Morphometric studies on the facial skeleton of humans and pongids based on CT-scans.

The changes of the skull, which we can observe during the anthropogenesis, are reflected especially in the different skull proportions. We carried out metric measurements at the median level on 10 adult skulls each of humans, chimpanzees and gorillas as well as 11 skulls of orangutans. All skulls were scanned with a CT at the median level. We measured the lines and angles of the scans and the means and the standard deviations were calculated. We carried out a correlation analysis to observe the relation of their characteristics. We showed that there is a relation between the length of the skull base and the facial length in all species. From the results of the correlation analysis, we can also conclude that a relation exists between the degree of prognathism and the different length measurements of the facial skeleton. We also found a bending of the facial skeleton in relation to the cranial base towards the ventral side, also known as klinorhynchy, in all observed species. The highest degree of klinorhynchy was found in humans and the lowest in orangutans. We will discuss the different definition of the term klinorhynchy and its importance in the evolution of the hominoids.

[Study of the degree of pneumatization of the viscerocranium in man and pongidae]. / Untersuchungen zum Pneumatisationsgrad des Viscerocranium beim Menschen und bei den Pongiden.

The volumes of the paranasal sinuses of 41 adult skulls of humans, gorillas, chimpanzees and orangutans, were examined with use of a Computertomograph type SOMATOM DR. The percentage distribution of the volumes of the different paranasal sinuses showed that the maxillary sinus always had the greatest volume. The maxillary sinus of the humans showed the smallest volume percentage in comparison with the pongids. The typical differences between humans and pongids were observed in the ethmoidal cells and the sphenoidal sinus. The ethmoidal cells of the gorilla and the orangutan have to be defined as rudimentary. Those of the humans come to more than 20% of the total volume of the paranasal sinuses of all hominoids. Differing from the humans, the sphenoidal sinus of the pongids pneumatizes almost the whole sphenoid bone. This volume percentage of the pongids is twice as high as that of the humans. In addition, an index was calculated from the volume of the facial skeleton volume and the total volume of the paranasal sinuses and defined as the degree of pneumatization. We found that the gorilla has the highest degree of pneumatization followed by the chimpanzee, the orangutan, and the humans. The lowest degree of pneumatization of the humans may be related to the reduction of the jaws.

[The morphology of the palatine arch of pongids]. / Beitrag zur Morphologie des Gaumengewölbes der Pongiden.

With the help of frontal cuts through casts of skulls of Pongids we demonstrated the postnatal development of the form of the hard palate. The form of the hard palate is similar to a semicircle in the frontal cut. In the Chimpanzee the palatal form in the frontal cut ist not as semicircular as in the other great apes and is similar to the palatal form of humans in the molar region. The differences between Pongo pygmaeus and the african apes consists in the fact, that the palate of the Pongo pygmaeus has a stronger vault in the canine region than the palate of the Gorilla and Chimpanzee.

[Functional morphology of the maxillo-mandibular apparatus in the miniature swine MINI-LEWE. 10. Dentition]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 10. Zahndurchbruch.

In the miniature pig MINI-LEWE the canines and 3rd incisors are already present at birth. Deciduous dentition is completed by the age of 3 months, and the denture consists of 28 teeth. The "replacement milk teeth" (Stehlin 1899) appear between the age of 6 and 8 months. Eruption of the permanent teeth (44 teeth altogether) is not yet over by the 24th month of life.

[Functional morphology of the maxillo-mandibular apparatus in the miniature swine MINI-LEWE. 11. Discussion of the findings of the metric studies and dentition (conclusion)]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. II. Besprechung der Befunde über metrische Untersuchungen und Zahndurchbruch (Schluss).

The graphs showing the dimensions and angles of the skull and jaw indicate that postnatal development trends are basically uniform. Comparison with the Vietnamese miniature pig shows that the miniature pig MINI-LEWE has a longer skull. Postnatal skull growth is accompanied by a distinct shift in proportions. The sequence of dentition if broadly identical to that of the domestic pig and the Pitmann-Moore miniature pig.

[The functional morphology of the maxillomandibular apparatus of the miniature swine MINI-LEWE. 9. Metric studies of the skull and mandible]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 9. Metrische Untersuchungen am Schädel und Unterkiefer.

Skull and jaw growth are described mathematically as a dynamic process. Graphs of the growth process show that basically the rate of growth decreases monotonically with increasing age. The maximum rate of growth was recorded at the time of eruption of the deciduous dentition during the first 4 months of life. As expected, the changes in the measured angles were greatest during the first 3 or 4 months after birth.

[Functional morphology of the maxillo-mandibular apparatus of the mini-Lewe minipig. 7. Intramuscular nerve ramification model of the masseter muscle of juvenile animals]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 7. Intramuskuläre Nervenverzweigungsmuster in den Kaumuskeln juveniler Tiere.

The ramification patterns are basically the same at all ages. The existing patterns of intramuscular innervation change gradually only by increasing ramification. The masseter and zygomaticomandibularis muscles are innervated jointly by branches of the massetericus nerve. The medial pterygoid muscle is supplied by 2 branches. In 3 d old animals the lateral pterygoid muscle is supplied by a single branch, but 2 branches are already present in animals aged 2 months. The temporal muscle is innervated by 5 branches.

[Functional morphology of the maxillomandibular apparatus in the mini-Lewe minipig. 6. Intramuscular nerve ramifications in the masticatory muscles of adult animals]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 6. Intramuskuläre Nervenverzweigungen in den Kaumuskeln adulter Tiere.

The masseter muscle is innervated by branches of 3 nerves. The zygomaticomandibular muscle must be regarded as part of the masseter as it is supplied by 2 branches of the massetericus nerve. Two branches of the medial pterygoid nerve enter the medial pterygoid muscle medially. The lateral pterygoid muscle is supplied by the lateral pterygoid nerve, which enters the muscle dorsally perpendicular to the muscle fibres. Five branches of the profound temporal nerves enter the temporal muscle from the ventral and medial sides. The branches of all nerves proceed parallel to each other in the dorsal direction towards the origin of the muscle.

[Functional morphology of the maxillo-mandibular apparatus in the miniature swine MINI-LEWE. 8. The development of the intramuscular nerve ramification pattern in the masticatory muscles]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 8. Besprechung der Ergebnisse über die Entwicklung des intramuskulären Nervenverzweigungsmusters in den Kaumuskeln.

Postnatal changes in the intramuscular innervation pattern of the masticatory muscles of the miniature pig MINI-LEWE are only gradual. There are no definite relationships between the paths of nerves and the positions of the fasciae. The few anastomoses found were in the masseter muscle. The only other nerve found to be implicated in the motor innervation of the masticatory muscles was the motor root of the trigeminal nerve. Innervation studies are a good way of identifying the bounds of muscles: the masseter and zygomaticomandibularis muscles, for instance, are innervated jointly by the massetericus nerve, so that the zygomaticomandibularis muscle can be regarded as belonging to the masseter muscle.

[Functional morphology of the maxillo-mandibular apparatus in the mini-Lewe minipig. 1. Miniature swine in oro-anatomically-oriented research]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 1. Das Miniaturschwein in der oral-anatomisch orientierten Forschung.

This bulletin marks the beginning of a cycle dealing with the structure, function, innervation and quantitative analysis of jaw muscles as well as postnatal cranial growth and dentition in the miniature pig MINI-LEWE. The aims, the importance of the miniature pig MINI-LEWE for medical research, the material and the methods are explained.

[Functional morphology of the maxillo-mandibular apparatus in the mini-Lewe minipig. 5. Structural and functional changes of the masticatory muscles and their dry weight development]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 5. Besprechung der Ergebnisse des Struktur- und Funktionswandels der Kaumuskulatur sowie deren Trockengewichtsentwicklung.

The basic pinnate structures caused by Sehnenspiegel in the jaw muscles are already present in newborn animals. The functional changes in the jaw muscles are described in terms of an analysis of force components based on the dry weights of the individual muscles involved in chewing action. Although the protractive and retractive components are relatively large in newborn pigs, the adductive components predominate clearly in adult animals. The development of the jaw muscles in terms of dry weight shows that the masseter muscle predominates at all ages. The miniature pig MINI-LEWE is assigned to the herbivorous type on the basis of the dry weight distribution.

[Functional morphology of the maxillo-mandibular system in the mini-Lewe minipig. Structures of masticatory muscles in juvenile animals]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 3. Kaumuskelstrukturen bei juvenilen Tieren.

The postnatal changes in the structures of the masticatory muscles are explained on the basis of the Sehnenspiegel. The jaw musculature of juvenile miniature pigs is similar in structure to that of adult animals. All Sehnenspiegel can be found in animals that are only 3 d old. Postnatal development of the masticatory musculature takes place on the basis of the pinnation existing prior to birth and consists in secondary pinnation.

[Functional morphology of the maxillo-mandibular apparatus of the mini-Lewe minipig. 2. Structure of the masticatory muscles of adult animals]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 2. Strukturen der Kaumuskeln adulter Tiere.

The masseter muscle is the most powerfully developed of the jaw muscles in the miniature pig MINI-LEWE. Its internal skeleton contains 5 Sehnenspiegel. The zygomatico-mandibular muscle acts as a link between the masseter and temporal muscles. The pinnate structure of the temporal muscle results from the internal tendons, which attach to the coronoid process. The medial pterygoid muscle with its 7 Sehnenspiegel has the most complex pinnate structure. The lateral pterygoid muscle has small tendinous slips only in the regions of its origin and attachment.

[Functional morphology of the maxillo-mandibular system in the mini-Lewe minipig. 4. Functional analysis of the masticatory muscles at various ages]. / Funktionelle Morphologie des maxillo-mandibulären Apparates beim Miniaturschwein MINI-LEWE. 4. Funktionelle Analyse der Kaumuskulatur in verschiedenen Altersstufen.

The percentage of dry weight distribution of the jaw muscles is described, and muscle growth is calculated by means of second degree homogeneous linear differential equations with constant coefficients. The components of the chewing muscles are calculated from the parallelogram of forces on the basis of their dry weights. Changes in the shape of the skull during postnatal development leads to an increase in the adductive components and a reduction of the protractive components. Changes in the reaction, medial tensile, lateral tensile and depressive components are minor.