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Aboral, literally “standing away from the mouth”: compound word, of Latin origin, derived from ab (from) and os, oris (mouth); its opposite is adoral or, simply, oral. The term is used in anatomy to indicate the opposite direction or location of the mouth, the pole opposite the oral pole: when speaking of localizations, or directions, […]

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Gross anatomy

Gross anatomy (also called topographical anatomy, regional anatomy, or anthropotomy) is the study of anatomy at the visible (related to the structure that can be seen through naked eyes) or macroscopic level; it is studied using both invasive and noninvasive methods with the goal of obtaining information of the macroscopic structure and organization of organs and

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The myelencephalon contains the medulla oblongata or bulb and is the caudocranial continuation of the spinal cord. It is the lower part of the brain stem. It protrudes, in its lower part, for a short distance outside the foramen magnum of the occipital bone. Externally it shows an anterior, two lateral and one posterior face. On the

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Permanent tissue

Permanent tissues may be defined as a group of living or dead cells formed by meristematic tissue and have lost their ability to divide and have permanently placed at fixed positions in the plant body. Meristematic tissues that take up a specific role lose the ability to divide. This process of taking up a permanent shape,

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Abducens nerve

The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocular muscles responsible for outward gaze. It is a somatic efferent nerve. The nerve originates from the nucleus of the abducens nerve of the pons tegmentum, emerges

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The metencephalon forms the cerebellum dorsally and its lumen forms the anterior portion of the 4th ventricle, which in some animals sends a diverticulum into the cerebellum. In Mammals, the ventral portion forms the Varolius bridge. The cerebellum is a nerve center of great importance in the coordination and regulation of motor activities and in the maintenance

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The term macrocephaly (from ancient Greek μακρός, macro, “long, large”; κεφαλή, kephalē, “head”), in human pathological anatomy, indicates a skull size greater than the 97th percentile of the comparison group of equal age and same sex. This abnormality may be evident in the newborn and may signal various conditions arising during embryonic development or in the first

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Glial cells [glia]

Glial cells (also called glia or neuroglia), are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses; supportive tissue of the brain, includes astrocytes, oligodendrocytes, ependymal cells and microglia. Unlike neurons, glial cells do not conduct electrical impulses; and they can reproduce. The largest percentage of

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Diencephalon [interbrain]

The diencephalon is a portion of the encephalon. Together with the telencephalon (the cerebral hemispheres plus the basal nuclei) it constitutes the brain. Median and symmetrical, with a truncated pyramid shape, it is intercalated between the lower axial centers (spinal cord, brainstem) and the upper axial centers (telencephalon). Within it is found the cavity of

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Neurons are the cells considered to be the basis of nervous tissue. They are responsible for the electrical signals that communicate information about sensations, and that produce movements in response to those stimuli, along with inducing thought processes within the brain. An important part of the function of neurons is in their structure, or shape. The

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Muscular system

The muscular system is composed of specialized cells called muscle fibers. Their predominant function is contractibility. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement. Nearly all movement in the body is the result of muscle contraction. Exceptions to this are the action of cilia, the flagellum on sperm cells,

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The encephalon (from greek ἐγκέφαλος, enképhalos, “inside the head”, composed of ἐν, en, “in” and κεϕαλή, kephalè, “head”) is that part of the central nervous system completely contained in the skull box and divided from the spinal cord by a conventional plane passing just below the decussation of the pyramids. Embryologically, the encephalon develops from three vesicles

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Mesencephalon [midbrain]

The mesencephalon (also called the “midbrain”) is the second of three vesicles that arise from the neural tube that forms the brain of developing animals. Caudally, the midbrain joins the metencephalon and rostrally the diencephalon. In the brain of a fully developed human, the midbrain becomes the least developed, both in appearance and in its own structure,

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The telencephalon is the largest portion of the brain in humans. Together with the diencephalon, it forms the brain, the primary organ of the central nervous system. Its main functions include receiving external stimuli and processing a motor response, memory, and decision-making skills. The telencephalon is ovoid in shape, with the major axis oriented anteroposteriorly, and is

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Blood is the only fluid tissue with a complex composition (plasma, red blood cells, white blood cells and platelets and other substances in solution) and non-Newtonian behavior. This tissue is enclosed in a system of channels communicating with each other (arterial vessels and venous vessels), in which it can circulate because it is pushed mainly by

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Bone marrow

Bone marrow, in humans, is the principal hematopoietic organ; it is a soft, nutrient-rich, spongy tissue that occupies the canals of the long bones and the central fascia of the flat bones. Under normal conditions it performs a primary function in the production, maturation, and destruction of blood cells. The production of blood cells depends

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The term tissue is used to describe a group of cells found together in the body. The cells within a tissue share a common embryonic origin. Microscopic observation reveals that the cells in a tissue share morphological features and are arranged in an orderly pattern that achieves the tissue’s functions. From the evolutionary perspective, tissues

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Stomach Structure

The stomach (in ancient Greek στόμαχος, stòmachos, hence Latin stomachus; in Latin also ventriculus) is an organ of the digestive system, located between the esophagus and the small intestine, whose function is to store food and initiate its digestion. The prefix “gastro-“, which identifies medical terms related to the stomach, comes from the Greek γαστήρ,

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An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that coexist in organ systems. They represent spatially and morphologically defined parts of the body, form specialized work units and present characteristic relationships, structure and functions. The organ is part and operates within a system or apparatus, which

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Neuroscience [neurobiology]

Neuroscience (or neurobiology) is the study of the nervous system, including anatomy, physiology and emergent proprieties. It is a field to which belong anatomy, molecular biology, mathematics, medicine, pharmacology, physiology, physics, engineering and psychology. The term neuroscience is a neologism coined by the American neurophysiologist Francis O. Schmitt. He argued that if we wanted to obtain a

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Muscle tissue

Muscle tissue is excitable, responding to stimulation and contracting to provide movement, and occurs as three major types: skeletal (voluntary) muscle, smooth muscle, and cardiac muscle in the heart. Muscle tissue is composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts. The tissue is

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