major plexuses and peripheral nerves

Question 0

draw the spinal cord demonstrating the spinal nerve diverging into the anterior and posterior rami, draw the additional divergence of the anterior rami and which constitutes to limb formation

Answer 0

see diagram

Question 1

draw the brachial plexus

Answer 1

include the radial, axillary, ulnar, median and muculocutaneous nerves

Question 2

decribe the cervical plexus

Answer 2

it includes CN12, and C1-5, the most notable feature is that the phrenic nerve which innervates the diaphragm arises from this plexuses and diverges from C3,4,5

Question 3

what are the motor and sensory functions of the axillary

Answer 3

deltoid (shoulder abduction), shoulder chevron

Question 4

the musculocutaneous nerve

Answer 4

flexes the forarm (biceps), and provides sensation to the lateral forearm

Question 5

the radial nerve

Answer 5

extension below shoulder (triceps), supination. provides sensation to the posterior forearm

Question 6

the median nerve is the thenar nerve and innevates which muscles and provides sensation where

Answer 6

LLOAF, and 3.5 of the palmar surface of the hand, and the tips of the three fingers and thumb on the dorsal surface

Question 7

ulnar nerve

Answer 7

covers 1.5 from the little finger in both palmar and dorsal surfaces of the hand, it is referred to as the hypothenar nerve and innervates all intrinsic hand muscles besides LLOAF and the flexor carpi ulnaris

Question 8

thumb movements are mediated by

Answer 8

RUM

opposition and abduction, extension and adduction

Question 9

the lumbar plexus

Answer 9

is from T12 to L5 and is within the psoas major

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iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator and femoral

Question 10

the sacral plexus

Answer 10

occurs from L4-S4

includes the sciatic nerve (the hamstring nerve), which has the common peroneal and tibial nerve

the pudendal nerve also arises from this plexus and innervates the urogential area

Question 11

the femoral nerve

Answer 11

flexes the hip and extends the knee and provides sensation to the anterior thigh and medial shin

Question 12

the lateral femoral cutaneous

Answer 12

has no motor function yet provides sensation to the anterolateral thigh

Question 13

the obturator

Answer 13

adducts the thigh and has sensation along the medial thigh

Question 14

the sciatic nerve

Answer 14

has no sensory input but flexes the knee

Question 15

the tibial and common peroneal

Answer 15

are opposites of each other

the tibial is posterior (plantar) and the common peroneal is anterior and lateral (dorsum)

the tibial allows plantarflexion, toe flexion, and inversion

the common peroneal allows foot eversion and forsiflexion and toe extension

Question 16

the brachial plexus is the most prone to damage of all plexuses decribe some common plexopathies

Answer 16

1. brachial neuritis - idiopathic condition common in males
2. klumpke’s palsy - trauma or traction of arm and shoulder during childbirth or following motor vehicle accident
3. apical lung tumour (non small cell) - causing pancoast syndrome, which may produce Horners syndrome and voice hoarseness if invaded the laryngeal nerve
4. thoracic outlet syndrome - compression of the brachial plexus by the clavicle and first rib, or by the scalenes, or by subclavian artery occulusion causing ischaemia and neuropathy
5. radiation plexitis

Question 17

decribe the common presentation of mononeuropathies

Answer 17

usually caused by entrapment, they present with pain which later develops into muscle weakness and atrophy

Question 18

decribe some of the common features of median nerve palsy

Answer 18

presentation will be that of a preachers hand with thenar wasting and atrophy

usual causes are carpal tunnel syndrome

the causes/aetiology:

MEDIAN TRAP - myxodema, odema, diabetes, idiopathic, acromegaly (men), neoplasm, trauma, rheumatoid, amyloidosis, preganancy

treated surgically by ligating the flexor retinaculum

Question 19

common causes of ulnar nerve palsies

Answer 19

patients present with a claw hand or a benedictian hand

common causes include entrapment caused from a former fracture of elbow, this nerve travels in the cubital tunnel of the elbow and has a tardy presentation of neuropathy

in the wrist - compression in Guyons canal - common in bike riders

Question 20

radial nerve palsies

Answer 20

present with a wrist drop and wasting of the interossei

the usual causes are a saturday night pasly or from trauma

Question 21

sensory loss in the anterolateral thigh is caused by

Answer 21

compression of the lateral femoral cutaneous nerve and is known as meralgia parasthetica and common causes include pregnancy and obesity, pregnancy

Question 22

femoral nerve palsies can be caused by

Answer 22

femoral angiography, haematoma, direct injury or a false aneurysm

Question 23

a foot drop can be seen in

Answer 23

an L4,5 radiculopathy or can even be caused by direct injury to common peroneal nerve as it is very superficial over fibula head on the lateral aspect of the leg