Lec 13 & 14 - peripheral nerve lesions of UE Flashcards
DR CUMBA
Dorsal Root
Ventral Root
Dorsal root - Sensory
Ventral root - Motor
*Suprascapular Nerve Entrapment
Innervates supraspinatus muscles first then infraspinatus
can be entrapped under transvers superior scapular ligament in suprascapular notch (affects supra and infra) or spinoglenoid ligament in spinoglenoid notch (would only affect infra, so no ER)
clavicular fractures may also harm
Know median and lateral head of the median N
Scalene Block
anesthetizes most of brachial plexus during surgery excpet C8 and T1
Common peripheral nerve injuries
pins-and-needles from pressure or awkward position
neuropraxia - type of peripheral nerve injury characterized by a temporary loss of function of the affected nerve without any structural damage. It is often caused by compression, stretching, or ischemia (lack of blood flow) to the nerve
What can neuropraxia progress to?
cumulative trauma disorders
more severe nerve injuries may involve interruptions of the axons (axonotmesis) or entire nerve (neurotmesis)
How do clinicians test peripheral nerve muscle function and sensory function?
manual muscle tests
close eyes and touch different peripheral innervates regions of arm and hand
Causes of PNI
diabetes
traction
neoplastic
direct trauma
compression
motor neuron diseases
autoimmune
inflammation/ischemia
**Thoracic outlet entrapment sites
between anterior and middle scalene (brachial plexus)
under pec minor - brachial plexus, axially artery and vein
between clavicle and 1st rib
UE in hyperabduction
cervical rib
Radial tunnel syndrome (entrapment sites)
“dont spend too much time on”
Radial nerve affects what movements?
wrist extension, wrist radial deviation (half, flexor can do other half), finger extension, thenar extension and abduction (half)
Common Radial nerve injury
Wrist Drop
not a contracture just cant move on own
radial nerve MOTOR impairment
If someone has radial nerve injury, can they still abduct thumb?
Yes, abductor pollicis brevis is median nerve
Does the deep radial nerve / PIN innervate any hand intrinsics?
No
Radial N - deep branch innervation
extensor digitorum
extensor carpi ulnaris
extenso digit minmi
Radial N innervation
tricpes
anconeus
brachioradialis
extensor carpi radialis longus (and brevis on sheet)
Does the median nerve innervate muscles in the brachium?
No
Radial N PIN (Posterior interosseous)
Abductor Pollicis Longus
Extensor Pollicis brevis
Extensor Pollicis longus
Supinator
Extensor Indices
List the divisions of the median nerve
Median N
AIN - Anterior interosseous Nerve
Recurrent branch
Digital branch
Median N
Pronator teres
(PL)
Flecor carpi radialis
Flexor digitorum superficialis
Median AIN
FDP
Flexor pollicis longus
Pronator quadratus
Median Recurrent
APB
FPB
Opponens Pollicis
Lumbricals (DIGITAL BRANCH)
Median N Digital
lateral 2 lumbricals and palm sensation
Where does the median nerve split?
travels through cubital fossa and innervates PT, PL, FCR first
sends a branch 1/4th way down forearm - anterior interosseous regions (AIN)
at distal radioulnar joint it splits into recurrent branch (thenar side) and digital branch for lumbricals and palm sensation
Median Nerve entrapment sites
Between A/P scalene
Pec minor
Pronator teres region - splits
AIN (degeneration)
Carpal tunnel
Pronator syndrome associated with what nerve
median
dont spend time on
Carpel tunnel contents
FDS, FDP
FPL
FCR
MEDIAN Nerve
Ape hand
Median Nerve
thumb rests in adduction because without median nerve innervating thenar muscles there is no one to counter adductor except APL
posture hand takes at rest
loss of web space
Hand of Benediction
median nerve injury usually happens with ape hand
bishops hand
inability to flex thumb, index and middle finger when asked to make a fist
(last digits are all the way down in fist)
What screening procedure can be used for AIN syndrome?
Make an OK sign with hand - not circle or pinch = bad
What motion is the median nerve entirely responsible for?
Pronation
What role does anconeus play in pronation
abducts ulna during pronation
carrying angel disapears
What nerve continues off the musculocutaneous arm and what area does it supply sensation to?
Lateral antebrachial cutaneous nerve
lateral forearm
What sensory and motor functions could test for musculocutaneous function?
elbow flexion
lateral forearm sensory
What can cause axillary nerve damage?
anterior shoulder dislocation
open shoulder surgeries
improper use of crutches
improper IM injection
What branch comes off the axillary nerve and what is its function?
The superior lateral cutaneous nerve of arm
innervates sensory area of axillary
Ulnar nerve entrapment sites
between first rib and clavicle
arcade of Struthers
between heads of flexor carpi ulnaris
cubital tunnel
guyons canal
What motor deficits result from ulnar nerve injury
lateral key pinch - thumb adduction
What is cubital tunnel syndrome?
pressure and tension of the ulnar nerve in cubital tunnel with flexed elbow
think texting in bed on stomach
medial, right below elbow joint
causes ulnar neuritis
Ulnar transposition
surgical relocation of the ulnar nerve in the cubital tunnel to the anterior medial epicondyle
Ulnar deep branch innervation
PAD
DAB
medial 2 lumbricals
adductor
hypothenars (FDM, ADM, ODM)
Guyons canal contents
ulnar nerve and artery
Ulnar nerve screening
thumb adduction
crossing fingers
squeezing paper between fingers
Common ulnar nerve injury
claw hand at rest
4th and 5th digits cant extend (FDP medial)
hyperextension of MCP, loss of IP extension in 4th and 5th
law of medial lumbricals (and other intrinsic hand muscles)
Superior trunk of brachial plexus injury
C5 C6
waiters tip or erb-duchenne palsy
neck movements
more important
Inferior trunk injury
C8 T1
less common (so dont worry)
UE pulled superiorly
claw hand
klumpke palsy
Middle trunk injury?
C7?
*Intrinsic plus position - what condition is associated?
MCP flexion with PIP and DIP extension
sandwich or sock puppet
PAD, DAB, lumbricals, flexor digit minimi
tenodesis - passive finger flexion with wrist extension
intrinsic minus
evil cousin of intrinsic plus
clawing of fingers
MCP hyperextension and IP flexion
*Grasp Patterns - cylindrical
midrange flexion of digits
tube shaped object
turning steering wheel
Grasp patterns - spherical
varied flexion of digits
rounded object
Grasp patterns - hook (what muscle is crucial)
flexion of PIPs and DIPs, extension of MCP
NEED FDP
carrying a bucket
Grasp patterns - composite
maximal flexion of all joints
wringing out towel
Pinch patterns - tip
precise movements
distal tips of thumb and index
threading needle
Pinch - three jaw chuck
tripod pinch
tip of thumb against tips of index and middle fingers
writing with a pencil
Pinch - lateral (key)
pad of thumb against radial side of index finger
unlock a door with key
What is the second strongest muscle
adductor pollicis
Tinels nerve exam
ulnar nerve
tap medial condyle, do they feel it in tips of digits 4&5?
scratch collapse test
reflextive collapse with external rotation after swiping finger over nerve
suprascapular nerve
what position would a wrist brace have the wrist in at night for treatment of carpal tunnel syndrome
wrist extension
Radial nerve injury treatment - radial nerve palsy orthosis
brace to assist with grasping and releasing objects
What movements would hurt with de quervains or texting thumb syndrome
Thumb extension and abduction
APL EPB
Treatment for De Quervains
thumb spica orthosis
nerve slides for sensory branch of radial nerve
Extensor hood functions
extension of IP joints
counterbalances flexor forces of extrinsic muscles
facilitates coordinated finger flexion(?)
Extensor hood - sagittal band fxn
stabilize volar plates and MCP joints, prevent bowstringing of extensor tendons
Extensor hood - central band fxn
extended PIP
Extensor hood - lateral band fxn
extends DIP joint
Extensor hood - terminal tendon
assocaited injury
extends DIP joint
mallet finger
swans neck
Swan neck deformity
damage to terminal tendon, direct blow to DIP while extended or progressive weakining (RA)
PIP in hyper extenstion and DIP in flexion
Boutonniere deformity
opposite of swan neck
injury to the central slip
PIP joint flexion and DIP hyperextension
ORL ligament
