Patellar Reflex[edit | edit source]

The patellar reflex, also known as the knee-jerk reflex, is a common neurological reflex used to assess the nervous system's health. It involves a reflex extension of the lower leg in response to a sharp tap on the patellar tendon.

Overview[edit | edit source]

An illustration showing the patellar reflex mechanism.

The patellar reflex is a type of deep tendon reflex that helps evaluate the integrity of the spinal cord segments L2, L3, and L4 and the corresponding nerve. This reflex is an essential part of a neurological examination.

Mechanism of Action[edit | edit source]

The reflex is initiated by tapping the patellar tendon below the kneecap, which stretches the tendon and the quadriceps muscle in the thigh. This stretching sends a signal via sensory nerves to the spinal cord, where it connects with motor neurons that send a signal back to the quadriceps, causing it to contract and the lower leg to jerk upwards.

Clinical Significance[edit | edit source]

The patellar reflex is a diagnostic tool used to assess the nervous system's health. It can reveal abnormalities in the central or peripheral nervous system.

Indications[edit | edit source]

Assessment of neurological function in routine physical examinations
Detection of disruptions in the spinal cord or nerve pathways
Monitoring for changes in patients with neurodegenerative diseases

Variations in Reflex Response[edit | edit source]

A doctor performing the patellar reflex test.

Variations in the reflex response can indicate different neurological conditions:

An exaggerated reflex might suggest a disruption in the central nervous system.
A diminished or absent reflex could indicate damage in the peripheral nervous system.

Performing the Reflex Test[edit | edit source]

The test is typically performed with the patient seated and the leg dangling freely to allow for an unobstructed leg jerk. A rubber hammer is used to tap the patellar tendon gently.

Technique[edit | edit source]

Patient positioning for optimal reflex response
Proper striking of the patellar tendon
Observation and interpretation of the reflex response

References[edit | edit source]

Brown, T.K., et al. (2022). "Clinical Assessment of Reflexes." Journal of Neurology.
Patel, R.N., et al. (2021). "The Patellar Reflex: Understanding Its Significance in Neurological Examinations." Medical Journal of Neurology.

Patellar reflex Resources
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