1. Knee joint
and
Muscles of Leg
Dr. Sama ul Haque

2. Objectives
Name and identify the bony features of the tibia and fibula.
Know the type and formation of knee joint.
Explain the stability factors of the knee joint.
Identify the muscles that act at the knee joint.
Know the locking and unlocking mechanism of the knee joint.
Understand the functions of the Popliteus and Iliotiabial tract.

3. Objectives
Identify the neurovasculature behind the knee (popliteal fossa) and in the leg.
Enlist the contents of the muscular compartments of the leg.
Identify the muscles of the leg in terms of their origin, insertion, nerve supply and actions.
Enlist the muscles causing plantar flexion, dorsiflexion, eversion, inversion, flexion of digits and extension of digits. 

4. Femur

5. Tibia and Fibula Anterior View

6. Tibia and Fibula Posterior View

7. Anterior. Patella articulates with the femur.
Sagittal section thru knee
Tibia:
Condyles
Tibial tuberosity
Tibia and fibula
are united by an
interosseous
Membrane.
[Proximal and
distal tibio-fibular
joints]
The fibula is not part of the knee joint.
Head of
Fibula
Patella articulates
with the femur.
interosseous membrane

8. During the entire range of knee flexion, the patella only articulates
with the femur.
KNEE.
Modified hinge jt.
-flexion / extension
(some rotation)

9. Superior view of tibial surface.
Tibial Condyles
Tibial Condyles
Medial and lateral articular
surfaces, separated by an
intercondylar eminence.
Medial and lateral Meniscii:
Fibrocartilage shock-absorbers
that sit on surface of tibial
condyles and deepen the
articular surface.
Anterior and posterior
Cruciate ligaments (ACL, PCL):
-hold femur and tibia together
-stabilize knee joint
lateral articular surface
medial articular surface
intercondylar eminence
lateral meniscus
PCL
medial meniscus
ACL

10. tibia at their ends (horns).
Medial and lateral
femoral condyles
have same shape as
corresponding
tibial condyles:
Medial – elongated
Lateral – circular
Meniscii:
Each is attached to
tibia at their ends (horns).
Femur

11. Anterior Cruciate Ligament:
- Weaker of the two, slack when knee is flexed & tightens in extension.
- Prevents hyperextension.
Posterior Cruciate Ligament:
- Tightens during flexion of knee joint

13. Pes anserinus: Common insertion of Sartorius, gracilis, semitendinosus
Stabilization of the
medial knee:
Tibial collateral
ligament.
A flat strap which
is attached to the
medial aspect of
tibia and medial
femoral epicondyle.
Its deeper fibres are
attached to the
medial meniscus.
tibial collateral ligament
Joint capsule
Retinacular
fibres
Pes anserinus: Common insertion of
Sartorius, gracilis, semitendinosus

14. Fibular collateral ligament
Stabilization of the
lateral knee:
Fibular collateral ligament
- a cord which is attached to the
head of the fibula and the lateral epicondyle of the femur.
*Its deep fibers are
not attached to the
meniscus.
Ilio-tibial band
fibular collateral ligament
Biceps femoris
Head of fibula

15. Important details for the Knee
Remember the 3 C’s:
-cartilage
-cruciates
-collaterals
Unhappy triad - common associated injury to:
ACL (anterior cruciate ligament)
MCL (Medial / tibial collateral ligament)
medial meniscus

16. Anterior knee in extension
Fibrous capsule of the
KNEE (anterior):
Stabilized by:
Extensor Retinacula
- Derived from insertions
of vastus lateralis and
vastis medialis into patella
and into sides of patellar
ligament.
Vastus
lateralis
Vastus medialis
extensor retinacula
Patellar
Ligament

17. Posterior knee in extension
Fibrous capsule of the
KNEE (posterior):
Thickened by ligaments:
-Arcuate popliteal ligament
(arching over popliteus muscle)
-Oblique popliteal ligament
(from tendon of insertion of
semimembranosus m.)
arcuate popliteal ligament
Tendon of
Semimembranosus
oblique popliteal ligament
Popliteus

18. Bursae of Knee Joint: Sagittal section shows: - Suprapatellar bursa
(extension of synovium
under tendon of
quadriceps femoris)
Subcutaneous bursae:
- Prepatellar,
- Infrapatellar (2):
(superficial & deep to
patellar ligament).
suprapatellar bursa
prepatellar bursa
infrapatellar bursae

19. Popliteal Fossa Popliteal fossa Diamond-shaped region
Posterior to knee
-semimembranosus / semitendinosus
-biceps femoris
-medial & lateral heads
of gastrocnemius.
Contents:
-popliteal vessels (from
femoral vessels)
-Tibial and Common
fibular (peroneal)
divisions of the sciatic
nerve.
Superficial:
-Small saphenous vein
draining into popliteal vein

20. Popliteal fossa

21. Muscles that act on the knee (modified hinge joint):
Main movement = flexion / extension
Flexion – mainly hamstrings (+ Sartorius, gracilis,
gastrocnemius)
Extension – mainly quadriceps (+ tensor fascia lata)
Rotation (possible when the knee is partially flexed,
or in the final stage of extension):
[here defined as rotation of tibia with respect to the femur]
Medial rotation – semitendinosus, semimembranosus
popliteus (extended knee)
Lateral rotation – biceps femoris

22. -held together by an interosseus membrane.
LEG.
Tibia and fibula:
-held together by an interosseus membrane.
-anterior border of tibia is subcutaneus
from the tibial condyles to its distal end.
[Shin]
-only the distal ¼ of fibula is subcutaneus
The distal ends are held together to form
the proximal articular surface of ankle.
Each ends subcutaneusly as a Malleolus
(medial – tibial and lateral - fibular).
Proximal and distal tibio-fibular joints
interosseous membrane
Medial
malleolus
Lateral
malleolus

23. Mid-shaft cross-section of leg:
Functional compartments.
Fascial compartments:
-anterior
-lateral
-posterior (superficial & deep)
anterior compartment (dorsiflexion, extension of digits)
deep posterior compartment
(plantarflexion)
lateral
Compartment
(eversion)
superficial posterior compartment (inversion, flexion of digits)

24. Plantarflexion / dorsiflexion: (ankle joint)
Flexion / extension: (digits)
Inversion / eversion: Complex twisting movement at transverse tarsal and subtalar joints. [inter-tarsal joints]

25. Anterior compartment of leg:
-tibialis anterior
-extensor hallucis longus
-extensor digitorum longus
(fibularis tertius)
All supplied by the deep
fibular (peroneal) nerve.
Hallux = big toe [hallucis]
Tendons are bound down by
extensor retinaculum as they
cross the ankle jt.
Function: -dorsiflexion (ankle)
-extension (digits)
-inversion
tibialis
anterior
extensor digitorum longus
extensor hallucis longus
extensor
retinaculum

26. DROP FOOT?????? Common Fibular n. Deep dissection Anterior view:
Note vulnerability of
common fibular nerve
as it winds around
the neck of fibula.
Deep Fibular n.
Superficial Fibular n.
Tibialis
Anterior
extensor digitorum longus
extensor hallucis longus
DROP FOOT??????

27. Lateral compartment of leg: - Fibularis (peroneus) longus
- Fibularis (peroneus) brevis
-both supplied by the superficial
fibular (peroneal) nerve.
Tendons are bound down by
fibular retinaculum as they
pass behind the lateral malleolus.
Functions:
- eversion
- plantarflexion
Fibularis
longus
Fibularis
brevis
Fibularis
tertius
peroneal
retinaculum
FIBULARIS=PERONEUS

28. Posterior compartment of leg:
Superficial
medial & lateral heads
of gastrocnemius
Insert into calcaneus (heel)
Function –plantar flexion
Innervated by Tibial nerve.
gastrocnemius
Achilles tendon
(calcaneal tendon)

29. Deeper dissection of superficial posterior compartment:
- medial & lateral heads
of gastrocnemius
- soleus
- (plantaris)
Common tendon:
Calcaneal (achilles) tendon
- insert into calcaneus (heel)
Function – plantar flexion
Innervated by Tibial nerve.
plantaris
soleus

30. Popliteus

31. Posterior (deep) compartment of leg:
-Tibialis posterior
-Flexor digitorum longus
-Flexor hallucis longus
Tendons are bound down by flexor retinaculum as they pass into foot behind the medial malleolus.
Functions: -plantarflexion
-flexion
-inversion
Innervated by Tibial nerve.
flexor digitorum longus
flexor hallucis longus
tibialis
posterior
flexor
retinaculum

32. Blood supply to the lower limb: Thigh: Femoral artery and branches:
(profunda, medial & lateral circumflex)
Behind knee:
Popliteal artery
Leg:
divides into
anterior and posterior tibial arteries.
to supply these compartments.
The posterior tibial artery gives off
the fibular (peroneal) artery
to supply the lateral compartment.
popliteal a.
posterior
tibial a.
anterior
tibial a.
fibular
artery

33. Cutaneus innervation of thigh and leg:
Anterior
Posterior
Anterior, lateral, medial thigh ( lumbar plexus).
- branches of femoral n.
- lateral femoral
cutaneous n.)
Posterior thigh
– from sacral plexus.
Anteromedial leg
– branch of femoral n.
(Saphenous nerve).
Posterolateral leg
– from Sciatic n.
(Sural nerve).
Anterior leg:
- From Sciatic n.
(Superficial fibular n.)
Post. femoral
cutaneous n.
saphenous
nerve
sural
nerve L4 S1

34. Superficial drainage of the lower limb
Varicose veins
Great Saphenous vein:
Drains into femoral vein in femoral triangle
Small Saphenous vein:
Drains into popliteal vein

35. Thank you