C. Angar. Globe Institute of Technology.
Articulations © The McGraw−Hill Anatomy order 200 mg extra super viagra causes of erectile dysfunction in late 30s, Sixth Edition Companies buy 200 mg extra super viagra free shipping erectile dysfunction caused by ptsd, 2001 232 Unit 4 Support and Movement FIGURE 8. What are the advantages of a hinge joint Critical-Thinking Questions slipped forward at the knee (“bureau over a ball-and-socket type? In the upper and lower the anterior cruciate ligament was movement, why aren’t all the synovial extremities of your own body, which are ruptured. Identify four types of synovial joints type of lever system is adapted for rapid, 4. In what ways do the anatomical found in the wrist and hand regions, and wide-ranging movements. The star runningback of a local high elbow, hip, knee, and ankle joints relate each. Discuss the articulations between the emergency room of the local hospital 5. In chapter 6, you learned that the pectoral and pelvic regions and the axial following a knee injury during the periosteum does not cover the articular skeleton with regard to range of championship game. Review the functions of the movement, ligamentous attachments, and from a hard blow (“clipping”) to the back periosteum and explain why it is not potential clinical problems. In anticipation of what you will learn about does a sprain differ from a strain or a of the anterior cruciate ligament, the ER muscles in the following chapter, explain luxation? What occurs within the joint capsule in that this diagnosis could be confirmed by movement. How does pulling the tibia forward as the knee was opposite movement of flexion, and rheumatoid arthritis differ from flexed. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Muscular System 9 Introduction to the Muscular System 234 Structure of Skeletal Muscles 235 Skeletal Muscle Fibers and Types of Muscle Contraction 240 Naming of Muscles 246 Developmental Exposition: The Muscular System 248 Muscles of the Axial Skeleton 250 Muscles of the Appendicular Skeleton 263 CLINICAL CONSIDERATIONS 285 Clinical Case Study Answer 289 Important Clinical Terminology 293 Chapter Summary 293 Review Activities 294 Clinical Case Study A 66-year-old man went to a doctor for a routine physical exam. The man’s medical history re- vealed that he had been treated surgically for cancer of the oropharynx 6 years earlier. The pa- tient stated that the cancer had spread to the lymph nodes in the left side of his neck. He pointed to the involved area, explaining that lymph nodes, a vein, and a muscle, among other things, had been removed. On the right side, only lymph nodes had been removed, and they were found to be benign. The patient then stated that he had difficulty turning his head to the right. Obviously perplexed, he commented, “It seems to me Doc, that if they took the muscle out of the left side of my neck, I would be able to turn my head only to the right. If not, how would you explain the reason for his dis- ability in terms of neck musculature? Hints: The action of a muscle can always be explained on the basis of its points of attachment and the joint or joints it spans. FIGURE: Understanding the actions of muscles is possible only through knowing their precise points of attachment. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 234 Unit 4 Support and Movement 3. The skeletal system provides a INTRODUCTION framework for the body, but skeletal muscles maintain pos- TO THE MUSCULAR SYSTEM ture, stabilize the flexible joints, and support the viscera. Certain muscles are active postural muscles whose primary Skeletal muscles are adapted to contract in order to carry out the function is to work in opposition to gravity. Some postural functions of generating body movement, producing heat, and sup- muscles are working even when you think you are relaxed. As you are sitting, for example, the weight of your head is Objective 1 Define the term myology and describe the balanced at the atlanto-occipital joint through the efforts three principal functions of muscles. If you start to get sleepy, your head will suddenly nod forward as the Objective 2 Explain how muscles are described according postural muscles relax and the weight (resistance) over- to their anatomical location and cooperative function. Muscle tissue in the body is of three types: smooth, cardiac, Myology is the study of muscles. Although these three types differ in make up the muscular system, and technically each one is an structure and function, and the muscular system refers only to organ—it is composed of skeletal muscle tissue, connective tissue, the skeletal muscles composed of skeletal tissue, the following and nervous tissue.
The ionotropic glutamate receptor subunits have a large extracellular amino terminal domain and a long intracellular carboxy terminal domain (Fig 200mg extra super viagra for sale does erectile dysfunction cause low sperm count. The P2X receptor subunits are unusual in having only two transmembrane domains with both the amino terminal and carboxy terminal located intracellularly buy extra super viagra 200 mg without a prescription impotence webmd. The ion channel is proposed by analogy with the structure of some potassium channels to be formed by a short loop which enters the membrane from the extracellular side (North and Surprenant 2000). Subunit stoichiometry The ion channel receptors are multi-subunit proteins which may be either homomeric (made up of multiple copies of a single type of subunit) or heteromeric (composed of more than one subunit type). These subunits come together after synthesis in the endoplasmic reticulum to form the mature receptor. A receptor composed of two a and three b subunits is therefore denoted as having a stoichiometry of a2b3. This can cause confusion when related subunits are given sequential numbers: b1, b2, b3, etc. The convention is there- fore that subunits are numbered normally while stoichiometry is indicated by subscripts so that a pentamer of a4 and b3 subunits might have a stoichiometry of a42b33. NICOTINIC RECEPTORS All receptors in the 4-TM domain family are thought to form pentameric receptors in which five subunits (Fig. Their structure has been most extensively studied in the case of the nicotinic acetylcholine receptor (analogous to the muscle endplate receptor) from Torpedo electroplaque (Unwin 2000) where there is now a detailed knowledge of the receptor in both resting and active conformations. The muscle receptor has a subunit stoichiometry of two a subunits, providing the agonist binding sites, and three other subunits (b, g and d). In adult muscle an e subunit is present instead of the g subunit which is found in the foetal-type receptor. The five subunits are arranged like the staves of a barrel around the central channel. Binding of ACh to the a subunits initiates a conformational change in the protein which, by causing rotation of all five TM2 domains lining the pore, opens the ion channel. Diversity among neuronal nicotinic receptors is generated by having nine more different a subunits (a2±a10) and three further b subunits (b2±b4). These receptors are activated by nicotine and blocked by the antagonists hexamethonium, mecamylamine and trimetaphan, and the erythrina alkaloid dihydro-b-erythroidine. The neuronal nicotinic receptors are found in autonomic ganglia and in the brain may be either heteromeric (e. The a7 receptor is likely to be the source of the a-bungarotoxin binding sites in the brain observed in autoradiograms of 123I-a- bungarotoxin binding to brain sections (Clarke 1992) and a-bungarotoxin sensitive nicotinic receptors have been shown in a number of studies to stimulate transmitter release from nerve terminals such as dopaminergic terminals in the striatum and glutamatergic terminals in the cortex. Its main functional role may therefore be as a presynaptic receptor regulating transmitter release. It has a high affinity for nicotine and so may mediate some of the central effects of nicotine. Notice that a homomeric receptor has implications for the interpretation of functional studies since the number NEUROTRANSMITTER RECEPTORS 65 of agonist (and antagonist) binding sites on the receptor must equal the number of subunits. In the case of a7 receptors, Hill coefficients (see Appendix) of around 1. GLYCINE RECEPTORS Inhibitory glycine receptors with high affinity for the antagonist strychnine are predominantly found in the spinal cord and brainstem. Three different a subunits have been cloned (a1±a3) and a single b subunit (b1). Interestingly, the foetal-type of glycine receptor which is a homomer (the adult stoichiometry is likely to be a3b2) has Hill coefficients nearer 3. GABA RECEPTORS The GABA receptor subunits are one of the most diverse groups of ion channel receptor subunits in the brain. Six different a subunits (a1±a6), four b subunits (b1±b4), four g subunits (g1±g4), an e subunit, a p subunit, and three r subunits (r1±r3) have been found. This diversity of subunits is reflected in the complicated pharmacology of the GABA receptors.
Thus cheap extra super viagra 200mg with amex erectile dysfunction uti, of pain extra super viagra 200mg lowest price erectile dysfunction treatment home veda, although degeneration in the disk may lead to the major diagnostic task is to distinguish the 95% of pa- pain by stretching of ligamentous tissue, nerve compres- tients with simple back pain from the 5% with serious un- sion, or inflammation. In this article, an overview of the spectrum of degenerative disease of the spine is provided. Special emphasis is directed to the mag- Disk Degeneration netic resonance imaging (MRI) appearance of degenerative spine disorders, since MRI has become the standard of ref- With aging, the nucleus pulposus becomes dehydrated erence regarding the evaluation of patients with back pain and tears occur in the anulus fibrosus. Radial or type 3 tears are of special interest in the setting of disk Anatomical Considerations degeneration since these types of anular tears concern the entire anulus fibrosus, and they correlate with shrinkage The intervertebral disk is a complex structure consisting and disorganization of the nucleus. Hydration and an- of hyaline cartilage, fibrocartilage, and mucopolysaccha- ular integrity seem to be important for the disk to absorb ride and dense fibrous tissue, which together gives the and transmit compressive loads to the vertebral column. The layer of the hyaline As the disk ages and degenerates, it progressively loses cartilage attached to the vertebral endplate and encircled this capacity. This results in disk-space narrowing and re- by the ring apophysis is called the cartilaginous endplate. Occasionally, gas or calcifi- Within the endplate are numerous vascular channels cation develops within a degenerating disk. One of the theories of disk degeneration is that ment of disk degeneration. The signal characteristics of the degenerative changes in the vertebral endplate impair dif- disk in T2-weighted sequences reflect changes caused by fusion into and out of the disk, impeding the function of aging or degeneration. The outer ring contains the densest grades to describe the different stages of lumbar-disk de- fibrous lamellae, which display low signal intensity on generation. The grading system is based on MR signal in- T2-weighted MR images due to the absence of ground tensity, disk structure, distinction between nucleus and an- substance. The cells in the outer ring of the anulus are al- nulus, and disk height (Table 1, Fig. Unlike the outer ring of the cients for intra- and interobserver agreement were excel- anulus, the inner ring contains predominantly chondro- lent for this system; thus it is useful in daily practice. Classification of disk degeneration based on sagittal T2-weighted magnetic resonance (MR) images (according to) Grade Differentiation of nucleus pulposus Signal intensity of nucleus pulposus from anulus Disk height I Yes Homogeneously hyperintense Normal II Yes Hyperintense with horizontal dark band Normal III Blurred Slightly decreased, minor irregularities Slightly decreased IV Lost Moderately decreased, hypointense zones Moderately decreased V Lost Hypointense, with or without horizontal hyperintense band Collapsed Fig. Sagittal T2-weighted images show the different degrees of disk de- generation according to the classification system proposed by Pfirrmann et al. Several classification systems have been proposed to describe disk abnormalities. Currently, the most widely accepted terms are: normal, bulging, protrusion, extrusion and sequestration. A disk is considered normal when it does not reach beyond the border of the adjacent vertebral bodies. Bulging is defined as circumferential, symmetric disk extension around the posterior vertebral border. Protrusion is defined as focal or asymmetric extension of the disk beyond the vertebral border, with the disk origin broader than any other dimen- sion of the protrusion. Extrusion is defined as a more ex- treme extension of the disk beyond the vertebral border, Fig. T2-weighted images in with the base against the disk of origin narrower than the di- the sagittal and axial planes ameter of the extruding material and a connection between demonstrate disk extrusion at the L4/5 disk level with com- the material and the disk of origin (Fig. Sequestration is pression of the right-sided L5 defined as a free disk fragment that is distinct from the par- nerve root ent disk and has intermediate signal intensity on T1-weight- ed images but increased signal intensity on T2-weighed im- ages (Fig. The above-mentioned classification system for disk abnormalities does not use the term disk herniation, which is defined as displacement of disk material beyond a b the normal margins of the intervertebral disk space. The herniated material may include nucleus pulposus, cartilage, fragmented apophyseal bone, or fragmented anular tissue. Some authors use the term disk herniation to collectively designate protrusions and extrusions. Intervertebral disk herniation or Schmorl’s node repre- senst an intervertebral displacement of nuclear material through a break in the vertebral endplate. Occasionally, it may present as a well-delineated cystic lesion within the vertebral body, the so-called giant cystic Schmorl’s node.
Only a few of the many clinical considerations of the cen- tral nervous system will be discussed here purchase 200 mg extra super viagra free shipping erectile dysfunction the facts. These include neuro- Creek logical assessment and drugs extra super viagra 200 mg with mastercard erectile dysfunction causes and solutions, developmental problems, injuries, (a) infections and diseases, and degenerative disorders. Third lumbar vertebra Neurological Assessment and Drugs Coccyx Neurological assessment has become exceedingly sophisticated and Spinal cord accurate in the past few years. In a basic physical examination, only the reflexes and sensory functions are assessed. But if the physician suspects abnormalities involving the nervous system, further neuro- logical tests may be done, employing the following techniques. Acis- needle ternal punctureis similar to a lumbar puncture except that the CSF is withdrawn from a cisterna at the base of the skull, near FIGURE 11. The pressure of the CSF, which is nor- needle between the third and fourth lumbar vertebrae (L3–L4) and mally about 10 mmHg, is measured with amanometer. Samples of (b) withdrawing cerebrospinal fluid from the subarachnoid space. In addi- tion, excessive fluid, accumulated as a result of disease or trauma, may be drained. With that speed, body functions as well as The condition of the arteries of the brain can be deter- structures may be studied. These types of data are important in detecting nique, a radiopaque substance is injected into the common early symptoms of a stroke or other disorders. Aneurysms and vascular constrictions or displacements by ply by examining brain-wave patterns using an electroen- tumors may then be revealed on radiographs. Sensitive electrodes placed on the The development of the CT scanner, or computerized scalp record particular EEG patterns being emitted from evoked axial tomographic scanner, has revolutionized the diagnosis of cerebral activity. The CT scanner projects a sharply focused, de- patients to predict seizures and to determine proper drug therapy, tailed tomogram, or cross section, of a patient’s brain onto a tele- and also to monitor comatose patients. The versatile CT scanner allows quick and The fact that the nervous system is extremely sensitive to accurate diagnoses of tumors, aneurysms, blood clots, and hemor- various drugs is fortunate; at the same time, this sensitivity has rhage. The CT scanner may also be used to detect certain types potential for disaster. Drug abuseis a major clinical concern be- of birth defects, brain damage, scar tissue, and evidence of old or cause of the addictive and devastating effect that certain drugs recent strokes. Much has been written on drug A machine with even greater potential than the CT scan- abuse, and it is beyond the scope of this text to elaborate on the ner is the DSR, or dynamic spatial reconstructor. A positive aspect of drugs is their administration CT scanner, the DSR is computerized to transform radiographs in medicine to temporarily interrupt the passage or perception of into composite video images. Injecting an anesthetic drug near a nerve, as in dimensional view is obtained, and the image is produced much dentistry, desensitizes a specific area and causes a nerve faster than with the CT scanner. Nerve blocks of a limited extent occur if an appendage is cross-sectional images in 5 seconds, whereas the CT scanner can cooled or if a nerve is compressed for a period of time. Before the xx Van De Graaff: Human Front Matter A Visual Guide © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Clinical Practicums These focused clinical scenarios challenge you to put your knowledge of anatomy to work in a clinical setting. Given a brief patient history and accompanying diagnostic images, you must apply the chapter material to diagnose a condition, explain the origin of symptoms, or even recommend a course of treatment. Detailed answers to the Clinical Practicum questions are provided in Appendix B. What is the dark line noted within the room with complaints of stabbing chest pain contrast-filled aorta? Which portions of the aorta are exam, the patient’s lungs are clear, and heart involved? An electrocardiogram is also nor- difference in blood pressure between mal. Because of his symptoms, you suspect the left and right arm, with the left arm an aortic dissection and order a CT scan. The incisors and canines have one root (b) The membrane of intestinal (pp. The digestive system mechanically andchemically breaks down food to forms (a) Humans are diphyodont; they have mucosa increases the absorptive that can be absorbed through the (b)deciduous and permanent sets of teeth.