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In layman's terms, the gizzard 'chews' the food for the bird because it does not have teeth to chew food the way humans and other mammals do. By comparison, although in birds the stomach occurs in the digestive tract prior to the gizzard, in grasshoppers the gizzard occurs prior to the stomach, while in earthworms there is only a gizzard, and ...
Individuals may have more or fewer bones than the average (even accounting for developmental stage) owing to anatomical variations. The most common variations include sutural (wormian) bones , which are located along the sutural lines on the back of the skull, and sesamoid bones which develop within some tendons, mainly in the hands and feet.
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones). The upright posture of humans is ...
A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In other species the rocks are ingested and pass through the digestive system and are frequently replaced.
A true endoskeleton is derived from mesodermal tissue. In three phyla of animals, Chordata, Echinodermata and Porifera (), endoskeletons of various complexity are found.An endoskeleton may function purely for structural support (as in the case of Porifera), but often also serves as an attachment site for muscles and a mechanism for transmitting muscular forces as in chordates and echinoderms ...
Humans have a foot arch rather than being flat footed. [7] When non-human hominids walk upright, weight is transmitted from the heel , along the outside of the foot, and then through the middle toes while a human foot transmits weight from the heel, along the outside of the foot, across the ball of the foot and finally through the big toe.
In humans, tail bud refers to the part of the embryo which develops into the end of the spine. [19] However, this is not a tail. [ 20 ] Infrequently, a child is born with a "soft tail", which contains no vertebrae, but only blood vessels , muscles , and nerves , but this is regarded as an abnormality rather than a vestigial true tail, even when ...
1 occipital bone; 2 parietal bones; 1 sphenoid bone; 2 temporal bones; The ossicles (three on each side) are usually not included as bones of the neurocranium. [6] There may variably also be extra sutural bones present. Below the neurocranium is a complex of openings and bones, including the foramen magnum which houses