Posterior Pituitary Gland

Posterior Pituitary Gland

pediagenosis    September 21, 2022   

Posterior Pituitary Gland

The neurohypophysis, including the neural stalk and the posterior pituitary lobe, is an extension of the hypothalamus. It is embryologically derived from neural ectoderm. During development, magnocellular neurons of the supraoptic and paraventricular hypothalamic nuclei send their axons inferiorly to form the neurohypophysis. These axons terminate in the posterior lobe of the pituitary. In addition, a smaller number of parvocellular neurons from the same nuclei send off shorter axons, which end in the median eminence or infundibular stem. Pituicytes, which are glial cells, support these axon terminals. Two nonapeptide hormones are secreted from distinct axon terminals in the neurohypophysis, including antidiuretic hormone (vasopressin) and oxytocin. After secretion, these hormones enter neurohypophyseal capillaries and are carried via the inferior hypophyseal veins into the systemic circulation.

REHABILITATION AFTER SPORTS INJURY

REHABILITATION AFTER SPORTS INJURY

pediagenosis    September 21, 2022    Comment   

REHABILITATION AFTER SPORTS INJURY

The goal of conservative management of ligament injuries of the knee is to stabilize the action of the knee with the remaining uninjured, supportive structures. Rehabilitation must begin as soon as possible after injury, because disuse atrophy of the muscles occurs rapidly. Rehabilitation focuses on muscle strengthening, particularly strengthening of the extensor (quadriceps) muscles and the flexor (medial and lateral hamstring) muscles.

Divisions of the Pituitary Gland and its Relationships to the Hypothalamus

Divisions of the Pituitary Gland and its Relationships to the Hypothalamus

pediagenosis    September 21, 2022   

Divisions of the Pituitary Gland and its Relationships to the Hypothalamus

The pituitary gland (hypophysis) is a midline structure at the base of the hypothalamus, to which it is connected through the pituitary stalk. The gland is approximately bean shaped, measures 6 mm (superior-inferior dimension) by 9 mm (anterior-posterior dimension) by 13 mm (transverse dimension), and weighs 500 to 600 mg.

The gland is composed of the adenohypophysis and the neurohypophysis, which are embryologically, anatomically, and functionally distinct. The former derives from the Rathke’s pouch, an ectodermal outgrowth of the primordial stomodeum, whereas the latter derives from the neural ectoderm and can be considered an extension of the hypothalamus.

Anatomy of the Basal Ganglia and Related Structures

Anatomy of the Basal Ganglia and Related Structures

pediagenosis    January 10, 2022    Comment   

Anatomy of the Basal Ganglia and Related Structures

BASAL NUCLEI (GANGLIA)

OVERVIEW OF MOVEMENT DISORDERS

For the past 30 years, movement disorders have encompassed the study of a group of conditions characterized by poverty of movement, the akinetic-rigid syndromes, and those with excessive movements, the hyperkinetic movement disorders (tremor, dystonia, myoclonus, chorea/ballism, tics, and others). This traditional view, in which disorders of basal ganglia resulted in the aforementioned syndromes, has now expanded to include the ataxias and disorders of gait and posture. Advances in surgical techniques and imaging studies have broadened the clinical horizon and catchments of the movement disorders specialist. With the increasing indications for botulinum toxin therapy, spasticity and others disorders are now managed by many movement disorders neurologists.

Ventilatory Patterns and the Apnea Test

Ventilatory Patterns and the Apnea Test

pediagenosis    January 10, 2022    Comment   

Ventilatory Patterns and the Apnea Test

Central Pattern Generator for Breathing. In health, the anatomic origin of the cyclic pattern of breathing is the brainstem. Sectioning the brainstem above the pons leaves breathing unaffected when the vagus nerve (cranial nerve X) carrying afferent information from the lungs is intact. Vagotomy results in a reduction in the breathing frequency and an increase in tidal volume. Transection below the medulla results in complete cessation of breathing. Sectioning above the central medulla results in rhythmic but irregular breathing, with vagotomy slowing the irregular pattern. Transection at the level of the upper pons leads to a slowing of respiration and an increase in tidal volume. If both vagus nerves are cut, the result is the cessation of breathing at full inspiration (called apneusis), or inspiratory spasms interrupted by intermittent expirations (called apneustic breathing). The central pattern generator for breathing is located within the medullary center.

Brain Death

Brain Death

pediagenosis    January 10, 2022    Comment   

Brain Death

Severe hypoxic-ischemic encephalopathy may result in brain swelling of such severity that all blood flow into the cranium is blocked, thereby worsening the ischemia to a terminal stage. Brain death is a clinical diagnosis based on the absence of neurologic function in the context of a diagnosis that has resulted in irreversible coma. In the United States, it indicates death of the entire brain; in the United Kingdom, it refers to death of the brainstem. Coma and apnea must coexist. A complete neurologic examination that includes the elements outlined in Plates 6-4 and 6-9 is mandatory to determine brain death, with all components appropriately documented. The current recommendation in adults is that a single evaluation suffices for the diagnosis of brain death. In children, two assessments should be performed, with the duration of interval between tests varying with age.

Vegetative State and Minimally Conscious State

Vegetative State and Minimally Conscious State

pediagenosis    January 10, 2022    Comment   

Vegetative State and Minimally Conscious State

Survivors of some severe circulatory event, who are initially comatose, may pass through a spectrum of clinical conditions before partially or fully recovering consciousness. If, after having been in a coma, the patient opens the eyes but remains unable to initiate voluntary motor activity, this behavior marks the transition to what is called the vegetative state (VS). The further transition to minimally conscious state (MCS) is characterized by reproducible evidence of simple voluntary behavior. Emergence from MCS is signaled by the return of functional communication or object use. Further developments lead to outcomes ranging from severe disability to a good recovery. If, however, the patient remains in the VS for more than 1 month after the occurrence of brain damage, this condition is called the persistent vegetative state (PVS). This state is not necessarily irreversible. Reversibility is much less likely in patients in the permanent vegetative state, that is, in VS lasting more than 3 months after hypoxic-ischemic damage or 1 year after traumatic brain injury.

Hypoxic-Ischemic Brain Damage

Hypoxic-Ischemic Brain Damage

pediagenosis    January 10, 2022    Comment   

Hypoxic-Ischemic Brain Damage

At a national level, out-of-hospital cardiac arrests are an all-too-frequent occurrence. One quarter of individuals experiencing such an arrest will receive emergency cardiopulmonary resuscitation. However, fewer than 20% of these events will lead to survival at hospital discharge even with the combined efforts of emergency and hospital critical care services. Of those who do survive, many will have profound neurologic injury and disability.

Atrial Enlargement

Atrial Enlargement

pediagenosis    January 10, 2022    Comment   

Atrial Enlargement

Enlargement of the right atrium, as compared to the left, occurs in patients with cor pulmonale, pulmonary hypertension, and tricuspid or pulmonary stenosis. As a result, the first atrial electric movement predominates, and the electric axis of the P wave generally is toward the foot and to the front. As a consequence, the P waves are small in lead I but are tall in leads II, III, and aV_F, often exceeding the upper limit of normal (2.5 mm) for lead II. The vector loop is down, forward, and large. Moderately tall P waves are present in leads V₁ and V₂.

Axis Deviation in Normal Electrocardiogram

Axis Deviation in Normal Electrocardiogram

pediagenosis    January 10, 2022    Comment   

Axis Deviation in Normal Electrocardiogram

In the normal individual the mean electric axis of the P wave, QRS complex, and T wave often reflects the anatomic position of the heart in the chest; an abnormal axis can result from heart disease. Plate 2-19 illustrates normal variations in the vectorcardiographic loop. The QRS and T loops in the frontal plane vary between −30 and +110 degrees and in the horizontal plane between +30 and −30 degrees, measured from the left arm.