1 Lecture 2 27.10.16 Spinal localisation Spinal cord segments T3-L3 C1-C5 C6-T2 L4-L6 L6-S1 Sciatic nerve Musculo-cutaneous, axillary, radial, median, ulnar nerves Femoral nerve Gait and postural changes · Gait +/- postural reaction deficits on pelvic limbs = lesion below the T3 spinal cord segment . Gait +/- postural reaction deficits on thoracic limbs = Lesion between the brain and T2 · Upper motor neurones are generally inhibitory to lower motor neurones therefore lesion of the upper motor neurone lead to disinhibition of the lower motor neurones UMN LMN LMN UMN Upper motor neurones vs lower motor neurones UMN LMN Paresis/ paralysis Spastic/ hypertonia Flaccid/ Hypotonia Spinal reflexes Normal to increased Reduced to absent Muscle atrophy Mild to slow Rapid and pronounced Loss of sensation Whole parts of the body Localised L4-S3 lesion (LMN) · Abnormal gait/ proprioception pelvic limbs · Normal gait/ proprioception thoracic limbs · Reduced/ absent reflexes in the pelvic limbs . Normal reflexes in the thoracic limbs T3-L3 lesion (UMN) · Abnormal gait/ proprioception pelvic limbs . Normal gait/ proprioception thoracic limbs . Normal/ increased reflexes in the pelvic limbs · Normal reflexes in the thoracic limbs C6-T2 lesion (LMN) · Abnormal gait/ proprioception pelvic limbs · Abnormal gait/ proprioception thoracic limbs . Normal/ increased reflexes in the pelvic limbs . Reduced/ absent reflexes in the thoracic limbs C1-C5 lesion (UMN) · Abnormal gait/ proprioception pelvic limbs · Abnormal gait/ proprioception thoracic limbs · Normal/ increased reflexes in the pelvic limbs . Normal/ increased reflexes in the thoracic limbs
27.10.16 2 Lecture 2 Spinal cord pathways and functions 1- conscious proprioception · Grade 1 = Pain · Grade 2 = Ataxia (effects CP and UCP) 2- unconscious proprioception · Grade 3 = Paresis (effects motor function) . Grade 4 = Complete loss of motor function but intact sensation 3- motor function 3 · Grade 5 = Complete loss of motor function and sensation 4- continence / pain Bladder dysfunction . S1-S3 region stimulates the bladder the contract and the urethral sphincters to relax . LMN bladder = If damaged then there will be a lack of sphincter tone and lack of muscle tone in the bladder wall so urine in easily expressed · UMN bladder = Difficult to express as increased sphincter tone and firm bladder wall so urine is not easily expressed E system = bladder filling ParaZ = bladder voiding Preganglionic cell bodies L2-L5 in cats L1-L4 in dogs S1-S3 Pelvic nerve (important in voiding) Motor (efferent) neuron to the external urethral sphincter Cell bodies in the caudal mesenteric ganglion Postganglionic axons of hypogastric nerve Bladder Sensory (afferent) neuron from the urethral sphincter Pudendal nerve Beta-receptors cause detrusor muscle to relax when activated to allow bladder filling Alpha-receptors cause the smooth muscle of the urethral internal sphincter to contract and close the sphincter