Reflex arc occurs when a muscle is suddenly stretched signal to spinal cord muscle contraction. Deep tendon reflexes test afferent nerve, the synaptic connection, the motor nerves and descending motor pathways.
Have patient relax – position them so that there is a slight stretch on muscle strike tendon briskly with reflex hammer.
If absent or diminished reinforce by having patient lock fingers and pull hands against each other (Jendrassik’s manoeuvre)
0 Absent/no response
1 Diminished/slight jerk
• innervated by L2-L4
• patient seated with knee flexed
• strike just below patellar
• innervated by S1-S2
• patient supine, flex hip and knee externally rotate leg so it rests across contralateral leg examiner dorsiflexes to resistance strike achilles tendon
• Babinski sign/extensor plantar response
• patient supine, knee slightly flexed – stroke foot firmly with hard blunt object from lateral heel to lateral forefoot and then medially across forefoot
• if hallux dorsiflexes and toes spread positive for CNS disorder
• positive Babinski’s sign is normal up to 6 months of age