Spinal Cord: Anatomical Overview and Selected Pathologies

The brain and spinal cord work together to provide sensory perception and motor function to the body. These processes are accomplished by connections that occur between the brain and peripheral nervous system through the spinal cord. Injury to the spinal cord can lead to significant deficits. Traumatic events can lead to compression, ischemia or destruction of the spinal cord with consequential weakness, paralysis, sensory disturbances or urinary incontinence. Traumatic spinal cord injuries are classified as either complete (complete loss of motor and sensory function) or incomplete injuries (preservation of some motor or sensory function distal to the site of injury). The spinal cord can also be the site of aberrant neoplastic growth (spinal cord tumours) or immune-modulated pathologies that lead to destruction and damage to the spinal cord (multiple sclerosis). Tumours, vascular diseases, infections, inflammatory diseases, demyelinating diseases and nutritional diseases can all result in damage to the spinal cord. Key concepts The vertebrae are specifically arranged to allow for protection of the spinal cord as well supporting and permitting movement of the trunk and limbs. The spinal cord is divided into distinct regions that receive their blood supply from different branches off of the aorta and provide innervation to different regions of the body. There are ascending sensory tracts and descending motor tracts connecting the spinal cord to the brain. These tracts are located regionally in the spinal cord according to function and injury to a particular region leads to symptoms that correlate with the respective function of the damaged area. Spinal cord tumours can be primary (arise from the spinal cord or its surrounding meninges) or secondary to metastastic spread. Tumours are classified according to their location relative to the dura mater which surrounds the spinal cord. Vascular malformations result in abnormal flow of blood within the spinal cord. They often shunt blood directly between arteries and veins, bypassing the capillary network. These malformations have a propensity to bleed. If an artery providing blood to the spinal cord is blocked or occluded, spinal cord infarct or stroke ensues. Pathogens in the blood can enter the central nervous system (CNS; brain and spinal cord) and lead to infection, inflammatory response and damage to the spinal cord. Inflammatory diseases often arise idiopathically (cause unknown); some association exists between viral infections and autoimmune diseases. Demyelination of nerves and destruction of spinal cord tracts typically result and is seen in conditions such as sarcoidosis, transverse myelitis, and Guillain–Barre. Autoimmune diseases result when a maladaptive immune system recognizes the host tissue as foreign and mounts an inappropriate immune response. multiple sclerosis and acute disseminated encephalomyelitis are two disorders where one's immune system mounts an attack against normal white matter of the CNS. Vitamin B12 is obtained through the diet and is important for the formation and maintenance of the myelin sheath that surrounds neurons. Traumatic injury to the spinal cord most commonly occurs due to motor vehicle accidents and can lead to paraplegia (lower extremity paralysis) or quadriplegia (upper and lower extremity paralysis). An incomplete spinal cord injury is one where some motor or sensory function is preserved distal to the level of injury. Treatment consists of realignment and stabilization of the vertebral column, decompression of mass lesions and prevention of hypoxia and hypotension (preventing the spinal cord from being deprived of oxygen and blood nutrients). Keywords: spinal cord injury; spinal column anatomy; spinal demyelinating diseases; spinal vascular malformations; spinal cord tumours