Clinical skills-upper limb nerves and vessels Flashcards
What are myotactic reflexes?
stretch reflexes that cause muscle contraction after the muscle is stretched
Describe function of afferent and efferent neurones?
afferent(sensory)-ipulses from sensory receptors in the muscle to the spinal cord
efferent(motor)-running fromthe anterior grey columns of the spinal cord to the effector organ
What is a monosynaptic vs multiosynaptic reflex arch?
monosynaptic- contains 2 neurons-sensory and motor
Multisynaptic-contains neurones connecting sensory and motor neurons
What is a tendon hammer used for?
Describe how it works?
small rubber hammer used to elicit reflex
it is tapped to the tendon muscle =stretching of the muscle spindle. This stimulus travels to the spinal cord ans stimulates the EFFERENT motor neurones in the ANTERIOR GREY COLUMNS(horns) resulting in involuntary contraction of the main muscle attached to that tendon
Of it is difficult to elicit a tendon reflex what can you do?
apply REINFORCEMENT- for example you will ask the patient to either clench the teeth or squeeze an object in their hand
What are 3 main myotactic reflexes to test in the upper limb?
which spine segment/nerve root does each test?
BICEPS tendon reflex-c5 and c6
TRICEPS tendon reflex- c7 and c8
BRACHIORADIALIS(supinator) reflex-c5 and c6
How do you test the triceps tendon reflex?
ask patient to relax their arm completely and bend it at a right angle at the elbow with forearm across the stomach
Then tap the tendon near the elbow with a tendon hammer
compare reflex on both sides
How do test the biceps tendon reflex?
ask patient to relax their arm completely and bend it at a right angle at the elbow with forearm across the stomach
Then tap the tendon near the elbow with a tendon hammer
How do you test the supinator reflex?
ask patient to relax their arm completely and bend it at a right angle at the elbow with forearm across the stomach
Then tap the tendon near the wrist with a tendon hammer
What are the laws of reciprocal innervation?
in the same limb the flexor and extensor muscles cant contract simultaneously
What can abnormally exaggerated myotactic reflexes mean?
UPPER MOTOR NEURON LESION in the brain (as higher centres of the brain influence spinal segmental reflex arch)
What does complete absence of reflexes(areflexia) suggest?
disorder in a component of the reflex arch-muscle spindles, afferent sensory neurons, efferent motor neurons and the effector organs-muscle itself
due to LOWER MOTOR NEURON LESION
Describe the grading system used to examine the character of reflexes?
0-absent 1+ -decreased, but still preset 2+ - Normal 3+ -hyper reflex 4+ -clonus-repetitive shortening of the muscle after a single stimulation
What is a dermatome and myotome?
dermotome-area of the skin supplied by a single spinal nerve (but possibly many peripheral nerves as the fibres from e.g. C5 are distributed between many peripheral nerves in the brachial plexus)
myotome-region of skeletal muscle innervated by a single spinal nervel
Why might the loss of a single spinal nerve root not cause any detectable sensory loss in a dermatome?
because on the skin adjacent dermotomes overlap considerably
So to be able to detect a significant sensory loss at least 3 adjacent dermotomes should be affected
Where are their no overaps of the dermotomes?
across the AXIAL lines of the limb
What would damage to a peripheral nerve cause?
effect large areas of skin(Dermotomes) and several muscles (myotomes) because they carry nerve components from several spinal segments to the skin and muscle area
What are the dermatome region of the upper limb?
C4-shoulder C5-lateral side of the arm C6-lateral side of the forearm and thumb C7-middle and ring finger C8-medial side of the hand, forearm and little finger T1-medial side of forearm and arm T2-Axilla