrated in a dozen families. Mothers with the SP phenotype had a high incidence of offspring with SP phenotypes. Most non-SP mothers having SP offspring had siblings or family members from previous generations with the SP type. This is the first study to examine variation in sutural patterns at the pterion in pedigrees. Variation of sutural patterns shows familial aggregation, suggesting that this variation is heritable. Future work will be focused on defining the inheritance patterns of variation at the pterion, with the ultimate objective of identifying the specific genes involved and their mechanism of action.     

Age-related changes in the anatomical landmarks of the osseous epipharynx

We investigated age-related spatial relations of the osseous epipharynx--the region between the vomer and the anterior border of the great occipital foramen (basion) on 60 skulls of both sexes: 16 adult (age range 21-59 years), 19 aged (age range 60-86 years), and macerated occipital bones, sphenoid bones, and vomers in 25 specimens of children disarticulated skulls aged 1-15 years. We measured the distances basion-tuberculum pharyngeum, tuberculum pharyngeum-ala vomeris, tuberculum pharyngeum-crista choanalis vomeris, basion-crista choanalis vomeris, width of the pars basilaris at the level of the tuberculum pharyngeum, narrowest width of the pars basilaris, width at the level of pyramidal apexes; and width at the level of laminae mediates processus pterygoidei of the sphenoid bone. We found a statistically significant increase in the frontal and sagittal measurements of the osseous epipharynx increasing from childhood to adulthood, without further significant changes into old age. In the aged adult and skulls, the distance from the tuberculum pharyngeum to the basion was half the distance to the vomer, whereas in children the ratio of these distances was 1:3. The major difference in the bony landmarks of the osseous epipharynx between children and adults were the attachments of muscles, m. longus capitis and m. rectus capitis anterior. Whereas the most common morphological feature of the m. longus capitis attachment was a bony fossa lateral to the tuberculum pharyngeum, the muscle attached to a prominent crest in children. These previously unreported findings illustrate the role of muscle activity in the formation of osseous landmarks of the epipharynx.     

The pterion in Turkish male skulls

This study was conducted to determine the location and type of pterion in Turkish males. The importance of the pterion is its relation to the middle meningeal artery, Brocas motor speech area on the left side, and surgical interventions relating to pathologies of the sphenoid ridge and optic canal. Specific measurements were taken on both sides of 26 Turkish human male skulls, none of which showed any obvious pathology or trauma. The sphenoparietal type of pterion was the most common (96% right side, 79% left side), followed by the frontotemporal (4% right side, 17% left side), and finally the epipteric type (4% left side only). The distances on the right and left sides respectively from the center of the pterion to the frontozygomatic suture were 3.30±0.40 cm and 3.44±0.39 cm, to the zygomatic arch 4.05±0.39 cm and 3.85±0.25 cm, to the optic canal 4.39±0.40 cm and 4.36±0.40 cm, and to the sphenoid ridge 1.40±0.33 cm and 1.48±0.32 cm. The thickness of the skull at the center of the pterion was 0.41±0.14 cm and 0.39±0.12 cm on the right and left sides respectively. These findings should be of use in surgical approaches and interventions via the pterion.     

Relations of the pterygoid hamulus and hard palate in children and adults: anatomical implications for the function of the soft palate.

We investigated spatial relations of the pterygoid hamuli to the hard palate on 65 skull bases: 31 disarticulated sphenoidal bones from the newborn up to 9 years of age, 19 skulls of adult skeletons (21-59 age group), and 15 skulls aged 60-100 years. We measured: (a) width of the hard palate in the choanal region, (b) length of the hamulus, (c) inclination of the hamulus from the perpendicular line, and (d) distance between the tips of the contralateral hamuli. The width of the hard palate in the choanal region was smallest in children (mean +/- standard deviation, 21.5 +/- 2.6 mm) compared with adult skulls (26.8 +/- 2.3 mm in the 21-59 age group and 25.4 +/- 1.9 mm in the 60-100 age group; P<0.05, one-way analysis of variance (ANOVA) and Student-Newman-Keuls post hoc test). Children had the shortest hamulus (3.6 +/- 1.5mm), and its length increased in the adult age group to 6.9+1.7mm (P<0.05), and then again decreased to 5.0 +/- 1.9 mm in the 60-100 age group (P<0.05 vs. adults and children). The distance between the tips of the contralateral hamuli and their lateral inclination from the perpendicular plane were also greater in the adult age group (38.0 +/- 2.7mm and 35.9 +/- 13.7 degrees, respectively) than either in children (31.0 +/- 3.7mm and 19.6 +/- 12.1 degrees) or the elderly (32.7 +/- 3.9mm and 19.7 +/- 10.3 degrees) (P<0.05). Our study showed that the anatomical measures of the pterygoid hamulus and its relation to the surrounding structures change with age, and occur with the changes in the function of pharyngeal and palatal muscles in deglutition. These changes may have clinical relevance for sleep apnoea and snoring.     

Morphology of the metopic suture during the fetal period

Assessment of the position and size of the metopic suture and anterior fontanelle is important in the routine examination during fetal period and in newborn infants. The aim of this study is to clarify the average size and its developmental changes of the anterior fontanelle and metopic suture by morphometry. Fifty-one cases were examined over a developmental period ranging from fetus of 14 weeks gestation to full term neonate. The width, and length of heads as well as head circumference of all fetuses were measured. The metopic suture and anterior fontanelle sizes were determined. The nearest distances between the parietal bones to the opposite frontal bones, and the distances between the nasion and lower angle of the anterior fontanelle, bregma and upper angle of the anterior fontanelle were measured. The averages of longitudinal and transverse diameters and areas of anterior fontanelle were calculated. Significant correlation was found between all the parameters and gestational ages, and between the sizes of the metopic suture and of skulls. There was no difference between male and female in any of the parameters. In our study, closed metopic suture was not observed. The anterior fontanelle is easy to palpate, and its enlargement might occasionally be helpful in the clinical examination of the newborn infants. The presence of a wide metopic suture may indicate the possibility of additional defects and anomaly in the newborn.     

An anatomical study of wormian bones from the eastern part of India: is genetic influence a primary determinant of their morphogenesis?

Over the years a number of investigators have analysed the morphology of wormian bones in different population groups across the world. There have been significant variations between findings reported in these studies, and this has prompted researchers to focus on the influence of genetic factors on the morphology of these bones. In the light of the above observation, we considered it justified to conduct anatomical studies on wormian bones in different population groups; hence, we undertook the present study to look into the morphological details of these bones among a population in the eastern part of India. We observed a total of 120 adult dry human skulls of unknown age and sex, and noted the anatomical details of wormian bones when present. It was observed that wormian bones were present in 45 % of skulls, and that 30 % of skulls had more than one wormian bone. We also found that 2.5 % of the skulls had ten or more wormian bones, which is considered as pathognomonic. Maximum incidence (53.33 %) was observed at the lambdoid suture and minimum incidence at the bregma and metopic suture (0.61 % in each case). We noted a high incidence (21.21 %) of Inca bone/lambdoid ossicle, and bilaterally symmetrical wormian bones were present in 12.5 % study skulls. There were statistically significant (P < 0.05) variations between the findings of the present study and values reported in previous studies conducted in other regions of India and different parts of the world. Our observations favour the view that genetic influence primarily determines the morphology of wormian bones.     

Sinus septi nasi: Anatomical study

The aim of this study was to perform a pioneering investigation into the incidence of pneumatization in human skulls. A total of 93 human skulls (≥20 years of age, 69 males, 24 females) were included in the study. The skulls were scanned in a fixed position using cone beam computed tomography (CBCT). The pneumatized space parameters within the nasal septum—width, length, and height—were measured. Two types of finding were identified: (a) Pneumatization, named “sinus septi nasi” (SSN), and (b) “spongy bone” (SB). The results showed SSN in 32 of the 93 skulls (34.4%). The SSN formations were from 0.5 to 4.2 mm wide, 3.5 to 18.8 mm long, and 3.8 to 17.7 mm high. Tumefactions filled with SB were found in 61 of the 93 skulls (65.59%). These were not suitable for precise measurements since the outer borders were not strictly and well defined on CT scans (perhaps because of the preparation process). In conclusion, the perpendicular plate of the ethmoidal bone is not always compact bone; in 34.4% of cases, it shows a degree of pneumatization. In contrast, an enlarged formation filled with SB is present in 65.59% of cases. The possible sources of pneumatization of this little‐investigated region are discussed: sphenoid sinus, frontal sinus, and vomeronasal organ. Clin. Anat. 30:312–317, 2017. © 2017 Wiley Periodicals, Inc.     

A quite rare condition: absence of sphenoidal sinuses

The absence of sphenoidal sinuses (SS) in an adult is an extremely rare condition. We investigated in agenesis of the sphenoid, maxillary, ethmoid, and frontal sinuses in 20 male adult cadavers. In a 50-year-old man, bilateral absence of the SS was observed. On the macroscopic examination, opening of the SS was not found on the lateral wall of the nasal cavity. There were multiple small mucosal grooves between the sphenoidal rostrum and the superior nasal turbinates. The bulging of the sphenoidal rostrum at the choanal level was flat. The body of the sphenoid bone was normal and consisted of a symmetrical bony structure with a total lack of pneumatization. Other paranasal sinuses agenesis was not observed. Surgeons should also consider the possibility of sphenoidal agenesis before transsphenoidal hypophysectomy. As a supplement to the traditional classification, agenesis of the SS can be described as the fourth type of pneumatization.     

额骨的观察与测量

本对昆明地区出土的100个成人颅骨（男51，女49）进行测量，测量结果，经性别差异检验，额骨最大宽，冠颞点间宽，额骨曲高，额骨曲度角，额骨倾角等，u值均小于1．96，无明显性别差异，额骨最小宽，额骨矢状弦，额骨矢状弧，额侧角，额鳞倾角，额骨下部顷角等，u值均大于1．96，性别差异明显，该数值可供法医性别鉴别时参考。     

Suture formation,premature sutural fusion,and suture default zones in Apert syndrome

On the basis of our studies, we postulate that suture formation in Apert syndrome is related to the relative maturity of abutting calvarial bones. The fused coronal suture, a consistent manifestation at birth, develops first because the ossification centers of the frontal and parietal bones are in intimate contact early during intrauterine life. Calvarial immaturity and the megalencephalic brain characteristic of the Apert syndrome appear to work in concert to produce a widely patent midline calvarial defect extending from the glabella to the posterior fontanelle. Because sagittal growth in the coronal sutures cannot take place, the megalencephalic brain grows upward and laterally, and bulges forward through the midline defect. The defect fills in by coalescence of bony islands without proper suture formation because the gap to be bridged is so great that the time window for developing sutural interdigitations may have closed. Other sutures, such as the lambdoid, squamosal, and sphenotemporal, develop with normal interdigitations because abutting bone margins are in close enough proximity to permit suture formation. © 1996 Wiley-Liss, Inc.     

新疆古代儿童颅骨正面观投影面积的年龄间比较*

目的：关于中国古代儿童颅骨年龄变化的研究较少,旨在探讨新疆古代儿童颅骨（2 ～ 15 岁）正面观投影 面积的年龄变化特点。方法：以新疆且末扎滚鲁克墓地出土的41 例儿童颅骨（2~15 岁）为研究对象,采用方差分析、 多重比较及年龄间变化率方法。结果：正面观投影面积的突增期为3 ～ 6 岁和12 ～ 15 岁,额骨投影面积的突增 期为12 ～ 15 岁,上颌骨投影面积的突增期为3 ～ 6 岁、6 ～ 9 岁和12 ～ 15 岁。结论：洋海墓地与扎滚鲁克墓地 儿童颅骨都体现出尺寸年龄变化的不均衡现象。由于儿童夭折的原因不明,故本文结论也可能受到古人群健康状 况、古病理状况的影响。     

Morphological peculiarities of the deep infratemporal fossa in advanced age

The main osseous landmarks of the border area between the infratemporal fossa and the para- and retro pharyngeal space are the sphenoidal spine and the pterygoid and styloid processes, and the styloid vagina. These landmarks, as well as some vascular anomalies, were studied in order to illustrate the variable anatomy, which is encountered in the surgical lateral transzygomatic infratemporal fossa approach. Hundred well-preserved human skull bases were examined. The deep infratemporal fossa was dissected into 54 halves of fixed cadaveric head and neck specimens of both sexes. Dry skull specimens of New and Old World monkeys, skulls of rodents, herbivora and carnivora, and computed tomograms of the head of Macaca fuscata Japonica, were also studied. In 91 of the human skull bases, the sphenoidal spine was prominent and well developed. In three skulls, the spine was absent. In four specimens, however, the spine was not sphenoidal but a part of the temporal bone, occurring in the form of a process, which emanated from the styloid vagina. In two further cases, there was unilaterally a duplicated spine; the anterior part represented a regular sphenoidal spine, while the posterior part constituted a part of the vagina of the styloid process. A complete osseous bar, arch or lamina—connecting the posterior border of the lateral lamina of the pterygoid process and the sphenoidal spine—existed in six of the human dry skulls. In ten of the human skulls examined, the breadth of the lateral lamina of the pterygoid process was greater than 10 mm; thus, the so-called pterygospinous (ps) and the pterygostyloid gates—of significance where surgical approaches are concerned—were less than 10 mm in width. Fibrous or muscular connections were also found in some cadaveric specimens between the posterior border of the lateral lamina of the pterygoid process and the sphenoidal spine: a ps ligament existed in 11 cases (20.4%) and a ps muscle in 5 cases (9.2 %), in 3 of which it inserted into both the medial wall capsule and the articular disc of the temporo-mandibular joint. Among the cadaveric specimens exhibiting ps structures was one in which an osseous ps bar occurred together with a ps muscle; in two cases a strong ps ligament was observed together with a ps muscle. The distribution pattern of the mandibular nerve was affected by the positioning of the ps bar, ligament and muscle when the latter were present. The existence of a wide ps bar was noted in all the skulls of herbivora, rodentia, carnivora, and Old World monkeys that were examined, but never in those of the New World monkeys; it is likely that, in the human, this ps bar represents a phylogenetic remnant. In the human dry skull specimens and cadaveric material, the ps ligament was found to be a reinforcement of the interpterygoid fascia, and the ps muscle to be a third head of the lateral pterygoid muscle. In two cases, the internal carotid artery exhibited a significant elongation and space-consuming tortuosity (so-called coiling behavior) in the depth of the infratemporal fossa.     

Anatomical variations of the frontal sinus and its relationship with the orbital cavity

The anatomy of the frontal sinus is highly variable and its variations affect the occurrence/course of pathological processes. We investigated its size and relationship to the orbit, searching for patterns that would allow it to be classified anatomically. Cone beam computed tomography was applied to 91 skulls (age range 21–86 years) to determine sinus height, width, length, and length of contact with the orbit in the coronal and sagittal planes. In addition, orbital roof pneumatization in the coronal plane was categorized as: none; only medial part pneumatized; the medial and a portion of the central part pneumatized; roof predominantly pneumatized. Sinus dimensions varied widely (mm): height 6.2–50.0; width 3.7–54.0; length 2.4–45.0; frontal orbital contact 4.0–41.6; sagittal orbital contact 0.0–41.2. Pneumatization of the orbital roof (coronal plane) mostly affected the medial and a portion of the central part (50%), or the roof was predominantly pneumatized (32%). Three “types” of sinus (cluster analysis) were distinguished by the extent of pneumatization of the orbital roof in the coronal plane: “small”, pneumatization absent or only of the medial part; “medium‐sized”, pneumatization of the medial and a portion of the central part; “large”, roof predominantly pneumatized. All dimensions were significantly different among the types (P < 0.001). Sinus type was fairly predictive of the extent of contact with the orbit in the sagittal plane (not routinely assessed clinically). The data confirm the variability of frontal sinus anatomy and suggest a simple and straightforward classification with potential clinical relevance. Clin. Anat. 31:576–582, 2018. © 2017 Wiley Periodicals, Inc.     

Localization of pterion in neonatal cadavers: a morphometric study

Purpose  

Pterion is defined as a junction of temporal, frontal, parietal, and sphenoid bones. In newborns, pterion may be defined as a region that shows variability in the exact location because of the lack of complete bony structure. The aim of this study is to define the topographic anatomy of this important surgical point, pterion, and the variability of its localization on craniums of newborn cadavers.     

The Dorsal Sagittal Venous Sinus Anatomical Variations in Brachycephalic,Dolichocephalic, and Mesocephalic Dogs and Their Significance for Brain Surgery

Dorsal sagittal venous sinus (DSVS) is an encephalic structure located in the midline of brain dorsal surface, starting behind the frontal venous sinus and following the brain falx in its extension. Knowing DSVS morphology and cranial‐cerebral relationships it is very important for surgeon when he is planning the placement of craniotomies, in order to prevent the damage of this structure. The main purpose of this study were to establish craniometric points that can be used as key points of neurosurgical importance providing an anatomic framework to brain access regarding the localization of DSVS, and to characterize the morphology of DSVS in the three groups considered in study according their type of skull (brachycephalic‐B, dolychocephalic‐D and mesocephalic‐M). The study was performed on 138 formalin‐fixed cerebral hemispheres of 69 adult dog cadavers (23 of each group) which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes placed on the five craniometric points considered: asterion(ast), bregma(br), glabella(g), stephanion(st) and pterion(pt). From the three groups, DSVS length and width were different, his geometry in B assumed a triangular appearance and in D, M a “butterfly” shape. From all craniometric points considered, only bregma (br) can be useful as a landmark to delimitate DSVS morphology in all three groups. Asterion in M, stephanion in B, glabella and pterion in all three groups, can not be used to compose a framework that help to understand skull surface projection of DSVS morphology, since their measurements were not uniform. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

西藏现代藏族人颅的颅型及其特点

测量７０个西藏现代藏族人颅４０项指标；计算指数１６项；根据指数确定颅型，额型，颌型，眶型，鼻型与腭型；进行数理统计；观察性别差异，发现男发性间各测量值差显著，