Dynamics of optic canal and orbital cavity development revealed by microCT.

PURPOSE: Numerous studies have attempted to clarify the exact anatomy and variations of the optic canal with non-conclusive results due to its close proximity to many vulnerable structures. We sought to determine the dynamics of growth and development of these structures on fetal skulls, which will help us to better understand of gender and age-dependent variations, as well as fatal malformations. METHODS: Fifteen previously macerated fetal frontal and sphenoid bones were analyzed and the diameters of optic canal, and distance of orbit from frontomaxillary suture to frontozygomatic suture were measured using 3D reconstruction images obtained by micro-CT. RESULTS: Average diameter of the optic canal in 300 mm fetus was measured to be 1,546 ± 36 µm, in 400 mm fetus 2,470 ± 123 µm and in 500 mm fetus 3,757 ± 203 µm. This trend indicates a linear enlargement of optic canal during the fetal period. During the same time period, diameter of the orbit enlarges from 12,319 ± 559 µm in 300 mm fetus to 19,788 ± 736 µm in 500 mm fetus. Growth curve is significantly lower in comparison with the same curve in optic canal data. We also calculated the ratio of orbit diameter and optic canal diameter between those groups which decreased from a value of 7.9 ± 0.4 for 300 mm fetus to 5.3 ± 0.2 for 500 mm fetus. CONCLUSION: Dynamics of optic canal and orbital cavity development is different in early and late fetal period. Diameters of those structures are in better correlation with the fetal length.

Postnatal changes in the styloid process, vagina processus styloidei, and stylomastoid foramen in relation to the function of muscles originating from the styloid process.

We investigated age-related changes in the styloid process in 88 skulls, aged from 5 months to 85 years of age. The osseous styloid process was not well developed in children. Its length increased significantly with age (from 2.3 mm in 11-20 age group to 16.3 mm in 61-85 group). In adolescent specimens (11-20 years of age), the median distance from the styloid process to the stylomastoid foramen was 0.7-0.8 mm, whereas in adult and old age specimens the two structures were completely adjacent or very close, usually less than 0.2 mm. The process was missing in 5% of the adult specimens. There was a statistically significant positive association between the length of the styloid process with age (r = 0.3210, 95% CI 0.0817-0.5254; P = 0.0097), whereas the distance from the styloid process to the stylomastoid foramen significantly decreased with age (r = -0.4518, 95% CI -0.6167 to -0.2490; P = 0.0001). Changes in the length and shape of the styloid process reflected altered function of the three muscles originating from the styloid process-m. stylopharyngeus, m. stylohyoideus and m. styloglossus. They have a common function of lifting the aerodigestive elements upward and backward, after the descent of the aerodigestive tract and final morphological differentiation of the vocal system during puberty. Relationship between altered muscle function and the morphology of the styloid process are important for understanding the clinical syndromes related to the styloid process, such as Eagle's syndrome.

Postnatal changes in osseous and mucosal morphology of the hard palate.

We investigated the postnatal changes in the dimensions, configuration, and surface pattern of the hard palate in 68 skulls, ranging in age from birth to 90 years of age. The number of palatine rugae of the palatine mucosa was assessed in 168 living subjects aged 11-98 years. Before the first dentition appeared, the osseous palate was concave, smooth, and lacked alveolar processes. In maxillar specimens from the end of the first year to the end of the fourth year of life, balloon-like osseous formations, containing the elements of permanent teeth, appeared bilaterally behind the deciduous incisors. With age, the concavity of the palate diminished and became flat with the loss of the teeth. The presence of teeth was associated with the height of the alveolar ridge, which decreased from 7.3 +/- 4.4 mm in specimens with intact teeth to 4.7 +/- 4.1 mm in specimens without teeth (P = 0.020). Palatine rugae were a common finding in living subjects, but were more often absent in older age (2.2% in 11-50 age group vs. 12.8% in 51-98 age group, P = 0.0183). Our results suggest that the morphology of the hard palate rapidly changes during deciduous and permanent teeth eruption and is related to the presence of alveolar ridges and teeth in adults. Palate osseous morphology may be morphologically and functionally independent from its mucosal morphology. Changes in the morphology of the osseous palate are clinically relevant for dental prosthetics and tooth implantation.

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.

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.

Lost and found anatomical terms: Crista choanalis vomeris.

Pars cuneiformis vomeris and Crista choanalis are morphological structures on the vomer listed in the current official anatomical nomenclature, Terminologia anatomica, but are either not mentioned or incorrectly described in different anatomical books. The term Crista choanalis vomeris was originally proposed by Drago Perovic in 1958 to describe the vertical crest beginning at the angle of the alae vomeris, running downwards to the posterior free margin of the vomer. Perovic also described the part of the vomer behind this crest was shaped as a cone, and termed it Pars cuneiformis vomeris. Because of their important contributions to the function of the respiratory pathway, Crista choanalis vomeris and Pars cuneiformis vomeris deserve proper definitions in the anatomical terminology.

Postnatal changes of the clivus.

We studied the size of the clival region (length, widest and narrowest diameter, and distance between two jugular tuberculi) in 77 skull bases or occipital and sphenoid bones from skeletons aged 3-80 years. The comparison of the measurement points among the age groups (3-10, 11-25, 26-60, and 61-80 years) showed that the final length of the clivus was reached by 11 years of life in both men and women, and then remained constant throughout life. All other measurements did not differ among the age groups. Also, only the length of the clivus strongly correlated with age (Pearson's r = 0.336, P = 0.0028). It seems that the postnatal age up to 11 years of life is the crucial time of the development of the clivus, when the final adult width of the clivus is first reached, followed by the finalization of its growth in length.

The neglected maxillary process of the palatine bone.

In most recent anatomy textbooks as well as in the latest anatomical nomenclature, the maxillary process of the palatine bone is not mentioned at all. The maxillary process is, however with rare exceptions, always present as an important part of the closure of the hiatus sinus maxillaris. In our material consisting of 200 disarticulated, macerated skull bones and 25 specimens of maxillary sinus, the maxillary process was missing in only 5 cases (2.2%). This process develops in the second year of life and displays different shapes. It can be long and slender or wide and round shaped. Its upper margin is more or less concave, corresponding to the margin of the hiatus over which it is bent. Its inferior margin can be smooth or irregular. In instances in which maxillary sinus is double, the os palatinum has two maxillary processes, so that both sinuses are partly closed with the maxillary process of the palatine bone.

Cranial base kyphosis and the surface morphology of the anterior cranial fossa.

We investigated the relationship between the surface morphology of the anterior cranial fossa and cranial base kyphosis (sphenoid angle) in 52 cephalometric craniograms. Among them there were 25 female (mean age 54 +/- 15; range 31-82) and 27 male (mean age 43 +/- 18, range 19-85) skulls. The sphenoid angle and the altitudes of the highest elevation of the endofrontal eminence (cranial base over the orbital roof in the anterior cranial fossa) and the middle point of the sphenoid planum, measured according to the Frankfort horizontal, were analysed using classical cephalometric and morphometric analysis. Statistical analysis was performed by Pearson's product-moment correlation and simple linear regression. The sphenoid angle ranged from 97 degrees to 137 degrees (mean 118 +/- 9 degrees). The altitude ratio of the highest elevation of the endofrontal eminence and the middle point of the sphenoid planum ranged from 1.5 to 1.8 (mean 1.6 +/- 0.1). A significant correlation was found between this ratio and the sphenoid angle (r = -0.65; p < 0.001; coefficient of determination = 0.43). The elevation of the endofrontal eminence relative to the sphenoid planum was higher in skulls with increased cranial base kyphosis, whereas reduced sphenoid angle was associated with an increase in the elevations of the endofrontal eminence. Although the sphenoid angle has a significant effect on the morphology of the anterior cranial fossa, only 43% of the variance in altitude of the endofrontal eminence is likely to be explained by its relationship with the sphenoid angle.

The fate of the arachnoid villi in humans.

Villi arachnoidales undergoes in the course of life changes in relation to the skull bones and sinuses. Our aim was to determine the relations of the villi arachnoidales to the skull bone and/or sinuses from the neonatal period to adults. The investigations were performed on collection of 50 disarticulated macerated skull bones from the new-born to 30 years of age and on 20 skulls from individuals in the life period from 30 to 80 years of age. Villi arachnoidales produced imprints on the skull bones in the shape of holes and/or furrows corresponding to different shape of the villi arachnoidales. These imprints appeared very early in the period when the bony sprouts of the large skull bones received a thin covering of compact bone, the future lamina vitrea. At that time villi arachnoidales had no connection with the dural sinuses but with the diploe and with the diploic veins. By agglomeration of the villi in larger and large formations, granula meningea, Pacchionian granulations, the contact to sinuses was realized by means of short channels. The structural changes of villi arachnoidales may produce thrombophlebitis and hydrocephalus externus, especially in children. The fate and the relations of the villi arachnoidales are therefore of great importance for neurologist, neurosurgeon and otorhinolaryngologist.

The sequence in appearance and disappearance of impressiones gyrorum cerebri and cerebelli.

We investigated the sequence and the intensity in the appearance and the disappearance of the impressiones gyrorum cerebri and cerebelli, of juga cerebralia and cerebellaria and of juga cerebellaria interlobularia in the collection of 34 macerated and disarticulated skull bones from the newborn to 30 years of age (68 specimens/halves of skulls) and 19 skulls in the period from 30 to 80 years of age (38 specimens). Juga cerebralia on the squama of the temporal bone and cerebral lamina of the frontal bone appeared already in the course of the first year of life, much earlier than cited in the literature. The intensity of the development of juga cerebralia increased to the third decade. After that age, the intensity decreased gradually, and the juga cerebralia disappeared completely in parietal bones, in the cerebral fossae of the occipital bones and finally in most cases also on the cerebral lamina of the frontal bones. Juga cerebellaria and impressiones gyrorum cerebelli appeared in the middle of the second year of age and persisted to the ten years of age, which coincides with the closure of the fissures among the parts of the occipital bone. Jugum cerebellare intersemilunare appeared in the first year of life and persisted in its complete length, or interrupted in different sections of its course, during the whole life. The intensity in appearance of juga is partly influenced by the increasing thickness of the diploe.

The superficial ulnar artery originating from the left brachial artery.

An anomalous superficial ulnar artery was found in the left arm of a 60-year-old man during anatomical dissection. It originated from the brachial artery approximately 6 cm distally to profound brachial artery. It crossed over the median nerve and coursed ventral to the nerve, but inferior to the bicipital aponeurosis and superficial to the flexor muscles. At the palm, it formed the superficial and deep palmar arches together with the branches of the radial artery. The clinical importance of the anomalous ulnar artery is discussed.