Examination of Peripheral: Motor and Sensory

Question 1

Suprascapula Nerve C6,C7

Answer 1

Motor = Supraspinatus - First 30 degrees of shoulder abduction

No sensory to the skin

Question 2

Axillary Nerve C5,C6

Answer 2

Motor

• Deltoid - Shoulder abduction
• Teres minor - Shoulder external rotation
• C5 myotome test

Sensory

• Capsulle of shoulder joint and skin superficial ot the deltoid
• C5 dermatome test

Origin/Course

• Posterior cord of the brachial plexus
• It passes beneath the shoulder joint through the quadrangular space with the posterior circumflex humeral artery. It then wraps around the surgical neck of the humerus

Question 3

Musculocutsneous Nerve C5,C6,C7

Answer 3

Motor

• Bicepps Brachii - Elbow flexion
• Brachialis - Elbow flexion with thumb to sky
• Coracobrachialis - Flexion and adduction of shoulder (120 degrees flexion + 1- degrees adduction)
• C6 Myotome Test

Sensory

• Anterior lateral forearm

Origin/Course

• Lateral cord of brachial plexus
• It leaves the axilla by piercing coracobrachialis muscle, it then passes down the arm beneath biceps muscle, it ends as the lateral cutaneous nerve of forearm

Question 4

Median Nerve

Answer 4

Motor

C7,C8 Myotome test

the median nerve does not supply any motor innervation to the axilla or upper arm all muscles of anterior compartment of forearm EXCEPT flexor carpi ulnaris and the medial two parts of flexor digitorum profundus

• Pronator teres and pronator quadratus – pronate forearm
• Flexor carpi radialis – flexes and abducts wrist
• Palmaris longus – flexes wrist and tenses palmar aponeurosis
• Flexor digitorum superficialis – flexes fingers at PIPJs
• Lateral two parts of flexor digitorum profundus – flex index and middle fingers at DIPJs
• Flexor pollicis longus – flexes thumb at IPJ

Intrinsic muscles of hand – LOAF muscles

• Lateral two lumbricals – flex MCPJs and extend IPJs of index and middle finger
• Opponens pollicis – opposes thumb
• Abductor pollicis brevis – abducts thumb
• Flexor pollicis brevis – flexes thumb at MCPJ

Ochsner’s clasping test to assess cubital fossa lesion

Sensory

• Palmar cutaneous nerve – palmar surface of lateral 3.5 fingers i.e. thenar eminence and lateral palm but not the digits. Takes its origin proximal to the flexor retinaculum of hand so not affected by carpal tunnel syndrome.
• Digital cutaneous branches – supplies the lateral 3.5 digits anteriorly, and dorsal tips of lateral 3 fingers
• For sensory loss: test pinprick over the hand – the palmar aspect of the thumb, index, middle and lateral half of the ring finger is often affected (C6, C7 dermatome test)

Origin/Course

• Lateral abd Medial cords of brachiual plexus
• The median nerve runs down the arm with the brachial artery: it initially lies lateral to the artery, then crosses over to lie medial to it about halfway down the arm
• It then passes through the medial part of the antecubital fossa between the two heads of pronator teres muscle
• It travels through the anterior forearm between the flexor digitorum superficialis and flexor digitorum profundus muscles and gives three main branches:
  
  • Anterior interosseous nerve – descends along the anterior interosseous membrane with anterior interosseous artery
  • deep branch – enters hand through the carpal tunnel beneath the flexor retinaculum of the wrist, between flexor carpi radialis and flexor digitorum superficialis tendons
  • superficial/palmar cutaneous branch – arises just before the wrist and pierces the palmar carpal ligament to enter the palm over the top of the carpal tunnel – this nerve is therefore not affected by carpal tunnel syndrome

Question 5

Radial Nerve C5-C8

Answer 5

Motor

C6-C7 Mytome Test

Posterior compartment of arm

• Triceps – extends and adducts shoulder, extends elbow

Posterior compartment of forearm

• Brachioradialis – flexes elbow (test with arm in elbow felxion, thumb up and try to pronate and supinate forearm)
• Anconeus – extends elbow, stabilises elbow joint
• Supinator – supinates forearm
• Extensor carpi radialis longus and brevis – extend and abduct wrist
• Extensor carpi ulnaris – extends and adducts wrist
• Extensor digitorum, extensor pollicis longus and brevis, extensor indicis and extensor digiti minimi – extend thumb and fingers at MCPJs and IPJs
• Abductor pollicis longus – abducts thumb

Sensory

• Posterior cutaneous nerve of the arm: posterior arm and forearm
• Superficial branch of the radius: dorsum of hand and first 3 1⁄2 fingers, excluding nail beds
• Test sensory loss over the anatomical snuff box: sensation is lost here if there is a radial nerve lesion before the bifurcation into the posterior interosseous (deep motor branch) and superficial (superficial sensory branch) at the elbow.

Origin and Course

• Posterior Cord of Bechial Plexus
• It passes behind the axillary artery and through the triangular interval to enter the posterior compartment of the arm
• It then winds around the spiral groove of the humerus with the profunda brachii artery, between the heads of triceps muscle
• It enters the antecubital fossa in front of the lateral epicondyle of the humerus, between the brachialis and brachioradialis muscles
• It then branches in the proximal forearm into two terminal branches:
  
  • Superficial branch (mainly sensory) – descends under brachioradialis muscle to end in the dorsum of the hand
  • Deep branch (mainly motor) – pierces supinator muscle and descends along the posterior interosseous membrane with the posterior interosseous artery

Question 6

Ulnar Nerve C7-T1

Answer 6

Motor

C7,T1 Myottome Test

Two muscles of anterior compartment of forearm

• Flexor carpi ulnaris – flexes and adducts wrist
• Medial two parts of flexor digitorum profundus – flex ring and little fingers at DIPJs

Most of the intrinsic muscles of the hand – HILA muscles

• Hypothenar eminence: opponens digiti minimi, flexor digiti minimi brevis and abductor digiti minimi – oppose, flex and abduct little finger
• Interossei – palmar interossei adduct, dorsal interossei abduct
• Medial two lumbricals – flex MCPJs and extend IPJs of ring and little finger
• Adductor pollicis – adducts thumb

NB// adductor pollicis is not part of the thenar eminence and actually lies deep beneath it as a separate structure

Sensory

• Medial forearm and the dorsal plus anterior aspects of medial 11⁄2 fingers and associated palm (C8, T1 dermatomes)

Origin/Course

• Medial Cord of Brachial Plexus
• The ulnar nerve runs down the arm on the medial side of the brachial artery
• It passes behind the medial epicondyle of the humerus and enters the forearm between the two heads of flexor carpi ulnaris
• It travels through the anterior compartment of the forearm beneath flexor carpi ulnaris with the ulnar artery
• It then enters the palm of the hand through Guyon’s canal

Question 7

Brachial Plexus

Answer 7

• Usually complain of pain or weakness in shoulders and arms.
• f there has been a root avulsion, pain is severe

A neurological cause is more likely if there is:

• Dull pain
• Hard to localise
• Not related to limb movement
• Worse at night
• No associated tenderness

It’s more likely to be orthopaedic if the pain is worse with movement, there are signs of inflammation, joint deformity or local tenderness.

Most are supraclavicular (infraclavicular are less severe – e.g. caused by cervical rib syndrome)

The rhomboids are usually spared – test by asking patient to pull both scapulae together with hands on the hips (supplied by C5 nerve root proximal to the upper trunk)

Causes: Inflammation, autoimmune conditions, radiotherapy, cancer, trauma

Complete lesions are rare

• Upper lesion (C5, C6) is called Erb’s palsy that presents with loss of shoulder abduction, elbow flexion and supination and wrist extension. Therefore the limb is extended, internally rotated and the wrist is in flexion (waiter’s tip position). There is lateral arm sensory loss.
• Lower lesion (C8T1) is called Klumpke syndrome, and presents with loss of wrist flexors and intrinsic muscles of the hand. The MCP joints are hyperextended (loss of lumbricals and interossei), and loss of T1 includes loss of sympathetics to the face (Horner’s syndrome). A claw hand results with sensory loss along the ulnar side of the hand and forearm

Question 8

Lateral Femoral Cutaneous Nerve L2-L3

Answer 8

A lesion is usally the reuslt if entrapment between the inguinal liagment and anterior suoerior iliac spine

• There is sensory loss over the lateral aspect of the thigh
• There is no motor loss
• If painful, it is called meralgia paraesthetica

Question 9

Femoral Nerve L2,L3,L4

Answer 9

Motor

L1,L2 and L3 Myotome Test

• Iliacus - Hip Flexion
• Quadriceps - Knee Extension

Sensory

• Anterior femoral cutaneous nerve: anteromedial aspect of the thigh (about L3 dermatome but more medial)
• Saphenous nerve: medial aspect of the leg (L4 dermatome test)

Question 10

Obturator Nerve

Answer 10

Motor

L2,L3 Myotome Test

• Adductor longus – adducts thigh
• Adductor brevis – adducts thigh
• Adductor magnus:
  
  • Adductor part – adducts and flexes thigh
  • Hamstring part – extends thigh
• Gracilis – adducts thigh
• Obturator externus – laterally rotates thigh

Sensory

• Sensory: terminal branch supplies the medial thigh (about L2 dermatome test)

Question 11

Sciatic Nerve L4,L5 - S1,S2,S3

Answer 11

Motor

L5-S1 Myotome Test

• Motor: hamstrings and adductor magnus: flexion of knee (L5-S1 myotome) and extension of hip

Sensory

• No sensation (note that sensation to the posterior thigh (S2 dermatome) is via the posterior femoral cutaneous nerve of the thigh (S1, 2, 3) which is a branch off the sacral plexus.

Question 12

Common peroneal, fibula nerve L4-S2

Answer 12

Motor

One of the two terminal branches off the sciatic at the popliteal fossa: runs anteriorly and laterally in the leg to the foot. It divides into the superficial and deep fibular:

• Superficial fibular: motor supplies fibularis longus and brevis (eversion, S1 myotome).
• Deep fibular: motor supplies tibialis anterior (dorsiflexion L4-5, and inversion L4 myotomes), extensor hallucis longus (big toe extension, L5 myotome), fibularis tertius (dorsiflex toes, and eversion), extensor digitorum longus and brevis (dorsiflex toes, and ankle dorsiflexion). Sensory supplies the skin between the great and second toes (where the thong goes).

Sensory

• Superficial Sensory supplies the skin over distal third of anterior aspect of leg and dorsum of foot (L5 dermatome)
• Deep Sensory supplies the skin between the great and second toes (where the thong goes).

Question 13

Tibial Nerve L4-S3

Answer 13

Motor

• Supplies gastrocnemius, plantaris and soleus (plantar flexion S1 myotome, with the hamstrings L5-S1 myotome), popliteus (knee flexion, L5-S1), tibialis posterior (inversion L4, plantar flexion S1 and responsible for maintaining the medial arch of the foot), flexor digitorum longus, flexor hallucis longus (toe flexion, S2 myotome)
• Branches in the foot are the medial plantar and lateral plantar nerves
  • Medial plantar: abductor hallucis (abduction and flexion of big toe, S2 myotome),flexor digitorum brevis and flexor hallucis brevis (toe flexion, S2 myotome).
  • Lateral plantar: supplies remaining muscles of foot.

Sensory

• Medial plantar Sensory is the skin over medial 2/3 of plantar surface of foot (S1 dermatome)
• Lateral plantar

supplies remaining muscles of foot. Sensory is the skin over lateral third of plantar surface of foot (S1 dermatome)

Question 14

Sural Nerve L4-S4

Answer 14

The tibial nerve supplies the medial branch that joins the lateral branch from the common fibular nerve to form the sural nerve. This nerve supplies the skin in the posterolateral corner of the leg, lateral foot and big toe.

• No motor or reflex

Question 15

Deep Tendon Reflexes

Answer 15

Deep Tendon Reflex

This is the simple stretch reflex. The reflex hammer stretches the muscles, exciting the spindles, which then elicit a monosynaptic response at the level of the spinal cord, causing a muscle contraction. It tells you whether the afferent to efferent arc is intact (spinal nerve is intact: the LMN) or whether the inhibitory effect of the UMN has been lost.

Reflexes should be compared between contralateral counterparts to detect any asymmetry. Reinforcement procedures can elicit the reflex, such as asking the patient to raise the limb very slightly to gently contract the muscle tested.

Wexler’s scale:

• 0 : absent reflex
• 1+: trace, or seen only with reinforcement
• 2+:normal
• 3+:brisk
• 4+: nonsustained clonus (i.e. repetitive vibratory movements)
• 5+: sustained clonus

Deep tendon reflexes are normal if they are 1+, 2+, or 3+ unless they are asymmetric or there is a big difference between upper and lower limbs.

• Hyporeflexia is associated with abnormalities in muscles, sensory neurons, lower motor neurons, and the neuromuscular junction; acute upper motor neuron lesions; and mechanical factors such as joint disease.
• Hyperreflexia is associated with upper motor neuron lesions. Reflexes can affected by metabolic diseases, electrolyte disturbances, and anxiety.

The Jendrassik Manoeuvre

• Added if the result is 0+
• It can be done in a number of ways, but the most common method to reinforce the lower limb reflexes is to ask the patient to hook the fingers together and pull outwards with force. You will say: “1…2…3…pull”, but actually start the reflex just a split second before you have said “pull”, as the effect this has to facilitate is only in the first few seconds of the contraction. Other methods are to ask the patient to clench the jaw, clench the wrists, push the feet together or turn the head toward the side tested.

Question 16

Deep Tendon Reflex Sites

Answer 16

Upper Limb

Biceps = Musculocutaneous Nerve C5 and C6

Brachioradilais = Radial Nerve C5 and C6

Triceps = Radial Nerve C6, C7 and C8

Lower Limb

Patella = Femoral Nerve L2, L3, and L4

Medial Hamstring =Sciatic Nerve L5

Achillies Tendon = Tibial Nerve S1 and S2

Question 17

Deep Tendon Reflex Superficial

Answer 17

Abdominal Reflex

This is a motor response to touching the skin, and is polysynaptic. It is simply graded as positive (present) or negative (absent). The absence could be due to dysfunction anywhere along the path, and could be UMN or LMN. Pyramidal tract lesions above the level of lost reflexes or peripheral nerve damage result in loss of these reflexes. These reflexes are affected and may even be absent in obese, multiparous, older patients or patients who have had abdominal surgery.

• Reflexes above the umbilicus tests T8-10
• Reflexes below the umbilicus tests T10-12
  
  • T5-7: epigastric quadrant
  • T7-9: right and left upper quadrants
  • T9-11: at the level of the umbilicus
  • T10-12: below the umbilicus

Cresmasteric Reflex

• Somatic reflex involving the genitofemoral nerve (L1-2). Lightly stroking the medial and superior thigh in a downward or upward direction results in the contraction of the cremaster muscle that pulls up the scrotum on the same side. Sensory afferents in the femoral branch of the genitofemoral synapse in the spinal cord on the motor fibres of the genital branch of the genitofemoral nerve to the cremaster muscle. The reflex is lost in testicular torsion, UMN and LMN lesions and spinal cord injury at L1-2.

Bulbospongiosus reflex (S2-4)

• Somatic polysynaptic reflex involving the pudendal nerve. Contraction of the anal sphincter in response to pressure applied to the glans penis (end of the corpus spongiosus), or the glans clitoridis (end of the corpus spongiosus equivalent in the female) or by tugging on an indwelling Foley catheter. Tests for spinal shock/spinal cord injury.

Saddle sensation and anal reflex

• Test for sensation on the buttocks or around the anus. In the anal reflex (S2, S3, S4) there is a contraction of the external sphincter in response to a pinprick test of the perianal skin.

Question 18

Abnormal Reflexes

Answer 18

Plantar Response

• The normal adult plantar response is a plantar flexion (although no response is also normal, providing it is a finding in both feet). An upgoing big toe or dorsiflexion and outward fanning of the other toes is normal in children up to 1 yr (plantar extensor reflex), but is abnormal beyond that and is called a Babinski sign. It indicates an UMN lesion.

Finger Flexor Response

• Similar to the Babinski sign, the Hoffmann’s reflex, elicited by holding the patient’s middle finger and flicking the fingernail downward, will result in thumb flexing and adducting abnormally. These two signs indicate the presence of an upper motor neuron lesion that is affecting the upper limb.

Frontal Release Signs

• Frontal lobe lesions result in the return of primitive reflexes that are normal in babies. These are the grasp, snout, root and suck reflexes

Question 19

Coordination and Gait

Answer 19

Gait requires the co-ordination of the sensory and the motor systems and the cerebellum

• Ordinary gait: ask the patient to walk and note stance (how far apart the feet are), posture, stability, how high the feet are lifted when walking, the trajectory of the leg swing during walking, leg stiffness, degree of knee bending, arm swing, tendency to fall or swerve in one direction, speed, difficulty starting or stopping, involuntary movements, ability to rise from a chair to start walking, ataxia (lack of order).
• Demonstrate the following and ask the patient to repeat the action:
  
  • Tandem gait (heel to toe along a line)
  • Forced gait (hop on one leg)
  • Walk on your heels (dorsiflexion test – L4-5)
  • Walk on your toes (plantarflexion test – S1-2)

Multiple sensory and motor systems are tested when looking at gait disturbances: vision, proprioception, lower motor neurons, upper motor neurons, basal ganglia, the cerebellum and higher- order motor planning in the association cortex.

Question 20

Abnormal Gait Patterns

Answer 20

Spastic Gait (UMN Lesion)

• Hemiparetic/plegic: decorticate posture (flexion upper limbs/extension lower limbs) and circumduction of limb. Loss of pyramidal control, and dominance of the extrapyramidal tracts.
• Diplegic: scissoring gait – flexed, internally rotated hip, lordosis, knee flexion and locked, plantar flexion and ball of foot first contact. Circumduction of legs

Cerebellar Ataxic Gait

• Lack of co-ordination due to balance problems. Broad based walk, “drunken” and veering toward the side of the lesion. Uncertain start/stop, unequal steps, positive tandem gait test. Can’t do the Romberg test, as they fall even before closing their eyes. Vestibulo or spinocerebellar (vascular, tumour, phenytoin, alcohol), common in MS

Sensory Ataxic Gait

• GSA: Lack of co-ordination due to loss of joint position sense. Called tabetic gait. Stamping, high-stepping gait due to lost proprioception (can’t work out where the foot is). Peripheral neuropathy or posterior columns (tabes dorsalis). Check joint position sense and test for a positive Romberg test
• SSA: vestibular ataxic or vertiginous gait. Inco-ordination (drunken gait) associated with vertigo, nausia and vomiting especially if of acute onset. Vestibular apparatus or pathway problems. Looks like the cerebellar ataxic gait, but positive Romberg test.

Basal Ganglia Lesion Gait

• Dyskinesia superimposed on the gait.
• Parkinsonian gait: Difficulty in starting and stopping. Short steps and speed increases in an unconscious attempt to “catch up” with a displaced center of gravity (festinating). Little or no arm movement and stooped forward (substantia nigra pars compacta)

Paretic/myopathic/waddling or Trendelenberg gait

• Marked dropping of pelvis on the side of the raised or moving leg, and shifting over of the centre of gravity to the supporting leg on the ground (waddling, cowboy gait). Drop is due to weakness in the proximal hip muscles. Proximal myopathies, bilateral hip dislocation

Cortical Lesion gait

• Frontal lobe: slow, shuffling, narrow, magnetic gait (feet don’t come off the floor)
• March á petit pas: Short rapid and tapping steps. An upright posture and exaggerated arm swing. Bilateral cortical dysfunction (often vascular)
• Gait apraxia: Inability to make walking movements, due to loss of cortical integration. Frontal lobe damage

High Stepping Gait

• Compensation for ‘foot drop’ i.e. inability to dorsiflex (tibialis anterior). Allows for ground clearance. Unilateral – common fibular or peroneal palsy, L4-5 radiculopathy. Bilateral – peripheral polyneuropathy

Antalgic Gait

• Pain in a limb or joint can cause buckling when weight bearing, and a compensation in weight bearing by the good limb. Arthritis, trauma etc.

Question 21

Cerebellar Function and Cerebellar ataxia

Answer 21

In order to show that gait and coordination abnormalities are due to cerebellar dysfunction, it is important to rule out problems with joint position sense, strength and reflexes, and the presence ofinvoluntary movements that could indicate basal ganglia disease, because problems here can affect gait. Cerebellar dysfunction is a diagnosis based on elimination of the other possibilities.

There are two kinds of cerebellar ataxia.

• Truncal ataxia affects the proximal muscles that stabilise gait, and is due to midline or vestibulocerebellar damage. Truncal ataxia presents with a wide-based, unsteady, drunk-like gait with no other significant abnormalities on exam. Inability to tandem gait.
• Appendicular ataxia affects movements of the arms and legs and is associated with lesions of the cerebellar hemispheres (spinocerebellar and cerebrocerebellar).

1. Vestibulocerebellum lesions: Presents with postural instability, and problems with balance and eye movements. Patient adopts a wide-based stance to prevent oscillating backwards/forwards. The instability is worse with the feet together, and asking them to stand in this way, with their eyes open will cause them to fall i.e. they fall before a Romberg test can even be done.
2. Spinocerebellum lesions: As this area regulates body and limb movement, patients present with a wide-based drunken gait, uncertain starts and stops, unequal steps and lateral deviations (cerebellar ataxia).
3. Cerebrocerebellum lesions: Disturbances in carrying out voluntary and planned movements. Patients present with intention tremours, slurred and staccato speech (dysarthria)

Question 22

Tests Cerebellar Function and Cerebellar ataxia

Answer 22

Tests for Cerebellar Truncal Co-ordination

• Testing for cerebellar axial ataxia
• The test commonly used here is the heel-to-toe walking test, also called the tandem gait test. Axial ataxia will cause the patient to fall when trying to walk a line, and they will try to prevent this by planting their feet wide apart when walking.

Tests for Cerebella Appendicular Co-ordination

• Testing for cerebellar appendicular ataxia
• Upper limb dysdiadokokinesia: rapid alternating movements of the hand within the other hand or onto the thigh.
• Lower limb dysdiadokokinesia: tap foot as fast as possible
• precision finger tap
• finger-nose-finger test: Hold your finger an arm’s length from the patient, and ask him to touch your finger with his index finger, and then touch his nose. Your finger can be moved from place to place. Problems elicited with this test are an intention tremour as the patient’s finger approaches your finger; his finger overshoots your finger (past pointing or dysmetria).
• heel-shin test overshoot: Have the patient lie down and ask her to lift her leg and place the point of her heel on her knee and then run her heel down the length of her shin.

The classic Charcot’s triad for cerebellar dysfunction is: nystagmus, dysarthria and intention tremour

Question 23

The Romberg Test

Answer 23

Ask the patient to stand with the feet together and eyes open. When the eyes are open there are 3 sensory inputs to the cerebellum: vision, proprioception pathways and vestibular sense. When the eyes are open, the patient is able to compensate for mild problems in proprioception. Next ask the patient to close the eyes. Closing the eyes will stop the visual compensation and the patient will fall (the test is positive) if there is a proprioceptive or vestibular problem. Apply gentle pushes to destabilase, known as Perturbations. Be ready to catch them if they sway and fall. A positive Romberg test suggests that the ataxia is sensory in nature, that is, due to loss of proprioception. If a patient is ataxic and Romberg’s test is not positive, it suggests that ataxia is cerebellar.
If there are severe abnormalities in the propriocepton or vestibular input, or a midline cerebellar lesion, the patient will not be able to compensate with vision, and will not maintain position even with the eyes open.