Body Organs

The term of sinus (a “channel” or “hollow space”) is defined as any cavity within a bone but is most often used to identify the muscus lined air cavities in the facial bones and certain blood passageways in animals . In humans, sinuses surround the nose and are known as the paranasal sinuses. They extend from the nasal cavities into adjoining bones and are connected to the nose by passageways. The panasal sinuses are thought to help warm and moisten inhaled air. They also reduce the weight of the skull and perhaps modify vocal sounds. The bones that contain sinuses are the frontal, sphenoid, ethmoid, and maxillary bones. The paranasal sinuses are lined with a mucosa, or moist membrane. Glands are present within the mucosa, and ciliated and gobiet cells occurs on the surface, exposed to the air space in the sinus. The ciliated cells exhibit hairlike processes that beat back and forth. They serve to keep the air that enters the lungs clean by trapping dust and dirt. The particles and mu...

The Hyoid bone is named from its resemblance to the Greek upsilon; it is also called the lingual bone, because it supports the tongue and gives attachment to its numerous muscles. It is a bony arch, shaped like a horseshoe, and consisting of five segments, a body, two greater cornua, and two lesser cornua. It is suspended from the tip of the styloid processes of the temporal bone by ligmentous bonds, the style hyoid ligaments. The body (basi hyal) forms the central part of the bone, and is of a quadric-lateral form; its anterior surface, convex, directed forward and upward, and is crossed at right angles by a horizontal ridge, so that this surface is divided into four spaces or depressions. At the point of meeting of these two lines is a prominent elevation, the tuberele. The portion above the horizontal ridge is directed upward, and is sometimes described as the superior border. The anterior surface gives attachment to the Genio-hyoid in the greater part of its extent; above, to the G...

The ear is the organ of hearing and equilibrium (balance) in vertebrates. The ear converts sound waves in the air to nerve impulses that are relayed to the brain, where they are interpreted as sound rather than as mere vibrations. The innermost portion of the ear maintains Biological Equilibrium through the so-called vestibular apparatus, which includes the semicircular canals. Any change in the position of the head or body causes the apparatus to transmit nerve impulses to the brain, evoking muscular apparatus is basically alike in all vertebrates; hearing structures evolved later in the higher vertebrates. Many vertebrates also have specialized sense organs, rather than ears, for hearing and equilibrium. Crickets and spiders, for example, have membranes much like sounding boards on the legs. Moths have a similar rudimentary ear on the thorax that apparently serves as a warning system for attacks by bats. Structure of the Ear The ear in humans and most other mammals consist of three p...