Topic:SOLE OF FOOT S-II-LM-109.
Foot has two surfaces:
Planter – sole of foot
Dorsal surface.
The arrangement of the structures in the sole of foot are same as in the other parts of body in general and in palm specially.
Skin (nerve supply):
Medial calcaneal branch (tibial nerve) supply the weight bearing area posterior over calcanear.
Remaining portion is supplied by medial and lateral planter nerve (tibial nerve) which perforate the planter aponeorosis along the each edge of strong central tendon.
Medial 3 ½ digits – medial planter nerve
Lateral 1 ½ digit – lateral planter nerve
Some of lateral side is also contributed by sural nerve (sciatic nerve).
Blood vessels accompany the cutaneous nerves:
The skin of sole is thick for protection.
Firmly adherent to under lying planter aponeorosis. It is creased
Superficial fascia (subcutaneous tissue):
It differs from the rest of body in being more fibrous.
The fibrous septa divide the tissue into small loculi filled with fluid fat under tension, so the cutaneous edge buldges, making a shock absorbing pad. This fascia also contains the vessels and nerves.
Deep fascia (Planter aponeorosis):
This is of great strength.
It forms the fibrous flexor sheaths in the toes.
It also forms the deep transverse metatarsal ligaments.
Central part:
This part is thickest and narrowest behind. Attached to the medial process of calcaneal tuberosity.
It becomes broader and thin distally and near the heads of metatarsal bones they divide into five process for each toe.
Each process splits opposite to metatarso pharyngeal joint into superfecial and deep stratum.
Superfecial stratum is attached to the skin of transverse sulcus which separate the toes from sole.
Deep stratum divides into two slips which flank the flexor tendons of toes and blends with their fibrous sheaths and deep transverse metatarsal ligament.
The central part is continuous with the medial and lateral part.
Lateral part – is deep to abductor digiti…. It is continuous medially with the central part and the fascia of dorsum of foot.
Medial part – It is thin and inferior to abductor hallucis(1) which is continuous with flexor retinaculum. From the margins of aponeorosis lateral and medial I/M septas pass deeply and divide the sole in 3 compartments.
Thinner transverse septas arise from the vertical septas and divide the muscles of sole in 4 layers.
Functions:
Fixes the skin of sole
Protects the deeper structures.
Maintaince of longitudinal arch.
Muscles of 1st layer arise.
Fibrous flexor sheaths:
These sheaths are made up of deep fascia of toes forming the osteoaponeorotic opening for the retaining of flexor tendon in position during the flexion of toes.
The muscles of planter region of foot may be divided into:
Medial, lateral and intermediate groups.
Medial and lateral group comprises of intrinsic muscles of Hallux and fifth digit respectively while the central or intermediate group includes the lumbricals interossi and short flexor tendons.
The planter nerves and vessels run between the 1st and 2nd layer.
1st layer:
Abductor hallucis:
It is along the medial border of foot and covers the origins of planter vessels and nerves.
Originates from Planter aponeorosis, flexor retinaculum, medial process of calcaneal tuberosity and the I/M septum between it and flexor digitorum brevis.
Its fibers end in a tendon which is attached together with the medial tendon of fexor Hallucis brevis (3rd layer) to the medial side of the base of proximal phalanx of great toe.
Medial planter nerve:
It abducts the great toe, abduction may be lost, due to damage to the medial planter nerve.
Flexor digitorum brevis:
Deep to central part of planter aponeurosis. Arises – Planter aponeurosis, medial calcaneal tuberosity, I/M septum between it and adjacent muscles. It divide in to four lateral tendons. At the bases of proximal phalanx each tendon divides into two slips and then reunite and partially decussate to form a grooved channel, for the tendon of flexor digitorum longus. This flexor tendon divides again and is attached on both sides of the shaft and intermediate phalynx.
M. Planter nerve
It flexes the toes.
Abductor digitorum minimi:
Lies along the lateral border of foot, arises from medial and lateral tubercles of calcaneus, I/M septas and deep fascia. It fuses with the tendon of flexor digiti minimi brevis (3rd layer) and is attached to the base of proximal phalynx of little toe.
Lateral planter nerve, abducts the little toe.
2nd layer:
- Flexor digitorum accessores:
Arises by medial and lateral heads Medial head is large and fleshy from the concave medial surface of calcaneos and its medial tubercle.
Lateral head is small tendinous and arises from lateral tubercle and long planter ligament.
Inserted with flexor digitorum longus on the planter surface of distal phalanx, Lateral planter nerve, flexes the toes through long flexor tendons.
Lumbricals:
They arise from the tendons of flexor digitorum longus and numbered from the medial side of foot with the exception of 1st which arises only from the medial side of flexor digitorum longus. Each other tendon arises from two adjoining tendons.
They end in tendons which pass distally on the medial sides of lateral four toes and attached on the dorsal digital expansion on the proximal phalanges.
N/S 1st is medial planter nerve
Lateral 3 by lateral planter nerves.
1st is unipinnate
Lateral 3 bipinnate.
Maintains the extension of digits at the interphalangeal joints, while the tendons of flexor digitorum longus are flexing the toes, so that it helps in running and walking.
3rd layer of foot:
Flexor Hallucis brevis:
It is the Y-shaped tendon, lateral limb arises from the medial planter surface of cuboid behind the groove for the peroneas longus and from the adjacent side of lateral cuniform bone.
Medial limb is a direct continuation of the tendon of tibialis posterior in foot. The muscle splits into medial and lateral parts and end in a tendon inserted to the corresponding side of base of proximal phalynx of great toe.
Supplied by medial planter nerve
Causes the flexion of proximal phalynx of great toe.
Adductor Hallucis: Arises by two heads.
Oblique from the bases of 2nd, 3rd and 4th metatarsal, from the tendon of peroneus longus.
Transverse head:
Deep metatarsal ligament and the planter ligaments of metatarsophalangeal joint of 3rd, 4th and 5th toe (No bony origin).
Inserted: Lateral side of the base of proximal phalanx of big toe in common with lateral tendon of flexor hallucis brevis.
Supplied: Lateral planter nerve (deep branch) causes the adduction of big toe and maintains transverse arches of foot.
Flexor digiti minimi brevis:
It arises from the base of 5th metatarsal bone and from the sheath of tendon of peroneas longus.
Inserted on lateral side of base of proximal phalanx of little toe.
Supplied – superfecial branch of lateral planter nerve.
Causes – the flexion of proximal phalanx of little toe.
4th layer:
Dorsal interossi:
Four bipinnate muscles arising by two heads i.e. from adjacent sides of two metatarsal bones. They are attached on to the proximal phalanxes and dorsal digital expansion.
1st reaches to the medial side of 2nd toe. Other 3 on to lateral side of 2, 3, 4 toes.
Planter interossi:
Arise from the bases and medial side of 3rd, 4th and 5th metatarsal bones and are attached to the sides of proximal phalanxes of same toes.
Supplied by deep branch of lateral planter nerve except in 4th interosseous space which is supplied by superfecial branch of lateral planter nerve.
Causes: Abduction and adduction of toes with reference of 2nd digit (3rd digit in hand)
Planter I – abduction of 3, 4, 5th toe
Dorsal I – Abduction.
Pleative metatarsophalngeal interphalangeal joint.
Nerves of foot:
Cutaneous branches:
Adjacent sides of 1 and 2 toes – (2nd digital nerve).
2nd and 3rd toes (3rd digital nerve)
3rd and 4th toes (4th digital nerve)
Digital nerve gives dorsal branches in toes nails, term and metatarsal)
Medial planter nerve:
Larger terminal branch of tibial nerve.
Muscular branches to:
Abductor Hallucs (1st layer), Flexor digitorum brevis (2nd layer)
Flexor Hallucs, brevis (3rd layer) lumbrical muscles (3rd layer)
Lateral planter nerve:
Smaller terminal branch.
Its main trunk supplies to.
Flexor digitorum accessories 2nd layer
Abductor digiti minimi 1st layer skin of sole
Superfecial branch:
Lateral flexor digiti minimi brevis (3) Interossi muscles of 4th interosseous space i.e. 3rd planter interossi, 4th dorsal interossi and the skin on lateral side of little toe.
Medial branch:
Communicates with MPN and the skin lining the 4th inter digital cleft.
Deep branch:
It lies in the concavity of planter arch. It ends by sinking in deep surface of oblique head of abductor Hallucs.
Supplies to:
2, 3, 4th lumbricals
Abductor Hallucs
5 Interossi of 1st 3 interosseous space
1, 2, 3 dorsal interossi.
1, 2 planter interossi.
Arteries of foot:
Medial planter artery:
Smaller branch of posterior tibial artery
Gives muscular branches to the muscles and end by joining with 1, 2, 3rd planter metatarsal arteries (branches of planter arch)
Lateral planter artery:
Larger terminal branch of posterior tibial artery.
End at the base of 5th metatarsal bone and be continuous with planter arch.
Muscular branches
Superficial branches
Anastomotic branches for dorsum of foot.
Clacaneus branch for skin of heel.
Planter arch:
Formation:lateral planter artery (Posterior tibial artery) and dorsalis pedis artery (Branch of anterior tibial artery).
Location: 5th metatarsal bone lateral to proximal part of 1st intermetatarsal space in 3rd and 4th layers of sole.
Branches – four planter metatarsal arteries which divide in two planter digital arteries. Perforating branches (Proximal and distal) which joins with dorsal metatarsal arteries.