2. Reflex activity. Anatomy and physiology. Pathological changes of extero- and proprioceptive reflexes.

Reflexes - classifcaiton, reflex arc, examination of normal reflexes

Definition of a Reflex

A reflex is an involuntary, rapid, stereotyped response of the body to a specific stimulus, mediated through the nervous system without conscious control.

Reflexes are important in clinical neurology because they help assess the integrity of the: Peripheral nerves. Spinal cord segments. Brainstem. Descending motor pathways

Reflex Arc: The reflex arc is the anatomical and physiological pathway through which a reflex occurs.

Components of a Reflex Arc

1. Receptor: Receives the stimulus.

• Examples: Muscle spindle (stretch reflex). Skin receptors. Tendon receptors

2. Afferent (Sensory) Neuron: Carries impulses from the receptor to the CNS.
3. Integration Center

• Located in: Spinal cord. Brainstem
• May involve: One synapse (monosynaptic). Several synapses (polysynaptic)

4. Efferent (Motor) Neuron: Conducts impulses from CNS to effector.
5. Effector Organ: Produces the response.

• Examples: Skeletal muscle. Smooth muscle. Glands

Classification of Reflexes

Reflexes can be classified according to several criteria.

A. According to Effector Organ

1. 1.Somatic Reflexes: Effectors are skeletal muscles.

• Examples: Biceps reflex. Triceps reflex.Patellar reflex

1. 2.Autonomic (Visceral) Reflexes: Effectors are smooth muscles. Cardiac muscle. Glands

• Examples: Pupillary light reflex.Accommodation reflex. Salivary reflex

B. According to Number of Synapses

1. 1.Monosynaptic Reflexes: Contain only one synapse between sensory and motor neuron.

• Example: Stretch (myotatic) reflex. Patellar reflex. Achilles reflex
• Characteristics:Fastest reflexes. Simple pathway

1. 2.Polysynaptic Reflexes: Contain one or more interneurons.

• Examples: Withdrawal reflex. Corneal reflex. Plantar reflex
• Characteristics: More complex.Slower

C. According to Development

1. 1.Unconditioned (Innate) Reflexes: Present at birth.

• Examples: Deep tendon reflexes. Corneal reflex.Pupillary reflex

1. 2.Conditioned (Acquired) Reflexes: Develop through learning and experience.

• Example: Pavlovian conditioned reflex

D. According to Receptor Location

1. 1.Exteroceptive Reflexes: Stimulus originates outside the body.

• Examples: Corneal reflex. Abdominal reflexes.

1. 2.Proprioceptive Reflexes: Stimulus arises from muscles, tendons, joints.

• Examples: Patellar reflex. Achilles reflex

1. 3.Interoceptive (Visceral) Reflexes: Stimulus originates in internal organs.

• Examples: Micturition reflex.Defecation reflex

Clinical Classification of Reflexes

For neurological examination, reflexes are divided into:

1. A. Superficial Reflexes: Produced by stimulation of skin or mucous membranes.

• Examples: Corneal reflex. Abdominal reflexes.Cremasteric reflex.Plantar reflex

1. B. Deep Tendon Reflexes (DTRs): Produced by tapping tendons.

• Examples: Biceps reflex. Triceps reflex.Brachioradialis reflex.Patellar reflex.Achilles reflex

1. C. Visceral Reflexes

• Examples: Pupillary light reflex.Accommodation reflex

Examination of Normal Reflexes

• General Principles

Patient should be: Relaxed. Comfortable. Symmetrical position

• Equipment: Reflex hammer
• Compare: Right vs left side. Symmetry of response

Deep Tendon Reflexes

1. Biceps Reflex

• Spinal Segments: C5–C6
• Nerve: Musculocutaneous nerve
• Technique: Flex elbow partially. Place thumb on biceps tendon. Strike examiner's thumb