Popliteal Fossa
POPLITEAL FOSSA
- It is a diamond-shaped space, behind the knee joint.
BOUNDARIES :-
Above &
Medially -
- Semitendinosus & semimembranosus
Above &
Laterally -
- Tendon of biceps femoris
Below &
Medially -
- Medial head of gastrocnemius
Below & Laterally
-
- Plantaris & Lateral head of gastrocnemius
Floor - It is formed from above downwards by-
- Popliteal surface of femur
- Oblique popliteal ligament
- Posterior part of upper end of tibia
- Fascia covering the popliteus muscle
- Floor is pierced by middle genicular vessels & nerve, genicular branch of obturator nerve.
Roof -
- Skin, superficial fascia, popliteal fascia
- Roof is pierced b small saphenous vein, posterior femoral cutaneous nerve.
CONTENTS :-
- Popliteal Artery
- Popliteal Vein
- Termination of Small Saphenous Vein
- Tibial Nerve
- Common Peroneal Nerve
- Posterior Femoral Cutaneous Nerve
- Genicular Branch of Obturator Nerve
- Popliteal Lymph Nodes
- Pad of Fat
POPLITEAL ARTERY :-
Course -
Extends as a continuation of femoral artery
from 5th osseo-aponeurotic opening of adductor magnus
Passes obliquely downward & laterally in close
contact with the floor of popliteal fossa
Ends at the lower border of popliteus muscle by
dividing into anterior & posterior tibial arteries.
Relations -
Deeply-
- Popliteal surface of femur
- Oblique popliteal ligament
- Fascia covering popliteus
Superficially-
- Crossed by popliteal vein & tibial nerve form lateral to medial side.
Laterally-
- In the upper part- Biceps femoris, tibial nerve & popliteal vein.
- In the lower part- Plantaris, Lateral head of gastrocnemius.
Medially-
- In the upper part- Semimembranosus
- In the lower part- Popliteal vein, tibial nerve & medial head of gastrocnemius.
Variations in
Termination -
- It may terminate at the upper border of popliteus.
- It may terminate by dividing into anterior tibial, posterior tibial & peroneal arteries at the lower border of popliteus.
Branches -
Cutaneous
branches-
- They pierce the roof & supply the skin of the back of leg.
Muscular
branches-
- They supply the adjacent muscles.
Articular branches-
- They are 5 in number.
- Superior medial genicular artery
- Superior lateral genicular artery
- Inferior medial genicular artery
- Inferior lateral genicular artery
- Middle genicular artery
- They supply the knee joint by forming genicular anastomosis around the knee.
Genicular
Anastomosis -
At the medial
femoral condyle-
- Superior medial
genicualr artery
anastomose with inferior medial genicular artery & descending genicular
branch of femoral artery.
At the lateral
femoral condyle-
- Superior
lateral genicular artery
anastomose with inferior lateral genicular artery & descending branch of
lateral circumflex femoral artery.
At the medial
tibial condyle-
- Inferior medial
genicular artery
anastomose with superior medial genicular artery & saphenous branch of
descending genicular artery.
At the lateral
tibial condyle-
- Inferior lateral genicular artery anastomose with superior lateral genicular artery, anterior & posterior tibial recurrent branches & circumflex fibular branch.
POPITEAL VEIN :-
- It accompanies the artery in the fossa.
- Crosses the artery superficially from lateral to medial side.
- Small saphenous vein
- Veins accompanying the branches of popliteal artery.
TIBIAL NERVE :-
- It is the larger terminal branch of sciatic nerve.
Root Value -
- Ventral divisions of ventral rami of L4 -S3.
Course -
It passes vertically from upper to lower angles of the
fossa
Crosses the
popliteal vessels superficially from lateral to medial side
Branches -
Muscular
branches-
- They supply both the heads of gastrocnemius, plantaris, soleus & popliteus.
- Branch to popliteus also supplies tibialis posterior.
- Lateral side of the nerve is danger, as most of
the muscular branches arise from its lateral side.
Articular
branches-
- They supply the knee joint.
- They are superior, inferior & middle genicular nerves.
Cutaneous
branch-
- Sural nerve- It joins with sural communicating nerve
after piercing the deep fascia of leg.
Vascular
branches-
- They convey post-ganglionic sympathetic fibres from T10-L2 spinal cord segments.
- They supply popliteal vessels.
COMMON PERONEAL
NERVE :-
- It is the smaller terminal branch of sciatic nerve.
Root Value -
- Dorsal divisions of ventral rami of L4-S2.
Course -
It appears in the fossa beneath the long head of
biceps femoris
Slopes downward & laterally along the medial
margin of biceps tendon
At the lateral angle of popliteal fossa it crosses
superficial to the plantaris & lateral head of gastrocnemius
Reaches back of head of fibula where it can be rolled
against the bone
It curves forward on to the lateral side of neck of
fibula
Deep to peroneus longus it divides into deep &
superficial peroneal nerves.
Branches -
Cutaneous
branches-
- Sural
communicating nerve- joins
with sural nerve.
- Lateral sural
nerve- supplies the skin
of upper part of lateral side of the leg.
- Superior & inferior lateral genicular nerves- Supply the knee joint.
- Recurrent genicular nerve- Supplies the antero-lateral part of capsule of knee joint & superior tibio-fibular joint.
POSTERIOR FEMORAL
CUTANEOUS NERVE :-
- It pierces the popliteal fascia in the middle of the fossa & become cutaneous.
- It supplies the skin over the popliteal fossa up to the middle of back of leg.
GENICULAR BRANCH
OF OBTURATOR NERVE :-
- It is the continuation of posterior division of obturator nerve.
- Pierces the oblique popliteal ligament & supplies the capsule of knee joint.
POPLITEAL LYMPH
NODES :-
- These are usually 6 in number.
- One is situated beneath the popliteal fascia at
the junction of small saphenous vein & popliteal vein, it drains the
lymph from lateral side of foot & back of leg.
- Few nodes are situated on both sides of popliteal
vessels, they drain the lymph from anterior & posterior tibial vessels.
- Few nodes intervene between the knee joint &
popliteal artery, they drain the lymph from knee joint.
- Efferents from popliteal nodes drain into deep inguinal lymph nodes.
APPLIED ASPECTS :-
Popliteal
Artery Aneurysm :-
- It is the abnormal dilatation of popliteal artery.
- Popliteal artery is more prone for aneurysm than other arteries in the body.
Bakerโs Cyst /
Popliteal Cyst :-
- A fluid filled cyst on the back of knee joint.
- Cause- Pathological injury to cartilages of knee
joint.
Injury to
Tibial Nerve :-
Symptoms-
- Motor paralysis
of gastrocnemius, soleus,
popliteus, tibialis posterior, flexor digitorum longus, flexor hallucis longus
& all intrinsic muscles of the foot except extensor digitorum brevis.
- Foot is dorsiflexed & everted.
- Sensory loss on the entire sole of foot & dorsal
aspect of terminal phalanges, may lead to trophic ulcers.
Injury to
Common Peroneal Nerve :-
Cause- Fracture of neck of fibula.
Symptoms-
- Motor paralysis
of peroneal & extensor
compartments of leg results in Foot drop.
- Foot is
plantarflexed & inverted.
- Sensory loss on the dorsum of foot & lower part of
front of leg.