By G. Basir. New Jersey Institute of Technology.
In addition order himcolin 30gm with amex, the costochondral articulations be- tween the ends of the ribs and the costal cartilages that attach to the sternum are examples of synchondroses generic 30 gm himcolin with amex. Elderly people often exhibit some ossification of the costal cartilages of the rib cage. This may restrict movement of the rib cage and obscure an image of the lungs in a thoracic radiograph. Discuss the function of the pad of fibrocartilage in a sym- Body of physis and give two examples of symphyses. SYNOVIAL JOINTS The freely movable synovial joints are enclosed by joint capsules containing synovial fluid. Based on the shape of the articular sur- faces and the kinds of motion they permit, synovial joints are cate- Distal epiphyseal gorized as gliding, hinge, pivot, condyloid, saddle, or plate ball-and-socket. Distal epiphysis Objective 8 Describe the structure of a synovial joint. The function of synovial joints is to pro- occurs at both the proximal and distal epiphyseal plates. The mitotic activity at synchondrotic joints is responsible for bone growth in vide a wide range of precise, smooth movements, at the same length. Synovial joints are the most complex and varied of the Synchondroses three major types of joints. A totally ossified synchondrosis may also be ness of the associated ligaments and tendons; and referred to as a synostosis. Range of motion at synovial joints is characterized involves the mitotically active epiphyseal plate of a synchondrotic by tremendous individual variation, most of which is related joint. If such an injury is left untreated, bone growth is usually to body conditioning (fig. Excessive obesity may also retarded or arrested, so that the appendage will be shorter than normal. Although some people can perform remarkable contortions and are said to be “double-jointed,” they have no extra joints that help synchondrosis: Gk. Articulations © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 8 Articulations 201 Arthroplasty is the surgical repair or replacement of joints. Ad- vancements in this field continue as new devices are devel- oped to restore lost joint function and permit movement that is free of pain. A recent advancement in the repair of soft tissues involves the use of artificial ligaments. A material consisting of carbon fibers coated with a plastic called polylactic acid is sewn in and around torn ligaments and tendons.
Others avoid indi- or not they should continue to work viduals with HIV infection because they (Nixon & Renwick cheap himcolin 30 gm line, 2003) purchase himcolin 30 gm with visa. Contextual fac- fear contagion and are not aware of the tors, such as disability and health insur- actual modes of transmission. Such soci- ance or drug plans, often influence etal concepts can result in ostracism and individuals’ decision (Ferrier & Lavis, discrimination against individuals with 2003). The components of a complete most serious impediments to successful blood count include the following: functioning in the workplace are the fear, • Red blood cell count: measurement of discrimination, and prejudice that they the total number of red blood cells in encounter. Many individuals who are HIV a cubic millimeter of blood positive encounter discrimination at work, • White blood cell count: measurement of and as a result they may withdraw from the total number of white blood cells the workplace altogether (Hunt, Jaques, in a cubic millimeter of blood Niles, & Wiezalis, 2003). Individuals with • Differential: measurement of the pro- HIV frequently fear that they will lose portion of each type of white blood their jobs as a result of their diagnosis, re- cell (i. Because infection can ma is normal) have such serious consequences for indi- viduals with HIV infection, they should Other types of blood tests used to meas- also avoid job situations in which they are ure speciﬁc components of blood are as likely to be exposed to infection. As the follows: HIV infection progresses and individuals • Reticulocyte count: assessment of bone experience increasing fatigue, they may marrow function by measuring its need to undertake less strenuous work or production of immature red blood arrange for shorter work schedules or cells (reticulocytes) more frequent rest periods. In the later • Platelet count: measurement of the stages of the disease, mental changes may number of platelets in a cubic mil- affect an individual’s capacity to function limeter of blood in the work setting. A complete blood count is a test Bleeding Time Test used to evaluate a number of different com- ponents in the blood. Sometimes these A bleeding time test measures the length various components are also measured of time it takes for bleeding to stop after Diagnostic Procedures for Conditions Affecting the Blood or Immune System 251 a small puncture wound. The test deter- speciﬁc part of the clotting mechanism mines how quickly a platelet clot forms. The bone marrow is then examined A prothrombin time test measures the microscopically for various abnormalities length of time that a blood sample takes in the number, size, and shape of the pre- to clot when certain chemicals are added cursors of red blood cells, white blood to it in the laboratory. Pro- ond test is negative, the test result is con- longation of clotting time indicates that sidered negative. If the result of the individuals may be prone to abnormal second test is positive, the Western blot bleeding. If the test indicates that clotting test is usually performed as a conﬁrmato- time is reduced, there may be blood hy- ry test. If the result of the Western blot test percoagulability, which could contribute is positive, it is highly suggestive that the to the formation of blood clots. HIV antibody is present and that the indi- vidual has been exposed to HIV. Partial Thromboplastin Time (PTT) Test Hemoglobin Electrophoresis A partial thromboplastin time test is used to evaluate a special part of the clotting Hemoglobin electrophoresis is a blood mechanism not evaluated by prothrom- test by which a deﬁnitive diagnosis of bin time. As with the prothrombin time sickle cell disease or sickle cell trait can be test, certain chemicals are added to a made. Prolongation of time in which it takes a clot to form is indicative of a Sickle cell prep is a blood test used in sick- bleeding disorder, such as that found in le cell screening.
The CNS develops from the neural plate (D4) of the ectoderm which then transforms into the neural groove (D5) and further into the Kahle discount himcolin 30 gm on-line, Color Atlas of Human Anatomy order himcolin 30gm online, Vol. Development of the Nervous System, Functional Circuits 3 A–C Models of primitive nervous systems (according to Parker and Bethe) 1 1 1 3 3 2 2 A Sensory cell with B Nerve cell connecting process to a a sensory cell and a muscle cell muscle cell C Diffuse neural network 10 11 12 4 9 5 15 13 16 6 14 E Functional circuit: response of an organism to environmental stimuli 7 8 14 13 12 17 7 8 11 7 10 D Embryonic development 8 of the central nervous system: F Functional circuit: influence of an spinal cord on the left, brain on organism on its environment the right Kahle, Color Atlas of Human Anatomy, Vol. The anterior the Body (A, B) division is called the forebrain (gray) (B8). The central nervous system (CNS) is The divisions of the brain stem, or encephalic divided into the brain, encephalon (A1), and trunk, have a common structural plan (con- the spinal cord (SC), medulla spinalis (A2). Genuine peripheral by a bony capsule; the spinal cord in the nerves emerge from these divisions, as they vertebral canal is enclosed by the bony do from the spinal cord. Both are covered by they are supported by the chorda dorsalis meninges that enclose a cavity filled with a during embryonic development. Thus, the CNS is features distinguish the brain stem from the protected from all sides by bony walls and forebrain. The subdivision chosen here the cushioning effect of a fluid (fluid cush- differs from the other classifications in ion). The peripheral nervous system (PNS) in- cludes the cranial nerves, which emerge The forebrain, prosencephalon, consists of through holes (foramina) in the base of the two parts, the diencephalon and the telen- skull, and the spinal nerves, which emerge cephalon or cerebrum. In the mature brain, through spaces between the vertebrae (in- the telencephalon forms the two hemi- tervertebral foramina) (A3). At the entry points of the afferent nerve fibers lie ganglia (A6); these are small oval bodies containing sensory neurons. When describing brain structures, terms like “top,” “bottom,” “front,” and “back” are inaccurate, because we have to distinguish between different axes of the brain (B). Owing to the upright posture of humans, theneuraltubeisbent;theaxis ofthespinal cord runs almost vertically, while the axis of the forebrain (Forel’s axis, orange) runs hori- zontally; the axis of the lower brain divi- sions (Meinert’s axis, violet) runs obliquely. The positional terms relate to theses axes: the anterior end of the axis is called oral or rostral (os, mouth; rostrum, beak), the pos- terior end is called caudal (cauda, tail), the underside is called basal or ventral (venter, abdomen), and the upper side is called dor- sal (dorsum, back). The lower brain divisions, which merge into the spinal cord, are collectively called Kahle, Color Atlas of Human Anatomy, Vol. Position of the Nervous System 5 1 9 2 4 4 3 6 5 5 A Position of the central nervous system in the body dorsal 8 oral (rostral) caudal oral (rostral) ventral dorsal 7 ventral B Axes of the brain: caudal median section through the brain Kahle, Color Atlas of Human Anatomy, Vol. A deep transverse sulcus (B15) is formed between the cerebellar an- Development of the Brain (A–E) lageandthemedullaoblongataasaresultof The closure of the neural groove into the the pontine flexure; the underside of the neural tube begins at the level of the upper cerebellum comes to lie in apposition to the cervical cord. From here, further closure membrane-thin dorsal wall of the medulla runs in the oral direction up to the rostral (p. The telencephalon, developmental events in the CNS proceed in which initially lagged behind all other brain the same directions. Thus, the brain’s divi- divisions in its development, now exhibits sions do not mature simultaneously but at the most intense growth (p. During the sixth month, the insula cephalon (yellow and red); the caudal ves- still lies free (D).
These origi- Medial Lemniscus (B) nate from the rostral part of the solitary nu- cleus (B12) best himcolin 30 gm, probably cross to the con- This fiber system includes the most impor- tralateral side buy cheap himcolin 30 gm on line, and occupy the medial mar- tant ascending pathways of the exteroceptive gin of the lemniscus. It is subdivided into the spinal lemnis- cus and the trigeminal lemniscus. The spinal lemniscus contains the sensory pathways Kahle, Color Atlas of Human Anatomy, Vol. Pyramidal Tract System, Medial Lemniscus 141 III III 2 IV IV V V VI 1 VII VII 11 10 9 X X XII 8 3 11 XI XI 12 A Pyramidal system: corticospinal tract and corticonuclear fibers 10 8 3 7 6 5 B Ascending pathways of the medial lemniscus 4 Kahle, Color Atlas of Human Anatomy, Vol. It reaches from the rostral midbrain into the spinal cord and interconnects numerous nuclei of the brain stem. On cross Internuclear Connections of the sections through the brain stem, it is found Trigeminal Nuclei in the middle of the tegmentum, ventrally Only a few secondary trigeminal fibers en- from the central gray (p. Crossed and uncrossed in the dorsolateral region of the tegmentum fibers run in the longitudinal fasciculus to the motor nuclei of cranial nerves; they from the lateral (A1), medial (A2), and infe- form the basis of numerous important re- rior (A3) vestibular nuclei to the abducens flexes. Crossed and uncrossed fibers run to nucleus (A4) and to the motor cells of the the facial nucleus as the basis of the corneal anterior horn of the cervical spinal cord. There are connections to the superior fibers ascend to the ipsilateral trochlear nu- salivatory nucleus for the lacrimal reflex. Fibers to the hypoglossal nucleus, to the The vestibular fibers finally terminate in the ambiguous nucleus, and to the anterior ipsilateral or contralateral interstitial nu- horncellsofthecervicalspinalcord(cellsof cleus of Cajal (A8) and in Darkshevich’s nu- origin of the phrenic nerve) are the basis of cleus (A9) (decussation of the epithalamic the sneezing reflex. The longitudinal based on fiber connections to the ambigu- fasciculus connects the vestibular apparatus ous nucleus, the posterior vagus nucleus, with the eye and neck muscles and with the and the motor nucleus of the trigeminal extrapyramidal system (p. Connections with the posterior vagus nucleus are the basis of the oculocardial re- Extrapyramidal part. The interstitial nu- flex (slow heart rate upon pressure on the cleus of Cajal and Darkshevich’s nucleus are eyeballs). They receive fibers from the striatum and pallidum and crossed fibers from the cerebellum. They send a fiber tract, the interstitiospinal fasciculus (A11), in the longitudinal fasciculus to the caudal brain stem and into the spinal cord. This consists of connect- ing fibers between motor nuclei of cranial nerves, namely, between abducens nucleus (A4) and oculomotor nucleus (A7), facial nucleus (A12) and oculomotor nucleus, fa- cial nucleus and motor nucleus of the trigeminal nerve (A13), hypoglossal nucleus (A14) and ambiguous nucleus (A15). The interconnections of motor nuclei of cranial nerves allow certain muscle groups to interact functionally, for example, during the coordination of eye muscles with the Kahle, Color Atlas of Human Anatomy, Vol. Medial Longitudinal Fasciculus 143 10 9 8 7 6 13 4 12 5 2 1 3 14 15 11 A Medial longitudinal fasciculus (ac- cording to Crosby, Humphrey, and Lauer) Kahle, Color Atlas of Human Anatomy, Vol. They originate or terminate, respec- The central tegmental tract is the most im- tively, in the septum, the oral hypothalamus, portant efferent pathway of the extrapy- the gray tubercle (B13), and the mamillary ramidal motor system (p.