Week 4 - Lower limb + nerves Flashcards
What are the roots of the lumbosacral plexus made of?
Ventral rami of the spinal nerve:
Lumbar - L2, L3 and 1/2 L4
Sacral - 1/2 L4, L5, S1, S2, S3
Where is the lumbar plexus?
Within the psoas muscle
Where do branches of the lumbar plexus emerge? What are the nerves that emerge?
From psoas major
Femoral nerve
Obturator nerve
Lateral cutaneous nerve
Which roots supply fibres to femoral?
Anterior compartment of the thigh
L2-4
Which roots supply fibres to obturator?
The medial compartment i.e. adductors
L2-3
What does the femoral nerve supply?
The whole anterior compartment of the leg:
Emerges lateral to psoas, supplies:
iliacus, then passes under inguinal ligament and supplies the quadriceps muscles and the sartorius.
Also supplies the cutaneous area
What does the obturator nerve supply?
Medial compartment of thigh:
After emerging medial to psoas, moves along pelvic wall and supplies the three adductors, gracilis and obturator externus
Where is the cutaneous area supplied by the femoral nerve?
Along the front of the thigh - the cutaneous femoral nerve splits into the intermediate and medial cuteneous nerves
Also has the saphenous nerve as one of the femoral nerves cutaneous branches
What does the saphenous nerve supply?
The area medial to the knee, leg and ankle, right down to the instep
Where do all nerves of the sacral plexus exit from?
The greater sciatic foramen
What are the four main nerves from the sacral plexus?
Inferior and superior gluteal nerves
Sciatic nerve
Posterior cutaneous nerve of the thigh
Describe the sciatic nerve
Emerges below the piriformis, and is essentially two nerves covered by a sheath
Branches into the tibial nerve (L4-S3) and the common fibular nerve (L4-S2)
This branching usually occurs 2/3 down the thigh
What general areas does the tibial nerve innervate?
Posterior compartment of the leg, and the foot –> plantar aspect
What general area does the common fibular nerve innervate?
The anterior and lateral compartments of the leg, and the extensors Digitorum/hallucis brevis
Describe the tibial nerves route through the thigh/leg
Midline course through the thigh, passes through the popliteal fossa
Runs deep to soleus
Crosses ankle medially
What are the specific muscles/areas the tibial nerve innervates?
The flexor compartments of the thigh and leg:
- Hamstrings
- Gastrocnemius-soleus, the long flexors of the toes, tibialis posterior and popliteus
- Muscles and skin of the medial and lateral plantar of the sole of the foot
Where does the inferior gluteal nerve go?
To gluteus maximus
WHat is the course of the fibular nerve down the thigh/leg?
Has a variable beginning
Courses laterally and then crosses the neck of the fibula
Then divides into superficial and deep ficular nerve
What does the superficial fibular nerve innervate?
- The lateral compartment of the leg (fibularis longus & fibularis brevis)
- Skin of the anterolateral aspect of the leg
- Dorsum of the foot - except web of big toe
What does the deep fibular nerve innervate?
- The anterior compartment of the leg, and the extensor breves of the foot
- The skin of the first web of the toes
What are the four arteries of the lower limbs?
Femoral (main)
Gluteal arteries
Obturator arteries
Profunda femoris artery
What is the course of the femoral artery?
- Down the front of the thigh, through the adductor magnus
- Turns into popliteal artery, which divides into anterior and posterior tibial arteries
- The anterior tibial artery turns into dorsalis pedis, the dorsal artery of the foot
- Posterior tibial artery goes to the sole of the foot
What is femoris profunda and what does it do?
It is the deep artery of the thigh, found high in the thigh
Supplies the hamstring muscles
What supplies blood to the head of the femur?
The trochanteric anastomosis
