The plantar reflex is a
reflex
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus.
Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...
elicited when the sole of the foot is stimulated with a blunt instrument. The reflex can take one of two forms. In healthy adults, the plantar reflex causes a downward response of the
hallux (
flexion). An upward response (
extension
Extension, extend or extended may refer to:
Mathematics
Logic or set theory
* Axiom of extensionality
* Extensible cardinal
* Extension (model theory)
* Extension (predicate logic), the set of tuples of values that satisfy the predicate
* E ...
) of the
hallux is known as the Babinski response or Babinski sign, named after the neurologist
Joseph Babinski. The presence of the Babinski sign can identify
disease of the
spinal cord and
brain in adults, and also exists as a
primitive reflex in
infant
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
s.
While first described in the medical literature by Babinski in 1896, the reflex has been identified in art at least as early as
Botticelli
Alessandro di Mariano di Vanni Filipepi ( – May 17, 1510), known as Sandro Botticelli (, ), was an Italian painter of the Early Renaissance. Botticelli's posthumous reputation suffered until the late 19th century, when he was rediscovered ...
's ''
Virgin and Child with an Angel'', painted in the mid-
15th century
The 15th century was the century which spans the Julian dates from 1 January 1401 ( MCDI) to 31 December 1500 ( MD).
In Europe, the 15th century includes parts of the Late Middle Ages, the Early Renaissance, and the early modern period.
M ...
.
Methods

The
lateral side of the
sole of the foot is rubbed with a blunt instrument or device so as not to cause pain, discomfort, or injury to the skin; the instrument is run from the heel along a curve to the
toes (
metatarsal pads). Many
reflex hammers taper at the end of the handle to a point which was used for testing the plantar response in the past; due to the tightening of
infection control regulation this is no longer recommended. Either a single use device or the thumb nail should be used.
There are three responses possible:
* Flexor: the toes curve down and inwards, and the foot
inverts; this is the response seen in healthy adults.
* Indifferent: there is no response.
* Extensor: the
hallux dorsiflexes, and the other toes fan out; this is Babinski's sign, which indicates damage to the
central nervous system if elicited in an adult, but normal reflex if elicited in infants (see below).
As the
lesion responsible for the sign expands, so does the area from which the
afferent
Afferent may refer to:
Anatomical structures
Meaning "conveying towards a center":
* Afferent arterioles, blood vessels that supply the nephrons
* Afferent lymphatic vessels, lymph vessels that carry lymph to a lymph node
* Afferent nerve fiber ...
Babinski response may be elicited. The Babinski response is also normal while asleep and after a long period of walking.
Interpretation

The Babinski sign can indicate
upper motor neuron lesion constituting damage to the
corticospinal tract. Occasionally, a pathological plantar reflex is the first and only indication of a serious disease process and a clearly abnormal plantar reflex often prompts detailed
neurological investigations, including
CT scanning
A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...
of the brain or
MRI of the spine, as well as
lumbar puncture
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to ...
for the study of
cerebrospinal fluid.
The phrase "negative Babinski sign" is sometimes used for the normal flexor plantar response.
In infants
Infant
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
s will usually show an extensor response. In one study of 256 healthy infants, the response to testing was extensor in 73.8%, flexor in 8.9%, and equivocal in 17.3% This extensor response occurs because the
corticospinal pathways that run from the
brain down the
spinal cord are not fully
myelinated at this age, so the reflex is not inhibited by the
cerebral cortex. The extensor response usually disappears – giving way to the flexor response – by 12 months of age. Its persistence beyond age 2–3 indicates a problem in the brain or spinal cord.
Pathways
* Afferent: Nociception detected in the S1 dermatome and travels up the tibial nerve to the sciatic nerve to roots of L5,S1 and synapse in the anterior horn to elicit the motor response.
* Efferent: Motor response back through the L5,S1 roots to the sciatic nerve to its bifurcation. Toe flexors are innervated by the tibial nerve. Toe extensors (extensor hallucis longus, extensor digitorum longus) are innervated by the deep peroneal nerve. Loss of normal adult descending pyramidal control of the reflex arc to suppress extensor withdrawal results in the upgoing toes in the plantar reflex known as Babinski's sign.
Relationship to Hoffmann's reflex
The
Hoffmann's reflex is sometimes described as the
upper limb equivalent of the Babinski sign because both indicate
upper motor neuron dysfunction. Mechanistically, they differ significantly; the finger flexor reflex is a simple
monosynaptic spinal reflex involving the
flexor digitorum profundus that is normally fully inhibited by upper motor neurons. The pathway producing the plantar response is more complicated, and is not monosynaptic.
Babinski-like responses
The plantar reflex can be elicited in a number of ways, which were described in the late 19th and early 20th century. These have their own eponyms.
*
Bing sign – multiple pinpricks on the
dorsum of the foot
*
Cornell sign – scratching along the inner side of the
extensor hallucis longus tendon
*
Chaddock sign – stroking the
lateral malleolus
* Doug's sign – electrically stimulating peripheral nerves during a
Nerve conduction study
*
Gonda sign –
flexing and suddenly releasing the 4th toe
*
Gordon sign – squeezing the calf muscle
*
Moniz sign
Moniz sign is a clinical sign in which forceful passive plantar flexion of the ankle elicits an extensor plantar reflex. It is found in patients with pyramidal tract lesions, and is one of a number of Babinski-like responses.It is named after Port ...
– forceful passive
plantar flexion of the ankle
*
Oppenheim sign – applying pressure to the medial side of the
tibia
*
Schaeffer sign – squeezing the
Achilles tendon
* Silva sign – pinching the
rectus femoris muscle
*
Stransky sign – vigorously
abducting and suddenly releasing the
little toe
*
Strümpell sign – patient attempts to flex the knee against resistance
*
Throckmorton reflex – percussion over the
metatarsophalangeal joint of the big toe
Abnormal reflexes seen as flexion of toes
*
Bekhterev-Mendel reflex – flexion of the 2nd to 5th toes on percussion of the dorsum of the foot
*
Rossolimo sign – exaggerated flexion of the toes induced by rapid percussion on the tips of the toes
References
{{DEFAULTSORT:Plantar Reflex
Reflexes