Term
| Dorsal column spinal-medial lemniscal pathway (DCML) |
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Definition
The DCML is located posteriorly in the spinal column white matter. There are two parts:
● Fasciculis gracilis (posteromedial): information from lower extremity
● Fasciculis cuneatus (posterolateral): information from upper extremity
Once inside the dorsal horn, the sensory input takes two different routes:
● Direct: fibers ascend ipsilaterally in the dorsal column
● Indirect:
o Fibers synapse with dorsal horn neurons
o Axons of those neurons first ascend in the ipsilateral dorsal column
o At the level of the medulla they synapse on neurons in the nucleus cuneatus or nucleus gracilis
o These form the medial lemniscus, that crosses to the opposite side and ascends to synapse on cell bodies in the thalamus
DCML transmits information about:
● Touch discrimination, for example stereognosis (helps identify objects)
● Position
● Movement |
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Term
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Definition
Fibers carrying sensory input synapse with sensory neurons in the dorsal horn and decussate within the next spinal cords segments above. Then they ascend to terminate in the ventro-lateral nucleus of the thalamus. The spinothalamic pathway is divided into
● Lateral spinothalamic tract: pain and temperature sensation
● Ventral spinothalamic tract: touch
Just like in the DCML, information from the upper and lower part of the body are separated within these tracts:
● Upper part: laterally
● Lower part: medially
The spinothalamic pathway transmits information about:
● Pain
● Temperature
● Discrete touch |
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Term
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Definition
● Increased deep tendon reflexes
● Increased muscle tone
● Clonus
● Abnormal reflexes
● Difficulty isolating the contraction of individual muscles |
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Term
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Definition
● Weakness/ atrophy
● Diminished/ absent deep tendon reflexes
● Fasciculations
● Trauma
● Vascular disorder
● Diseases that target the anterior horn cell |
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Term
| A hemisection results in the Brown-Sequard syndrome |
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Definition
● Loss of voluntary motor function, with normal motor function contralaterally
● Below the lesion ipsilateral loss of position sense and contralateral loss of pain/ temperature sense |
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Term
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Definition
| ● More motor dysfunction in the upper extremities, proximal more than distal - note the position of the motor tracts on a cross section of the spinal cord |
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Term
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Definition
● Loss of motor function below lesion – note corticospinal tracts
● Also loss of pain and temperature sense - note spinothalamic tracts |
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Term
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Definition
● Motor function preserved – affects only sensory tracts: position sense, discrimination, vibration
● Watch out for wide-based gait |
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Term
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Definition
use familiar odor such a coffee. Failure to recognize could indicate:
● Upper respiratory infection
● Normal decline of olfactory capacity with aging
● Frontal lobe damage |
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Term
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Definition
● Central visual acuity: read signs across the room
● Peripheral vision: movements outside the focus of the patient’s visual field |
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Term
| Oculomotor, trochlear, and abducens nerves (III, IV, and VI): |
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Definition
● Movements of the eyes; tested by moving a pen in front of the patient. Observe for symmetry and speed of motion
● Pupillary reaction to light; both pupils should constrict when light is directed at one eye |
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Term
| Trigeminal nerve (V) tests: |
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Definition
● Sensory: light touch to the side of face, in the three regions of the branches
● Motor: palpation for contraction of the muscles of mastication |
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Term
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Definition
| ● Facial expressions, relating both to upper and lower parts of the face |
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Term
| Vestibulocochlear nerve (VIII): patients may complain of: |
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Definition
patients may complain of:
● Dizziness, nausea, balance problems (vestibular portion)
● Tinnitus or hearing deficit (cochlear portion); hearing tests address both air-transmitted sound and sound conducted in bone (Weber’s test) |
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Term
| Glossopharyngeal, and Vagus nerves (IX and X): |
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Definition
● These work together in swallowing and the gag reflex. If you limit your testing to swallowing, that is more acceptable to the patient!
● Glossopharyngeal supplies taste buds on the posterior 1/3 of tongue |
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Term
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Definition
| ● Motor supply of upper trapezius and sternomastoid |
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Term
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Definition
● Motor supply of the tongue
● Unilateral weakness results in deviation of tongue, on protrusion |
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