Reflexes Powerpoint

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Questions and Answers

What is a reflex defined as?

A reflex action that is always inhibited by the brain.

An automatic and involuntary response that requires conscious control.

A conscious thought response to a stimulus.

An automatic, involuntary response to a stimulus that does not require conscious thought. (correct)

Which type of reflex involves muscle spindles?

Polysynaptic reflex

Monosynaptic reflex (correct)

Excitatory reflex

Autonomic reflex

In the reflex arc, which component comes directly after the Afferent neuron?

Synapse in the spinal cord (correct)

Sensory receptor

Response

Efferent neuron

What characterizes the difference between monosynaptic and polysynaptic reflexes?

Monosynaptic involves one synapse, while polysynaptic involves more than one. Signup and view all the answers

What is the primary function of reflexes in the nervous system?

To provide a rapid motor response without direct cortical involvement. Signup and view all the answers

Which type of reflex involves inhibition by the Golgi tendon organs?

Inhibitory reflex Signup and view all the answers

What is a key characteristic of autonomic reflexes?

They typically involve smooth muscles. Signup and view all the answers

Which statement is true regarding the central nervous system's role in reflexes?

The CNS can inhibit reflexes, allowing for flexible responses. Signup and view all the answers

What is the primary initial step to elicit a Deep Tendon Reflex?

Put the joint in a neutral position Signup and view all the answers

Which reflex testing method is specifically used to enhance the excitability of reflex circuits?

Jendrassik maneuver Signup and view all the answers

What signifies a grade of 1+ in the reflex activity scale?

Minimal/decreased response Signup and view all the answers

What is typically observed in a patient with hypertonia after a cerebrovascular accident (CVA)?

Increased uniform resistance throughout range of motion Signup and view all the answers

Which condition is characterized by flaccidity and can result from lower motor neuron injury?

Hypotonia Signup and view all the answers

What action should be taken if there is no visible movement or muscle contraction after the initial reflex strike?

Palpate the muscle while repeating the tap Signup and view all the answers

Which of the following reflexes is related to the nerve root C5-6?

Biceps Signup and view all the answers

What distinguishes rigidity from spasticity in muscle tone abnormalities?

Uniform resistance throughout range of motion Signup and view all the answers

What is one method to assess reflexes without using the upper extremities?

Utilize the Jendrassik maneuver Signup and view all the answers

Study Notes

What is a Reflex?

Reflexes are automatic, involuntary responses to a stimulus
They occur without conscious thought
They can involve neural pathways called reflex arcs which act on an impulse before it reaches the brain
Reflexes can be inhibited and are contextually flexible

Types of Reflexes

Somatic reflexes involve skeletal muscles
Autonomic reflexes involve smooth muscles

Somatic Reflexes

Monosynaptic reflexes involve only one synapse in the spinal cord. An example is the knee-jerk reflex. This reflex utilizes muscle spindles.
Polysynaptic reflexes involve more than one synapse in the spinal cord, utilizing interneurons. An example is the withdrawal reflex.

Reflex Arc Summary

Sensory to motor pathway occurs at the spinal level
No direct cortical control
The CNS can anticipate and inhibit reflexes
Reflexes allow for very rapid motor responses

How to Elicit a Deep Tendon Reflex

Take up the slack in the muscle by putting the joint in a neutral position
Use a reflex hammer to strike the tendon with a quick, brief tap
If the movement is not visible, palpate the muscle upon repetition
Utilize a reinforcement maneuver bilaterally for proper comparison
Always compare bilaterally

Jendrassik Maneuver

Used for testing reflexes except for upper extremities (UE)
To perform:
- Hook fingers together and resist contralateral pull as much as possible
- Elicit a reflex during the isometric pulling action
Function:
- Acts as a distraction, potentially increasing excitability
- Helps the reflex circuitries function
For UE reflexes, you may have the patient make a fist with the opposite extremity, count, or give the names of their family members.

Deep Tendon Reflex Testing

Biceps (C5-6)
Brachioradialis (C5-6)
Triceps (C6,7,8)
Patellar (L2,3,4)
Achilles Tendon (S1-2)

Determining the Degree of Muscle Reflex Activity for DTR

0: Absent, no response (flaccidity)
1+ Minimal/Decreased response (hypotonia)
2+ Normal response
3+ Brisk/strong, exaggerated response (mild/moderate hypertonia)
4+ Sustained response, clonus (severe hypertonia)

Abnormalities of Muscle Tone

Hypertonia: Upper motor neuron (UMN) syndrome
- Hyperreflexia or clonus
- Spasticity: Often seen in those who have had a stroke (CVA). Velocity-dependent resistance to passive stretch.
- Rigidity: Classic symptom of Parkinson's disease. Increased/uniform resistance throughout ROM (independent of velocity).
Hypotonia: Often due to Lower motor neuron (LMN) injury.
- Flaccidity (decreased or absent muscle tone)
- Diminished (or absent) resistance to passive movement and reflexes
- Characteristic of Down Syndrome
- Commonly assessed in pediatrics
Dystonia: Disordered tone and involuntary movements of the body. Transmission of motor impulses to/from the cerebral cortex and cerebellum.

Muscle Tone Assessment

Observation of resting posture
Palpation of muscle belly
Passive and active motion testing (vary the speed of movements to check for tone)

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Description

Explore the fascinating world of reflexes, which are automatic responses to stimuli that occur without conscious thought. This quiz covers types of reflexes, including somatic and autonomic, and delves into the neural pathways involved, such as reflex arcs. Test your understanding of how reflexes function and their importance in rapid motor responses.