Elbow Extensor Muscles in Humans and Chimpanzees: Adaptations to Different Uses of the Upper Extremity in Hominoid Primates.

The anatomical and functional characteristics of the elbow extensor muscles (triceps brachii and anconeus) have not been widely studied in non-human hominoid primates, despite their great functional importance. In the present study, we have analyzed the muscle architecture and the expression of the myosin heavy chain (MHC) isoforms in the elbow extensors in humans and chimpanzees. Our main objective was to identify differences in these muscles that could be related to the different uses of the upper extremity in the two species. In five humans and five chimpanzees, we have analyzed muscle mass (MM), muscle fascicle length (MFL), and the physiological cross-sectional area (PCSA). In addition, we have assessed the expression of the MHC isoforms by RT-PCR. We have found high MM and PCSA values and higher expression of the MHC-IIx isoform in the triceps brachii of chimpanzees, while in humans, the triceps brachii has high MFL values and a higher expression of the MHC-I and MHC-IIa isoforms. In contrast, there were no significant differences between humans and chimpanzees in any of the values for the anconeus. These findings could be related to the participation of the triceps brachii in the locomotion of chimpanzees and to the use of the upper extremity in manipulative functions in humans. The results obtained in the anconeus support its primary function as a stabilizer of the elbow joint in the two species.

Three-dimensional geometric morphometric analysis of the distal radius insertion sites of the palmar radiocarpal ligaments in hominoid primates.

OBJECTIVES: To identify anatomic differences in the insertion sites of the palmar radiocarpal ligaments in different species of hominoid primates that may be related to their different types of locomotion. MATERIALS AND METHODS: We have used three-dimensional geometric morphometrics (3D GM) to analyze the distal radius ligament insertion sites in 31 Homo sapiens, 25 Pan troglodytes, 31 Gorilla gorilla, and 15 Pongo pygmaeus. We have also dissected the radioscaphocapitate (RSC), long radiolunate (LRL) and short radiolunate (SRL) ligaments in six H. sapiens and five P. troglodytes to obtain quantitative values that were then compared with the results of the 3D GM analysis. RESULTS: H. sapiens had a relatively larger insertion site of the RSC + LRL ligament than the other hominoid primates. P. pygmaeus and P. troglodytes had a relatively large SRL ligament insertion site with a palmar orientation. In G. gorilla, the two ligament insertion sites were relatively smaller and the SRL insertion site had an ulnopalmar orientation. DISCUSSION: The morphological differences observed can be related to the types of locomotion used by the different species and to quantitative data obtained from the dissection of ligaments in H. sapiens and P. troglodytes. 3D GM analysis of ligament insertion sites can help in interpreting the types of locomotion used by extinct hominoid primates through the analysis of preserved fossilized fragments of the distal radius.

A possible new etiology for ophthalmic varicose veins: disseminated intracranial hyperostosis

We wanted to see if cranial anatomical alterations could influence the vascularization of the eyeball, particularly in the production of ophthalmic varicose veins. Orbital dissection of 85 years old woman (who suffered from Alzheimer's disease and respiratory failure).We observed, when performing a horizontal section of the skull to access the roof of the orbit, that the intracranial surface of the anterior and middle cranial fossae was partially covered by bony outgrowths, with the optical aperture and superior orbital fissure included. Also, when removing the roof of the orbits and beginning to extract the orbital fat we saw a dark, bilateral mass in the upper part of the orbital cavity corresponding to very dilated vessels. Bone alteration of the internal face of the skull was a diffuse intracranial hyperostosis and the dark dilated masses were superior ophthalmic varicose veins.Our hypothesis is that the origin of these ophthalmic varicose veins was the narrowing of the superior orbital fissure due to excessive bone proliferation. Intracranial hyperostosis produces a difficulty in draining orbital venous blood and, consequently, venous dilation. For this reason, we should consider this in the differential diagnosis

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Quantification of Myosin Heavy Chain Isoform mRNA Transcripts in the Supraspinatus Muscle of Vertical Clinger Primates.

Vertical clinging is a specialized form of locomotion characteristic of the primate family Callitrichidae. Vertical clinging requires these pronograde primates to maintain a vertical posture, so the protraction of their forelimbs must resist gravity. Since pronograde primates usually move as horizontal quadrupeds, we hypothesized that the supraspinatus muscle of vertical clingers would present specific characteristics related to the functional requirements imposed on the shoulder area by vertical clinging. To test this hypothesis, we quantified by real-time quantitative polymerase chain reaction the mRNA transcripts of myosin heavy chain (MHC) isoforms in the supraspinatus muscle of 15 species of pronograde primates, including vertical clingers. Our results indicate that the supraspinatus of vertical clingers has a specific expression pattern of the MHC isoforms, with a low expression of the transcripts of the slow MHC-I isoform and a high expression of the transcripts of the fast MHC-II isoforms. We conclude that these differences can be related to the particular functional characteristics of the shoulder in vertical clingers, but also to other anatomical adaptations of these primates, such as their small body size.

Biometry and statistical analysis of the styloid process.

The hyoid apparatus is made up of three osteocartilaginous elements that go from the base of the cranium to the hyoid bone; the portions, cranially to caudally, are as follow: stylohyal, ceratohyal, and apohyal. Fusion and ossification of these three components will bring about somewhat long stylohyoid processes, whereas the stylohyal portion is the one that gives rise to the authentic stylohyoid process. The variability of the hyoid apparatus may imply associated compressive pathologies, for which an etiological diagnosis is important. A study was undertaken of 835 craniums of a homogeneous male and female adult population, involving a morphometric analysis of the styloid processes in which quantification was made of the following continual descriptive measurements: thickness, length, sagittal angle, transversal angle, and the distance between vertices. Multivariate data analysis techniques were applied to the data set to describe the relationships between these measurements. The main conclusion from the analysis is the existence of two different groups of styloid processes and the derivation of a prediction score.

Psicobiología de las conductas agresivas / The Psychobiology of agressive behaviours

En este artículo hacemos una revisión sobre qué es la agresión y la violencia, para desentrañar sus posibles causas psicobiológicas, ya que consideramos que el estudio de los mecanismos psicobiológicos de la agresión hará posible un mayor entendimiento de la evolución de este comportamiento hasta el ser humano, así como una mejor clasificación de las manifestaciones patológicas de las conductas violentas. Definimos la violencia como una agresión destructiva que implica imposición de daños físicos a personas o a objetos de su propiedad, en cuanto que tales objetos son medios de vida para las personas agredidas o símbolos de ellas. Presentamos los diversos modelos psicobiológicos: genéticos, endocrinológicos, etológicos y neurobiológicos; describiendo cómo ciertos tipos de conductas violentas impulsivas patológicas, pueden ser abordadas como un problema comportamental con cierto correlato biológico (AU)