The basilar artery is a single artery located at the base of the skull. It is formed by the junction of two vertebral arteries. It supplies blood to the internal ear and parts of the brain. The basilar plexus is a network of small arteries between the layers of membrane that protect the brain (the dura mater) over the base of the skull. Blockage, or occlusion, of the basilar artery causes many serious problems, ranging from blindness to paralysis. Research Basilar Posterior Cerebral Artery
The brain is the primary component of the nervous system, occupying the cranial cavity. Without its outermost protective membrane, the dura mater, the brain weighs an average of 1.4 kilograms, comprising about 97% of the entirecentral nervous system. The brain is connected to the upper end of the spinal cord (which connects through the foramen magnum of the skull) and is responsible for issuing nerve impulses, processing nerve impulse data, and engaging in the higher order thought processes. The brain is divided into three parts: the large cerebrum, the smaller cerebellum, and the brainstem leading to the spinal cord. The brainstem is also descriptively divided into the medulla oblongata, the midbrain, and the pons. The right hemisphere of the brain is a part of the cerebrum. The cerebrum, or forebrain, forms the bulk of the brain, formed of a large mass of white and grey neural fiber in the upper cranium. It is responsible for the higher thought processes (memory, judgement, reason), processing sensory data, and with initiating willful motor processes, such as voluntary muscle flexion. The cerebrum is composed of two lateral halves, or hemispheres, which feature a number of folds (gyri) and furrows (sulci) and which are connected in the middle at the medulla. Containing about a trillion neurons, the human brain is the most complex mechanism known, and its many functions are still largely a mystery. Research Brain
The term falx describes a curved fold or process of the dura mater or the peritoneum. The term is especially applied to one of the partition-like folds of the dura mater which extend into the great fissures of the brain. Research Falx
The veins in the brain return blood from the dura mater and partially from the bones. They terminate in various sinuses, among which are the inferior sagittal sinus, the superior sagital sinus, and the straight sinus. The sagital sinuses are situated near the parietal bone. Research Sagittal Sinus Vein
The spinal cord is one of the primary portions of the central nervous system, serving as a medium for signals to be sent from the brain to the structures of the body, and received from them in return. Extending from the medulla oblongata, through the foramen magnum in the base of the skull, to the base of the vertebral column, the spinal cord is about half of a centimeter in diameter, and is slightly flattened. The spinal cord itself passes through the vertebral canal created by the vertebral arches, and sends out roots and branches. These structures contain bundles of nerve fibres which extend all the way down the body, innervating even the skin of the tips of the toes. The spinal cord features both efferent and afferent nerve pathways, so that nerves may be transmitted to the body's structures as well as received from them.
Paired sets of nerves branch out from the spinal cord along the vertebral column, with the lowest of these forming the sacral plexus of nerves. The sympathetic nerves travel alongside the spinal cord in the sympathetic nerve trunk, which features periodic clusters of nerves, called ganglia, which deal with specific organ groups. The spinal cord floats in a spinal fluid which protects and nourishes it and, as with the brain, is covered by a meningeal membrane composed of three layers: the pia mater, the arachnoid, and the dura mater. Damage to the spinal cord results in inability to transmit and receive nerve impulses to and from the specific area supplied by the damaged section of the spinal cord, and all sections below it, resulting in paralysis and numbness. Inflammation of the spinal covering is a condition called spinal meningitis. Research Spinal Cord
A suture is an anatomical term for an articulation found only in the skull, where the margins of the bones articulate with one another, but are separated by a thin layer of fibrous tissue (sutural ligament) and is continuous externally with the periosteum on the outside of the skull and internally with the fibrous layer of the dura mater. Research Suture
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Basilar Posterior Cerebral Artery
