Lumbosacral plexus Flashcards
Wilson
Which anterior rami supply the Lumbosacral plexus?
Lumbar Plexus (L1-L4)
Sacral Plexus (L4-S4)
Limb buds develop from two myotomic groups.
What are they?
dorsal muscle mass
Ventral muscle mass
Dorsal muscle mass of limb development give rise to which muscles?
Extensors
Ventral muscle mass give rise to which muscles?
Flexors
The mass of cells between the dorsal and ventral muscle mass is a precursor for?
Precursor for bones and tedons
Anterior division of the lumbar and sacral plexus procide innervation for?
Flexors
The posterior division of the lumbar and sacral plexi provide innervation for?
Extensors
The femoral n. receives ventral primary rami from which divisions?
Posterior divisions
It will supply extensor muscles
The obturator n. receive ventral primary rami from which divisions?
anterior divisions
It will supply flexor muscles
Common fibular n. receive ventral primary rami from which divisions?
Posterior divisions
It will supply extensors
Tibial n. receive ventral primary rami from which divisions?
anterior division
What are the branches of the Lumbar plexus (L1-L4)?
Iliohypogastric n. (L1)
Ilioinguinal n. (L1)
genitofemoral n. (L1 and L2)
Lateral femoral cutaneous n. ( L2 and L3) - posterior division
Femoral nerve, which is mixed (L2, L3, and L4) - posterior division
Obturator n., which is mixed ( L2, L3, and L4) - anterior division
Lumbosacral trunk, to sacral plexus (L4 and L5)
What is the different about the lower limb rotation during fetal development compared to the upper limb
Lower limb rotates medially, whereas the upper limb rotate laterally
EXTENSORS - Anterior portion of lower limb
FLEXORS - posterior portion of lower limb
(THIS IS OPPOSITE COMPARED TO UPPER LIMB)
Posterior and anterior division of the lumbar plexus innervate which compartment of the thigh?
Posterior division - anterior compartment of thigh
Anterior division - medial compartment of thigh
Femoral n. innervates which compartment of the thigh?
Anterior compartment of the thigh
The obturator n. innervates which compartment of the thigh?
Medial compartment of the thigh
The posterior division of the sacral plexus come from which ventral primary rami?
L4-S2
The anterior divisions of the sacral plexus come from which ventral primary rami?
L4-S3
Superior gluteal n. recieves nerve branches from which ventral primary rami?
Posterior division of L4-S1
The inferior gluteal n. recieves nerve fibers from which ventral primary rami?
Posterior division of L5-S2
The nerve to piriformis recieves nerve fibers from which ventral primary rami?
Posterior divison of S1 and S2
Which two nerves come together to form the sciatic nerve?
Common fibular nerve (Posterior division L4-S2)
Tibial nerve (Anterior division L4-S3)
The nerve to obturator internus and superior gemellus recieves nerve fibers from which ventral primary rami?
Anterior division of L5 + S1
The nerve to quadratus femoris and inferior gemellu recieves nerve fibers from which ventral primary rami?
Anterior division of L4 + L5
What is the course of the sciatic nerve?
leaves the pelvis -> gluteal region via greater sciatic foramen -> emerges inferiorly to the piriformis muscle and descends in an inferolateral direction.
As the nerve moves through the gluteal region, it crosses the posterior surface of the superior gemellus, obturator internus, inferior gemellus and quadratus femoris muscles. It then enters the posterior thigh by passing deep to the long head of the biceps femoris.
Within the posterior thigh, the nerve gives rise to branches to the hamstring muscles and adductor magnus. When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the tibial and common fibular nerves.
Why is the piriformis an important landmark in the body?
The sciatic nerve emerges into the gluteal inferior to the piriformis
Damage/inflammation of the piriformis can cause Sciatica
The tibial division of the sciatic nerve innervates which part of the thigh?
Posterior compartment of the thigh
(Hamstrings)
What is the exception of the hamstring muscles and their nerve innervation?
All muscles of the hamstring are innervated by the tibial division of the sciatic nerve except the short head of biscep, which is innervated by the common fibular division of sciatic nerve.
Where does the sciatic nerve divided into the common fibular and tibial nerves?
In the popliteal fossa
Tibial nerve goes straight down and the common fibular nerve curves laterally at the neck of the fibula to go to the anterior compartment.
The common fibular nerver goes anteriorly at the neck of the femur and spilts into two branches. What are they?
Deep fibular n.
Superficial fibular n.
The deep fibular nerve innervates where?
The anterior compartment of the leg (Extensors)
The superficial fibular nerve innervates where?
Lateral compartment of leg
(Fibularis longus and brevis)
After innervating these muscles it becomes a cutaneous nerve for the lateral side of the leg
The tibial nerve innervates where?
Posterior compartment of the leg
What does the tibial nerve cross before it terminates in the foot?
Medial malleolus
What are the two terminal branches of the tibial nerve and what do they supply?
Medial Plantar nerve
Supplies medial compartment of the foot
Lateral plantar nerve
(supplies lateral, interosseus, and central compartment of foot)
What is an exception to innervation of the central compartment of the foot?
The flexor digitorium brevis and the 1st lumbrical are innervated by the medial plantar nerves
Map of cutaneous innervation of the Lower limb
What does the femoral nerve become after crossing the knee medially?
The Saphenous nerve
Decreased sensation in a single dermatome is caused by what?
Lesion of the dorsal root and/or the spinal nerve
A lesion of a ventral or dorsal primary ramus results in what?
Decreased sensation restricted to a portion of a dermatome
(Notice in the image that only L3 ventral dermatome is red so there is a lesion in the Ventral primary rami at L3)
Lesions proximal to a plexus produces what?
Sensory Loss in a single dermatome
Example damage to root L3 which cause loss of L3 dermatome
What does it mean if sensory loss involves 2 or more dermatomes?
This suggest lesion of a plexus of its branches
Example: damage to L2, L3, and L4 dermatome = Femoral nerve cutaneous branch is lesioned
The main blood supply of the lower limb arises from where?
external Iliac artery
When does hte external iliac artery become the femoral artery?
When it passes beneath the inguinal ligament
What does the abdominal aorta terminarte as?
The abdominal aorta terminates as the common iliac which divides into the external and internal iliacsarteries
What are the characterisitcs of the femoral artery?
1) bissects inguinal ligament
2) very superficial
3) lies anterior to femoral head
Which artery can be compressed against femoral head to control hemorrhage?
Femoral a.
What are the good locations for taking pulse in the lower limb?
- Femoral artery (also a place for catherization)
- Popliteal artery (deep palpation)
- Dorsalis pedis artery (its right under the skin)
- Tibialis posterior (ankle)
Pulse should be taken bilaterally
A cathater in the femoral artery or vein enters what side of the heart?
Cathater in femoral vein will enter right side of heard.
Cathater in femoral artery will enter left side of the heart
What is the path of the femoral artery?
What is the major branch of the femoral artery?
Deep femoral artery
(comes off the posterior portion of the femoral artery and supplies anterior muscles)
What are the branches of the deep femoral artery?
Medial femoral circumflex artery
latral femoral circumflex artery
Perforating arteries (1-4)
Which arterires are the main blood supply to the head of the femur?
Medial and latral femoral circumflex arteries
What is the cruciate anastomosis?
It is a important collateral routes if femoral artery is occluded
Located at he level of the lesser trochanter
Visual of cruciate anastamosis
(Transverse vs vertical limb)
What is the popliteal artery?
The popliteal artery is a continuation of the femoral after it traverses the adductor hiatus.
The branches that anastamose around the knee come from which artery?
Popliteal artery
When the popliteal artery terminates at the inferior border of the popliteus what does it give rise to?
Anterior tibial artery
Posterior tibial artery
What is the course of the anterior tibial artery?
Pierces and runs anteriror on the interosseous membrane
(Anterior interosseous artery)
Then it terminates at the malleoili as the dorsalis pedis artery
The anterior tibial artery supplies what?
Anterior compartement of the leg
Dorsalis pedis artery is a continuation of which artery?
anterior tibial artery
The posterior tibial artery supplies what?
The posterior compartement of the leg
What is a major branch of the posterior tubial artery?
The fibular artery
This artery supplies the deep compartments of the posterior leg and often runs in the flexor hallucis longus
What is the course of posterior tibial artery?
Runs inferiorly on the posterior leg and crosses the ankle posterior to the medial malleolus, between the tendons of flexor digitorium and hallucis longi. It then terminate in the sole of the foot.
What is the tarsal tunnel?
It is a flexor retinaculum that protects the tibials posterior artery. It is bordered by the Flexor hallucis, tibialis anterior, and flexor digitorium longus (Tom, Dick, and Harry)
Lateral plantar artery and medial plantar artery are terminal branches of which artery?
Posterior tibial artery
What do the plantar arterires run between?
between the 1st two muscle layers of the foot
A weak pulse on one side is an indication of what?
It is a sign of Peripheral arterial Disease (PAD) or obstruction
This can be caused by atherosclerosis
What Excerxise-Induced Claudicaiton?
Build up of fatty substance in the wall of an artery that can lead to tissue ischemia distal to a vascular lesion.
This is intermitent
Can cause: Muscle weakness, pain (or tingling), and/or crampin may result, especially after exercise
What is the organization of veins in the lower limb?
They are organized into three groups
Deep veins
Superficial veins
Perforating veins
This type of vein runs with artries supplying the compartments. They share their names with arterirs.
Deep veins
This type of vein runs beneath the skin without acoompanying artrires. They are important for thermal regulation.
Superficial veins
What are the two major superficial veins of the lower limb?
Great Saphenous ( drains into femoral v.) - begins at the dorsum of the foot as an arch
Lesser Saphenous ( drains into popliteal v.) - originate posterior to lateral malleolus
The greater saphenous veins runs with what?
The greater saphenous nerve
The lesser saphenous vein runs with what?
Sural n.
What is the purpose of perforating veins?
They connect superficial veins to deep veins (not the other way around)
They contain valves
What give rise to the perforating veins?
The vena comitantes, these are veins that surround arteries. When the arterires expand it pushes the blood in the vein up towards the heart. The valves prevent back flow
What are the mechanism to direct blood from the foot to the heart?
Mechanism 1: Veins have values which allow only one-way movement of blood towards the heart
Mechanism 2: The energy of the arterial pulse is transferred into the venae comitantes generating movement of blood.
Mechanism 3: Deep veins, such as the fibular vein, run with or in muscles. Contraction and relaxation of muscles squeezes the vein and pumps blood towards the heart (this occurs in venous calf pump)
Mechanism 4: Perforating veins shunt blood from the superficial veins towards the deep veins where blood can be pump back towards the heart.
Why is the center of gravity anterior to the rotational axis of the ankles which produces a tendency to sway forward?
- Readiness for flight/fight
- Calf-pump
What are varicose veins?
Diseased or damaged valves in the perforating veins allow blood to pool in the superficial veins
i.e. where there is no pumping
