The two-point discrimination subtest highlights the density of sensory endings, and therefore receptive fields in the skin. Her knee-jerk reflex is normal and she exhibits a plantar reflex negative Babinski reflex. The spinal nerves, which contain sensory fibers with dendritic endings in the skin, connect with the skin in a topographically organized manner, illustrated as dermatomes. Which part of her cord is likely to be compressed? Lateral differences in strength—being able to push against resistance with the right arm but not the left—would indicate a deficit in one corticospinal tract versus the other. A loss of sensation in his torso B inability to breathe C problems with moving his arms D uncontrollable sweating of his feet E problems moving his legs 61 Mary is in an automobile accident and suffers a spinal cord injury. D Reflex responses can be enhanced by repetition. C It can provide sensory and motor anesthesia, depending on the anesthetic selected.
The corticospinal tract represents the neurons that send output from the primary motor cortex. Spasticity is an excess contraction in resistance to stretch. E suffered no damage to her spinal cord. A loss of sensation in his torso B inability to breathe C problems with moving his arms D uncontrollable sweating of his feet E problems moving his legs 40 The preganglionic fibers that connect a spinal nerve with an autonomic ganglion in the thoracic and lumbar region of the spinal cord and carries visceral motor fibers that are myelinated form the A white rami communicantes. Mistaking painful stimuli for light touch, or vice versa, may point to errors in ascending projections, such as in a hemisection of the spinal cord that might come from a motor vehicle accident. Identify and describe the anatomical features of the spinal cord and spinal nerves 2. The ventral horn motor neurons then project to skeletal muscle and cause contraction.
To test the sensory fields, a simple stimulus of the light touch of the soft end of a cotton-tipped applicator is applied at various locations on the skin. E suffered no damage to her spinal cord. B injured one of her ascending nerve tracts. To assess the limit of this sensitivity, two-point discrimination is measured by simultaneously touching the skin in two locations, such as could be accomplished with a pair of forceps. The patient keeps their eyes closed while the examiner switches between using both points of the caliper or just one.
Other superficial reflexes are not commonly tested, though a series of abdominal reflexes can target function in the lower thoracic spinal segments. These fibers travel through the deep white matter of the cerebrum, then through the midbrain and pons, into the medulla where most of them decussate, and finally through the spinal cord white matter in the lateral crossed fibers or anterior uncrossed fibers columns. The opposite is true on the other side. The trauma would be at the level just before sensory discrimination returns to normal, helping to pinpoint the trauma. The dorsal column information ascends ipsilateral to the source of the stimulus and decussates in the medulla, whereas the spinothalamic pathway decussates at the level of entry and ascends contralaterally.
She has lost feeling in her lower body. The patient then must indicate whether one or two stimuli are in contact with the skin. The waiter brings a very hot plate, telling you to be careful about touching it. These results suggest that Tina has A injured one of her descending nerve tracts. The perception of pain can be tested using the broken end of the cotton-tipped applicator.
C the spinal cord would not be able to process information at that level. Her knee-jerk reflex is normal and she exhibits a plantar reflex negative Babinski reflex. In addition to testing perception at different positions on the skin, it is necessary to test sensory perception within the dermatome from distal to proximal locations in the appendages, or lateral to medial locations in the trunk. The reason for this is that the dorsal column pathway ascends ipsilateral to the sensation, so it would be damaged the same way as the lateral corticospinal tract. B You have no conscious control or modification ability over reflex action.
Voluntary movements require these two cells to be active. A parallel B reverberation C serial D convergent E consensual 84 Which statement is false regarding reflexes? Whereas the brain develops into a complex series of nuclei and fiber tracts, the spinal cord remains relatively simple in its configuration. Within the spinal cord, the two systems are segregated. This test can indicate deficits in dorsal column pathway proprioception, as well as problems with proprioceptive projections to the cerebellum through the spinocerebellar tract. Muscle Strength and Voluntary Movement The skeletomotor system is largely based on the simple, two-cell projection from the precentral gyrus of the frontal lobe to the skeletal muscles.
The fiber synapses directly on the ventral horn motor neuron that activates the muscle, causing contraction. An overall loss of strength, without laterality, could indicate a global problem with the motor system. The somatic senses are those that usually make up the conscious perception of the how the body interacts with the environment. Using the cotton tip of the applicator, or even just a fingertip, the perception of tactile movement can be assessed as the stimulus is drawn across the skin for approximately 2—3 cm. On the paralyzed leg, a patient will acknowledge painful stimuli, but not fine touch or proprioceptive sensations.
Without visual feedback that the body is in a vertical orientation relative to the surrounding environment, the patient must rely on the proprioceptive stimuli of joint and muscle position, as well as information from the inner ear, to maintain balance. The patient is asked to stand straight with feet together. Discuss the functions of the spinal cord and spinal nerves and understand how they help maintain homeostasis in the body 3. On the functional leg, the opposite is true. Why is the distance between the caliper points closer on the fingertips as opposed to the palm of the hand? Testing these stimuli provides information about whether these two major ascending pathways are functioning properly. If a muscle is stretched, it reflexively contracts to return the muscle to compensate for the change in length. Movement disorders may be the result of changes to the muscle tissue, such as scarring, and these possibilities need to be ruled out before testing function.