stretch reflex

STRETCH STRETCH REFLEXREFLEX

Group 3ConsunjiCuaDe LeonDolencio

ObjectivesObjectives

To elicit and observe examples of stretch reflexes

To analyze abnormal reflex responses from a knowledge of the reflex pathways.

TheoryTheoryReflexReflexReflex is an involuntary response to

a stimulus by the animal organism. It consists of the stimulation of an afferent nerve through a sense organ, or receptor, followed by transmission of the stimulus to an efferent motor nerve, resulting in action of a muscle or gland, called the effector.

Stretch Reflex ( Deep Tendon Stretch Reflex ( Deep Tendon Reflex)Reflex)

Brisk contraction of a muscle when stimulated by a sharp tap by the rubber reflex hammer on the part where the muscle is inserted is the deep tendon reflex(DTR) or the stretch reflex.

How is a Stimulus Detected? Some cells are specialized to react to

a specific stimulus.These are called receptors.

When the receptor is stimulated, it sends a message to a

part of your body that effects the correct response. This is

called the effector.

How the Message Travels How the Message Travels From theFrom theReceptor to the Effector.Receptor to the Effector.

How is the Hammer Tap How is the Hammer Tap Detected?Detected?

◦Stretch receptor: muscular spindles -Provide the central nervous system with sensory

information regarding the muscle length and the rate of change in the muscle length

Each muscle spindle measures about 1 to 4 mm in length and is surrounded by a fusiform capsule of connective tissue.

Within the capsule are the Intrafusal muscle fibers and outside the muscular spindles are the Extrafusal muscle fibers.

Types of Intrafusal Fibers Types of Intrafusal Fibers and Its Sensory Endingsand Its Sensory Endings

Nuclear bagNuclear chain

Two types of sensory Two types of sensory innervation of muscle innervation of muscle spindles:spindles:

Annulospiral endings

Flower-spray endings

How the Message Travels How the Message Travels From theFrom theReceptor to the Effector.Receptor to the Effector.

Stretch ReflexStretch Reflex

Response ReflexesResponse Reflexes

STATIC RESPONSE-primary and secondary endings-slowly stretched

DYNAMIC RESPONSE-primary endings-rapid change in spindle length

Dynamic ReflexDynamic Reflex-elicited by dynamic signal from

primary endings of muscle spindle

-instantaneous, strong reflex contraction

Purpose of Stretch Purpose of Stretch ReflexesReflexesThe stretch reflexes (often called

deep tendon reflexes) provide information on the integrity of the central and peripheral nervous system.

Generally, decreased reflexes indicate a peripheral problem, and lively or exaggerated reflexes a central one.

ProcedureProcedureANKLE JERK KNEE JERK

TRICEPS JERK BICEPS JERK

RESULTSRESULTSREFLEX RESPONSE (Movement Elicited) NATURE OF RESPONSE (Brisk, Weak)

1)Achilles Tendon Reflex (Ankle jerk)

Right Left Relaxed (Right and Left)

Monkey Grip (Right and Left)

Plantar flexion of ankle joint on tapping the Achilles tendon

Plantar flexion of ankle joint on tapping the Achilles tendon

Weak plantar flexion of ankle joint

Brisk plantar flexion of ankle joint

2) Patellar Tendon Reflex (Knee Jerk) Extension of knee

joint on tapping the patellar tendon

Extension of knee joint on tapping the patellar tendon

Weak extension of knee joint

Brisk extension of knee joint

3) Triceps Tendon ReflexExtension of the elbow joint

Extension of the elbow joint

Weak extension of the elbow joint

Clenched Teeth (Right and Left)

brisk extension of the elbow joint

4) Biceps Brachii Tendon Reflex Flexion of the elbow

joint by tapping the biceps tendon

Flexion of the elbow joint by tapping the biceps tendon

Weak flexion of the elbow joint

Brisk flexion of the elbow joint

JENDRASSIK MANEUVERJENDRASSIK MANEUVERA reinforcement of the reflexMonkey gripUsed to distract the patient to

enhance the chances of obtaining the reflex.

DiscussionDiscussion REFLEX ARC

-refers to the neural pathway that a nerve impulse follows. The reflex arc typically consists of five components (5):

 1. The receptor at the end of a sensory neuron 2. The sensory (afferent) neuron 3. The integration center consists of one or more

synapses in the CNS. 4. A motor (efferent) neuron 5. An effector

Muscle Spindle (Stretch Muscle Spindle (Stretch Reflex)Reflex)

Monosynaptic and Monosynaptic and Polysynaptic reflex arcPolysynaptic reflex arc

MONOSYNAPTIC◦-consists of single sensory and motor◦-presence of a single chemical synapse

POLYSYNAPTIC◦-one or more interneurons connect

sensory and motor signals◦-number of synapse in each branch

varies

Receptors of ReflexReceptors of Reflex

Muscle spindle Golgi Tendon Organ

Roles of Muscle Spindle Roles of Muscle Spindle ( Stetch Reflex)( Stetch Reflex)A muscle spindle is a small cluster of

specialized muscle fibers within a muscle. Also called stretch receptors, they detect stretch (changes in the length) in the muscle.

When a muscle stretches, the muscle spindle detects how much and how fast the muscle is stretching and sends signals to the spine with this information.

The purpose of muscle spindles stretch reflex is to help maintain muscle tone and to protect your body from injury caused by overstretching.

Superficial and Deep Superficial and Deep reflexesreflexesDEEP REFLEX

-involuntary muscular contraction following percussion of a tendon or bone-also called “jerk”

SUPERFICIAL REFLEX-any withdrawal reflex elicited by noxious or tactile stimulation of the skin, cornea, or mucous membrane-

SUPERFICIAL SUPERFICIAL REFLEXESREFLEXES

ABDOMINAL REFLEXCREMASTER REFLEXNORMAL PLANTAR

RESPONSEANAL WINK

CORNEA REFLEX

Example of superficial reflex cornea reflex

Pathologic reflexPathologic reflexThe Snout reflex

-This reflex is tested in a neurological exam and if present, is a sign of brain damage.

Babinski response - appearance of this reflex suggests the

presence of an upper motor neuron lesion

Hoffman response- affecting upper extremity

Guideline in Accurate Guideline in Accurate reflex testreflex test0 – absence+ - weak Hyporeflexive++- Normoreflexive+++ - Hyperreflexive without

clonus++++- hyperreflexive with

clonus

ReinforcementsReinforcementsThe muscle that would be tested

should be supportedThe muscle should also be

relaxed

Importance to OT Importance to OT professionprofessionTo determine the spasticity or

flaccidity of the muscle tone.

To know the abilities and capacities of the patient before giving an activity