By H. Uruk. Ohio Northern University. 2018.
Infection Cleft palate is a congenital deformity in which there Osteomyelitis (os-te-o-mi-eh-LI-tis) is an inflammation of is an opening in the roof of the mouth owing to faulty bone caused by pyogenic (pi-o-JEN-ik) (pus-producing) union of the maxillary bones cheap flomax 0.2 mg visa mens health ideal body weight calculator. It may remain localized best flomax 0.2mg androgen hormone 2, or it may spread through fect has difficulty nursing because the mouth communi- 140 ✦ CHAPTER SEVEN ◗ Closed fracture, which is a simple fracture of the bone with no open wound ◗ Open fracture, in which a broken bone protrudes through the skin or an external wound leads to a bro- ken bone ◗ Greenstick fracture, in which one side of the bone is broken and the other is bent. Protection by simple splinting after careful evaluation of the situa- cates with the nasal cavity above, and the baby therefore tion, leaving as much as possible “as is,” and a call for ex- sucks in air rather than milk. Such injuries may be classified as follows: dons, ligaments, and skin contributes to the stiffness so Closed Open Greenstick Impacted Comminuted Spiral Transverse Oblique Figure 7-28 Types of fractures. The bones in this type of primarily to a thinning of the intervertebral disks (be- joint have a potential space between them called the tween the bodies of the vertebrae). This lubricant, synovial fluid, resembles costal (rib) cartilages become calcified and less flexible, uncooked egg white (ov is the root, meaning “egg”) and and the chest may decrease in diameter by 2 to 3 cm is secreted by the membrane that lines the joint cavity. They may also be classified according to More About Synovial Joints the degree of movement permitted (Table 7-2): The bones in freely movable joints are held together by ◗ Fibrous joint. Also, for strength and protection, of joint is immovable and is termed a synarthrosis (sin- there is a joint capsule of connective tissue that encloses ar-THRO-sis). Iliofemoral Types of Synovial Joints Syn- ligament ovial joints are classified according to the types of movement they allow, as Pubofemoral described and illustrated in Table 7-3. Greater ligament Listed in order of increasing range of trochanter motion, they are: ◗ Gliding joint ◗ Hinge joint ◗ Pivot joint ◗ Condyloid joint ◗ Saddle joint ◗ Ball-and-socket joint A Movement at Synovial Joints The chief function of the freely mov- able joints is to allow for changes of position and so provide for motion. For example, there are four kinds of angular movement, or movement that changes the angle Femur between bones, as listed below: Ligament of the Greater head of the femur ◗ Flexion (FLEK-shun) is a bending trochanter motion that decreases the angle be- of femur tween bones, as in bending the fin- Synovial cavity gers to close the hand. The bone surfaces in freely movable joints are pro- A combination of these angular movements enables tected by a smooth layer of hyaline cartilage called the ar- one to execute a movement referred to as circumduc- ticular (ar-TIK-u-lar) cartilage (see Fig. To perform this movement, complex joints may have cartilage between the bones that stand with your arm outstretched and draw a large acts as a cushion, such as the crescent-shaped medial imaginary circle in the air. Rotation refers to a twisting or turning of a bone on Near some joints are small sacs called bursae (BER- its own axis, as in turning the head from side to side to se), which are filled with synovial fluid (see Fig. If abnormal amounts of fluid accu- ◗ Supination (su-pin-A-shun) is the act of turning the mulate in the joint cavity as a result of injury, it can be palm up or forward; pronation (pro-NA-shun) turns drained by a tapping procedure called arthrocentesis (ar- the palm down or backward. Herniated Disk The disks between the vertebrae of the ◗ In dorsiflexion (dor-sih-FLEK-shun), the foot is bent spine consist of an outer ring of fibrocartilage and a central upward at the ankle, narrowing the angle between the leg mass known as the nucleus pulposus. In the case of a her- and the top of the foot; in plantar flexion, the toes point niated disk, this central mass protrudes through a weak- Box 7-3 Hot Topics Arthroplasty: Bionic Parts for a Better LifeArthroplasty: Bionic Parts for a Better Life ince the first total hip replacement in the early 1960s, mil- the hip socket (acetabulum) and is bonded to the pelvis using Slions of joint replacements, called arthroplasties, have screws or glue. The ball, made of pain in older people with arthritis and other chronic degen- metal or ceramic, replaces the femoral head and is attached to erative bone diseases after other treatments such as weight the stem, which is implanted into the femoral shaft. Stems designed to promote bone arthroplasties and an equal number of knee replacements growth into them are usually used in younger, more active pa- performed each year in the United States. Until recently, arthroplasty was rarely performed on young Artificial, or prosthetic, joints are engineered to be strong, people because prosthetics had a short lifespan of about 10 nontoxic, corrosion-resistant, and firmly bondable to the pa- years. Computer-controlled machines now produce individu- crease the lifespan to 20 years or more, and young people who alized joints in less time and at less cost than before. The herniated TYPE OF or “slipped” disk puts pressure on the TYPE OF JOINT MOVEMENT EXAMPLES spinal cord or spinal nerves, often caus- ing back spasms or pain along the sci- Gliding joint Bone surfaces slide Joints in the wrist and ankles atic nerve that travels through the leg, a over one another (Figs. Osteoarthritis occurs mostly Joint between the metacarpal in joints used in weight bearing, such Condyloid joint Allows movement in two directions and the first phalanx of the as the hips, knees, and spinal col- finger (knuckle) (Fig. Degenerative changes include the formation of spurs at the edges of the articular surfaces, thickening of the synovial membrane, atrophy of the cartilage, and calcification of the ligaments. Saddle joint Like a condyloid Joint between the wrist and ◗ Rheumatoid arthritis is a crippling joint, but with the metacarpal bone of the condition characterized by swelling deeper articulating thumb (Fig. Treat- Flexion/extension Pronation/supination Abduction/adduction 7 Circumduction Dorsiflexion/plantar flexion Rotation Inversion/eversion Figure 7-31 Movements at synovial joints. Spinous process Endoscope Spinal nerve root Spinal nerves Patella Nucleus Tibia pulposus Femur Herniated disk compresses nerve root Fibrocartilage Figure 7-32 Arthroscopic examination of the knee. The central portion (nucleus scope is inserted between projections at the end of the femur to pulposus) of an intervertebral disk protrudes through the outer view the posterior of the knee. If there happens and bone to be an overproduction of uric acid, or for some reason not enough is excreted, the accumulated uric acid forms crystals that are deposited as masses around the joints and other parts of the body.
They found that observation and imagery conditions led to a similar facilitation in MEP amplitude in the relevant hand muscle flomax 0.4 mg line prostate 100cc. In addition 0.2 mg flomax otc man health zone, during action observation, a condition of “active” observation (with the instruction to subsequently imitate) yielded larger MEPs than a purely passive observation. Although MEP facilitation was weaker during action representation than during physical execution of the same action, the ﬁnding clearly calls for a unitary mechanism based on action simulation. Considering the above body of data about the activity of the motor system during covert actions, there are two possible explana- tions for this absence of motor output. The ﬁrst interpretation postulates that the transfer of the motor engrams elaborated within premotor or supramotor cortical Copyright © 2005 CRC Press LLC areas (e. The prefrontal cortical areas, which are found to be active during motor imagery,30 could represent a possible locus for this behavioral inhibition. Although in this patient a normal activation (mapped with PET) of the left sensorim- otor cortex was observed during movements of the right “good” leg, no such acti- vation was observed on the right side during unsuccessful attempts to move the left “bad” leg. Instead, the right anterior cingulate and orbitofrontal cortices were sig- niﬁcantly activated. This result suggests that these prefrontal areas exerted a state- dependent inhibition on the motor system when the intention to move the left leg was formed. Subjects were instructed to perform ﬁnger movements while they were observing another person executing either congruent or incongruent movements. When the observed movements were incongruent with respect to the instructed ones, the subjects had to inhibit their spontaneous tendency to imitate the movements of the other person. This task resulted in a strong activation of the dorsolateral and frontopolar areas of the prefrontal cortex. The hypothesis of a cortico-cortical “disconnection” is not compatible, however, with the simple fact that the motor cortex remains activated during action representation. A possible interpretation for the above data could be that the prefrontal cortex is involved, not in inhibiting the execution of represented actions, but rather in a process of selecting the appropriate representation. While executing an instructed action incompatible with an observed one, one has to select the endogenous representation and ignore the representation arising from the outside; in other words, one has to prevent oneself from being distracted by an external event. In order to account for the empirical data showing the involvement of the motor cortex, we must conclude that the inhibitory mechanism is localized downstream of the motor cortex, possibly at the spinal cord or brainstem level. A tentative hypothesis would be that a dual mechanism operates at the spinal level. The subthreshold preparation to move, reﬂected by the increased corticospinal tract activity, would be paralleled by an inhibitory inﬂuence for suppressing the overt movement. They showed that, during the waiting period where the monkey is ready to move, spinal inter- neurons are activated, hence indicating that the spinal motor network is being primed by the descending cortico-motoneuronal input. Because the overt movement was suppressed during this period, Prut and Fetz hypothesized a superimposed global inhibition, possibly originating in the premotor cortex, and propagating to the spinal cord, parallel to the excitatory input. This hypothesis would account for both the increased motoneuron excitability and the block of muscular activity during action representation. Its empirical basis accumulated from experiments in cognitive neuroscience in the past two decades. One of the most inﬂuential results showed that visual mental images rely on acti- vation of the early stages of information processing of the visual system. The primary visual cortex (V1) is consistently involved in visual mental imagery,52,53 with an additional selective involvement of the inferotemporal cortex during imagery of visual objects and of the occipitoparietal cortex in visual spatial imagery. The explanation put forward for an activation of low-level processing areas during a high-level cognitive activity is that activation of topographically organized areas, such as V1, is needed for replacing the image within a spatial frame of reference. Higher-order areas, because they lack topographical organization, would not be able, by themselves, to achieve this task. In other words, the processing of visual imagery would have to follow the same processing track as visual perception for giving an image its spatial layout, a process that requires the participation of V1. The deﬁnition we gave at the beginning of this paper for represented actions is that they correspond to covert, quasi-executed actions, a deﬁnition that accounts for many of the properties of action representations that have been described here. Thus, by drawing a parallel with perceptual representations such as visual mental imagery, we come to the proposition that, if a represented action is a simulated action, then it should involve the mechanisms that normally participate in motor execution. In the above sections, we have seen a large amount of data that satisfy this proposition. Conversely, the content of motor images is explained by the involvement of neural structures such as M1, the premotor cortex, the basal ganglia, and the cerebellum, because this is where the aspects of action related to execution are normally pro- cessed. In other words, if the mental content of motor images is what it is, this is because the neural correlates include the structures required for execution.
Many single M1 neurons have outputs that diverge to innervate multiple spinal motoneuron pools cheap flomax 0.4 mg visa prostate cancer nih. The fact that divergent connections remain today suggests cheap 0.4 mg flomax mastercard mens health omelette, however, that they are important to the present function of the motor cortex. Their importance may lie in the fact, described above, that the most frequently performed behavioral tasks, such as grasp- ing, require the simultaneous contraction of multiple muscles acting on multiple ﬁngers. These movements may be controlled most efﬁciently through M1 neurons with divergent connections to multiple muscles. Because the output of many single M1 neurons diverges to multiple muscles (often muscles that move different digits and/or the wrist), different muscles receive inputs from intersecting sets of M1 neurons. The sets of M1 neurons that provide input to two muscles acting on the digits and wrist also are intermingled in the physical space of the cortex. Consequently, the neurons that provide input to any given muscle are spread over a relatively large cortical territory (typically a few millimeters in diameter in nonhuman primates) and the territory providing input to one muscle overlaps extensively with the territory providing input to other mus- cles. When ﬁnger movements are made, then, active neurons are found over a rela- tively large M1 territory, and similar territories are activated for different ﬁnger movements. Widespread activation of the M1 hand representation during individu- ated ﬁnger movements has been observed in both monkeys and humans. In monkeys, Copyright © 2005 CRC Press LLC microelectrode recording typically reveals a burst of the background “hash” (which presumably reﬂects the discharge of action potentials by numerous neurons and axons in the vicinity of the microelectrode tip) with every ﬁnger movement, no matter where within the M1 hand region the microelectrode tip is located. Single neurons likewise are observed to discharge in relation to multiple ﬁnger and wrist movements. The distribution of neurons active during movements of particular digits gives little if any evidence of somatotopic segregation of neurons controlling differ- ent digits. Similarly in humans, functional magnetic resonance imaging (fMRI) shows that a similar cortical territory is activated no matter which digit is moved. M1 lesions do not impair the function of particular muscles in isolation, but rather impair many functionally related muscles at the same time. In monkeys, injection of the gamma amino butyric acid (GABA) agonist, muscimol, at a single location in the M1 hand representation produces partial inactivation, impairing some ﬁnger movements but not others. Rather than producing selective impairment of different ﬁngers in different patients, however, such infarcts impair either the radial digits (thumb and index ﬁnger) more than the ulnar digits (little, ring, and middle ﬁngers) or vice versa. Conceivably, even if groups of functionally similar neurons were not spatially segregated in a somatotopic fashion in M1, groups of similar neurons still might control particular ﬁngers, muscles, or muscle synergies. Neurons of different distinct functional groups could be intermingled in the physical space of M1. We have used cluster analysis to search populations of M1 neurons for such groups of functionally similar neurons. In three monkeys, however, cluster analysis revealed only two consistent groups of M1 neurons. A relatively large group consisted of neurons that increased discharge during most if not all ﬁnger and wrist movements; another small group decreased discharge during most movements. These two groups were found in all three monkeys, were robust against changing the method of quantifying neuronal activity or changing the clustering algorithm, and were not reproduced when the data was randomly reshufﬂed. In contrast, small groups of neurons that discharged during particular subsets of ﬁnger and wrist movements varied from monkey to monkey, changed when the means of quantifying neuronal activity or the clustering algorithm was changed, and appeared in randomly reshufﬂed data. This analysis suggests that during individuated ﬁnger and wrist movements, M1 neurons do not work as groups of functionally similar neurons. The view of M1 activity during individuated ﬁnger movements that has devel- oped up to this point appears chaotic. Although voluntary movements of different ﬁngers obviously can be made as desired, which ﬁnger movement is performed does not appear to be determined by where in M1 neurons are active, nor by the activity of neuronal groups controlling particular muscles, muscle synergies, digits, move- ments, or movement primitives. And yet the M1 neuronal populations do transmit ﬁring rate information about which ﬁnger movement is made. Population analyses using population vector, logistic regression, and softmax approaches, all show that the discharge of M1 neurons transmits information that speciﬁes which ﬁnger move- ment will be performed. The elements of the M1 layer then could be quite diverse, without categorical groups of similar neurons. M1 neurons could be diverse both in terms of the particular motoneuron pools to which they connect and in terms of their activity patterns across a set of movements. Activity of a selected subset of M1 output neurons then could facilitate activation of the correct motoneuron pools for a given movement. The population analyses described above suggest that a computer model of a fully connected neural network, in which the weights of connections between M1 neurons and motoneuron pools are adjusted by an output-optimizing algorithm, would certainly be able to reproduce output patterns of muscle activity from input patterns of a population of M1 neurons.