Lec 18 Peripheral Nerve Injuries Flashcards
Explain dermatome patterns - front of leg
starting at inner thigh L1, then L2 moving laterally then L3, L4 makes it down to shin and medial malleolus, L5 comes from back side and wraps around at knee and cover dorsum of foot, S1 is pinky tow and lateral malleolus
KNOW PERIPHERAL INNERVATION OF THE LOWER LEG AND FOOT
KNOW PARENT STRUCTURES
Describe dermatomes back of leg
L5 upper lateral thigh/glute wraps around to front before the knee
moving in is S1, from top to bottom, S2,
bottom of foot is S2 and L5 (wrapped over toes from dorsum)
Name the peripheral nerves in the inguinal region and their general location
Genitofemoral nerve
Ilioinguinal nerve
From lateral to medial its femoral branch, ilioinguinal, genital branch
Peripheral sensory location of Obturator Nerve
upper medial thigh
remember sural =
saphenous =
sural = lateral
saph = medial
Peripheral sensory location of lateral cutaneous nerve
what’s its parent structure?
lateral thigh
from lumbar plexus L2 L3
describe the peripheral nerve map of the leg
femoral front of thigh
obturator upper medial thigh
lateral cutaneous femoral nerve on lateral thigh (not a branch of femoral!)
posterior cutaneous nerve on back of thigh past knee
femoral nerve saphenous branch on medial lower leg
common fibular lateral cutaneous on upper half of lateral leg
common fibular superficial on lower half of lateral lower leg and dorsum of foot
tibial nerve sural branch on lateral ankle and 5th toe
Femoral nerve peripheral sensory location
anterior thigh (anterior cutaneous nerve)
describe the peripheral nerves of the foot and their location (list their parent structure)
saphenous nerve (femoral) medial ankle
common fibular nerve superficial branch (common fibular nerve, then sciatic) on lateral ankle and dorsum of foot
lateral cutaneous nerve of foot (sural nerve)
dorsal digital nerve (from deep fibular nerve) between toe 1 and 2
medial plantar nerve (tibial nerve) on medial plantar side, toes 1-4.5, wraps around to toes on dorsal side (like the palm)
lateral plantat nerve (tibial nerve) on lateral plantar surace, toes 4.5-5
medial calcaneal branch (tibial nerve) on heel
Saphenous nerve Peripheral sensory location
What is its parent structure?
Medial lower leg
Femoral nerve branch
Common fibular nerve (lateral cutaneous) Peripheral sensory location
What is its parent structure?
superior half of lateral lower leg and lateral calf
Common fibular nerve
Peripheral sensory location of common fibular nerve (superficial branch)
inferior half of lateral lower leg and dorsum of foot
Peripheral sensory location of common fibular nerve (deep branch)
in between 1st and 2nd toe
Tibial nerve (sural) and (medial calcaneal branches) Peripheral sensory location
sural - lateral edge of foot and back of lateral ankle
medial calcaneal - back of heel
Peripheral nerves on the plantar surface of the foot
medial plantar nerve and lateral plantar nerve
Posterior cutaneous nerve of thigh Peripheral sensory location
posterior end of glute down just passed knee
so the entire plantar surface is supplied with peripheral nerves from what parent nerve?
tibial nerve
Who is the main hip medial rotator?
TFL!
What are causes of sciatica?
Herniated NP
Spondylosis
Spondylolysis/Spondylolisthesis
Spinal stenosis
Osteophytes
Piriformis
Hamstring strain
the piriformis divides the greater sciatic foramen into …
superior and inferior portions
What nerves are names based on their location relative to piriformis?
superior gluteal nerve
inferior gluteal nerve
tibial nerve course
The tibial nerve runs down the posterior thigh and posterior calf innervating muscles there before splitting into the medial and lateral plantar nerves at the ankle, which then provide sensory and motor innervation to the foot
common fibular nerve course
The common fibular nerve travels laterally around the fibular head (near the knee), then divides into its two terminal branches.
The deep fibular nerve innervates the anterior compartment of the leg (muscles that dorsiflex the foot, such as tibialis anterior).
The superficial fibular nerve innervates the lateral compartment of the leg (fibularis longus and brevis muscles).
How is Piriformis Syndrome caused? What will it affect?
portion of the sciatic nerve can pierce the piriformis or the piriformis can become chronically tight/spasms especially in women and cyclist
Will affect ROM (hip internal rot)
What would increase sciatic pain in piriformis syndrome? In what direction do you stretch it to relieve symptoms?
muscle contraction would compress the nerve causing symptoms
stretch in opposite direction of its main action - so do hip internal rotation (with extended hip) and adduction with flexed hip (?)
The sciatic nerve runs down the entire…
posterior leg, entire foot, entire anterior lower leg
think about these areas if the sciatic nerve was injured
Where does the lateral femoral cutaneous nerve get entrapped?
Why does this happen?
under the inguinal ligament
tight clothing - the Britney spears!
obesity/weight gain
pregnancy
local trauma
diabetes
What is the result of entrapment of the lateral femoral cutaneous nerve?
paresthesia and/or decreased sensation
What is Meralgia paresthetica related to?
when the lateral femoral cutaneous nerve becomes irritated, burning tingling sensation on lateral thigh
Spinal levels of lateral cutaneous femoral nerve
L2 L3
Femoral nerve entrapment sites
Spinal levels?
beneath iliopsoas
inguinal ligament
femoral triangle
adductor canal
L2 L3 L4
Where is the obturator nerve commonly injured? What motions/sensory areas would this affect?
injury as it passes through the obturator canal - covered by the obturator membrane in the obturator foramen
anterior hip dislocation or prostate surgery
results in difficult adducting and decreased sensation of upper medial thigh
L2 L3 L4
Superior Gluteal Nerve entrapment (location), what does it cause (symptoms)?
caused by piriformis muscle compression
achy-type claudication buttock pain, tender to palpation and WADDLING gait (trendelenburg)
Why does entrapment of the superior gluteal nerve cause waddling gait/trendelenburg?
because SG nerve innervated glute medius which stabilizes the pelvis with SL stance
so when the right leg comes up, you lean to the right bc you left glute can stabilize you well
What nerve is most often injured in the lower limb? Why?
Common fibular - runs very superficial around head of fibula
How can the common fibular nerve be injured?
direct trauma (its very superficial)
severed during fracture of the fibular neck
severely stretched when the knee joint is injured or dislocated
What would result from injuries to the common fibular nerve? Think about the muscles it innervates
common fibular nerve - flaccid paralysis of all muscles in the anterior and lateral compartments of the leg
loss of dorsiflexion, no eccentric control and makes a clop sound when walking, steppage gait
loss of sensation to anteriolateral lower leg and b/w first two toes
*if it was just the superficial branch injured, would you have drop foot? NO
What gait consequences will the patient perform to compensate from drop foot?
they will have to lift their leg higher or foot will drag, they will lean onto stronger side
How can the deep fibular nerve be entrapped? Where would you feel pain?
excessive use of the muscles supplied by the deep fibular nerve (during skiing, running etc) may result in muscle injury and edema to anterior compartment
*nerve is deep to inferior extensor retinaculum and EHB in dorsum of foot
also occur in soccer players - can get “ski boot syndrome” with tight shoes
pain in dorsum of foot and between 1st and 2nd toes
If you are wearing tight shoes, and compress your deep fibular nerve, an injury may occur. Would this affect your tibialis anterior?
No, because it would already be innervated before the top of the foot
location of entrapment matters!
How is the superficial fibular nerve commonly entrapped?
chronic ankle sprains may produce recurrent stretching of the superficial fibular nerve which may cause pain on lateral side of leg and dorsum of foot and ankle
inversion would stretch lateral features
What are symptoms of pudendal nerve entrapment?
chronic, severely disabling neuropathic pain, pudendal neuralgia, pain with sitting
What two ligaments does the pudendal nerve exit between? What space does it go through after?
sacrospinous and sacrotuberous
transverses through pudendal canal formed by the obturator fascia and ST ligament
What is a popliteal cyst?
fluid filled growth behind the knee, continuation of the bursa
complication of chronic knee joint effusion
common in children but can grow large in adults
How is the tibial nerve injured at the knee?
What motion or sensory would you lose?
Ca be severed during a posterior dislocation of the knee (tibia on femur)
Lose plantarflexion and flexion of toes, sensation on lateral ankle, heel and bottom of foot
Besides the knee, where is another problem site for the tibial nerve? Symptoms?
Tarsal tunnel - runs posterior to medial mall, deep to flexor reticulum
Causes edmea and tightness, synovial shealths tightness, heal pain, foot burning and weakness
Sural nerve entrapment sites
fibrous arcade at lower lateral leg
baker cyst (popliteal)
gastroc strains
fracture of 5th metatarsal
Sural nerve entrapment symptoms
achy posterolateral calf pain
neuropathic pain in sural nerve distribution
How is sural nerve entrapment tested for?
positive tinels - tapping the location of entrapment to look for pain
hypoaesthesia - reduced sensation
provocation (increasing tension on the nerve) by ankle DF and inversion to see if symptoms arise
diagnostic injection
consider imaging, EDT
What are the three branches of the tibial nerve
calcaneal branch
medial plantar nerve
lateral plantar nerve
What foot position is related to tarsal tunnel syndrome?
overpronation
also causes pes planus - flat feet
Describe what is meant by “double crush” of the tibial nerve
you can have irritation at spinal levels and get low back pain (sciatic parent structure) and irritation of tibial nerve at tarsal tunnel causing toe weakness
What is Baxters Neuropathy
What area of the body would be affected?
Medial nerve entrapment - compressive irritation as it passes deep to the flexor retinaculum or curves deep to abductor hallucis
medial side of sole and foot and in navicular tuberosity region
What foot position causes medial plantar entrapment/baxters neuropathy?
eversion
common in runners - joggers foot (footwear important)
Describe pronation and what joints participate
normal rotation of front of foot laterally relative to back of the foot
ankle DF, Hindfoot eversion, forefoot abduction (all three planes of motion)
talocrural joint
subtalar joint (hindfoot)
transtarsal joints
tarsometatarsal
Describe supination and what joints participate
normal rotating of the front of foot medially relative to the back
ankle PF
hindfoot inversion
forefoot adduction
talocrural joint
subtalat joint
transtarsal joints
tarsometatarsal
What happens to the medal foot arch in supination vs pronation?
pronation - medial arch lowers
supination - medial arch rises
if you do the movements you can feel your arch get bigger and smaller
A high ankle sprain is what kind of sprain? What structures are involved?
Synesdmotic ankle sprain
Tibiofibular syndesmosis
Interosseos membrane
Anterior tibiofibular ligament
What foot movements are common mechanisms for a high ankle sprain?
External rotation and DF
Where does a chophart injury occur?
dislocation of midtarsal joints of foot, transverse tarsal joint
often fractures of clacaneus, cuboid and navicular bone with it
What is Charcot Marie tooth?
Neurological disorder - hereditaty sensory and motor neuropathy
Lack of muscle, high arches (pes CAVUS) or low arch (pes PLANUS), claw toes
What is mallet toe, what causes it?
flexion of the distal phalanx of a long toe
ill fitting shoes, arthritis, trauma, neuromuscular and or metabolic disease
What is hammer toe? What can form with it?
Proximal phalanx hyperextended at MTP
middle phalanx flexed at PIP
DIP hyperextended
callus can form on PIP
What muscles could be weak that result in hammer toe?
Lumbricals - they cause MTP flexion and PIP extension (opposite of hammer toe)
and extrinsic muscles that affect toes
claw toes
hyperextended MTP and flexion of DIP of lateral 4 toes
What is morton’s toe? What might it affect?
2nd toe extends more distal than the other digits
from metatarsal origin
can affect your gait and shoe style
(10-30% of people)
Describe what mortons neuroma is and what nerve is affected
What 2 toes are most affected?
Morton’s neuroma is a benign growth (often a thickening or fibrosis) of nerve tissue, typically occurring in the intermetatarsal spaces of the foot. It most commonly affects the common digital nerve (from media, or plantar nerves from tibial n) between the third and fourth toes (interdigital)
caused by nerve irritation, which often results from repetitive stress or compression on the nerve, leading to the formation of the neuroma (a benign tumor-like thickening of the nerve)
cause - improper shoe type!
Joggers foot
Aching burning numbness and tingling on medial side of sole of foot and navicular tuberosity region
Constant eversion
Medial nerve entrapment / baxters
