Sensory System Flashcards
Peripheral Nerve
Part of spinal nerve distal to the spinal nerve root and plexus
Bundles of nerve fibres from more than one dermatome
Mononeuropathy
Peripheral nerve damaged individually (trauma/compression)
What is a common cause of peripheral neuropathy?
Diabetes
Ulnar nerve
Little finger and medial part of ring finger
Median Nerve
First 3 fingers (thumb, pointer, middle)
Radial Nerve
Tissue next to thumb
Sciatic nerve
Backside of leg entire
Lateral cutaneous nerve
Anterior part of thigh (lateral)
Femoral nerve
Medial anterior part of thigh, passes knee
Peroneal nerve
Foot and lateral part of shin
Spinal nerve organization
Ventral motor root
Dorsal sensory root
Dermatome
Area of skin supplied by a single spinal nerve from a single sensory root
C5
Lateral/radial side of antecubital fossa just proximal to elbow
C6
thumb
C7
Middle finger
C8
Little finger
T1
Medial/ulnar side of antecubital fossa just proximal to elbow
T4
Level of nipples
T10
Horizontal level of umbilicus
L2
Antero-lateral upper thigh
L3
Medial aspect distal thigh/knee
L4
Great toe, medial malleolus
L5
3rd toe
S1
Calcaneus, lateral malleolus, 5th toe
Dorsal columns
Carry sensory information about fine touch, vibration and joint position (TVP)
Run on ipsilateral side of spinal cord until they reach medulla = cross
Spinothalamic Tract
Pain and temperature sensation
Fibres enter spinal cord, synapse in dorsal horn and then travel in contralateral side to thalamus and reticular formation
Why is light touch examination least helpful in determining site of lesion?
Fibres relaying info about light touch travel in both the posterior columns and anterior spinothalamic tract
When does Brown Sequard syndrome occur?
When one half of the spinal cord is damaged
- ipsilateral motor weakness and loss of vibration/joint position sense
- contralateral loss of pain and temperature
Hemi-neglect
Lesions affecting right parietal lobe
Neglect visual, somatosensory or auditory stimuli on left side
Hemi-neglect
Lesions affecting right parietal lobe
Neglect visual, somatosensory or auditory stimuli on left side
What is the key test stimulus when using the neurotip?
Sharp - limit the number of dull checks
What is tested in the sensory exam?
Light touch
Superficial pain
Proprioception - Joint Position Sense
Vibration
