Front of the leg and dorsum of the foot

Front of the leg and dorsum of the foot Dr. Eman

The deep fascia (crural fascia)
the fascia lata of the thigh continuous onto the leg and called the crural fascia.
It is connected to the bones by intermuscular septa,and forms thickened bands at the ankle called retinacula which act as a pulley around the tendons of ms.

The Retinacula:

1- superior extensor retinacula it is broad extends between the fibula and the medial surface of the tibia.
2- Inferior extensor retinacula is Y shaped.

3-Superior peroneal retinaculum extends from the lateral malleolus downwards and backwards attached to the lateral surface of the calcaneum
4-Inferior peroneal retinaculum attached to the lateral surface of the calcaneum above and below the peroneal muscles.
5-Flexor retinacula extends from the medial malleolus downwards and backwards to be attached to the medial tubercle of calcaneum
The dorsum of the foot contains the structures which extend from the anterior compartment of the leg.
The fascia of the dorsum of the foot is thin, it is continuous with the extensor retinacula curves over the margins of the foot and becomes the fascia of the sole.

Intermuscular septa:

These are extensions from the deep fascia of the leg to the tibia and fibula so that it separate the leg into 3 compartments. These septa are:
1- The interosseous membrane between the tibia and fibula separate the anterior and posterior compartments.
2- Anterior intermuscular septa attached to the anterior border of the fibula separate the anterior and lateral compartments.
3- The posterior septa attached to the posterior border of the fibula separate the posterior and lateral compartments. From the posterior septa a broad transverse intermuscular septa separating the superficial and deep groups of calf muscles.
Anterior compartment of the leg
the anterior compartment ( dorsiflexion) lies in front of interosseous membrane and the fibula,. it contains the following muscles:,Tibialis anterior m.,.extensor hallucis longus m., extensor digitorum longus m., peroneus tertius m.
Vessels of this compartment are the anterior tibial vessels and the nerve is the deep peroneal nerve.
muscle
origin
insertion
Tibialis anterior( TA)
Upper 2/3of lateral surface of tibia +interosseous membr.
Medial cuneiform +adjacent part of first metatarsal.
Extensor digitorum longus(EDL)
Upper 3/4of anterior surface of fibula +interosseous membr
Via 4 tendon into the lateral toes ,for extensor expantion
Extensor halucis longus (EHL)
Middle 1/3of ant. surface of fibula +interosseous membr
Base of distal phalanx of big toe
Peroneus tertius (PT)
lower 1/4of antrior surface of fibula +interosseous membr
base of 5 metatarsal
Action : TA: dorsiflexion of foot (at ankle)+ inversion of foot. EDL:extension of toes +dorsiflexion of foot. EHL:extension of big toe+dorsiflexion. PT:eversion of foot


Extensor expansions
It is formed on the dorsum of the proximal phalanx by the union of 5 tendons: 1- tendon of the extensor digitorum longus 2- tendon of the extensor digitorum brevis 3- tendon of one lumbrical muscle. 4-tendon of two interossel m. the expantion divides into 3 parts .The thick central part inserted in the base of the middle phalanx. The lateral and medial parts of the expansion continue distally fused together and inserted in the base of the distal phalanx. The big toe has no ext.expantion. the ext. expantion of little toe is formed by the union of 3 tendone
1-tendone of extensor digit. Longus
2- tendon of one lumbrical muscle
3- tendon of one interossel m.
Anterior tibial artery
Arises from the popliteal artery at the lower border of the popliteus m. it passes forwards above the upper border of the interosseous membrane close to the neck of the fibula then descends forward on the membrane with the deep peroneal nerve passing behind the superior extensor retinaculum. The tendon of extensor hallucis m. lies on its medial side and the deep peroneal nerve and tendons of extensor digitorum m. on its lateral side. It ends in the front of the ankle joint by becoming the dorsalis pedis artery midway between the malleoli.
Branches:
1- muscular branches to the muscles of the anterior compartment.
2- Anterior tibial recurrent artery passes upwards to the knee joint.
3- Medial and lateral malleolar arteries to the lateral and medial malleoli,
Deep peroneal nerve( ant. Tibial nerve)
Arises from the common peroneal nerve lateral to the neck of the fibula. it pierces the peroneus longus m and descends in the anterior compartment between EDL and TA in upper part then between EHL and TA. It pass lateral to the anterior tibial vessels, near the ankle joint it crossed by the extensor hallucis longus m. enters the dorsum of the foot midway between the malleoli with the dorsalis pedis artery. It gives :
articular branch to ankle joint
Muscular branches to all muscles of the anterior compartment.

Lateral side of the leg

Composed of the muscles which cover the lateral surface of the leg. These are peroneus longus and brevis ms. supplied by the superficial peroneal nerve.

muscle

origin
insertion
Peroneus longus
Upper 2/3 of lateral surface of fibula
In the base of 1st metatarsal and medial cuneiform on their lateral sides
Peroneus brevis
Lower 2/3 of lateral surface of fibula
On the medial aspect of base of 5th metatarsal bone
Action :both act as everter of foot (mainly) .
Assist in planter flexion.


Superficial peroneal nerve:
Descend in the peroneus longus m. to reach the peroneus brevis m. supply both muscles, then it descend between it and extensor digitorum longus m. pierce the deep fascia in the distal 1/3 of the leg and divides into medial and intermediatecutaneous nerves. It supply the skin of the lower third of the front of the leg, the greater part of the dorsum of the foot and most of the dorsal surface of the toes expect the first interdigital cleft and the lateral side of the little toe.
The back of the leg
The transverse intermuscular septa divide the back of the leg into superficial posterior compartment and the deep posterior compartment, they supplied by the tibial nerve. The superficial layer consist of the muscles which inserted in the heel by the tendocalcaneus, these muscles are the powerful planter flexors of the ankle joint, include gasterocnemius, soleus and plantaris muscles.
the deep layer consist of long flexors muscles of the toes these are, flexor hallucis and flexor digitorum longus muscles and popliteus, ,tibialis posterior.

muscle

origin
insertion
gastrocnemius
Arises by 2 heads lateral and medial from lateral and medial condyle of femur
By tendocalcaneus tendon into the dorsum of calcaneum bone
soleus
1-Post. Surface of head of fibula +post . surf. Of upper 1/3 of fibula 2-Solial line of tibia

plantaris

Lower part of lateral supracondylar ridge of femur
Back of calcaneum
Action :raises the heel of the foot on the ground on propulsive movement during walking in addition they share in planter flexion of foot.
muscle
origin
insertion
popliteus
Lateral surface of lateral condyle of femur
Posterior surface of tibia above the soleal line
Flexor digitorum longus
Posterior surface of tibia
Via its 4 tendon to the bases of the distal phalanges of lateral 4 toes
Flexor halucis longus
Lower 2/3of Posterior surface of fibula
Distal phalanx of big toe
Tibialis posterior
Posterior surface of tibia and fibula
Mainly into tuberosity of navicular bone and to the all tarsal bone except the talus


Action: fl. Hallucis :flexion of big toe +planter flexion
Fl.digit. flexion of toes+planter flexion
Tibialis post. Inversion of foot +planter flexion

The princible nerve of the back of the leg is the Tibial nerve (L4,5,S1,S2,S3) passes under the tendinous arch of the soleus muscle and descend under the transverse intermuscular septum superficial to the posterior tibial vessels. in the upper part of the leg it lies on the popliteus m. then posterior to the tibialis posterior m. in the lower third of the leg it lies between tendons of flexor digitorum longus and flexor hallucis longus ms. the tibial nerve divides deep to the flexor retinaculum into medial and lateral planter nerves.
Branches in the leg:
1- muscular branches to the tibialis posterior, flexor digitorum longus, flexor hallucis longus and deep part of soleus m.
2- cutaneous branches include medial calcanean nerve (S1) arise in the ankle pierce the flexor retinaculum supply the skin on the posterior and lower part of the heel.
3- Small articular branch to the capsule of the ankle joint.
The posterior tibial artery
It is the direct continuation of the popliteal artery, supply the muscles of the back and it is the main artery of the foot begin at the lower border of the popliteus m. then descend with the tibial nerve and two venae commitants deep to the gastrocnemius, soleus and the transverse intermuscular septum of the leg. it runs first laterally to give the peroneal artery then it inclines medially passes behind the medial malleolus, ends by dividing into medial and lateral planter arteries deep to the flexor retinaculum.
Branches in the leg:
1- peroneal artery it is the largest branch, arises from the posterior tibial artery 2-3 cm below the lower border of the popliteus muscle, descend obliquely along the back of fibula deep to the flexor hallucis m. and ends in branches to the ankle and heel. it gives:
a- muscular branches to the muscles of the lateral compartment of the leg.
b- Nutrient branch to the fibula.
c- Perforating artery which pierces the distal end of the interosseous membrane

The peroneal artery ends by giving post. lateral malleollar branch to the lateral side of the back of the heel
2- circumflex fibular artery runs around the neck of the fibula
3- Nutrient artery to the tibia.
4- Muscular branches to the deep muscles of the back of the leg
5-Posterior medial malleolar to the posterior part of the medial
malleolus.
6- medial and lateral planter art.