1.Describe the functional anatomy of the spinal cord using the following terms: white matter, gray matter, tracts, roots and spinal nerves. The spinal cord consists of a superficial White matter and a deep Gray matter. The white matter consists of myelinated axons, which form nerve tracts and the Gray matter consists of neuron cell bodies, dendrites and axons. The white matter in each half of the spinal cord is organized into ventral, dorsal and lateral columns. Each column is subdivided into tracts also called pathways. A collection of axon inside the CNS is called a tract but outside the CNS it is called a nerve. Spinal nerves arise from numerous rootlets along the dorsal and ventral surfaces of the spinal cord.
Six of these rootlets combine to form a ventral root and the other six to form a dorsal root. Dorsal roots contain only sensory axons, so action potentials are conducted to the spinal cord only and the ventral root contain motor axons so action potential is conducted away from the spinal cord. This means spinal nerves have both the sensory and motor axons. Tracts combine to form roots (dorsal and ventral), roots combine to form the Spinal nerve(twelve pairs) which are in the spinal cord.
2.Define the terms reflex and spinal reflex and identify the components of a reflex arc. A reflex is an automatic response to a stimulus produced by a reflex arc. It occurs without conscious thought. Reflexes are homeostatic. A spinal reflex is any reflex action mediated through the center of the spinal cord. A reflex arc is the nerve pathway involved in a reflex action including at its simplest a sensory nerve and a motor nerve with a synapse between. It consist of five components namely Receptor; Site of the stimulus action, Sensory Neuron; transmits afferent impulses to the central nervous system, Integration Center (interneurons) which is always within the central nervous system. The fourth component is motor neuron; Conducts efferent impulses from the integration center to an efferent organ and lastly Effector; muscle fiber or gland cell that responds to the efferent impulses (by contracting or secreting).
3.Define the term spinal cord injury (SCI) and state its prevalence A spinal cord injury (SCI) refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence. Spinal cord injuries can be complete or incomplete. With a complete spinal cord injury, the cord can’t send signals below the level of the injury. As a result, you are paralyzed below the injury. With an incomplete injury, you have some movement and sensation below the injury. In the UK every year, there are around 1200 people paralyzed from a spinal cord injury. There are currently thought to be approximately 40,000 people in the UK living with paralysis. This statistic only shows the people who have been through a spinal cord injury center, and does not include those who have suffered paralysis and been treated in a general hospital.
A person is paralyzed every 8 hours. It is estimated that the current annual cost of caring for people paralyzed by spinal cord injury is more than £500 million. 21% of people discharged from Spinal Cord Injury Centers go into nursing homes; institutionalized settings rather than their own homes. 4.Define the terms neurological level, tetra(quadri)plegia, and paraplegia Neurological level is usually described as the normal level immediately above the damaged level. By definition, the level of neurological lesion refers to the lowest segment of the spinal cord with normal sensory and motor function on both sides of the body. Paraplegia is a type of paralysis which may be complete or incomplete. Both legs, the trunk and feet may be paralyzed but the arms and upper body are not usually affected. Quadriplegia is also termed tetraplegia. Both terms are defined as “paralysis of four limbs”; tetraplegia is more commonly used in Europe than in the United States. Quadriplegia is paralysis to some degree in all four limbs. In this type of paralysis, the abdominal and chest muscles can also be affected, resulting in difficulty breathing, coughing, or clearing the chest.
5.Define the terms dermatome and myotome and explain how each relates to SCI. Spinal nerves have motor fibers and sensory fibers. The motor fibers innervate certain muscles, while the sensory fibers innervate certain areas of skin. A skin area innervated by the sensory fibers of a single nerve root is known as a dermatome. A group of muscles primarily innervated by the motor fibers of a single nerve root is known as a myotome. Myotomes are necessary for proper motor functioning; making it possible to bend the knee, straighten the elbow, flex fingers, and manipulate other muscle groups. Nerve fibers allowing for the sensation of touch or feeling pain to a corresponding sensory sector of the skin are dermatomes. These nerves originate from the spine and therefore can be useful in spinal injuries to evaluate the level of deficit. Pain, lack of sensation, or abnormal functioning of dermatomes can help pinpoint spinal nerve damage. Each myotome (muscle) and dermatome (region of skin) of the body is supplied by a particular level or section of the spinal cord and by its corresponding spinal nerve.
There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves and five sacral nerves. Each of these nerves relays sensation (including pain) from a particular muscle or region of skin to the brain. By examining the dermatomes and myotomes this way, level and completeness of a spinal cord injury can be determined. 6.Define the term stretch reflex and describe how such reflexes are used to anatomically localize SCI. The stretch reflex (myotatic reflex) is a muscle contraction in response to stretching within the muscle. It is a monosynaptic reflex which provides automatic regulation of skeletal muscle length. Stretch reflexes are abnormal reflexes that work to increase muscle resistance to passive motion.
They are frequent complications of spinal cord injury and contribute to muscle spasticity or continuous spasm. It is believed that the damaged nerves send messages via neurotransmitters that are carried by serotonin and norepinephrine. Following spinal cord injury, there is a change in the balance of neurotransmitters that may cause the increased stretch reflex intensity. Stretch reflexes are used to determine which areas of the body that the CNS does not respond to. For instance, if you tap your knee to check reflex, and the leg doesn’t move, then you will know that the peripheral nerves that lead to the knee are non-responsive or that the brain isn’t receiving a signal from that area.
7.Based upon the results of Jason’s neurological exam, what is the neurological level of his SCI? According to Jason’s neurological exam, he has Paraplegia.
8.Discuss the management of SCI and the factors that determine the prognosis for this condition. Following spinal cord injury, the first priority often is to help the patient develop as much strength as possible in the arms and legs, since these limbs are crucial for movement and communication. Patients may need to learn to use devices like walkers, wheelchairs, or leg braces, as well as devices to help them write, type, and talk on the phone. Physical therapists work with patients to build muscle strength and occupational therapists can help patients develop skills required for day-to-day activities, such as dressing, grooming, and going to the toilet. Patients also learn how to cope with other issues, including pain and spasticity. Vocational rehabilitation specialists can help patients determine employment options.
They assess how work skills and dexterity have been affected by the injury, find job sites that complement the patient’s expertise and abilities, and help secure adaptive devices. For patients who are unable to work, vocational specialists help find opportunities for meaningful projects to keep them active and build self-esteem. Specialists also can provide recreational therapy, which helps patients participate in athletic and recreational activities. In this way, patients can get out with other people, have fun, and lead as normal a lifestyle as possible. The outcomes associated with spinal cord injuries vary greatly according to where along the spinal column the spinal cord has been injured, the severity of the injury, and which nerve fibers are damaged.
Field-Fote, Edelle C. Spinal Cord Injury Rehabilitation. Philadelphia, PA: F. A. Davis, 2009. Print. Vaccaro, Alexander R., Michael Fehlings, and Marcel F. Dvorak. Spine and Spinal Cord Trauma: Evidence-based Management. New York: Thieme, 2011. Print. Williams, Margie. Journey to Well: Learning to Live after Spinal Cord Injury. Newcastle, CA: Altarfire Pub., 1997. Print.
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