Coma The term consciousness refers to a state of awareness of self and one's environment. Assessing consciousness in another person relies on judging that individual's performance or behavior in some mental function and arousal or response of awakening to a…
Anatomic Relationships of the Hypothalamus The hypothalamus is a small area, weighing about 4 g of the total 1,400 g of adult brain weight, but it is the only 4 g of brain without which life itself is impossible. The hypothalamus is so…
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…
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…
Muscle Fiber Anatomy: Basic Sarcomere Subdivisions The basic function of skeletal muscle is to move various parts of the body via muscle contraction. Muscle structure is specifically related to its function. Muscles are composed of numerous multinucleated muscle cells called…
Neuromuscular Junction The outflow of nearly all behavior depends upon the neuromuscular system, where nerves emanating from the spinal cord and brainstem make connections with skeletal muscles that allow us to move, stand, and express ourselves. The numbers of skeletal…
Peripheral Nervous System: Overview The major function of the nervous system is the transmission and processing of information. This relies on propagation of electrical signals between the peripheral nervous system and the central nervous system. The somatic peripheral nervous system…
Neonatal Hypotonia Neonatal hypotonia, often referred to as the “floppy infant,” is the main presenting clinical feature of most neuromuscular diseases of early life. However, disorders of the central nervous system may also manifest with hypotonia. Two types of muscle…
Pain Pathways Anatomy Ascending Pathways Endorphin System Pain propagation is initiated with activation of nociceptors, distributed within skin, muscle, joints, and viscera. These receptors include small-diameter Aδ and C-fiber free nerve endings representing distal primary afferent neurons. Cutaneous Aδ fibers…