1. Leg Muscles

2. OBJECTIVES
Identify and name the contents of the muscular compartments of the leg.
Name the muscles causing plantar flexion, dorsiflexion, eversion, inversion, flexion of digits and extension of digits.
Identify the neurovasculature behind the knee and in the leg

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

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

6. Fascia of the Leg
The deep fascia surrounds the leg and attached to Anterior & Medial borders of Tibia.
Three Intermuscular Septa
Pass from the deep aspect of this fascia to be attached to :
Anterior border of fibula (Anterior fascial septum)
Posterior border of fibula (Posterior fascial septum)
Transverse intermuscular septum
Interosseous membrane:
A thin & strong membrane, that binds the interosseous borders of tibia & fibula. It binds the two bones and provides attachment for muscles.

7. Fascial Compartments of Leg
Together with the interosseus membrane, the septa divide the leg into
(3) Compartments : Anterior
2-Lateral (peroneal)
3-Posterior
Each has its own Muscles, Blood and Nerve supply.

8. Anterior Compartment MUSCLES NERVE SUPPLY TIBIALIS ANTERIOR DEEP
PERONEAL
Extensor Digitorum
Longus
PERONEUS TERTIUS
Extensor Hallucis
LONGUS

10. 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

11. Tibialis Anterior & Extensor Digitorum Longus
Muscle
Origin
Insertion
Action
Tibialis anterior
Lateral surface of shaft of tibia and interosseous membrane
Medial cuneiform and base of first metatarsal bone
Extends foot at ankle joint; Inverts foot at subtalar & transverse tarsal joints &
Holds up medial longitudinal arch of foot
Extensor digitorum longus
Anterior surface of shaft of fibula
Extensor expansion of lateral four toes
Extends toes; Extends foot at ankle joint

12. Peroneus Tertius, & Extensor Hallucis Longus
Muscle
Origin
Insertion
Action
Peroneus tertius
Anterior surface of shaft of fibula
Base of 5th metatarsal bone
1-Extends foot at ankle joint;
2-Everts foot at subtalar and transverse tarsal joints
Extensor hallucis longus
Anterior surface of shaft of fibula
Base of distal phalanx of great toe
Extends big toe, Extends foot at ankle joint;
Inverts foot at subtalar and transverse tarsal joints

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

14. Lateral Compartment of Leg
MUSCLES
NERVE
PERONEUS
LONGUS
Superficial Peroneal
BREVIS

15. Peroneus Longus Origin Lateral surface of shaft of fibula
Insertion
Action
Lateral surface of shaft of fibula
Base of first metatarsal and the medial cuneiform
Plantar flexes foot at ankle joint;
Everts foot at subtalar and transverse tarsal joints; Supports Lateral longitudinal & Transverse arches

16. Insertion Action Origin
Peroneus Brevis
Insertion Action Origin
Lateral surface of shaft of fibula
Base of fifth metatarsal bone
Plantar flexes foot at ankle joint;
Everts foot at subtalar and transverse tarsal joint; Supports Lateral longitudinal arch of foot

17. Peroneal Retinacula Superior peroneal retinaculum
Connects the lateral malleolus to calcaneum & holds the tendons of peroneus longus & brevis
Inferior peroneal retinaculum
Synovial Sheaths of Peroneal Longus & Brevis:
Tendons of peronei are surrounded by a single common tubular synovial sheath,
deep to inferior peroneal retinaculum, they have separate sheaths

18. Popliteal Fossa Diamond-shaped region Posterior to knee bounded:
Sup.Medially: semimembranosus / semitendinosus
Sup.Laterally:
-biceps femoris
Inferiorly:
-medial & lateral heads
of gastrocnemius.

20. Popliteal Fossa Contents: 2. Small saphenous vein 3. Tibial nerve.
1. Popliteal vessels
2. Small saphenous vein
3. Tibial nerve.
4. Common peroneal nerve.
5. Posterior cut. nerve of thigh.
6. Connective tissue & popliteal lymph nodes.

21. CONTENTS OF THE POSTERIOR FASCIAL COMPARTMENT OF THE LEG
The transverse intermuscular septum of the leg is a septum divides the muscles of the posterior compartment into superficial and deep groups.
Contents:
Superficial group of muscles
Deep group of muscles
Posterior tibial artery
Tibial nerve

23. SUPERFICIAL GROUP
Gastrocnemius 2. Plantaris Soleus

25. SUPERFICIAL GROUP Muscle Origin Insertion Nerve Action
Gastrocnemius
Lateral head from lateral condyle of femur & medial head from above medial condyle
Posterior surface of calcaneum via tendo calcaneus
Tibial
Plantar flexes foot at ankle joint; flexes knee joint
Plantaris
Lateral supracondylar ridge of femur
Posterior surface of calcaneum
Soleus
Shafts of tibia and fibula
Together with gastrocnemius and plantaris is powerful plantar flexor of ankle joint; provides main propulsive force in walking and running

26. DEEP GROUP
Popliteus Flexor digitorum longus Flexor hallucis longus
4. Tibialis posterior

28. DEEP GROUP
Popliteus
Lateral surface of lateral condyle of femur (Intracapsular)
Post surface of shaft of tibia above soleal line
Tibial
Flexes leg at knee joint; Unlocks knee joint by lateral rotation of femur on tibia
Flexor digitorum longus
Posterior surface of shaft of tibia
Bases of distal phalanges of lateral four toes
Flexes distal phalanges of lateral four toes; plantar Flexes foot at ankle joint; Supports medial and lateral longitudinal arches
Flexor hallucis longus
Posterior surface of shaft of fibula
Base of distal phalanx of big toe
Flexes distal phalanx of big toe; plantar flexes foot at ankle joint; supports medial longitudinal arch
Tibialis posterior
Posterior surface of shafts of tibia and fibula and interosseous membrane
Tuberosity of navicular bone and other neighboring bones.
Plantar flexes foot at ankle joint; inverts foot at subtalar and transverse tarsal joints; supports medial longitudinal arch

29. 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

30. 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

32. Cutaneous 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

33. Superficial drainage of the lower limb
FYI - varicose veins
Great Saphenous vein:
Drains into femoral vein in femoral triangle
Small Saphenous vein:
Drains into popliteal vein