Somatic spinal cord reflexesAnd

Spinal cord lesions & shock

Ashish Patil MD/PhD

All Saints School of Medicine Dominica

13-2

The Stretch Reflex stretch (myotatic) reflex - when a muscle is stretched, it ‘fights back’

and contracts which maintains increased tonus, making it stiffer than unstretched muscle helps maintain equilibrium and posture

head starts to tip forward as you fall asleep muscles contract to raise the head

stabilize joints by balancing tension in extensors and flexors smoothing muscle actions

stretch reflex is fine tuned by the brain not strictly a spinal reflex

knee-jerk (patellar) reflex is monosynaptic reflex one synapse between the afferent and efferent neurons

testing somatic reflexes helps diagnose many diseases

reciprocal inhibition - reflex phenomenon that prevents muscles from working against each other by inhibiting the antagonist

Inverse stretch refelex

reciprocal inhibition - reflex phenomenon that prevents muscles from working against each other by inhibiting the antagonist

Inverse stretch reflex

Deep Tendon reflexes

Withdrawal Reflex

Golgi Tendon Reflex

Golgi Tendon Reflex

Note Tapping on patellar tendon does not stretch golgi tendon of quadriceps femoris, it stretches quadriceps femoris

Supraspinal control of stretch refelx

Supraspinal control of stretch reflex

Brown Sequard Syndrome

Half sided cortex lesions

Half sided mid brain lesion

Spinal Shock

Spinal shock is a combination of areflexia/hyporeflexia and autonomic dysfunction that accompanies spinal cord injury. The initial hyporeflexia presents as a loss of both cutaneous and deep tendon reflexes below the level of injury accompanied by loss of sympathetic outflow, resulting in hypotension and bradycardia

Spinal Cord Blood Supply

Anterior Spinal Cord Syndrome

Syringomyelia

Central Cord lesions seen in syringomyelia

Polio affect anterior horn cells

ALS has both UMNL and LMNL

Subacute combined degeneration of spinal cord

Internal capsule all 3 limbs supplied by lenticulostriate artery

Stroke of lenticulostriate artery