By I. Miguel. West Virginia Wesleyan College.

When the two semi- upper five thoracic vertebrae and inserts on the mastoid spinalis capitis muscles contract together purchase arava 10mg otc, they extend the head process of the temporal bone (fig. This muscle extends at the neck, along with the splenius capitis muscle. If one of the the head at the neck, bends it to one side, or rotates it muscles acts alone, the head is rotated to the side. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 256 Unit 4 Support and Movement FIGURE 9. Suprahyoid Muscles The sternohyoid muscle originates on the manubrium of the sternum and inserts on the hyoid bone. It depresses the hyoid The group of suprahyoid muscles located above the hyoid bone as it contracts. The digastric is a two-bellied muscle of double origin that When this muscle contracts, the larynx is pulled downward. The anterior origin is on the mandible The short thyrohyoid muscle extends from the thyroid car- at the point of the chin, and the posterior origin is near the mas- tilage to the hyoid bone. It elevates the larynx and lowers the toid process of the temporal bone. The long, thin omohyoid muscle originates on the superior The mylohyoid muscle forms the floor of the mouth. It acts to de- originates on the inferior border of the mandible and inserts on press the hyoid bone. It aids swallowing The coordinated movements of the hyoid bone and the larynx by forcing food toward the back of the mouth. The hyoid bone does not articulate with any other bone, yet it has eight paired muscles attached to it.

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Once a stimulus has subsided and the fibers cient number of skeletal muscle fibers are activated buy generic arava 20 mg line, the muscle within muscle tissue are relaxed, they may be stretched contracts and causes body movement. The fibers are then prepared for another (2) heat production, and (3) body support and maintenance of contraction. The most obvious function performed by dency to recoil to their original resting length. A histological description of each of the three muscle types Even the eyeball and the auditory ossicles have associated was presented in chapter 4 and should be reviewed at this skeletal muscles that are responsible for various move- time. The contraction of skeletal muscle is equally impor- chapter 13 in the autonomic nervous system and in chapter 16, tant in breathing and in moving internal body fluids. Smooth muscle is widespread stimulation of individual skeletal muscle fibers maintains a throughout the body and is also involuntary. It is discussed in state of muscle contraction called tonus, which is impor- chapter 13 and, when appropriate, in connection with the organs tant in the movement of blood and lymph. The remaining information presented in this important in continuously exercising skeletal muscle fibers. Muscles are usually described in groups according to Likewise, the involuntary contraction of cardiac muscle tis- anatomical location and cooperative function. Body temperature is held remarkably skeleton include those that act on the pectoral and pelvic girdles constant. Metabolism within the cells releases heat as an and those that move limb joints. The Knowledge Check rate of heat production increases greatly during strenuous exercise.

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A strong acid Normally safe arava 10mg, carbohydrates and fats are completely oxidized (HCl) (right to left) or strong base (NaOH) (left to right) was added and the resulting solution pH recorded (y-axis). Incomplete oxi- a given amount of acid or base is least) when the solution pH is dation of carbohydrates occurs when the tissues do not re- equal to the pKa of the buffer. In such states, glucose me- Food intake tabolism yields lactic acid (pKa 3. Incomplete fatty acid oxidation occurs in uncontrolled diabetes melli- tus, starvation, and alcoholism and produces ketone body Absorption acids (acetoacetic and -hydroxybutyric acids). At blood pH, they Cell metabolism buffering response response of food mostly dissociate into their anions and H , making the + + H H blood more acidic. Bound by Sulfate body buffer CO2 Phosphate bases Protein Metabolism Generates Strong Acids Chloride CO 2 The metabolism of dietary proteins is a major source of Extracellular H. The oxidation of proteins and amino acids produces New strong acids such as H SO , HCl, and H PO. The oxi- fluid HCO - 2 4 3 4 [HCO -] 3 3 dation of sulfur-containing amino acids (methionine, cys- teine, cystine) produces H2SO4, and the oxidation of cationic amino acids (arginine, lysine, and some histidine Extracellular residues) produces HCl. H3PO4 is produced by the oxi- fluid [HCO -] dation of phosphorus-containing proteins and phospho- 3 CO2 esters in nucleic acids. H+ Excreted (combined with urinary On a Mixed Diet, Net Acid Gain Threatens pH buffer bases) A diet containing both meat and vegetables results in a net Excreted production of acids, largely from protein oxidation. To Sulfate Sulfate some extent, acid-consuming metabolic reactions balance Phosphate Phosphate Chloride Chloride H production. When these are oxidized to CO2 and water, H ions are consumed (or, amounting to The maintenance of normal blood pH by FIGURE 25. The balance of acid- chemical buffers, the respiratory system, forming and acid-consuming metabolic reactions results in and the kidneys. On a mixed diet, pH is threatened by the pro- duction of strong acids (sulfuric, hydrochloric, and phosphoric) a net production of about 1 mEq H /kg body weight/day in an adult person who eats a mixed diet.

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An injection near the foramen rotundum of the skull generic 10mg arava mastercard, called a second- under the lateral portions of the mandible and firmly squeezing division nerve block, desensitizes all of the upper teeth on one side medially. Hyoid Bone Auditory Ossicles The single hyoid bone is a unique part of the skeleton in that it does not attach directly to any other bone. It is located in the Three small paired bones, called auditory ossicles, are located neck region, below the mandible, where it is suspended from the within the middle-ear cavities in the petrous part of the temporal styloid process of the temporal bone by the stylohyoid muscles bones (fig. The hyoid bone has a body, two lesser cornua malleus (“hammer”), incus (“anvil”), and stapes (“stirrup”). As described in chapter 15, their movements transmit sound im- pulses through the middle-ear cavity (see p. Skeletal System: © The McGraw−Hill Anatomy, Sixth Edition Introduction and the Axial Companies, 2001 Skeleton 158 Unit 4 Support and Movement FIGURE 6. State which facial and cranial bones of the skull are paired and which are unpaired. Also, indicate at least two struc- tural features associated with each bone of the skull. Describe the location of each bone of the skull and indi- cate the sutures that join these bones. What is the function of each of the following: sella turcica, foramen magnum, petrous part of the temporal bone, crista galli, and nasal conchae? The bodies of the vertebrae are separated by intervertebral discs, which allow flexibility. VERTEBRAL COLUMN support the skull and allow for its movement, articulate with the The vertebral column consists of a series of irregular bones called rib cage, and provide for the attachment of trunk muscles. The vertebrae, separated from each other by fibrocartilaginous inter- intervertebral discs lend flexibility to the vertebral column and vertebral discs.