Body Organs

The cranial nerves arise from some part of the corebrospinal center and are transmitted through formina in the base of the cranium. They pass through the dura mater lining the base of the skull. Other names are also given to them, derived from the parts to which they are distributed or from their functions. Taken in their order, from before backward, they are as follows: 1. Olfactory 2. Optic 3. Motor oculi 4. Trochlear (Pathetic) 5. Trifacial (Trigeminus) 6. Abducent 7. Facial (Portio dura) 8. Auditory (Portio mollia) 9. Glosso Pharyngeal 10. Pneumogastric (or Vague) 11. Spinal accessory 12. Hypoglossal All the cranial nerves are connected to some part of the surface of the brain. This is termed their superficial or apparent origin. But their fibre may, in all gray matter, termed a nucleus. This is called their deep or real origin. The foramina or tubular prolongations in the dura mater, leave the skull through foramina in its base, and pass to their final distribution.

The coccyx, so called from having been compared to a cuckoo’s beak is usually formed of four small segments of bone, the most rudimentary parts of the vertebral column. In each of the first three segments may be traced a rudimentary body, articular and transverse processes; the last piece (sometimes the third) is a mere nodule of bone, without distinct processes. All the segments are destitute of pedicles, laminae, and spinous processes, and consequently of intervertebral foramina and spinal canal. The first segment is the largest; it resembles the lowermost sacral vertebra, and often exists as a separate piece; the last three, diminishing in size from above downward, are usually blended together so as to form a single bone. The gradual diminution in the size of the pieces gives this bone a triangular form, the base of the triangle joining the end of the sacrum. It presents for examination an anterior and posterior surface, two borders, a base and an apex. The anterior surface is sligh...

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...

The stomach is the principal organ of digestion. It is the most dilated part of the alimentary canal, and is situated between the termination of the esophagus and the commencement of the small intestine. Its form is somewhat pyriform with the large end (fundus) directed upward and the small end bent to the right. It is situated in the left hypochondriae and epigastric regions, and is placed, in part, immediately behind the anterior wall of the abdomen and beneath the Diaphragm. Viewing the stomach from in front it appears that the right margin of the esophagus is continued downward as the upper tow-third of this border bending sharply backward and to the right, to complete the smaller curvature. The greater curvature begin at the left border of the termination of the esophagus in a somewhat acute angle; it lies in contact for some distance, and then sweeps downward with a convexity to the left and continued across the middle line of the body, finally turns upward and backward, to t...

Excretory systems are special structures in organism through which waste products of metabolism are rid and the proper balance of water and salts in the blood and other body fluids is maintained at the same time. Detection is the elimination of undigested material from the body and is a function of the digestive system. Urinary system The major excretory organs in vertebrates are the kidneys , which are two paired organs, one on each side of the body. The kidneys and associated organs that store and eliminate urine are collectively called the urinary system. The kidneys dispose of toxic wastes, such as ammonia, urea and uric acid, and excess salt and water in the form of urine. The heart, in a sense, pumps blood blindly, but the kidneys monitor the quality of blood so that the organism is not poisoned by the end products of its own metabolism and the proper volume and composition of its body fluids are maintained. The kidneys continually form urine by filtering many material...