Physical reflexes

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There is a complete list of physical reflexes on this page, and there are quite a lot of them; some not very well known.  Many of these came from our evolutionary past where a fast, automatic response assisted our survival where thinking is too slow.  Most are under direct control of the reptilian brain.  They operate automatically and involuntarily.  You can’t stop them by thinking about it.

kneejerk.pngYou may want to try out (carefully!) some of the more unfamiliar ones at home.

  1. Accommodation reflex – reflex action of the eye when the lens is near an object.
  2. Acoustic reflex – contraction of muscles in the middle ear in response to loud sounds.
  3. Ankle jerk reflex – ankle jerks when the Achilles tendon is struck with a hammer.
  4. Arthrokinetic reflex – muscular activation or inhibition in response to joint mobilisation.
  5. ATNR – in young infants, when the head is turned to the side the arm will straighten.
  6. Babinski reflex – in infants the toes spread in response to stroking the side of the foot.
  7. Baroreflex – homeostatic counter-effect to a sudden elevation or reduction in blood pressure.
  8. Bezold-Jarisch reflex – cardiovascular and neurological processes which cause hypopnea and bradycardia.
  9. Biceps reflex  – a jerking of the forearm when the biceps brachii tendon is struck with a hammer.
  10. Blushing  reddening of the face caused by embarrassment, shame, or modesty.
  11. Brachioradialis reflex — a jerking of the forearm when the brachioradialis tendon is hit with a hammer
  12. Corneal reflex  blinking of both eyes when the cornea of either eye is touched.
  13. Cough reflex – a rapid expulsion of air from the lungs usually due to an irritation of the trachea.
  14. Cremasteric reflex – elevation of the scrotum and testis caused by stroking part of the upper thigh.
  15. Crossed extensor reflex – a contraction of a limb in response to ipsilateral pain, and extension of the contralateral limb.
  16. Galant reflex – in young babies a rotation of the upper body towards one or other side of the back when that side is stroked.
  17. Glabellar reflex – repetitive tapping of the forehead can cause a blinking response.
  18. Golgi tendon reflex – a normal muscle lengthening and shortening response when another muscle in tensed.
  19. Hering–Breuer reflex – a reflex triggered to prevent over-inflation of the lung.
  20. Jaw jerk reflex – a tap to the lower jaw will cause the upper jaw to open slightly.
  21. Knee jerk – well known kick response when the patellar is struck with a hammer.
  22. Mammalian diving reflex – body response slowing heartbeat and respiration when the face is immersed in very cold water.  Assists in surviving for longer periods without oxygen.
  23. Moro reflex – in young babies, a sudden symmetric spreading of the arms, then unspreading and crying, caused by an unexpected loud noise or the sensation of being dropped. It is the only unlearned fear in humans.
  24. Palmar grasp reflex – in young babies, a closing of the hand in response to an object being placed in it.
  25. Photic sneeze reflex – a sneeze caused by sudden exposure to bright light.
  26. Plantar reflex – in infants up to 1 year of age, a curling of the toes when something rubs the ball of the foot.
  27. Pupillary accommodation reflex – a reduction of pupil size in response to an object coming close to the eye.
  28. Pupillary light reflex – a reduction of pupil size in response to light.
  29. Rooting reflex – turning of an infant’s head toward anything that strokes the cheek or mouth.
  30. Shivering – a common response to cold, shaking of the body.
  31. Sneeze – another very common response expelling air from the lungs.  Normally triggered by irritation nasal cavity.
  32. Suckling reflex – sucking at anything that touches the roof of an infant’s mouth.
  33. Stretch reflex – muscle contraction in response to stretching within the muscle.
  34. Triceps reflex – jerking of the forearm when the triceps tendon is hit with a  hammer.
  35. Vagovagal reflex – contraction of muscles in the gastrointestinal tract in response to distension of the tract following consumption of food and drink.
  36. Vestibulocollic reflex – corrects the orientation of the body when it is taken out of its normal upright position.
  37. Vestibulo-ocular reflex – movement of the eyes to the right when the head is rotated to the left, and vice versa.
  38. Yawn – a common reflex when we are tired  simultaneous inhalation of air and the stretching of the eardrums, followed by an exhalation of breath.  The mechanism of yawning and how it can spread to others nearby, is not well understood.

yawn