Practical Neurophysiology Exam of Motor Nervous System 2025 PDF

Practical neurophysiology examination of motor nervous system section 1  Examination of the Motor System The motor system is the part of nervous system that support motor functions. formed of 2 neurons : UMN ( pyramidal and extra-pyramidal t...

Practical neurophysiology examination of motor nervous system section 1  Examination of the Motor System The motor system is the part of nervous system that support motor functions. formed of 2 neurons : UMN ( pyramidal and extra-pyramidal tract) LMN (peripheral nerve fiber) Motor functions: 1- Muscle bulk 2- Muscle tone 3- Muscle power or strength 4- Coordination of movement 5- Reflexes 6- Gait Tools needed: - Percussion hammer (Patellar hammer) - Tongue depressors - Pencil torch light - Measuring tapes 1) Examination of the Muscle bulk This can be easily estimated by inspection, palpation, and by measuring the circumference of limbs in certain points. 1- Inspect and palpate the muscle concerned. 2- With the measuring tapes, measure the bulk of biceps (5 inches above elbow) and compare between the two sides. 3- In lower limbs measure the circumference 9 inches above knee and 6 inches below it. 4- Compare the thenar and hypothenar eminences with your own. 5- If there is wasting describe it in details: unilateral or bilateral. If bilateral symmetrical or asymmetrical and if distal more than proximal or vice versa Results: 1- normal muscle tone. 2- muscle wasting (atrophy) as in LMNL. 3- muscle hypertrophy. 2) Examination of Muscle Tone Definition: Muscle tone is continuous, alternating, reflex, subtetanic contraction of muscle fibers. Base of muscle tone: Static stretch reflex Procedure: 1- Muscle tone is tested by noting the resistance offered to passive movements done by the examiner on various joints of the subject. 2- Flex the following joints of your subject: Elbow joints, wrist joints, knee joints and the neck and note the ease or difficulty with which a joint can be moved 3- Compare both sides What are types and causes of tone abnormalities? Atonia or Hypotonia: *LMNL as in Peripheral neuritis & Poliomylitis *Hypothyroidism *Sleep &Anesthesia Hypertonia: *UMNL *Anxiety *Hyperthyroidism Why muscle tone does not produce fatigue? -Alternate contraction of different muscle fibers. -Contraction is subtetanic -Muscle fibers involved in muscle tone are the red muscle fibers which contract slowly & con sustain force for a long time. 3) Muscle Power 1. Muscle power is tested by asking the subject first to move parts of the body (active), and then against the resistance of the examiner’s hand, and compared with similar muscles on opposite limb 2. Ask the subject to close his eyes while holding his arms straight in front of him with palms up. Watch how he maintains this position against gravity on each side. Try to depress the subject outstretched arms against gravity.  Practical neurophysiology examination of motor nervous system section 2 4) Coordination of movement: This term refers to the smooth interaction of groups of muscles in order to perform a definite motor task. It depends on impulses coming from muscle and joint receptors, integrity of dorsal columns, cerebellum and state of muscle tone. Testing muscular coordination in the upper limbs: 1- Finger-nose test: Ask the subject to touch the tip of his nose with each index finger from the distance of his extended arm, first with the eyes open and then with the eyes closed. Observe if all movements progress smoothly and report any tremors. 2- The subject is asked to draw a large circle in air with his forefinger. Testing muscular coordination in the lower limbs: 1- Heel-knee test: Ask the subject to lift one leg high in the air and place the heel of this leg on the opposite knee and then to slide the heel down along the shaft of tibia towards the ankle. Observe if all movements progress smoothly 2- The subject is asked to draw a large circle in air with his toe. Romberg’s sign & its significance -Inability to maintain erect position and falling while closing his eyes -Sensory ataxia due to lesion in dorsal column. 5) Examination of reflexes in man A Reflex is an involuntary contraction of a muscle or a group of muscles in response to a specific stimulus, and involves a part of CNS. Superficial reflexes -Corneal reflexes -Abdominal reflexes -The planter reflex -The pupillary reflex (light reflex) Deep reflexes (tendon jerk) -Knee jerk reflex -Ankle jerk reflex -Biceps jerk reflex -Triceps jerk reflex A. Superficial Reflexes: 1) Corneal Reflex: 1- Ask the subject to look at the far wall. 2- Twist a small piece of cotton to a fine hair. 3- Approaching from the side touch the lateral aspect of the cornea. 4- Bilateral blinking is the response, Compare both sides It indicates that the ophthalmic division of the trigeminal nerve as well as in the motor fiber of the facial nerve (which closes the eye), are intact 2) Abdominal Reflexes: Strip off the subject to the waist, who lies on a bed in supine posture. Elicit by stroking the relaxed abdomen briskly with an instrument which is slightly sharp (pin of the percussion hammer works satisfactorily). This should be performed in all quadrants of the abdomen watching the umbilicus which is pulled towards the quadrant stimulated 3) The Plantar reflex: It is a polysynaptic spinal reflex. Stimulus: Firm scratch of the lateral aspect of the sole with a key starting from the heel towards the little toe, then along the bases of the toes medially. Center: S1&S2  Normal response: Is the flexion (i.e., downward movement) of the great toe while the other toes flex and come together Abnormal response: Damage to the pyramidal motor tracts produces. Babinski sign, in which there is dorsiflexion of the great toe and fanning of the other toes (i.e., big toe up). Causes of Babinski sign : 1.Damage to the pyramidal and extrapyramidal tract (UMNL) 2.Deep sleep, deep coma, deep anaethesia. 3.Infant less than 1 year. 4) The Pupillary Reflex (Light Reflex) Procedure: Each eye is tested separately 1- The subject is asked to look at a distance 2- Use a pencil torch light and bring it from behind the subject to shine on one of his eye, the pupil constricts (direct light reflex). 3- A hand is placed between the two eyes 4- Repeat the above procedure and observe the effect on the opposite eye (consensual light reflex Direct and consensual light reflex  Practical neurophysiology examination of motor nervous system section 3 B. Deep Reflexes or Tendon Jerks 1- These are spinal, monosynaptic deep reflexes 2- These reflexes are obtained in a subject who is relaxed. 3- If by reflex cannot be obtained it can be enforced by the Jendrassik maneuver: - Ask the subject to clinch fist for a fraction of a minute before striking the patellar tendon. - Let the subject grind his teeth during the elicitation of the reflex. - Ask the subject to clasp both his hands and pull - While the subject is doing the maneuver, proceed to elicit the reflex.  Jendrassik maneuver increases gamma efferent impulses to muscle spindle so enforcing the reflexes. 4- Stimulus: A sudden tap is applied to the muscle tendon using a hammer 5- Response: sudden contraction followed by sudden relaxation 1-Knee Jerk Reflex - The subject is asked to relax his legs, and semiflex them (90o degree). - Strike the patellar tendon, midway between the patella and the insertion of the tendon on the tibial tuberosity, and observe the resulting contraction of the quadriceps muscles and extension of the leg. Center: L3 - L4 2-Ankle Jerk Reflex - The subject kneels on a chair, with his or her back to the examiner and feet (shoes and socks off) projecting over the edge. - Put some tension on the gastrocnemius muscle of the subject by pressing on the great toe with the hand. - Strike the Achilles tendon at the level of the ankle, and observe the resulting extension of the foot. Center: S1- S2 3-Biceps Jerk Reflex It is obtained by striking the thumb or forefinger placed directly over the biceps tendon when the forearm is flexed at ninety degrees. The biceps will contract and further flex the forearm. Center: C5 –C6 4-Triceps Jerk Reflex - The subject lies on his or her back with the elbow bent so that the arm lies loosely across the abdomen. - Strike the triceps tendon about 2 inches above the elbow. If there is no response, repeat this procedure, striking to either side of the original point. - If this procedure is correctly performed, the triceps muscle will twitch but will not usually contract strongly enough to produce arm movements. Center: C6 –C7 N.B.: If there was exaggerated jerk with hypertonia: 1- Hyperthyroidism 2- Nervousness 3- Upper motor neuron lesion If there was decreased jerk with hypotonia: 1- Hypothyroidism 2- Sleep 3- Anesthesia 4- Lower motor neuron lesion Clonus: - It is regular rhythmic contractions of the muscle when it is subjected to sudden maintained stretch. - It is a sign of hypertonia. 6) GAIT Abnormalities of Gait: Type of the lesion Gait Unilateral UMNL Spastic (circumduction) gait Bilateral UMNL Scissor LMNL Waddling gait Posterior column lesion High steppage  Practical neurophysiology examination of motor nervous system by students section 4  Practical neurophysiology examination of sensory nervous system section 5  Examination of Somatic Sensations Sensation is the feeling produced by change in the environment or by the application of a stimulus to the receptors or nervous pathway. SOMATIC SENSATIONS Mechanoreceptive sensations Thermal Pain Tactile Position Cold Cutaneous Touch: Fine Static Warm Deep Crude Kinetic Visceral Pressure Stereognosis Vibration Somatic Sensory Pathways Dorsal Column: Fine touch, stereognosis, vibration, Fine pressure, position Ventrolateral Tract: 1- Lateral Spinothalamic: Pain and temperature. 2- Ventral Spinothalamic: Crude touch and Crude pressure General rules for testing any sensation: 1- Work in pairs, one student acting as a subject and the other as observer. 2- Examine the subject while closing his eyes. 3- Start examination from periphery then proceed inwards. 4- Compare the results of both side. 5- The observer should ensure that the subject’s answers are honest and based on the actual sensation felt. 6- Do not suggest the response either verbally or by allowing him to see the stimulus. I-Touch Sensation: It includes: 1- Crude touch: Touch with poor intensity discrimination and localization Pathway: ventral spinothalamic tract Procedure: a. It is examined by a piece of cotton. b. Ask the person if he feels touch or not c. Compare both right and left sides of the body 2- Fine touch: Touch which is highly discriminative and sharply localized Pathway: Dorsal column, It includes: a) Tactile Localization: Definition: The subject is able to localize accurately the site of stimulation while closing his eyes Procedure: 1. Ask the subject to close his eyes. 2. Touch different parts of the body with blunt non sharp object. 3. Ask him to locate the exact area touched. 4. Compare corresponding points on both sides of the body.  b) Two-point discrimination Definition: The ability to feel 2 touched points simultaneously as 2 separate points supposing that they are separated by a threshold distance. Materials: Weber’s compass: It has 2 points and a scale to read the distance between the 2 points. Procedure: 1. Ask the subject to close his eyes. 2. With the calipers of the compass closed, touch two areas at the back of the hand. 3. Ask the subject to say whether he feels two points of touch or a single point. The subject should report one, two or don’t know 4. Now increase the distance between two limbs of the caliper and measure in millimeters the minimum distance that he can feel the points as two distinct points. 5. Determine the two-point threshold distance in the following areas: lips, back of hand, palm of hand, fingertips, back of neck and forearm. 6. Record your results in a table and compare to the normal values below: Threshold distance: It is the minimal distance at which the 2 points of skin touched are felt as 2 separate points, below this distance they are felt as one point. Factors determining the threshold distance: - Number of afferents - Number of receptors - Cortical representation  The more the number of receptors, afferents and cortical representation, the less the threshold distance is and better two point discrimination. c) Texture of materials: It is the ability of the person to detect the texture of a material given.  Practical neurophysiology examination of sensory nervous system section 6 II-Stereognosis: It is the ability to recognize the familiar objects (needs previous experience) placed in the hand by touch while both eyes are closed. Receptors: mixture of touch, pressure, stretch and temperature Pathway: dorsal column Procedure: 1. Ask the subject to close his eyes. 2. Place any common object like coins, keys, pen etc. in his palm and ask him to identify the object without looking at it Stereognosis Clinical importance: Loss of recognition of object is called as astereognosis that indicates that the patients is suffering from a lesion of somatic sensory area I & somatic sensory association area. III-Weight discrimination (pressure sensation): It is the ability to feel weights (crude pressure) and distinguish between different weights (fine pressure) Pathway: crude pressure (ventral spinothalamic) and fine pressure (dorsal column) Procedure: 1. Ask the subject to close the eyes and place his hand on the table. 2. Place different weights in his hands. 3. Ask him to indicate if he could identify the variations in the weights placed on his hand. IV-Vibration sense: It is the ability to feel the vibrations of a tuning fork put on any part of the body, but more prominently on bony eminences (Magnify the stimulus). Receptors: Paccinian 500 c/sec – Meissner 80 c/sec Pathway: dorsal column Tools needed: Tuning fork: low frequency (128-250 c/sec) and long arms Procedure: 1- Ask the subject to close his eyes. 2- Strike the tuning fork and place its foot successively over identical bony prominences on each side of the body such as knuckles, head of radius, elbow, patella, malleoli, styloid process, iliac crest, etc. 3- Ask the subject to acknowledge whether he feels the vibration and whether it is of the same intensity on the two sides. The normal subject feels a vibratory tremor not just sensation of touch. 4- Test if the subject can accurately identify when the vibration stops. Vibration Sense V-Proprioceptive sensation Receptors: Slowly adapting(static position sensation). *Muscle spindle in skeletal muscles *Golgi tendon organs in tendons Rapidly adapting(kinetic position sensation): *Paccinian corpuscles in joints Pathway: dorsal column procedure: 1-Show the patient, with eyes open, the position of his big toe (dorsoflexion , planter flexion ) during lower limb examination. 2-Ask the patient to close his/her eyes following the previously mentioned general rules. 3-Move the big toe of the patient from the sides and ask him if he feels it moving (kinetic position sensation) and if so in which direction (static position sensation). Record the result. 4-Do the same steps during examination of upper limb VI-Temperature sensation : The tools: two test tubes containing cold and warm water. Pathway: lateral spinothalamic tract The procedure: 1-Follow the general rules and do not forget to ask the subject to close her/his eyes 2-Use two test-tubes containing warm , not more tha 45˚C and cold water , not leass than 5˚C to avoid elicit painful responses touch at different sites of the body of your subject. 3-Ask him to identify the temperature differences VII-Pain Sensation: This sensation can be tested either with a cutaneous stimulus, such as the prick of a pin, or by pressure on deeper tissues, such as muscles and bone. Receptors: Free nerve endings Pathway: lateral spinothalamic tract Procedure: a. Superficial Pain 1- Ask the person to close his eyes 2- Elicit the sensation of pain on the nail bed, pulp of fingers, palms and back of the hands and arms using an ordinary pin. b. Pressure Pain Put pressure on deep structures such as calf muscles, tendoachilis or wrist bones and ask him whether he feels pain. c. Referred pain: Place the elbow in ice water, at first pain is felt in the region of elbow, then pain is felt along distribution of ulnar nerve (ring finger, little finger and inner side of the hand).  Practical neurophysiology examination of sensory nervous system by students section 7  Practical neurophysiology examination of sensory nervous system section 8  Sensory pathway All somatic sensations are transmitted in the form of nerve impulses from their specific receptors along afferent nerve fibers to the spinal cord where they ascend to their final destination in the cerebral cortex via one of two sensory pathways: 1- The Dorsal Column: -Fine touch and fine pressure. -Vibration. -Stereognosis -Position sense (proprioception sensation) First Order Neurons: dorsal root ganglia (DRG), fibers then ascend upwards on the ipsilateral (same) side as dorsal column (gracile and cuneate tracts) Second Order Neurons: gracile and cuneate nuclei in the medulla on the same side; Fibers then cross to the opposite side Third Order Neurons: ventrobasal (VBN) nuclei of the thalamus. Fibers then reach the somatic sensory cortex on the opposite side 2-The Spinothalamic (Ventrolateral) Tract: -Pain -Temperature -Crude touch and crude pressure First Order Neurons: dorsal root ganglia (DRG). Second Order Neurons: ipsilateral (same side) posterior horn cells of spinal cord. Fibers carrying pain and temperature cross immediately in-front of the central canal, and ascend as the lateral spinothalamic tract Fibers carrying crude touch, crude pressure and tickle and itch sensations cross farther from the central canal and ascend as the ventral spinothalamic tract Third Order Neurons: VBN of the thalamus. Fibers ascend to end in the somatic sensory cortex on opposite side  Somatic Sensory Cortex A- Somatic sensory area I (SSI): Body representation: a. It is crossed: b. It is inverted: c. The area of representation is directly proportional to the number of specialized sensory receptors in this area. So thumb & lips have large representation area while the back and trunk have smaller areas and viscera are the least represented. Functions of somatic sensory area I: a. Recognition of fine touch, stereognosis, vibration and proprioceptive sensations. b.Localization of the source of all sensations (locality of sensory code). c. Discrimination of fine gradations of weight and temperature. B- Somatic Association area: Connections: it receives signals from: 1- Somatic sensory area I 2-Ventrobasal nuclei of thalamus. Functions: Integration and interpretation of different sensory inputs from different sensory areas to decode and understand their meaning  Practical neurophysiology examination of sensory nervous system section 9  Lesions of the Sensory System Lesions of sensory pathway can occur at any level from the afferent peripheral nerve to the somatosensory cortex. ` I) Peripheral Nerve Lesions 1. Mononeuropathy: Injury or lesion of one peripheral nerve leads to loss of all sensations in the area supplied by this nerve. 2. Polyneuropathy (peripheral neuritis): diffuse lesion of all peripheral nerves, as in case of Vitamin B12 deficiency or diabetic neuritis, that affects the peripheral ends of sensory nerves at the distal parts of the limbs leading to "glove and stocking" sensory disturbance (numbness, tingling, burning then total sensory loss). 3. Herpes Zoster: - It is a viral infection, in which the herpes virus attacks a dorsal root ganglion (DRG) in patients with history of varicella (chicken pox) infection. - Virus starts to reproduce causing irritation of pain afferents in the DRG leading to severe pain felt in the dermatomal segment supplied by the infected ganglion. - The virus also migrates with neuronal cytoplasmic flow towards the peripheral axons to their cutaneous terminals, where it reproduces leading to painful skin rash and vesicular formation II) Spinal Cord Lesions: (1) Tabes dorsalis: It is a neurosyphilitic disease that causes slow degeneration of the sensory nerves in the dorsal root and dorsal column mostly in the lumbosacral spinal cord lead to Degeneration and Atrophy of the Dorsal Column leading to: Loss of vibration sense. Loss of proprioceptive sensation leads to incoordination of voluntary movements known as "Ataxia". Sensory ataxia is characterized by high steppage (or stamping) gait and +ve Romberg's sign (the patient can't maintain his erect position with closed eyes). (2) Syringomyelia: In this disease there is widening of the central canal of spinal cord. This leads to damage of pain and temperature fibers crossing immediately in front of the central canal first. Later the fibers of crude touch are affected. (However, fine touch is intact) The lesion is bilateral and usually affects the cervical region leading to "jacket" loss of pain and temperature sensations. N.B.: Because dorsal column sensations remain intact, the condition is described as dissociated sensory loss. (3) Spinal cord Hemisection: (Brown Sequard syndrome) Injuries that cause hemisection of the spinal cord results in the following manifestations: A. At the level of lesion: - Sensory lesion to the posterior root leads to loss of all sensations at the dermatome supplied by that posterior root entering at the site of injury on the same side. - Motor lesion to the anterior root leads to flaccid paralysis (lower motor neuron lesion, LMNL) and loss of all reflexes initiated by the affected root on the same side. B. Below the level of lesion: 1- On the same side: Sensory lesion to the dorsal column leads to loss of all sensations carried by it (fine touch and pressure, vibration, sense of position, and of movement). 2-On the opposite side: Sensory lesion to the spinothalamic tract leads to loss of pain and temperature on the opposite side, touch is not lost but decreased on both sides. Thank you