Epiphysis Sixth sense
The small, cone-shaped pineal gland is located in the roof of the third ventricle of the diencephalon (chapter 8), where it is encapsulated by the meninges covering the brain. The pineal gland of a child weighs about 0.2 g and is 5 to 8 mm (0.2 to 0.3 in.) long and 9 mm wide. The gland begins to regress in size at about age 7 and in the adult appears as a thickened strand of fibrous tissue. Although the pineal gland lacks direct nervous connections to the rest of the brain, it is highly innervated by the sympathetic nervous system from the superior cervical ganglion. The principal hormone of the pineal gland is melatonin. Production and secretion of this hormone is stimulated by activity of the suprachiasmatic nucleus (SCN) in the hypothalamus of the brain via activation of sympathetic neurons to the pineal gland (fig. 11.32). The SCN is the primary center for circadian rhythms in the body rhythms of physiological activity that follow a 24hour pattern. The circadian activity of the...
There was a time not long ago when the patient with rheumatoid arthritis was viewed as a collection of inflamed joints. The very concept of the disease as a systemic affliction, developed by clinicians of yesteryear such as Bauer, Ragan, Copeman, and Hench, was critical to the development of rheumatology as a discipline of internal medicine, while placing perhaps undue emphasis on systemic features. These pages help to restore the concepts that all that hurts is not systemic disease, that articular symptoms are the major feature of rheumatoid arthritis, and that those who would deal with disease manifesting as musculoskeletal pain must also be aware of local afflictions such as march fracture, tennis elbow, and slipped capital femoral epiphysis. These pages represent the happy juxtaposition of the medical and orthopedic surgical expertise of the Hospital for Special Surgery, a hospital with an enviable tradition of cooperation and of excellence in both disciplines.
The first sick hamster was autopsied 4 months after subcutaneous and intracerebral inoculation. A large cerebellar medulloblastoma (Fig. 2.5) demonstrated not only the oncogenic potential of JC virus but also a difference in tumor phenotype from neoplasms induced in the same host by mouse polyoma virus and SV40. Overall, in numerous experiments, medulloblastomas remained the most frequent tumor type. However, JC virus behaved uniquely polyon-cogenic for the nervous system (Zu Rhein, 1983), a joy and challenge for a neuropathologist. Tumors of the pineal gland had never before been experi-
At about the time of birth or thereafter, a secondary center of ossification, or epiphysis, develops at each end of the developing long bone. d. A plate of cartilage, called the epiphyseal plate, remains between the diaphysis and each epiphysis. In the early years of life, the cartilage grows faster than the diaphysis can tear it down. This results in gradual lengthening of the long bone. e. At the proper time, between puberty and adulthood, the bone development overtakes completely destroys the cartilage. After this, the diaphysis and the epiphysis are solidly fused to one another. The dense bony line of fusion between the diaphysis and epiphysis is called the epiphyseal line. The epiphyseal line is easily visible in the radiographs ( x-rays ) of young adults.
Tanycytes are found in clusters in the walls of the third ventricle and cerebral aqueduct, in the floor of the fourth ventricle, and in the cervical spinal canal. Clusters of tanycytes are often associated with circumventricular organs, namely the median eminence, the area postrema, the subcommissural organ, and the pineal gland.18
Melatonin is a hormone produced by the pineal gland in the brain. The use of melatonin obtained from animal pineal tissue is not recommended because of the risk of contamination. The synthetic form of melatonin does not carry this risk. However, melatonin is an over-the-counter dietary supplement and has not been evaluated for safety, effectiveness, and purity by the FDA. All of the potential risks and benefits may not be known. Supplements should be purchased from a reliable source to minimize the risk of contamination. Melatonin has been used in treating insomnia, overcoming jet lag, improving the effectiveness of the immune system, and as an antioxidant. The most significant use is for the short-term treatment of insomnia at low doses. Individuals wishing to use melatonin should consult with their primary health care provider or a pharmacist before using the supplement. Possible adverse reactions include headache and depression. Drowsiness may occur within 30 minutes after taking...
During middle childhood, many orthopedic appliances are frequently used to treat skeletal trauma or to correct a variety of deformities. Device use in this age group should take into account the ongoing physical growth of these children, as well as their high energy level and active lifestyle. Long-bone fractures occur frequently and are different from those seen in adulthood. The healing and remodeling abilities of developing bones in children are greater, and care must be taken to avoid long-term growth problems. Problems with non-union are rare, and some non-displaced fractures may need only minimal intervention, either simple splinting or casting. However, there may be separation or damage to the epiphysis (growth plate) and these fractures require open surgical reduction with device fixation and pinning. Device technology has evolved and flexible
An important variant is the triplane fracture, which occurs in children nearing skeletal maturity, as the physis closes in an asymmetrical fashion. These are generally two or three-part fractures, difficult to recognize on X-ray, which require careful reduction and fixation. The principle fragments are (i) the tibial metaphysis, (ii) the medial and posterior fragment of the distal epiphysis with a metaphyseal spike posteriorly, and (iii) the antero-lateral corner of the distal epiphysis. Evaluation is better with CT or plain tomography.
Although humans are considered to be nonseasonal mammals, we are undoubtedly sensitive to photoperiod (9), as exemplified by seasonal affective disorder and by seasonal trends in the frequency of births and in the incidence of twins. Such effects are most obvious in northern Europe, where photoperiodic changes are most extreme (10). Furthermore, both longitudinal and cross-sectional studies have demonstrated that sperm counts in men are consistently approx 30 lower in summer than in winter (11,12), although not all studies have reported such effects, and they may be less apparent or absent in tropical countries (13). An alternative explanation is that it is exposure to the higher summer temperature that is responsible for lowering sperm production (see section on scrotal temperature), although temperature changes do not account for all of the seasonal trends in births, especially in northern Europe (3). If the reported seasonal changes in sperm counts are an echo from our seasonally...
Femoral neck stress fractures may be bilateral. Voss and coworkers 76 reported a case of bilateral stress fractures of the femoral neck in a 30-year-old amenorrheic patient who had low caloric intake. Stress fractures of the femoral neck in children who have open capital femoral epiphysis are very rare, but
A typical long bone (Fig. 19-5) has a shaft or diaphysis composed of compact bone tissue. Within the shaft is a medullary cavity containing the yellow form of bone marrow, which is high in fat. The irregular epiph-ysis at either end is made of a less dense, spongy bone tissue containing the blood-forming red bone marrow. A thin layer of cartilage covers the epiphysis and protects the bone surface. Between the diaphysis and the epiphysis at each end of the bone, in a region called the metaphysis, is the growth region or epiphyseal plate. When the bone stops growing in length, this area becomes fully calcified but remains visible as the epiphyseal line. The thin layer of fibrous tissue that covers the outside of the bone, the periosteum, nourishes and protects the bone and also generates new bone cells for growth and repair. Proximal epiphysis Distal epiphysis
Germinomas are uncommon extrasellar tumors that often cause delayed puberty. Polydipsia, polyuria, and visual disturbances are the most common presenting symptoms, followed by arrested growth and delayed puberty. Germinomas are located in the pituitary stalk, in the suprasellar region of the hypothalamus, or close to the pineal gland. Seeding of the tumor into the cerebrospinal fluid is common and can be used in diagnosis, i.e., examination of tumor markers (human chorionic gonadotropin hCG -P, or a-fetoprotein) or germ cells (with positive placental alkaline phosphatase staining). These laboratory findings, together with typical clinical features, and an excellent response to radiation therapy are so characteristic of this condition that surgery is rarely indicated, except for biopsy to establish a histological diagnosis (60,61).
Pineal body Pineal body The epithalamus is the dorsal segment of the diencephalon containing a choroid plexus over the third ventricle, where cere-brospinal fluid is formed, and the pineal gland (epiphysis). The pineal gland secretes the hormone melatonin, which may play a role in the endocrine control of reproduction (discussed in chapter 20).
Low levels of hypocretin and hypocretin receptors have been detected in other peripheral tissues. In humans prepro-Hcrt is expressed in the stomach, kidney, colon, colorectal epithelial cells and placenta.72 In the rat, Hcrtr1 mRNA has been detected in the kidney, thyroid, ovary and placenta66 (our unpublished data). In addition, Hcrtr2 mRNA has been found in rat lung, placenta66 (our unpublished data) and pineal gland.84
Spinal leptomeningeal metastases or drop metastases are neoplastic deposits in the subarachnoid space more commonly seen in the lumbar spine where they are frequently visualized in the dependent portion of the thecal sac, hence the term drop metastases. Leptomeningeal metastatic disease accounts for the majority of malignant extramedullary, intradural masses. These include CNS and non-CNS etiologies. Primary CNS neoplasms include medulloblastomas, ependymomas, glioblastomas, ana-plastic astrocytomas, choroid plexus tumors, and pineal gland tumors such as germinomas, pineocytomas, and pineoblastomas. Systemic malignancies such as lung, breast, and gastrointestinal carcinomas, lymphoma, leukemia, and melanoma may also produce meningeal carci-nomatosis. MRI offers superior anatomic depiction of these lesions showing thickening and clumping of the enhancing nerve roots, enhancing nodules in the subarachnoid space and pial enhancement on the surface of the spinal cord.
The pineal gland is situated between the two hemispheres of the brain and is connected to the brain by a little stalk. It produces the hormone melatonin from the amino acid tryp-tophan. The release of melatonin by the pineal occurs in the dark and therefore marks the length of the night. Exposure to light inhibits the release of melatonin.
This 10-year-old boy fell during a soccer game his right leg was in external rotation, he was unable to walk a, b. Radiographs taken the next day showed a right-sided neck fracture in the presence of a large juvenile bone cyst involving neck and trochanter c, d. During surgery a massive angle-stable Deyerle plate and three wires having threads at their tips were used. In addition, the epiphysis was fixed with two Kirschner wires. The cyst was curetted, exposing a large defect in the bone wall. The cavity was later filled twice with cancel-lous bone from the bone bank e. One and a half year later, we observed a loss of head sphericity at the weight bearing area. We transferred to the neck and head a pedicled bone graft attached to the quadratus femoris muscle and stabilized it with a Kirschner wire f. After 19 years the remodeling of the femoral head, its anatomic contour and the multiple small cysts and or resorption cavities in head and neck are well seen. A shortening of the femoral...
And cholinergic neurons of the laterodorsal tegmental nucleus.90 HcrtR2 receptor localization was confirmed in parvalbumin neurons in the medial septum,71 the motor trigeminal nucleus, pontine reticular formation, Barrington's nucleus, and the ventral cochlear nucleus.90 Both hcrtrl and hcrtr2 mRNA80 and immunoreactivity50 were found in the pineal gland.
Displaced Milch type I and II fractures require open reduction and fixation, either with smooth K-wires or small fragment screws. Where there is doubt about the degree of displacement or stability, there should be a low threshold for surgical exploration and fixation. The fracture is exposed through a postero-lateral approach, reduced with minimal disturbance of the soft tissues (especially posteriorly) and stabilized. If possible, fixation should be through the metaphyseal bone spike. To prevent rotation, two pins are required and where the metaphyseal spike is small, the pins can pass through the epiphysis, without causing significant growth disturbance in the majority of cases. One transverse and one oblique K-wire provides the greatest rotational stability. Screw fixation through the metaphyseal fragment is more stable, and very good results are reported, without growth disturbance. Overall, 90 of patients have excellent or good results. 2. Cubitus valgus is caused by non-union of...
Requires anatomical reduction usually with ORIF. Some authors do not even accept 2 mm of displacement. Fixation is with transverse wires or screws, fixing epiphysis to epiphysis. Growth arrest is common, but frequently unimportant as the fracture occurs around the time of skeletal maturity.
The major parts of the brain are the cerebrum, diencephalon, cerebellum, and brainstem. The diencephalon can be further divided into the hypothalamus, hypophysis, thalamus, and epiphysis, whereas the brainstem consists of the mesencephalon, pons, and medulla oblongata. Usually, tumors of the brainstem are highly malignant and, unfortunately, they reside in an inaccessible location. In general, brain tissue can be divided into gray matter and white matter which are made up of cell nuclei and axons, respectively. Blood perfusion of gray and white matter differs remarkably. The corresponding ratio is about five to one.
Endochondral ossification is the principal system of bone formation and growth. Initially a cartilaginous model, derived from mesenchymal tissue condensation, is formed. Vascular invasion, with osteoprogenitor cells differentiating into osteoblasts, leads to the formation of a primary centre of ossification. The epiphysis is a secondary centre at the bone ends, leaving an area between for longitudinal growth - the physis.
There may be some limb overgrowth, rarely 1 cm, with conservative treatment and hence it is acceptable to allow the fracture to heal with some shortening. Overgrowth is more marked between the ages of 2 and 10 years. IM nailing beyond the age of 12 years, avoiding violation of the distal epiphysis, is considered safe practice.
The physis is normally stabilized by mammillary projections and lappets. The mammillary projections are interdigitating bumps between the metaphysis and epiphysis. The lappets are extensions of the physis up and around the metaphysis. Physeal injuries make up approximately 15 of all childhood fractures and are most commonly seen in the phalanges (37 ), distal radius (18 ), distal tibia (11 ) and distal fibula (7 ). Type I (8 ). Complete separation of the epiphysis and metaphysis through the physis. This is seen in younger children. Type III (6.5 ). A split of the epiphysis, extending into the joint. Type IV (12 ). A vertical split through the epiphysis, physis and metaphysis.
Paget's disease begins at one epiphysis and progresses to the other epiphysis of bone. Resorptive lytic flame is seen early at the leading edge of the lesion. Reactive bone formation enlarges the overall bone dimensions and leaves coarsened trabeculae and sclerosis.
In addition to the three commissures developing in the lamina terminalis, three more appear. Two of these, the posterior and habenular commissures, are just below and rostral to the stalk of the pineal gland. The third, the optic chiasma, which appears in the rostral wall of the diencephalon, contains fibers from the medial halves of the retinae (Fig. 19.30).
The diencephalon, which develops from the median portion of the prosencephalon (Figs. 19.5 and 19.17), is thought to consist of a roof plate and two alar plates but to lack floor and basal plates (interestingly, sonic hedgehog, a ventral midline marker, is expressed in the floor of the diencephalon, suggesting that a floor plate does exist). The roof plate of the diencephalon consists of a single layer of ependymal cells covered by vascular mesenchyme. Together these layers give rise to the choroid plexus of the third ventricle (see Fig. 19.30). The most caudal part of the roof plate develops into the pineal body, or epiphysis. This body initially appears as an epithelial thickening in the midline, but by the seventh week it begins to evagi-nate (Figs. 19.24 and 19.25). Eventually it becomes a solid organ on the roof of the mesencephalon (see Fig. 19.30) that serves as a channel through which light and darkness affect endocrine and behavioral rhythms. In the...
This candidate hormone is produced by the pineal gland, an outgrowth from the roof of the diencephalon of the brain (shown but not labeled in Figure 8-38). The exact functions of melatonin in humans are uncertain, but this hormone probably plays an important role in the setting of the body's circadian rhythms and in sleep (Chapter 7). Its secretion is stimulated by sympathetic neurons that constitute the last link in a neuronal chain primarily triggered by receptors in the eyes darkness stimulates melatonin secretion, and light inhibits it. Melatonin secretion, therefore, undergoes a marked 24-h cycle, being high at night and low during the day. Environmental lighting does not cause the circadian rhythm, which is of internal origin, but entrains it (see Chapter 7) . Melatonin's ability to reduce the symptoms of jet lag when administered in small amounts at the