Peripheral nerve injury Flashcards by Cialmar Janesa Pelovello

The peripheral nervous system is made up of ____ Cranial nerves and ___ Spinal nerves

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In the cervical and lumbar regions, the spinal nerves intemingle to create _______ which form individual peripheral nerves

Plexus

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The basic neural structure consists of : (3)

Neuron
Associated axons
Nerve fiber

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An axon invested solely by a schwann cell wrapping around it several times is known as

Myelinated fiber

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Most common cause of localized injury yo a single nerve ( mononeuropathy)

Trauma

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focal conduction block without axonal damage

Seddon Classification
Sunderland Classification

Neuropraxia

First degree

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Axon damage with wallerian degeneration, supporting structures are intact

Seddon Classification
Sunderland Classification

Axonotmesis

Second degree

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Damage to axon and endoneurium

Seddon Classification
Sunderland Classification

Neurotmesis

Third degree

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Damage to perineurium and endoneurium

Subderland class

Fourth degree

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Damage to axon and all supporting structures

Sunderland class

Fifth degree

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At the area of the injury, the axon distal to the site of injury is the one that undergo degeneration

Wallerian degeneration

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Transitory localized conduction block with no development of signs of denervation

Neuropraxia
Ex. Numbness of hand after holding an ice
Recovery within days or weeks

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Describes lesions that cause axonal interruption in which the connective tissue and schwann cell basement membrane remain intact

Axonotmesis

- complete loss of motor, sensory, and sympathetic functions in the autonomous distribution of the injured nerve

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Damage to the axon and connective tissue or COMPLETE transection of the nerve

Neurotmesis

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Hyperirritable sensation

Dysesthesias

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Can be used to study the pattern of denervation and later re-innervation

Electromyogram

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Can ascertain the site and nature of injury

Nerve conduction velocity

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Long thoracic nerve root

C5,6,7

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Winging of scapula is an action of

Long thoracic nerve

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Supraclavicular nerve
Root
Muscle
motion

C5,6
Supraspinatus
Shoulder abduction

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Axillary

Root
Muscle
motion
Sensation

C5,6
Deltoid
Arm abduction
Lateral arm below shoulder

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Musculocutaneous

Root
Muscle
motion
Sensation

C5,6,7
Biceps and brachialis
Elbow flexion
Lateral forearm

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Radial

Root
Muscle
motion
Sensation

C5-T1
Extensor carpi, radialis longus and brevis

Extension of elbow and wrist
Post lat arm and dorsum of hand

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Median nerve

Root
Muscle
motion
Sensation

C5-T1
Pronator teres and quadratus, flexor carpi radialis, flexors of fingers

Flexion of wrist and fingers
Radial palm, palmar surface, tips of lateral 3 1/2 fingers

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Ulnar Root Muscle motion Sensation

C8-T1 Inteossei and lumbricals and adductir pollices Movement of medial 2 fingers Ulnar and dorsal palm and medial 1/2 fingers

Passes under the bicipital aponeurosis before entering antecubital fossa medial to biceps tendon

Median nerve

_______ crosses over the median nerve

Ligament of struthers

Supplies medial portion of medial portion of FDO, FPL, pronator quadratus

Anterior Interosseous Syndrome

After exiting the tunnel, the median nerve supplies the: | 4

1st and 2nd lumbricals Opponens pollicis Abductir pollicis brevis Cutaneous to the skin of the 1st to the lateral portion of the 4th finger

Anterior interosseous nerve can be compressed at the fibrous arch formed by : (2)

Flexor digitorum superficialis | Pronator teres

(+) aching pain in forearm but no sensory loss

Anterior interosseous syndrome

(+) pain and parasthesia jn the 1st 3 fingers of the hands, mimicking carpal tunnel syndrome

Pronator teres syndome

(+) involvement of skin over thenar eminence which is usually spared in CTS

Pronator teres syndrome

Pain may be provoked by resisted flexion, pronation and finger flexion

Pronator teres syndrome

Tenderness over the area entrapment

Tinel’s sign

EMG shows denervation potentials in all muscles supplied by median nerve except PT

PT syndrome

Median nerve is compressed within the carpal canal, approx _____ beyond the distal wrist crease

1-2cm

Cause has been assoc with repetitive hand and wrist movement or use of vibratory tools

Carpal tunnel syndrome

Often assoc with DM, hypothyroidism and rheumatoid arthritis as well as obesity and pregnancy

Carpal tunnel syndrome

Numbness and pain along the median nerve distribution, radiating to the forearm

Carpal tunnel syndrome

Signs on carpal tunnel syndorme (3)

Tinel’s sign 1-2 cm distal to wrist crease Atrophy to thenar eminence Phalen’s sign

Courses along the medial aspect of the upper arm in close proximity to the median nerve

Ulnar nerve

Proximal to the elbow it runs superficially in the groove made by the medial epicondyle and the olecranon

Ulnar nerve

It innervates the distal 3rd of the palmar and dorsal aspects of the medial hand

Ulnar nerve

The ulnar nerve enters the _______ in the wrist between the hook of hamate and pisiform

Guyon’s canal

Symptoms: Difficulty eating and dressing Loss of dexterity and grip strength

Ulnar neuropathy at elbow

Signs: Pos tinel’s sign in the retriepicondylar region CLAWING OF THE HAND

Ulnar neuropathy

Compression within the guyon’s canal | Altered sensation in the 4th and 5th digits

Ulnar neuropathy at the wrist

Weakness of all ulnar innervated hand muscles

Ulnar neuropathy at the wrist

Largest terminal branch of brachial plexus

Radial nerve

Supplies triceps then winds around the spinal groove of the humerus

Radial nerve

Enters forearm between biceps and brachioradialis muscles and divide into PIN and superficial radial nerve at the elbow

Radial nerve

Posterior interosseous nerve courses around the neck of the radius thru the _____ which is made up of the proximal border of supinator

Arcade of frohse

Supply sensation to dorsolateral position of the hand and 1st 3 digits

Radial nerve

From fracture of the humerus External compression from tourniquets Honeymooner’s palsy Saturday night palsy

Radial nerve injury at the spiral groove

``` S/s Wrist drop Inability to extend fingers Abn sensation in lateral aspect of dorsumof the hand and dorsum of digits 1-4 Diminished or absent BR reflex ```

Radial nerve injury at the spiral groove

Radial nerve injury at the spiral groove Surgical exploration is warranted with no recovery within _____ Tendon transfer when no functional recovery in ______

8-10 weeks 1 year

Post interosseous neuropathy | Common is entrapment at the

Arcade of frohse

AKA supinator syndrome

Posterior interosseous neuropathy

Weakness seen in finger extensor and ECU | BR and radial wrist extensors are spared

Post inter neuropathy

Largest nerve jn the body

Sciatic nerve

Sciatic nerve consists of

Tibia and common peroneal

Freq injured by gunshot or stab wounds or intramuscular injection of drugs

Sciatic nerve

Represents a sciatic neuritis due to compression between bony edge of the notch and piriformis muscle

Piriformis syndrome

Pain in the low back and in the leg along the course of the nerve

Sciatica

Runs with tibial nerve in the posterior thigh as part of the sciatic nerve

Common peroneal neuropathy

Lesions of the peroneal nerve often occur at the ________from the compression during surgery, prolonged bed rest, improperly placed casts or splints

Fibular head

Foot drop

Peroneal mononeuropathy

Sensation is diminished in lower 2/3 of the lateral leg and dorsum of foot

Peroneal mononeuropathy

It innervates all the hamstring muscles except the short head of the biceps femoris

Tibial nerve

Partially innervates the adductor magnus. | At the ankle it passes through within the popliteal fossa it gives off the SURAL SENSORY NERVE

Tibial nerve

Maybe injured by penetrating wounds in the popliteal fossa and in the leg, fractures and dislocations about the knee, knee surgeries and compression from swelling within the post muscle compartments

Proximal tibial neuropathy

Loss of ankle jerk and plantar reflex

Proximal tibial neuropathy

Compression of the posterior tibial branch at the medial malleolus

Tarsal tunnel syndrome

Supplies the psoas muscle in the pelvis

Femoral nerve

Travles between the psoas and iliacus then pass under the inguinal ligament

Femoral nerve

Unilateral thigh weakness and numbness of the anterior thigh and leg

Femoral nerve neuropathy

Present with sensation of knee buckling, difficulty negotiations stairs if nerve is affected within pelvis hip flexion

Femoral nerve neuropathy

Purely sensory arising from l2-l3 nerve roots coursing around the pelvic brim to exif under the inguinal ligament just medial to the ASID

Lateral femoral cutaneous nerve

Mononeuropathy is known as

Meralgia paresthetica

Exterbal sources of compression : Heavy tool belts Habitually leaning against a table or wearing waist bands Surgery

Meralgia paresthetica