Sensory Pathways 1 Flashcards
What type of information do A alpha fibres carry?
Proprioception
What type of information do A beta fibres carry?
Touch, pressure
What type of information do A delta fibres carry?
Pain, temperature
What type of information do C fibres carry?
Temperature, pain, itch
What do free nerve endings detect?
Pain
What do Merkel’s disks detect?
Static touch
Pressure
What do Meissner’s corpuscles detect?
Touch, pressure
What do Pacini’s corpuscles detect?
Vibration
What do Ruffini corpuscles detect?
Skin stretch
Which sensory fibres innervate muscle spindles?
Group Ia and II
Which sensory fibres innervate golgi tendon organs?
Group Ib
What type of information do the spinocerebellar tracts transmit?
Proprioceptive information
What type of information does the spinothalamic tract transmit?
Pain
Which type of nerve fibres are present in the dorsal columns?
Large A beta fibres
Where do neurons project to from the medial lemniscus in the DCML pathway?
Ventral Posterolateral Lobe of Thalamus
What is a classic sign of gait ataxia?
Stamp and stick - slap foot down to get max sensory input and maintains a broad based stance
Which signs on examination indicate dorsal column disease?
Inability to feel joint position or vibration by a tuning fork
Positive Romberg’s test
What are the cortical functions of the dorsal column pathway?
Determine shape and texture of objects
What happens if someone has a lesion in the somatosensory association cortex?
Unable to regonise complex objects by touch (on opposite side)
Patients may neglect one whole side of body - overlook motor output
Which sensory receptor is found only in glabrous skin types?
Meissner’s corpuscles
Which sensory receptor has a high activation threshold?
Free nerve endings
What is the purpose of lateral inhibition?
Sharpens the discrimination between two points
What is lateral inhibition?
Lateral inhibition is the capacity of an excited neurone to reduce the activity of its neighbours
Why does damage to the gracile fasciculus cause gait ataxia?
Brain is deprived of information about the position of the feet
Why do people with dorsal column disease experience parasthesias?
Ectopic discharge in damaged dorsal column axons
What is amorphosynthesis?
Inability to recognise complex objects by touch on the opposite side of the lesion
