8. Localization and Differentiation of Neurologic Diseases Flashcards
What area of the brain maintains mental alertness?
The Ascending Reticular Activating System (ARAS) of the brainstem. (repetitively signals the forebrain to maintain consciousness)
What is the function of the spinocerebellar tracts?
Convey proprioceptive information from the spinal cord to the cerebellum
What does an inability to resist a tail pull at rest indicate?
Suggestive of a lower motor neuron (spinal cord grey matter, nerve roots, or peripheral nerves) of L3-S2 spinal cord segments on the side being tested
Unilateral lesions in the medulla oblongata or spinal cord cause severe proprioceptive and postural deficits in the _________ limbs
Ipsilateral
Unilateral lesions rostral to the medulla oblongata produce mild to moderate proprioceptive and postural deficits in the _________ limbs
Contralateral
Animals that are in lateral recumbency and unable to lift the head from the ground may have lesions….
Peripheral or brainstem vestibular centers or in the cervical spinal cord cranial to C4 when lesion side is up
A laterally recumbent animal that can lift head but not rotate thorax may have a lesion…
C7 to T2
When rising, animals with lesions of the thoracolumbar and lumbosacral spinal cord (T3 to S3 spinal cord segments) can…
Usually, lift the head and neck, arise on the thoracic limbs, and assume a dog-sitting position
Define Upper Motor Neuron
A nerve cell contained completely within the CNS, with cell bodies in the brain and axons that terminate at synapses within the brain or spinal cord.
Define Lower Motor Neuron
The cell bodies are in the nuclei of of cranial nerves in the brainstem or in the ventral horn grey matter of the spinal cord. The axons exit the CNS and terminate at neuromuscular junctions
Diseases affecting lower motor neurons result in… (5)
- Decreased spinal reflexes
- Ataxia
- Moderate to severe weakness
- Decreased muscle tone (flaccidity)
- Rapid, pronounced atrophy of the denervated muscles.
Diseases affecting upper motor neurons result in…(3)
- Normal to increased spinal reflexes
- Variable severity of weakness
- Variably increased muscle tone (spasticity)
Lesions in the spinal cord cranial to the level of the reflex arc and lesions of the brain result in ______ myotatic reflexes
Normal to Increased
Lesions in either the afferent or the efferent components of the reflex arc result in _____ myotatic reflexes
Decreased to Absent
The triceps reflex measures the integrity of the ____
Radial nerve and C7, C8, T1 spinal segments
The Biceps reflex measures the function of the ____ (Slight difference between horses and cattle)
Musculocutaneous nerve and spinal cord segments C6 to C8 in ruminants and C7 and C8 in horses
The thoracic limb flexor reflex tests the integrity of the _______
Axillary, median, and musculocutaneous nerves and spinal cord segments C5 through T2, as well as the flexor muscles of the limb
The pelvic limb flexor reflex is mediated by ______
Sciatic, peroneal, and tibial nerves; the pelvic limb flexor muscles; and spinal cord segments L6 to S2
The perineal reflex is mediated by the _____
Pudendal nerve and spinal cord segments S1 to S5
The Cutaneous trunci reflex evaluates ___
C8 to T1 in ruminants and C8 to T2 in horses and the lateral thoracic nerve
The cervical reflex evaluates ____
the integrity of the dorsal funiculi of cervical spinal cord segments and the facial nerve in the medulla oblongata.
Reduced or absent laryngeal adductor reflexes are found in animals that have lesions of ____
The cervical spinal cord, caudal brainstem, vagus nerve, and left recurrent laryngeal nerve
The tone of the thoracic limbs is controlled through (Spinal segments and 6 nerves)
spinal cord segments C6 to T2 and the radial, musculocutaneous, median, ulnar, axillary, and long thoracic nerves
The motor tone of the pelvic limbs is controlled through (spinal segments and 4 nerves)
L3 to S2 and the femoral, cranial and caudal gluteal and sciatic nerves
Loss of oculomotor nerve function results in
Ventrolateral strabismus, loss of PLR, ptosis
Trochlear nerve dysfunction results in
Dorsomedial strabismus
Loss of abducent nerve function results
Medial strabismus and inability to retract the globe
Functions of the Trigeminal Nerve
Sensory to the face and motor to the muscles of mastication
Equine Vertebral Formula
C7T18L5-6Cd15-21
Ox Vertebral Formula
C7T13L6S5Cd18-21
What can cause Horners Syndrome?
Lesion along preganglionic or postganglionic sympathetic nerve fibers or in spinal segments T1-3 or rarely in the upper motor neuron component of the sympathetic pathway in the cervical spinal cord or brainstem