Ella Sexton July 23, 2020 Anatomy
Joints are points at which two bones meet. They enable a range of movements like rotation, abduction, adduction, protraction, retraction and more. Based on flexibility and mobility, joints can be further classified into movable joints and immovable joints. Movable joints are flexible while immovable joints (also called fixed joints) are non-flexible since the bones are fused.
The need for thinner, more transparent tissue specimens for study under the light microscope stimulated the development of improved methods of dissection, notably machines called microtomes that can slice specimens into extremely thin sections. In order to better distinguish the detail in these sections, synthetic dyes were used to stain tissues with different colours.
Muscles are specialised tissues which assist the bones in locomotion. Muscles are attached to the bones through tendons. Movement of limbs happens due to the contraction and relaxation of corresponding muscles present in that region. Joints help in the flexibility of bones, but a bone cannot be bent or stretched until a muscle acts on it. In other words, the muscles attached to that bone pulls it to the direction of movement.
This is the result of humans having ancestors that began walking on their hind limbs rather than using all four limbs. Most of our anatomical insight was gained through the dissection of corpses (cadavers), and for a long time, it was the only way we could gain anatomical knowledge about the human body. It was a rather grotesque affair, but it made up the bulk of medical literature for centuries. These days, technological innovation has made it possible to explore human anatomy at a microscopic level.
Comparative anatomy, the other major subdivision of the field, compares similar body structures in different species of animals in order to understand the adaptive changes they have undergone in the course of evolution.
The use of the microscope in discovering minute, previously unknown features was pursued on a more systematic basis in the 18th century, but progress tended to be slow until technical improvements in the compound microscope itself, beginning in the 1830s with the gradual development of achromatic lenses, greatly increased that instrument’s resolving power. These technical advances enabled Matthias Jakob Schleiden and Theodor Schwann to recognize in 1838–39 that the cell is the fundamental unit of organization in all living things.
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