Deep Tendon Reflex: Patellar Tendon

What is the patella tendon reflex also known as?

Knee jerk reflex

What spinal segment does a deep tendon reflex involve?

L3-L4

Is the patellar tendon reflex, voluntary or involuntary?

Involuntary

A patellar Tendon reflex is a contraction of the

quadriceps

What is the patellar tendon reflex for?

A neurological examination to assess lower motor neuron function

When is the patellar tendon reflex test performed?

During routine physical examinations as a part of a comprehensive neurological assessment, investigating potential nerve/muscle disorders, and to monitor the progression of certain neurological condition conditions

Why is the patellar tendon reflex important?

It provides insight into the functioning of the nervous system, helps identify potential spinal cord or nerve root problems, can indicate issues with muscle strength, or tone, and assist in diagnosing condition conditions like hyperthyroidism or vitamin B12 deficiency

Patient position through the patellar tendon reflex test

Patient sat on the edge of the exam table, legs dangling freely, not touching the floor, patient is relaxed and comfortable, and ask the patient to close their eyes to prevent anticipation

Procedure for the patellar tendon reflex test

Locate the patella tendon below the kneecap, use a reflex hammer to strike the tendon firmly, observe the immediate response of the lower leg, and repeat the test on both knees for comparison.

What does a normal patella tendon reflex response look like

Quick/brisk extension of the lower leg, amplitude of movement is moderate, response to symmetrical in both legs, no delay between tap and response

What does grade 0 mean for the patellar tendon reflex?

No Response

What does grade 1 of the patellar tendon reflex look like?

Diminished, but present

What does grade 2 of the patellar tendon reflex look like?

Normal response

What does grade 3 of the patellar tendon reflex look like?

Increased, but not necessarily abnormal

What does grade 4 of the patellar tendon reflex look like?

Very brisk/fast, hyperactive

abnormal responses of the patellar tendon reflex test

Hyperreflexia, Hyporeflexia, Asymmetry, and Clonus

Hyperreflexia

Exaggerated reflex response

Hyperreflexia Indicating

upper motor neuron lesions

Possible Causes of hyperreflexia

Spinal cord injury above L4, multiple sclerosis, and stroke affecting the corticospinal tract

Hyporeflexia

Administered or absent reflex response

Hyporeflexia Indicating

Lower motor neuron issues

Possible causes of hyporeflexia.

Peripheral neuropathy, Guillain Barré syndrome, and lumbar radiculopathy (L3-L4)

Asymmetry

Different responses between left and right knees

Asymmetry indicating

Unilateral nerve root compression or injury

Possible causes of asymmetry

Herniated disc, spinal stenosis, localized trauma or inflammation

Clonus

Rhythmic involuntary muscle contractions

Clonus indicating

Upper motor neuron dysfunction

Where is clonus seen in?

Spinal cord injury, cerebral palsy, and severe multiple sclerosis

Factors that affect patellar tendon reflex

Age, medication, fatigue, and distraction

How does age affect patellar tendon reflex?

Reflexes may diminish in older adults

How does medication affect patellar tendon reflex?

Some drugs can alter reflex responses

How does fatigue affect patella tendon reflex?

Can temporarily reduce reflex intensity

How does distraction affect patellar tendon reflex?

Patient focus can influence the response

What needs to be taken into consideration during patellar tendon reflex test?

The patient’s medical history and symptoms

Should results of the patellar tendon reflex test be interpreted right away after the exam or after other findings?

After other findings

Reflex

Autonomic (Involuntary) response to a stimulus that helps protect the body from injury

Reaction

Somatic (voluntary) response to a stimulus and changing the bodies position to respond to a stimulus

Is closing your eyes a reflex or reaction?

A reflex

How quick are reflexes

Very rapid and short duration

How quick are reactions?

May also be rapid and short of duration, but they aren’t always

Reflexes or reactions involve the brain

Reaction

Picking up something very hot and dropping it to prevent a serious burn is a…

Reflex

Does a reflex or a reaction involve the spinal cord/brain stem?

A reflex

Which two muscles does the Achilles contain?

Gastrocnemius and soleus

Which 4 muscles does the patellar contain?

Rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius.

Plantar flexion is the foot moving

down

Dorsiflexion is the foot moving

Up

What muscle action does the brachioradialis do?

Wrist flexion

What muscle action does the patellar do?

Knee extension

What are nerve roots?

The initial position of a nerve when it leaves the vertebral column.

How many deep tendon reflexes are there assessed by medical professionals?

5

Which nerve innervates the biceps?

Muscutaneous nerve

Which nerve innervates the brachioradialis?

Radial nerve

Which nerve innervates the triceps?

Radial nerve

Which nerve innervates the patellar

Femoral nerve

Which nerve innervates the Achilles?

Tibial nerve

Vertebrae numbers were nerve roots exit for biceps

C5-C6 (POSSIBLY C4 and C7)

Vertebrae numbers were nerve roots exit for brachioradialis

C5-C6

Vertebrae numbers were nerve roots exit for triceps

C6,C7, T1

Vertebrae numbers where nerve roots exit for patellar

L2, L3, L4 (MAYBE L5 ASWELL)

Vertebrae numbers were nerve roots exit for Achilles

S1 (MAYBE S2 ASWELL)