Major Plexuses and Peripheral Nerves Arising from Them Flashcards
Composition of a spinal nerve
dorsal and ventral roots
Each spinal nerve divides into:
ventral and dorsal ramus
Dorsal ramus
innervates strip of skin and muscles along back
Ventral Ramus
innervates anterolateral parts of trunk and limbs
How does the ventral ramus innervate the thoracic region?
as intercostal nerves
How does the ventral ramus innervate non thoracic region?
converge with each other to form network of nerve plexuses
Function of brachial plexus
provides major sensory and motor innervation to upper limbs
Function of lumbosacral plexus
provides major sensory and motor innervation to the lower extremities and pelvis
Define Plexopathy
a type of neuropathy, pathology of plexuses causing motor/sensory dysfunction of extremities, may affet one trunk or all, may have acute or chronic presentation
Plexopathy: causes
traumatic, mechanical compression by bony abnormalities, radiation, inflammatory lesions, neoplastic infiltration, diabetes
C5-C6 plexopathy: alternative name
Erb-Duchenne palsy “waiter’s tip”
C5-C6 plexopathy: symptoms
weakness of should er abduction, elbow flexion, arm supination, numbness of lateral aspect of forearm, arm held at side, internally rotated, with writ flexion
C5-C6 plexopathy: main cause
accidents and newborns when head is pushed away from shoulder
C8-T1 plexopathy: alternative name
Klumpke’s Palsy
C8-T1 plexopathy: symptoms
severe hand weakness, atrophy, claw hand, numbness if medial aspect of hand and forearm
C8-T1 plexopathy: when does Horner’s syndrome occur?
if the T1 root is damaged proximal to the sympathetic trunk
Sypmtoms of Horner’s syndrome
ptosis, myosis (pupila pequeña) y anidrosis (no hay sudoracion)
C8-T1 plexopathy: common cause
ussually occurs when the arm and shoulder are pulled up (upward traction) such as when grabbing a branch during a fall from a tree
C8-T1 plexopathy: syndrome that can present this
neurogenic thoracic outlet syndrome and Pancoast Syndrome
Neurogenic Thoracic Outlet Syndrome: pathology
lower brachial plexus is compressed between the clavicle and the first rib
Neurogenic Thoracic Outlet Syndrome: symptoms
severe hand weakness with numbness/parethesias, increased by raising and external rotation of the arm…pain of hand (ulnar) ad arm usually not prominent but cna also involve the chest and shoulder
Neurogenic Thoracic Outlet Syndrome: causes
caused by a cervical rib, bony abnormality, postural abnormalities, muscle imbalanca
Neurogenic Thoracic Outlet Syndrome: secondary symtpoms
swelling of extremity/decreased pulses due to vacular compression
Neurogenic Thoracic Outlet Syndrome: common patient
common in patients who pratice overhead arm activities
Pancoast Syndrome: pathhology
lower brachial plexus injury by an apical lung tumor (usually non-small cell carcinoma)
Pancoast Syndrome: symptoms
severe hand weakness, atrophy, numbness of medial aspect of hand and forearm and pain
Pancoast Syndrome: other diseases involved
Horner’s symdrome sometimes and recurrent laryngeal nerve involvement
Pancoast Syndrome: long run symptom
may eventually invade the entire plexus-completely weak, insensate arm
Idiopathic Brachial Plexitis: alternative name
Parsonage-Turner Syndrome
Idiopathic Brachial Plexitis: cause
an immune-mediated inflammatory process
Idiopathic Brachial Plexitis: onset characteristics
acute onset shoulde and arm pain (usually intense) followed by weakness and sensory loss
Idiopathic Brachial Plexitis: prognosis
usually resolves within days to weeks with some residual motor/sensory loss
Idiopathic Brachial Plexitis: patient arm position
arm in an elbow-flexion/should adduction position
Diabetic Lumbosacral Plexopathy: onset characteristics
begins rapidly over a few days to a few weeks
Diabetic Lumbosacral Plexopathy: definition
rare proximal neuropathy
Diabetic Lumbosacral Plexopathy: symptoms
burning, lancinating pain on hips and anterior thigh, followed by weakness and wasting of thigh muscles, causing bukling of knee due to quadriceps weakness
Diabetic Lumbosacral Plexopathy: location
mainly, asymmetric involvement of muscles supplied by L3 an L4 (quadriceps, hip adductors, ilepsoas) but can have weakness in any muscle innervated by the lumbosacral plexus
Diabetic Lumbosacral Plexopathy: causes
poor glycemic control in adult patientt
Diabetic Lumbosacral Plexopathy: development
maximum defecit in wks, stable fr weeks to months, improvement over months to yrs
What does each peripheral nerve exiing the plexuses have>
axonal fibers from different spinal nerves
True or False: damage to a single spinal nerve will completely paralyze a limb
false
Region of sensory loss with neuropathy: radial nerve
posterior cutaneous nerve of arm, posterior cutaneous nerve of forearm, dorsal digital nerves
Region of sensory loss with neuropathy: median nerve
first three fingers (thumb index and el dedo malo)
Region of sensory loss with neuropathy: ulnar nerve
4th and 5th finger
Region of sensory loss with neuropathy: axillary nerve
skin where the deltoid muscle goes
Region of sensory loss with neuropathy: musculotaneous nerve
lateral forearm
Region of sensory loss with neuropathy: femoral nerve
medial thigh and leg
Region of sensory loss with neuropathy: obturator nerve
upper inner thigh
Region of sensory loss with neuropathy: sciatic nerve
lateral posterior leg, anterior medial leg
Region of sensory loss with neuropathy: tibial nerve
sole of foot
Region of sensory loss with neuropathy: superficial peroneal nerve
lateral leg and dorsum of foot (with fingers)
Region of sensory loss with neuropathy: deep peroneal nerve
la parte entre medio del hallucis and 2nd fingerr
Nerve motor function: radial nerve
extension of arm, wrist, and finger joints below the shoulder, forearm supination, thumb abduction
Nerve motor function: median nerve
thumb flexion and opposition, flexion of digits 2 nd 3, wrist flexion and abduction, forearm pronation
Nerve motor function: axillary nerve
abduction of arm at shoulder beyond first 15 degrees
Nerve motor function: musculotaneous nerve
flexion of arm at elbow, supination of forearm
Nerve motor function: femoral nerve
leg flexion at the hip, leg extension at the knee
Nerve motor function: obturator nerve
adduction of the thigh
Nerve motor function: sciatic nerve
leg flexion at the knee
Nerve motor function: tibial nerve
foot plantar flexion and inversion, toe flexion
Nerve motor function: superficial peroneal nerve
foot eversion
Nerve motor function: deep peroneal nerve
foot dorsiflexion, toe extension
Neuropathy of Peripheral nerves Arising from the Major Plexus: affecter fibers
sensory, motor, or both
Neuropathy of Peripheral nerves Arising from the Major Plexus: symptoms
decreased sensation, abnormal sensation, weakness, atrophy, and muscle twitching (fasciculation)
Neuropathy of Peripheral nerves Arising from the Major Plexus: causes
diabetes, infections, mechanical, toxins,
malnutrition, immune disorders, hereditary,
medications
Where do the palmar cutaneous branch of the median nerve arise?
prior to carpel tunnel, travels superficial to the flexor retinaculum of the hand
Is the palmar cutaneous branch of the median nerve involve in carpel tunnel?
no, it can be spared
Phalen’s and Tinel’s Signs: symptoms
increasing pressure in carpal tunnel, compression of median nerve, tapping over median nerve, reproduction of sensory symptoms
Carpal Tunnel Syndrome: pathology
Entrapment syndrome by compression of median nerve as passes under flexor retinaculum on flexor surface of wrist
Carpal Tunnel Syndrome: cause
Associated with repetitive stress injury of wrist, pregnancy, hypothyroidism…
What does the median nerve innervvate after it passes through carpal tunnel?
LOAF: Lumbricals I, II, opponens pollicis brevis, abductor pollicis brevis, flexor brevis pollicis- superficial head
Carpal Tunnel Syndrome: symptoms
Sensory loss of 1rst,2nd,3rd digits with abnormal sensation
paresthesias)…May have Tinel’s sign and Phalen’s sign- provoke abnormal sensation (paresthesias
Common Peroneal Nerve Palsy: symptoms
Foot drop, with weakness of foot dorsifexion and eversion, and sensory loss over dorsolateral foot and shin
Common peroneal nerve passes around…
Common peroneal nerve passes around
fibular head near skin surface
Common Peroneal Nerve Palsy: causes
Vulnerable to laceration, stretch injury by forcible foot inversion, or compression by stockings, cast, trauma
Common Peroneal Nerve Palsy: diseases to take into consideration in differential diagnosis
L5 radiculopathy
Femoral Neurpathy: symptoms
Weakness of thigh flexion, knee extension, loss of patellar reflex, and sensory loss in anterior thigh
Femoral Neurpathy: causes
pelvic surgery, diabetes
mellitus, compression by pelvic
mass ,retroperitoneal hematoma,
pelvic fracture
Femoral Neurpathy: diseases to take into consideration in differential diagnosis
Consider in the differential
diagnosis an L3 or L4
radiculopathy
Meralgia Paresthetica: pathology
Lateral femoral cutaneous nerve entrapped as passes under inguinal ligament and fascia lata
Meralgia Paresthetica: symptoms
Abnormal sensation (paresthesias) and loss of sensation in lateral thigh
Meralgia Paresthetica: associated conditions
Associated to obesity, pregnancy, weight loss, heavy equipment belts
Ulnar Neuropathy: common cause
Associated to trauma as passes in ulnar
groove of elbow
Ulnar Neuropathy: pathology
entrapment due to
degenerative disease, habit of resting
elbows on hard table
Ulnar Neuropathy: symptoms
Weakness of wrist flexion and adduction, finger adduction and abduction, and flexion of 4th and 5th digits, together with sensory loss and paresthesias in ulnar
distribution
Ulnar Neuropathy: diseases to take into consideration in differential diagnosis
Differential diagnosis includes C8 and T1 radiculopathy, brachial plexus injury
Radial Neuropathy: common causes
Associated to sleeping with arm slung over
object, improper crutch use, tight wrist bands or
hand cuffs
Radial Neuropathy: symptoms
Weakness of extensors of arm, hand and fingers,
sensory loss in radial nerve distribution, often
with wrist drop
Sciatic Neuropathy: common causes
Associated to posterior hip dislocation, acetabular
fracture, intramuscular injection placed too medially and
inferiorly in buttocks
Sciatic Neuropathy: symptoms
Weakness of all foot and ankle muscles and of knee
flexion, loss of Achilles tendon reflex
Sciatic Neuropathy: diseases to take into consideration in differential diagnosis
Differential diagnosis includes lesions in foot area of
motor cortex
Case: 3 week-old infant with hx of complicated birth due to shoulder dystocia
(difficulty delivering the shoulder) presents right arm weakness. There was
significant traction on the right neck and shoulder during birth. Has Decreased tone of right arm, internally rotated at infants side with decreased spontaneous movements. No flexion at elbow nor
abduction. Prominent weakness of deltoid, biceps, infraspinatus, wrist
extensors. Right biceps reflex absent.
C5-C6 plexopathy
60 yo man with hx of lung cancer (apical) gradually develops severe
pain, with progressive weakness and numbness in his right arm. Pain is described as shooting, with swelling of the arm. Eventually, all strength and sensation is lost on the arm. Right arm and hand 0/5 strength with flaccid tone, absent DTR’s right arm, absent light touch, pinprick, vibration sense in entire arm up to the deltoid
Pancoast’s Syndrome
Male pt develops pain and tingling in his right thumb, index and middle fingers that is worse at night.On exam
• decreased pinprick sensation as shown
• 4/5 weakness on right opponens pollicis
• Tinel’s and Phalen’s sign positive
Median nerve neuropathy (not C6-C7 radiculopathy because there is no neck pain that radiates)… mild weakness of right opponens pollicis
Male pt slipped on wet floor and twisted right foot
toward the left, causing pain and weakness.On exam:
• Decreased sensation to pinprick as shown
• 0/5 strength right tibialis anterior, 3/5
strength strength right foot evertors
Common peroneal nerve palsy (not L5 radiculopathy becausethere is no back pain with radiation, the onset of sensory deficit is rapid and there is specific foot weakness)
A diabetic male after weeks in intensive care unit notices weakness and numbness and tingling in left leg, over anterior thigh down to medial calf above foot. On exam
– Decreased pinprick sensation as shown
– 4/5 strength in left ileopsoas and quadriceps femoris, no other weakness, with absent left patellar reflex
peripheral femoral nerve lesion (not L2, L3, L4 radiculopathy because there is no back pain), not obturator nerve because there is no weakness of adduction of thigh
After giving birth, a woman develops pain and numbness in the right lateral thigh. On exam:
– Decreased sensation to pinprick as shown
– Motor strength and reflexes normal
Dysfunction of lateral femoral cutaneous nerve (not L2 radiculopathy because there is no back pain, and history of pregnancy)
Male patient develops tingling and numbness in his left 5th digit, in the medial aspect of his left fourth digit, and along medial surface of his left hand and forearm, exacerbated by resting elbows on hard surface On exam:
– Decreased sensation to pinprick as shown
– Weakness of left 5th finger abduction
Ulnar Nerve lesion (not C8, T1 radiculopathy because no neck pain, and worsened by resting elbow on hard surface)
After a fall, a female patient is unable to move her right
foot and has a tingling sensation on her right lateral lower leg and foot.On exam
– Decreased pinprick sensation as shown
– Strength 0/5 right tibialis anterior, extensor hallicus
longus, foot invertors , foot evertors, and
gastrocnemius
– Strength 3/5 right hamstrings
– Absent right Achilles tendon reflex
Sciatic Nerve Lesion(not L5, S1 radiculopathy because no back pain)
