Limbic System The limbic system is the only brain area receiving major hypothalamic input and providing interconnection with widespread cortical areas. Major limbic structures include the amygdala, piriform cortex (parahippocampal gyrus, uncus + amygdala) , hippocampus, substantia innominata, and septal…
Electroencephalography The electroencephalogram (EEG) is a record of the electrical activity of the nerve cells in the brain. The EEG is based on the measurement of electrical fields generated by volume conduction of ionic currents from nerve cells through the…
Surfaces of Cerebrum The cerebrum is divided into right and left hemispheres by a longitudinal fissure. Each hemisphere has three surfaces—superolateral, medial, and inferior—all of which have irregular fissures, or sulci, demarcating convolutions, or gyri. Although there are variations in…
Initial Specification of the Nervous System: The Embryo at 18 Days After fertilization and implantation, the embryo consists of a single cell layer called the inner cell mass. The inner cell mass sits at the bottom of a fluid-filled cavity…
Skull: Anterior and Lateral Aspects The anterior, or facial, aspect of the skull is composed of the frontal part of the calvaria (skullcap) above and the facial bones below. The facial contours and proportions are largely determined by the underlying…
Overview of Headaches Headache is one of the most common reasons for consulting a physician and is one of the top three reasons for lost work days. Rather than a disease, headache is a symptom, frequently providing a valuable warning…
Clinical Presentations of Brain Tumors Brain tumors commonly present with symptoms of elevated intracranial pressure or focal neurologic dysfunction. Elevated intracranial pressure can directly result from an enlarging mass or can be secondary to the development of hydrocephalus stemming from…
Bacterial Meningitis Pathophysiology. Bacterial meningitis is initially an acute purulent infection of the meninges and subarachnoid space that is followed by an inflammatory reaction in the subarachnoid space, the brain parenchyma, and the cerebral arteries (arteritis) and veins (dural sinus…
Multiple Sclerosis: Overview In temperate climates, multiple sclerosis (MS) is the most common episodic neurologic illness of early adult years. The process begins as periodic and focal loss of central nervous system (CNS) myelin and the oligodendrocytes (OGCs) that synthesize…
Overview and Approach to Stroke Patient Arterial Supply to the Brain and Meninges Overview and Cervical Segments The brain and meninges are supplied by branches that originate from the aorta. The brachiocephalic trunk (or innominate artery ) divides behind the…