Lateral & posterior compartment of leg

1. Lateral & Posterior Compartment of Leg
Dr. Prabhakar Yadav
Assistant Professor
Department of Human Anatomy
B.P. Koirala Institute of Health Sciences

6. LATERAL COMPARTMENT OF LEG
Boundaries :
Anterior: Anterior intermuscular septum.
Posterior: Posterior intermuscular septum.
Medial: Lateral surface of fibula.
Lateral: Deep fascia of leg.
Contents:
Muscles: Peroneus longus & Peroneus brevis.
Nerve: Superficial peroneal nerve.
Artery: Branches of peroneal artery,
reaches lateral compartment by piercing flexor
hallucis longus & posterior intermuscular septum.
Veins: Small unnamed veins- drain into
small saphenous vein

7. PERONEAL RETINACULA: Thick fibrous band of deep fascia
SUPERIOR PERONEAL RETINACULUM:
Situated just behind lateral malleolus
Attachments:
• Anteriorly: To back of lateral malleolus.
• Posteriorly: To lateral surface of calcaneum &
Superficial transverse fascial septum of leg.
 Tendons of both muscles lie in a single compartment.
 Tendon of peroneus longus lies superficial to peroneus brevis.
 Both tendons are enclosed in common synovial sheath.

8. INFERIOR PERONEAL RETINACULUM
Situated anteroinferior to lateral malleolus
Attachments
Superiorly: To anterior part of superior surface of calcaneum
close to the stem of inferior extensor retinaculum
Inferiorly: To lateral surface of calcaneum.
In between: Attached to peroneal trochlea, forming 2 loops
 Tendon of peroneus brevis passes through superior loop &
 Tendon of peroneus longus passes through Inferior loop
 Each tendon is enclosed in a separate synovial sheath
Applied:
Synovial sheaths enclosing tendons of peroneus longus & brevis are
subject to friction & inflammation in athletes who wear tight shoes.

9. PERONEUS LONGUS:
Origin:
• Head of fibula, Upper 2/3rd of lateral surface of shaft of fibula
• Anterior & posterior intermuscular septa of leg & deep fascia
overlying it.
Insertion:
Undersurface of distal end of medial cuneiform & base of 1st metatarsal
• Tendon contains a sesamoid bone where it binds around calcaneus.
Nerve: Superficial fibular (peroneal) nerve [L5,S1,S2]
Action: Eversion & plantarflexion of foot
Maintain longitudional & transverse arch of foot

10. PERONEUS BREVIS:
Origin:
• Lower 2/3rd of lateral surface of shaft of fibula
• Anterior and posterior intermuscular septa of leg
Insertion: Lateral tubercle at base of 5th metatarsal
Nerve: Superficial fibular (peroneal) nerve [L5,S1,S2]
Action: Eversion of foot
Maintains the lateral longitudinal arch
Clinical testing of peroneus longus and brevis
Tendons of peroneus muscles can be seen & palpated inferior to lateral
malleolus when foot is everted against resistance.

11. Applied Anatomy:
 Injury of superficial peroneal nerve
 paralysis of the peroneal muscles
 overactivity of invertor muscles of foot- Talipes varus.
 Paralysis of anterior tibial muscles (invertors of foot)
 Overactivity of peroneal muscles - Talipes valgus.

12. Superficial Peroneal Nerve (Musculocutaneous nerve of leg) :
begins on lateral side of neck of fibula, under cover of
peroneus longus.
upper 1/3rd: descends through substance of peroneus longus.
Middle 1/3rd : Descends between peroneus longus & brevis
Reaches the anterior border of peroneus brevis & descends in
a groove between peroneus brevis & extensor digitorum
longus under cover of deep fascia .
At the junction of upper 2/3rd & lower 1/3rd , it pierces deep
fascia to become superficial.
Divides into a medial & lateral branch which descend into foot.

13. Branches and Distribution
1. Muscular branches : peroneus longus & peroneus brevis.
2. Cutaneous branches:
Supplies: Lower 1/3rd of the lateral side of leg &
dorsum of foot, except territories supplied by saphenous, sural
& deep peroneal nerves.
Medial terminal branch : divides into 2 dorsal digital nerves,
one for medial side of big toe & other for 2nd interdigital cleft.
Lateral terminal branch: divides into 2 dorsal digital nerves for 3rd & 4th
interdigital clefts.
Injury of superficial peroneal nerve:
 Loss of eversion of the foot due to paralysis of peroneus muscles
 Sensory loss on lateral aspect of the leg.
 Sensory loss on dorsum of the foot except for 1st inter digital cleft &
dorsal aspect of all the toes which is supplied by deep peroneal nerve

14. Back of leg:
Contents of superficial fascia;
2 superficial; 7 cutaneous nerves.
Short (Small) Saphenous Vein
• Formed at lateral border of dorsum of foot
by union of lateral end of dorsal venous
arch & lateral dorsal digital vein of little
toe.
• Ascends behind lateral malleolus.
• In leg, it ascends in the mid-line
• In popliteal fossa, pierces deep fascia to
join popliteal vein.
 It drains the lateral side of foot, ankle &
back of leg.
 It is accompanied by sural nerve on its
lateral side
 It is connected with the great saphenous
veins and the deep veins.

15. CUTANEOUS NERVES
Saphenous Nerve
Pierces deep fascia on medial side of
knee & accompanies great saphenous
vein.
Supplies:
Medial side of knee, leg, & medial
border of foot up to the ball of big toe.

16. Posterior Division of Medial
Cutaneous Nerve of Thigh
Pierces deep fascia a little above knee
Supplies: uppermost part of medial
1/3rd of calf
Posterior Cutaneous Nerve of Thigh
(S1, S2, S3)
Pierces deep fascia in middle of
popliteal fossa
Descends with small saphenous vein
Supplies:
Upper ½ of intermediate area of calf.

17. Sural Nerve
• Branch of tibial nerve in popliteal
fossa.
• is joined by the sural (peroneal)
communicating nerve about 2
inches above the heel.
• Pierces deep fascia in middle of leg
& runs along short saphenous vein.
• After passing behind the lateral
mlleolus, nerve runs forward along
lateral border of foot & ends in the
skin on the lateral side of little toe.
• Supplies:
Lower lateral part of the back of leg,
lateral border & adjoining part of
dorsum of foot & lateral side of little
toe.

18. Lateral Cutaneous Nerve of Calf
• Branch of common peroneal nerve in
popliteal fossa.
• Pierces deep fascia over lateral head of
gastrocnemius
• Supplies : upper 2/3rd of lateral area of
leg.
Sural (Peroneal) Communicating Nerve
• Branch of common peroneal nerve.
• Pierces deep fascia about 1 inch below
lateral head of gastrocnemius & join
sural nerve about 2 inches above the
heel.
• Supplies: Posteromedial part of lateral
area of calf.
Medial Calcaneal Branch
• Branch of the tibial nerve
• perforates the flexor retinaculum
• Supplies: heel & adjoining medial side of
sole of foot.

19. POSTERIOR COMPARTMENT OF LEG
BOUNDARIES
Anterior: Posterior surfaces of tibia, fibula, interosseus
Membrane & posterior intermuscular septum.
Posterior: Deep fascia of leg extending from medial
border of tibia to posterior intermuscular septum
SUBDIVISIONS
3 parts: Superficial, Middle & Deep
superficial transverse septum: attached
Medially to medial border of tibia &
Laterally to posterior border of fibula
Deep transverse septum: attached
Medially to proximal part of soleal line & vertical ridge
on posterior surface of tibia &
Laterally to medial crest of fibula.

20. Superficial part
• Lie between Deep fascia & Superficial transverse septum
• Contains: Gastrocnemius, soleus & plantaris
Middle part
• Lie between superficial & deep transverse fascial septa
• Contains: Flexor digitorum longus, flexor hallucis longus,
tibial nerve & posterior tibialvessels.
Deep part
• Lie between deep transverse fascial septum & Posterior
surfaces of interosseous membrane, tibia & fibula
• Contains: Tibialis posterior.
Contents
Muscles: Superficial and deep groups of the muscles
Arteries: Posterior Tibial & peroneal arteries.
Nerve: Tibial nerve.

21. FLEXOR RETINACULUM
situated on medial side of ankle, below & behind medial malleolus
Function:
Attachments
Anteriorly or above: Posterior border & tip of medial malleolus
Posteriorly or below : Medial process of calcaneal tuberosity.
Structures passing deep to flexor retinaculum:
From the medial to lateral side:
1. Tendon of Tibialis posterior
2. Tendon of flexor Digitorum longus,
3. Posterior tibial Artery and its branches
4. Posterior tibial Nerve and its terminal branches, and
5. Tendon of flexor Hallucis longus.

22. Tarsal tunnel syndrome:
Cause: Tibial nerve is compressed deep to the flexor retinaculum
Presentation: Burning, tingling, & pain in the sole of foot.
Rx: Symptoms are relieved by dividing the flexor retinaculum.

23. Gastrocnemius:
Origin:
• Medial head: Popliteal surface of femur &
posterosuperior surface of medial condyle of femur
• Lateral head: posterolateral surface of lateral condyle
of femoral
Insertion:
Via calcaneal tendon, to posterior surface of calcaneus
Nerve:
Tibial nerve
Action: flexes knee & Plantarflexes foot
Tennis leg:
Painful calf injury due to tear/strain of Medial head of
gastrocneminus at its musculotendinous junction due to
overstretching.

24. Plantaris:
Origin:
• Lower part of lateral supracondylar line
• Oblique popliteal ligament
Insertion:
Via calcaneal tendon, to posterior surface of calcaneus
Nerve:
Tibial nerve
Action: Plantarflexes foot & flexes knee
Tendon grafting:
Plantaris is vestigial muscle ; absent in 5–10% of
people.
Tendon is used for grafting (e.g reconstructive surgery
of tendons of hand).

25. Soleus:
Origin:
• Posterior aspect of head & upper 1/4th of posterior
surface of shaft of fibula
• Soleal line & middle 1/3rd of medial border of tibia
• Tendinous soleal arch between fibula & tibia
Insertion:
Via calcaneal tendon, to posterior surface of calcaneus
Nerve:
Tibial nerve [S1,S2]
Action: Plantarflexes foot
Gastrocnemius & soleus: calf muscle pump
Soleus muscle: peripheral heart

26. Popliteus:
Origin:
Posterior surface of proximal tibia
Insertion:
Lateral femoral condyle
Nerve:
Tibial nerve
Action: Unlocks knee joint

27. Flexor hallucis longus:
Origin:
Posterior surface of fibula & adjacent interosseous
membrane
Insertion:
Plantar surface of distal phalanx of great toe
Nerve:
Tibial nerve
Action: Flexes great toe

28. Flexor digitorum longus:
Origin:
Medial side of posterior surface of the tibia
Insertion:
Plantar surfaces of bases of distal phalanges of
lateral four toes
Nerve:
Tibial nerve
Action: Flexes lateral four toes

29. Tibialis posterior
Origin:
Posterior surfaces of interosseous membrane &
adjacent regions of tibia & fibula
Insertion:
Tuberosity of navicular & adjacent region of
medial cuneiform
Nerve:
Tibial nerve
Action:
• Inversion & plantarflexion of foot
• support of medial arch of foot during
walking

30. Posterior Tibial Artery:
• Larger terminal branch of popliteal artery
• supply posterior & lateral compartment & sole of foot
Course and Relations
 Begins at lower border of popliteus, between tibia
fibula, deep to gastrocnemius
 Passes deep to tendinous arch of soleus.
 Runs downward & medially to reach posteromedial
side of ankle, midway between medial malleolus &
medial tubercle of calcaneum.
 Terminates deep to the flexor retinaculum by dividing
into large lateral plantar & small medial plantar artery
 Throughout its course, it is accompanied by tibial
nerve, which crosses the artery from the medial to lateral
side.

31. Branches
1. Peroneal (fibular) artery: largest & most important branch. It arises 2.5 cm distal to inferior border of popliteus
2. Muscular branches: To the muscles of posterior compartment
3. Nutrient artery to tibia: largest nutrient artery in the body. Enters nutrient foramen of tibia below the soleal line

32. Branches
4. Circumflex fibular artery: Encircles lateral side of the neck of fibula.
5. Communicating branch: Joins with the communicating branch of peroneal artery about 5 cm above the ankle
6. Medial malleolar branch: Passes toward medial malleolus.
7. Calcaneal branch: Pierces the flexor retinaculum & supplies soft tissues of the heel.
8. Terminal branches: These are medial and lateral plantar arteries of the sole.

33. Posterior tibial pulse:
Felt against calcaneum; 2 cm below & behind the medial malleolus.

34. PERONEAL ARTERY (Fig. 29.13)
Branch of posterior tibial artery.
Provides blood supply to posterior & lateral
compartments
Course and Relations
 Arises 2.5 cm below the lower border of popliteus.
 Runs toward fibula & descends along medial
crest of the fibula in a fibrous canal between tibialis
posterior & flexor hallucis longus.
 passes behind inferior tibiofibular & ankle joints
 Ends on the lateral surface of calcaneus &
terminates by giving lateral calcaneal arteries.

35. Branches
1. Muscular branches: to posterior & lateral compartments.
2. Nutrient artery : to fibula.
3. Communicating branch: joins Communicating branch of
posterior tibial artery about 5 cm above the ankle.
4. Perforating branch: pierces interosseous membrane about 5 cm
above the ankle, appears in anterior compartment of & terminates
by anastomosing with lateral malleolar branches of anterior tibial
& dorsalis pedis arteries.
5. Lateral calcaneal artery: Terminal branch which
takes part in the formation of lateral malleolar plexus
Dorsalis pedis artery pulse:
Felt just lateral to tendon of extensor hallucis longus against tarsal
bones.

36. TIBIAL NERVE
Larger terminal branches of sciatic nerve.
Origin and Course
Arises on back of thigh at junction of upper 2/3rd & lower 1/3rd & enters popliteal fossa
enters into the posterior compartment of the leg, by passing deep to the tendinous arch
of soleus along with the posterior tibial vessels.
Terminates deep to flexor retinaculum by dividing into medial and lateral plantar nerves.
Branches
1. Muscular branches:
2. Cutaneous branches:
Medial calcaneal branches- pierce flexor retinaculum & supply skin of the back
& lower surface of the heel—the weight bearing area of the heel.
3. Articular branches: To the ankle joint.

37. THANK YOU