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Article

brain  

Julius Rocca

Knowledge of the brain as a body part is ancient. The term encephalos is found in Homer, but cognitive function was not ascribed to its contents. Certain of the Presocratics linked cognitive capacity to the brain. Similar views existed in the Hippocratic writings. For Plato, the brain’s cognitive role is due to its housing the rational soul. Aristotle regarded heart and brain as exerting sovereign control. In the Hellenistic period, the brain was systematically investigated, its cognitive and sensory capacities experimentally verified. Galen, building on this legacy and applying a rigorous experimental methodology, provided overwhelming proof that the brain mediated sensation and voluntary motion.The epistemological justification for cognitive, motor, and sensory functions to be ascribed to the structure lying “within the head” (encephalon) makes a relatively late appearance in antiquity. Empirical observations based on head injuries are far older. Babylonian medicine of the First Dynastic period (2nd millennium .

Article

Penile erection is a part of the human male sexual response, involving desire, excitation (erection), orgasm (ejaculation), and resolution, and autonomic nerves are involved in all phases. Autonomic innervation of smooth-muscle cells of the erectile tissue is provided by the cavernous nerve. Motor and sensory innervation is derived from the pudendal nerves and their terminal branches, that is, the dorsal nerves of the penis, which carry impulses from receptors harbored in the penile skin, prepuce, and glans. Erection begins with an increased flow in the pudendal arteries and dilatation of the cavernous arteries and helicine arterioles in association with relaxation of the smooth muscles of the trabecular network, causing engorgement of blood in the corpora. This leads to compression of subtunical venules by the resistant tunica albuginea and erection. During detumescence these events are reversed.

Article

The tongue is composed entirely of soft tissue: muscle, fat, and connective tissue. This unusual composition and the tongue’s 3D muscle fiber orientation result in many degrees of freedom. The lack of bones and cartilage means that muscle shortening creates deformations, particularly local deformations, as the tongue moves into and out of speech gestures. The tongue is also surrounded by the hard structures of the oral cavity, which both constrain its motion and support the rapid small deformations that create speech sounds. Anatomical descriptors and categories of tongue muscles do not correlate with tongue function as speech movements use finely controlled co-contractions of antagonist muscles to move the oral structures during speech. Tongue muscle volume indicates that four muscles, the genioglossus, verticalis, transversus, and superior longitudinal, occupy the bulk of the tongue. They also comprise a functional muscle grouping that can shorten the tongue in the x, y, and z directions. Various 3D muscle shortening patterns produce large- or small-scale deformations in all directions of motion. The interdigitation of the tongue’s muscles is advantageous in allowing co-contraction of antagonist muscles and providing nimble deformational changes to move the tongue toward and away from any position.

Article

Marie K. Huffman

Articulatory phonetics is concerned with the physical mechanisms involved in producing spoken language. A fundamental goal of articulatory phonetics is to relate linguistic representations to articulator movements in real time and the consequent acoustic output that makes speech a medium for information transfer. Understanding the overall process requires an appreciation of the aerodynamic conditions necessary for sound production and the way that the various parts of the chest, neck, and head are used to produce speech. One descriptive goal of articulatory phonetics is the efficient and consistent description of the key articulatory properties that distinguish sounds used contrastively in language. There is fairly strong consensus in the field about the inventory of terms needed to achieve this goal. Despite this common, segmental, perspective, speech production is essentially dynamic in nature. Much remains to be learned about how the articulators are coordinated for production of individual sounds and how they are coordinated to produce sounds in sequence. Cutting across all of these issues is the broader question of which aspects of speech production are due to properties of the physical mechanism and which are the result of the nature of linguistic representations. A diversity of approaches is used to try to tease apart the physical and the linguistic contributions to the articulatory fabric of speech sounds in the world’s languages. A variety of instrumental techniques are currently available, and improvement in safe methods of tracking articulators in real time promises to soon bring major advances in our understanding of how speech is produced.

Article

heart  

Julius Rocca

The heart (καρδία, κῆρ) was one of the most discussed bodily parts in antiquity. This is due, not so much to any assertion that it was the centre of the vascular system, but that it was widely regarded it as the seat of cognition and governor of movement and sensation. From the Hellenistic era onwards, these supposed attributes were set against the counter claim that the brain mediated these functions. This debate remained unsettled, despite Galen’s efforts, and the heart’s association with emotional states persists to this day.Babylonian medicine possessed terms for the irregularity of the pulse, which served as labels for the heart. Egyptian medicine named the heart (ib, haty), and a vessel system (metu), which transported fluids of the body (including blood and air), as well as pathological and waste products. The connection between the heart beat and the peripheral pulse seems to have been recognised. The Iliad provides vivid examples of fatal wounds to the heart.