W29-L1: Nerves of the lower leg Flashcards
Where is the lumbar plexus?
Within psoas major
What makes up the lumbar plexus?
Ventral rami of L1-4
What nerves arise from the lateral border of psoas major?
-Illioinguinal and iliohypogastric nerves (onto quadratus lumborum)
-lateral cutaneous nerve of thigh
-femoral nerve
(both onto illiacus)
What rami give rise to Illioinguinal and iliohypogastric nerves ?
L1
What rami give rise to the lateral cutaneous nerve of thigh?
L2,3
What rami gives rise to femoral nerve?
L2,3,4
What do Illioinguinal and iliohypogastric supply?
cutaneous to inguinal area and motor to arching fibres of internal fibres and transverse oblique
What does damage to Illioinguinal and iliohypogastric mean?
they can’t contract and bring the roof of the inguinal canal and prevent hernias
What nerve arises onto the anterior surface of psoas major?
Genitofemoral nerve (L1,2)
What nerve arises onto the medial surface of psoas major?
Obturator nerve (L2,3,4)
Where does lateral cutaneous nerve of thigh run?
runs into anterior compartment of thigh and tucks in next to ASIS beneath inguinal ligament
What is the role of the femoral nerve?
motor to anterior compartment of the thigh and sensory to anteromedial thigh and medial side of knee, leg and ankle
What are the two branches of the gentiofemoral nerve?
- L1 is femoral branch of supplies area of skin immediately beneath inguinal ligament
- L2 is genital branch, supplies the spermatic cord
Where is the sacral plexus formed?
Piriformis from S1-4 and contribution from lumbar, L4 whats left over and doesnt contribute to lumbar plexus and L5
How does the femoral nerve supplies each muscle?
breaks into key terminal branches for each muscle it supplies
Where is the obturator cutaneous supply?
Medial side just superior to the knee
What is the obturator nerve motor supply?
Adductor muscles
How does the obturator run in the leg?
splits into anterior and posterior branches, one each side of adductor brevis (in front btwn it and longus and it and magnus), as well as a branch off to gracilis
What supplies the pelvis peritoneum and where is pain referred to as a consequence?
Obturator, medial thigh above the knee
What makes up the sciatic nerve?
Tibial and common fibular components
How does the sciatic nerve run?
exits pelvis via greater sciatic foramen, emerges beneath piriformis posterior to hip joint, descends on the posterior thigh and divides at the apex of popliteal fossa
What does the sciatic nerve supply before it divides?
Hamstrings (except for short head of biceps-fibular)
How can you damage the sciatic nerve?
Posterior dislocation of the hip
What nerve does gluteas medius and maximus?
Superior gluteal
What nerve does the gluteus maximus?
Inferior gluteal
What is the path of the tibial nerve?
Vertical descent through popliteal fossa
beneath fibrous arch of Soleus, descends on Tibialis Posterior in calf, posterior to medial malleolus, sole of foot then becomes medial and lateral plantar nerves
What is motor supply of the tibial nerve?
Posterior leg and sole of foot
What is the sensory supply of the tibial nerve?
posterior leg (sural nerve) and sole of foot (medial calcaneal, medial and lateral plantar nerves)
What is the course of the common fibular nerve?
medial to biceps then superficial to lateral headof Gastrocnemius, winds round the neck of the fibula then Fibularis Longus, terminal branches
What does the common fibular nerve do?
Sensory to upper lateral leg via lateral sural cutaneous nerve, terminal divisions provide motor
What does the deep fibular do?
Motor to anterior compartment of leg and EDB and sensory to 1st toe cleft
What does the superficial fibular do?
motor to lateral compartment of leg and sensory to lower lateral leg and
dorsum of foot
What does a fracture to the neck of the fibular cause?
Damages common fibular nerve and so get a dropped foot (can’t dorsiflex or evert)
What do you need to know the dermatomes?
map segmental supply to show damage back at the level of the plexus rather than at peripheral nerve
