Okay everyone, you are going to get a real kick out of this video, because we're going to talk about the anatomy of the foot.The foot can be divided into two main parts - the sole or plantar region, which is the part of the foot contacting the ground, and the dorsum of the foot or the dorsal region, which is the part directed superiorly.Alternatively, it can be divided into three sections - the hindfoot, containing the talus and calcaneus; the midfoot, containing the navicular, cuboid, and cuneiforms; and the forefoot, which includes the metatarsals and phalanges.The foot also has two important landmarks - the heel, which is the sole of the foot underlying the calcaneus, and the ball of the foot, which is the sole underlying the heads of the medial two metatarsals.So let’s talk a bit about the foot’s components.

The most superficial elements are skin and fascia, which vary in thickness and strength across the foot, depending on if the area has roles in weight-bearing, ground contact, or compartmentalization.The skin on the dorsum of the foot is much thinner and less sensitive than the one on the sole.

By contrast, the thick skin on the sole is ticklish, hairless, and has numerous sweat glands.The fascia of the foot can be divided into superficial and deep fascia.

The superficial fascia or the subcutaneous fat tissue is loose and deep to the dorsal skin.It is much more fibrous in the sole and is thicker than in other areas of the foot, making the heel act as a shock absorbing pad.The deep fascia of the dorsum of the foot is rather thin and continuous proximally with the inferior extensor retinaculum.It is also continuous with the plantar fascia, the deep fascia of the sole, over the lateral and posterior aspects of the footSpeaking of which, the plantar fascia on the plantar aspect of the foot helps protect the sole from injury, and supports the longitudinal arches of the foot.It consists of a thick central part, called the plantar aponeurosis, and weaker medial and lateral parts.The plantar aponeurosis is strong, because it consists mostly of longitudinal bundles of dense fibrous connective tissue that invests the central plantar muscles.These longitudinal fibers originate as a single entity on the medial process of the tuberosity of the calcaneus, and as they move towards the toes, they divide into five bands that become continuous with the fibrous digital sheaths that enclose the flexor tendons that pass to the toes.Each band splits opposite to the metatarsophalangeal joints into a superficial and a deep slip, blending with the skin and deeper ligaments of the distal foot and also embracing the flexor tendons to the toes.Now, in the midfoot and forefoot, the plantar aponeurosis has vertical intermuscular septa that extend superiorly from its margins toward the 1st and 5th metatarsals, forming the medial, central and lateral compartments of the sole.The medial compartment is covered superficially by the thinner medial plantar fascia and it contains muscles and neurovascular structures of the foot.The central compartment of the sole is covered by the dense plantar aponeurosis and contains muscles and tendons of the foot as well as neurovascular structures.There is also the lateral compartment of the sole, which is covered superficially by the thinner lateral plantar fascia.Additionally, there is an interosseous compartment of the foot containing the interosseous muscles and a few other structures, as well as the dorsal compartment of the foot which has the extensor muscles of the foot passing through it.Now, the sole purpose of this section was to toe-tally blow you away!

And before we move on to the components of the foot, let’s have a break and review its structure.So now, let’s look at the muscles of the foot.

There are up to 20 individual muscles in the foot, and most of them are on the plantar surface. These plantar muscles are conveniently grouped into 4 different muscle layers.On an important side note, despite their compartmental and layered arrangement, the plantar muscles function primarily as a group during the support phase of the stance of walking, maintaining the arches of the foot.They essentially resist the forces that tend to reduce the longitudinal arch of the foot as weight is received at the heel, where the posterior end of the arch is, and then transferred to the ball of the foot and great toe, where the anterior end of the arch is.They also play a role in maintaining balance and individually, they help control the movement of the toes.

Now before we start, to help remember how many muscles are in each muscle layer, just think of 3-2-3-2.There are three muscles in the first layer, two groups of muscles in the second layer, three again in the third layer, and two in the fourth layer.To make that even easier to remember, think the odd layers, or the 1st and 3rd, have 3 muscles, which is an odd number, and the even layers, 2 and 4, have an even 2 muscles each.So the three muscles in the first layer are the flexor digitorum brevis, abductor hallucis, and abductor digiti minimi.

Flexor digitorum brevis lies immediately deep to the plantar aponeurosis.It originates on the medial tubercle of the calcaneus and l tuberosity and the plantar aponeurosis, then moves towards the toes inserts on the middle phalanges of the 4 lateral toes.

This muscle flexes the lateral four toes at the metatarsophalangeal and proximal interphalangeal joints.The abductor hallucis forms the medial margin of the foot and it originates on the medial tubercle of the calcaneal tuberosity and plantar aponeurosis, from where it travels to and inserts on the medial side of the base of the proximal phalanx of the great toe.

This muscle mostly abducts and flexes the great toe at the metatarsophalangeal joint.And finally, there is the abductor digiti minimi muscle which is located on the lateral side of the foot.

It originates on the lateral and medial tubercles of the calcaneal tuberosity and on the plantar aponeurosis.Then, it inserts on the lateral side of the base of the proximal phalanx of the 5th digit - or pinky toe - which it flexes and abducts at the metatarsophalangeal joint.The second layer, composed of 2 muscles, is made up of the quadratus plantae muscle and the four lumbricals, which we will count as a group.

The quadratus plantae is a square muscle located deep to the flexor digitorum brevis muscle.This muscle originates on the medial and lateral plantar surface of the calcaneus and it inserts on the posterolateral margin of the tendon of flexor digitorum longus.

By inserting on the flexor digitorum longus, it assists this muscle in flexing the lateral four digits.And then there are the four lumbricals, which counts as 1 for our 3-2-3-2 memory trick.

The’re located medial to and attach to their respective tendons of the flexor digitorum longus, like little satellites. This group of muscles causes flexion of the metatarsophalangeal joints and extension of both interphalangeal joints.The third layer has 3 muscles: the flexor hallucis brevis, flexor digiti minimi brevis, and adductor hallucis muscles.

Flexor hallucis brevis is located on the medial side of the foot, and it originates from the plantar surfaces of the cuboid and lateral, or third, cuneiform bone.It then splits into a medial and lateral head with its own tendon, with each tendon encompassing a sesamoid bone, and distally inserts to both sides of the base of the proximal phalanx of the great toe.

This muscle flexes the proximal phalanx of the great toe at the metatarsophalangeal joint.Flexor digiti minimi brevis originates on the base of the fifth metatarsal.

It travels to the tips of the toes and then attaches to the lateral side of the base of the pinky toe’s proximal phalanx in order to flex the pinky at the metatarsophalangeal joint.And then, there’s the adductor hallucis muscle, which is located lateral to the flexor hallucis brevis.

It consists of both an oblique and transverse head.The oblique head originates from the bases of the 2nd, 3rd, and 4th metatarsals.

The transverse head originates from the plantar ligaments of the metatarsophalangeal joints. Both heads insert to the lateral base of the proximal phalanx of the great toe.Ultimately, this adductor, well, adducts the great toe and assists in maintaining the transverse arch of the foot.

And the fourth and final layer is made up of 2 groups of muscles, the plantar interossei and dorsal interossei.Okay, so there are 3 plantar interossei that are located between the metatarsals.

Each originates from the medial sides of the metatarsals of toes three to five and they insert on the medial sides of the proximal phalanges of digits 3-5.

The plantar interossei adduct and flex toes three to five at the metatarsophalangeal joint.And finally, the 4 dorsal interossei are also located between the metatarsals, and each of them originates from the adjacent sides of the shafts of metatarsals 1 to 5.When it comes to insertions, the first dorsal interosseous muscle attaches to the medial side of the proximal phalanx of the second digit, whereas the second to fourth interossei attach to the lateral sides of the proximal phalanges of digits two to four.The dorsal interossei abduct toes two to four and flex the metatarsophalangeal joints.

A good way to remember the action of the three plantar interossei and four dorsal interossei is to remember the mnemonic 3 PAD and 4 DAB.This stands for the 3 Plantar interossei ADducting the toes, and the 4 Dorsal interossei ABducting the toes!

Now that we’re done with the plantar muscles, let’s also talk a bit about the dorsal ones.There are only two muscles located exclusively in the dorsal region of the foot - the extensor digitorum brevis and the extensor hallucis brevis.

These muscles lie deep to the tendon of the extensor digitorum longus.They share a common muscle belly and originate from the calcaneus, and from this muscle belly four tendons arise and attach to the extensor expansion of digits 2 to 4.A portion of this muscle then goes on to attach to the base of the proximal phalanx of the great toe and is the extensor hallucis brevis muscle.These muscles extend digits 2 through 4 at the metatarsophalangeal and interphalangeal joints, and the great toe at the metatarsophalangeal joint.

How about we take a break and review the muscles of the sole and dorsum?Let's move on to the nerves supplying the foot, starting with the 4 muscle layers of the foot, which are all innervated by either the medial or lateral plantar nerve, which are terminal branches of the tibial nerve.The medial plantar nerve is the larger and more anterior of the two terminal branches, and arises deep to the flexor retinaculum.It enters the sole of the foot by passing deep to the abductor hallucis, then runs anteriorly between the abductor hallucis muscle and the flexor digitorum brevis in a neurovascular plane between the 1st and 2nd muscular layer, supplying both the abductor hallucis and flexor digitorum brevis motor branches.The medial plantar nerve then provides motor branches to the flexor hallucis brevis and 1st lumbrical muscle, and a sensory branch that goes on to innervate the skin on the medial side of the sole.Finally, the medial plantar nerve terminates near the bases of the metatarsals by dividing into three sensory branches called the common plantar digital nerves.These branches supply sensory information for the skin of the medial three and a half digits, including the dorsal skin and nail beds of their distal phalanges, and the skin of the sole proximal to them.So in total, the medial plantar nerve innervates 2 muscles in the first layer, then 1 muscle in the second layer and 1 muscle in the third layer, along with its cutaneous innervation.Next, the lateral plantar nerve, which is the smaller and more posterior of the two terminal branches, also courses deep to the abductor hallucis but runs anterolaterally between the 1st and 2nd layers of plantar muscles.The lateral plantar nerve terminates as it reaches the lateral compartment, dividing into superficial and deep branches, where the deep branch courses in a neurovascular plane between the 3rd and 4th muscle layers.The lateral plantar nerve, along with its superficial and deep branches innervate the rest of the muscles on the plantar surface of the foot not innervated by the medial plantar nerve.This means the lateral plantar nerve provides motor innervation to the abductor digiti minimi in the first layer and the quadratus plantae in the second layer.Meanwhile its deep branch gives motor innervation to the lateral three lumbricals.

Then in the third layer, it innervates the adductor hallucis.While the superficial branch provides motor innervation to flexor digiti minimi brevis.

Finally, in the fourth layer, the deep branch innervates all of the plantar and dorsal interossei.In regards to cutaneous sensory innervation, the superficial branch divides, and goes on to supply the skin of the plantar aspects of the lateral one and a half digits, the dorsal skin and nail beds of their distal phalanges, and the skin of the sole proximal to them.The rest of the cutaneous innervation of the foot is supplied medially by the saphenous nerve; laterally by the sural nerve; on the dorsum of the foot by the superficial and deep fibular nerves; inferiorly, on the sole of the foot, by the medial and lateral plantar nerves as we said before; and posteriorly, at the heel, by the medial and lateral calcaneal branches of the tibial and sural nerves, respectively.First, the saphenous nerve is the longest and most widely distributed cutaneous branch of the femoral nerve, and passes anterior to the medial malleolus to the dorsum of the foot, where it supplies skin along the medial side of the foot as far anteriorly as the head of the 1st metatarsal.Second, the sural nerve is formed by branches of the tibial and common fibular nerve, and it usually passes inferior to the lateral malleolus, where it accompanies the small saphenous vein, and supply the ankle joint and skin along the lateral margin of the hind and midfoot.Next, we have the superficial and deep fibular nerves, both branches of the common fibular nerve.When it comes to the superficial fibular nerve, it supplies sensory information to the skin on the anterolateral aspect of the leg and its branches continue across the ankle to supply most of the skin on the dorsum of the foot.Its terminal branches supply the skin of the dorsal aspect of the medial half of the great toe and that of the lateral three and a half digits.And second, the deep fibular nerve, supplies motor innervation to the intrinsic muscles on the dorsum of the foot, the extensor digitorum brevis and the extensor hallucis brevis, and emerges as a cutaneous nerve to supply sensory innervation to only a small area of skin that remains available for innervation: the web of skin between and contiguous sides of the 1st and 2nd toes.Okay!

So it's time to put an end to this nerve-er-ending story! Before we switch to blood vessels, let’s see if you can remember what each nerve of the foot innervates.Moving on to blood vessels, the main arteries of the foot are the plantar arteries and the dorsalis pedis artery.

Dorsalis pedis is the terminal branch of the anterior tibial artery.The plantar arteries are the terminal branches of the posterior tibial artery and make up the prolific blood supply of the sole of the foot.There are two main plantar arteries, namely the medial and lateral plantar arteries, which typically follow their similarly named medial and lateral plantar nerve.

The medial plantar artery is the smaller terminal branch of the posterior tibial artery.It arises beneath the flexor retinaculum and appears in the sole deep to abductor hallucis, usually accompanied by the medial plantar nerve on its lateral side.It terminates on the medial side of the big toe by dividing into two branches.

The smaller one is called the deep branch and it mainly supplies the muscles of the great toe.The larger one is called the superficial branch and it supplies the skin on the medial side of the sole and has digital branches that accompany the digital branches of the medial plantar nerve, the more lateral of which anastomose with medial plantar metatarsal arteries.Occasionally, a superficial plantar arch is formed when the superficial branch anastomoses with the lateral plantar artery or the deep plantar arch.

Second, the lateral plantar artery arises with and accompanies the lateral plantar nerve.From its origin, the artery runs laterally and anteriorly, at first deep to the abductor hallucis and then between the flexor digitorum brevis and quadratus plantae.Ultimately, the lateral plantar artery arches medially across the foot with the deep branch of the lateral plantar nerve to form the deep plantar arch, which is completed by the union with the deep plantar artery, a branch of the dorsalis pedis artery.As it crosses the foot, the deep plantar arch gives rise to four plantar metatarsal arteries.

The plantar metatarsal arteries divide near the base of the proximal phalanges to form the plantar digital arteries, supplying adjacent toes.The plantar digital arteries typically provide most of the blood reaching the distal toes, including the nail bed, via perforating and dorsal branches.Now let’s switch gears and look at the dorsalis pedis artery, which directly continues the anterior tibial artery.It begins midway between the malleoli and runs anteromedially, on the lateral side of the extensor hallucis longus and the extensor digitorum longus tendons on the dorsum of the foot.This is the artery that we palpate when we locate the pulse on the foot, and it can be easily found by lifting up the big toe, and going lateral to the tendon of the extensor hallucis longus!The dorsalis pedis artery then passes to the first interosseous space, where it divides into the 1st dorsal metatarsal artery and a deep plantar artery.The deep plantar artery passes deep between the heads of the first dorsal interosseous muscle to enter the sole of the foot, where it joins the lateral plantar artery to form the deep plantar arch.Now, the dorsalis pedis also gives off plenty of branches, such as the lateral tarsal artery, which runs laterally in an arched course beneath the extensor digitorum brevis to supply this muscle and the underlying tarsals and joints.Then there’s the arcuate artery, which runs laterally across the bases of the lateral four metatarsals, deep to the extensor tendons, to reach the lateral aspect of the forefoot, where it may or may not anastomose with the lateral tarsal artery to form an arterial loop.Additionally, the arcuate artery gives rise to the 2nd, 3rd, and 4th dorsal metatarsal arteries.

These vessels run distally to the toes and are connected to the plantar arch and the plantar metatarsal arteries by perforating branches.Distally, each dorsal metatarsal artery divides into two dorsal digital arteries for the dorsal aspect of the sides of adjoining toes.

Venous drainage of the foot is ensured by both superficial and deep veins within the foot.Most of the blood of the foot is drained by the superficial venous drainage, which is located in the subcutaneous tissue and unaccompanied by arteries.

Superficial veins are mostly a series of small veins like the dorsal digital veins, of which there are two on each toe.Each joins the corresponding vein of the adjacent toe, along with plantar digital veins, to form the dorsal metatarsal veins which terminates in the dorsal venous arch of the foot, proximal to which a dorsal venous network covers the remainder of the dorsum of the foot.On the plantar surface of the foot, superficial veins form a plantar venous network which can drain around the medial border of the foot and converge with the medial part of the dorsal venous arch to form a medial marginal vein, eventually becoming the great saphenous vein.Or, the plantar venous network drains in the lateral margin and converges with the lateral part of the dorsal venous arch to form the lateral marginal vein, which becomes the small saphenous vein.The deep veins are an anastomosing network of paired veins that accompany all arteries internal to the deep fascia.Finally, just a few words on the lymphatics of the foot.

There are both superficial and deep lymphatic vessels that follow the superficial veins and major vascular bundles.The medial superficial lymphatic vessels are the largest and drain the medial side of the dorsum and sole of the foot.These vessels converge on the great saphenous vein and accompany it to the vertical group of superficial inguinal lymph nodes, and then to the deep inguinal lymph nodes along the proximal femoral vein.On the other hand, the lateral superficial lymphatic vessels drain the lateral side of the dorsum and sole of the foot, and most of these vessels accompany the small saphenous vein to the popliteal fossa, where they enter the popliteal lymph nodes.The deep lymphatic vessels follow the main blood vessels: fibular, anterior and posterior tibial, popliteal, and femoral veins.These lymphatic vessels also drain into the popliteal lymph nodes, and from them follow the femoral vessels, carrying lymph to the deep inguinal lymph nodes and eventually to the iliac lymph nodes.Toe-riffic!

We've reached the end. Before recap, let’s take a break and see if you can remember the main vessels of the foot.Alright, as a quick recap: The most superficial elements of the foot are skin and fascia.

The deep plantar fascia has a central part called the plantar aponeurosis that gives off vertical intermuscular septa.The septa form the three compartments of the sole - medial, central and lateral, each containing many plantar structures of the foot.The muscles of the sole can be divided in 4 layers.

The first layer consists of 3 muscles: flexor digitorum brevis, abductor hallucis, and abductor digiti minimi.The second layer contains the quadratus plantae muscle and the group of four lumbricals.

The third layer includes another 3 muscles, the flexor hallucis brevis, flexor digiti minimi brevis, and adductor hallucis muscles.And the fourth layer is made up of the plantar and dorsal interossei.

The dorsal region only has two muscles: the extensor digitorum brevis and the extensor hallucis brevis.The innervation to the four muscle layers is provided by one of the terminal branches of the tibial nerve, either the medial or the lateral plantar nerve.The cutaneous innervation of the foot is handled by several nerves, including the saphenous nerve, the sural nerve, the superficial and deep fibular nerve, as well as the medial and lateral plantar nerves.Next, arteries!

The medial and lateral plantar arteries course with their respective nerves.The lateral plantar artery forms the deep plantar arch alongside the deep plantar artery, a branch of the dorsalis pedis artery.

The dorsalis pedis artery is a direct continuation of the anterior tibial artery.The deep veins of the foot course with their respective arteries, while superficial venous drainage is ensured by a dorsal and plantar venous network, which receives a series of smaller veins distally.Finally, the medial superficial lymphatic vessels accompany the great saphenous vein to the superficial and deep inguinal lymph nodes.The lateral superficial lymphatic vessels accompany the small saphenous vein to the popliteal fossa, where they enter the popliteal lymph nodes.The deep lymphatic vessels of the foot follow the main blood vessels, and also drain into the popliteal lymph nodes, and eventually travel to the deep inguinal and subsequent iliac