The white matter is split into three funiculi on each side: anterior, lateral, and posterior.Īscending tracts convey information into the brain from the periphery. Spinal cord neural pathways are located within white matter of the spinal cord. The nerve roots L2-S5 originate from the distal end of the spinal cord, forming a bundle of nerves known as the cauda equina. Posterior Roots – Supplies nerve fibers to the vertebral column synovial joints, deep back muscles, and overlying s skin.Īnterior Roots – Supplies nerve fibres, both motor and sensory, to most of the remaining body area. Then the spinal nerve leaves the vertebral canal through the intervertebral foramina, then divides into two: These roots arise from the spinal cord, and form a single spinal nerve at the intervertebral foramina. Human have 31 left–right pairs of spinal nerves, each roughly relating to a segment of the vertebral column:Įach spinal nerve begins in the form of an anterior (motor) and a posterior (sensory) root nerve. The spinal nerves are mixed nerves forming the peripheral nervous system that originate from the spinal cord. Eventually, this network empties through the vertebral (neck) and segmental (trunk) veins. Anterior and posterior spinal veins drain into radicular veins, which then empty into the vertebral venous plexus (internal and outer). The arteries are surrounded by similar named veins. Segmental arteries, such as the deep cervical, ascending cervical, and posterior intercostal arteries, give rise to 31 pairs of radicular arterial branches that supply spinal nerve roots. The vertebral artery is responsible for the formation of anterior and posterior spinal arteries. Blood Supply:īranches of the vertebral and segmental arteries supply the spinal cord. The subarachnoid area is between the arachnoid and pia mater and it is filled with cerebrospinal fluid. Dura mater has two layers (periosteal and meningeal) in between space is epidural space. The outermost is the dura mater, the arachnoid material underneath and the deepest is the pia mater. The roots of the spinal cord and the spinal nerve are wrapped within three layers known as meninges. It includes pathways which connect the brain to the rest of the body. White matter encircles the gray matter and consists of axons. It shows horns that are anterior, lateral, and posterior. The gray matter is the main component of the spinal cord which is shaped like a butterfly and consists of neuronal cell bodies. They include anterior (fissures) and sulci (anterolateral, posterolateral, and posterior). This shows four surfaces: anterior, back, and two laterals. Like other areas of the CNS, the spinal cord is composed of gray and white matter. Similarly, as the vertebral column, the spinal cord is divided into segments: cervical, thoracic, lumbar, sacral, and coccygeal. The spinal cord displays two well-defined enlargements for the innervation of the upper and lower limbs along its length: one at the cervical (upper limbs) and one at the lumbosacral (lower limb). A thin thread called filum terminale stretches all the way to the 1st coccygeal vertebra (Co1) from the tip of the conus medullaris and anchors the spinal cord in place. This runs from the foramen magnum at the skull base to the L1 / L2 vertebra where it ends as the medullary cone (conus medullaris). The spinal cord is an extension of the brain stem. That is the reason why the spinal cord only occupies the upper two thirds of the vertebral canal in adults. The spinal cord grows at age 4 while the vertebral column ends up rising at age 14-18. There is a disproportion in development between growth of the spinal cord and growth of the vertebral column. This is found within the vertebral canal of the vertebral column. The spinal cord is the major part of CNS. In this section spinal cord anatomy and spinal cord structure (spinal cord parts) is discussed in detail. The below picture illustrates the schematic diagram of the human spinal cord running via the vertebral column. Cerebrospinal fluid (CSF) fills the space between the outer and middle envelopes, a clear colorless fluid which cushions the spinal cord against jarring shock. Like the brain, three connective-tissue envelopes, called the meninges, protect the spinal cord. The spinal cord is formed by nerve fibers which transmit impulses to and from the brain. The central nervous system consists of the spinal cord and the hippocampus. In the spinal cord thirty-one pairs of spinal nerves originate: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal. The central nervous system is made of the spinal cord and the brain. It is a tubular bundle of nervous tissue that extends from the brainstem to the lumbar vertebrae and supports cells. The main nerve tissue column that is connected to the brain and lies within the vertebral canal from which the spinal nerves emerge.