Ankle

The Foot and Ankle: an overview

The foot and ankle play an important role in human movement. This versatile platform has evolved differently from the hand in that the phalanges have shortened and are more in line with the great toe (hallucis) sacrificing dexterity for propulsion and a stable base. The foot has 3 main arches which adapt to an uneven surface and are supported by the bony architecture as well as a network of muscles and ligaments. Think about how the foot has evolved and the negative effect of consistantly walking on a flat uniform surface.

The Medial Longitudinal Arch

Supported By:

Tibialis anterior and posterior,
Peroneus longus,
Flexor digitorum longus,
Flexor hallucis, and the intrinsic foot muscles

The Lateral Longitudinal Arch

Supported By:

Peroneus longus,
Flexor digitorum longus, and the intrinsic foot muscles.

The Transverse Arch

Supported By:

Adductor hallucis
Peroneous longus

Consider the long term effects of landing on a flat surface (modern society) in comparison to native Britain 10,000 yrs ago. Which is better and why? Try to identify these arches on yourself.

Ligaments

The ankle is made up of 2 joints, the inferior tibiofibular joint (ITFJ) and the Talocrural joint (TCJ) at the distal end of the tibia and fibular. These bones form a different type of joint known as a fibrous joint. The ITFLJ is the only fibrous joint in the appendicular skeleton. They come together to form a mortise which receives the talus. This joint is the TaloCrural Joint.

The ankle joint is stabilised by a number of ligaments.

Lateral ankle Ligaments

Lateral calcaneofibular ligament (LCL)
Anterior talo fibular ligament (ATFL)
Posterior talo fibular ligament (PTFL)

Which one is commonly injured in inversion injuries?

Medial ankle Ligament

The deltoid ligament is composed of:

1. Anterior tibiotalar ligament 2. Tibiocalcaneal ligament 3. Posterior tibiotalar ligament 4. Tibionavicular ligament.

It consists of two sets of fibers, superficial and deep.

Now spend some time looking up the ligaments above. Think of the mechanism which would stress these ligaments resulting in injury (What movements are they designed to resist?)

Bone and bony Points

IMG_3341.MOV

key bony points

Medial Malleolus
Lateral Malleolus
The base of the 5th Metatarsel
The navicular tubercle
Sustentaculum Tali

TASK: Bony Points

Now spend some time feeling these points on your own foot. As you do consider how you might talk through identifying this bony point in an exam for example:

The base of the 5th metatarsel bone can be found by locating the lateral malleolus moving inferiorly then distally along the lateral surface of the foot. The first bony promince you come to is the base of the 5th.

Now do this with the other bony points.

Want more! Find these bony points on others as they can feel very differnet - remember to ask for consent!

Clinical Practice

Now you can find these bony points lets apply this to practice. The Ottawa ankle rules would apply in an acute setting when treating a sprained ankle. If any of the bony points below are tender and the patient is unable to take 4 steps the risk of a fracture is high and an X-ray is indicated.

The Muscles and tendons of the ankle

Lateral

Peroneus Brevis / Longus / Tertius

Medial

Tom (Tib post), Dick ( flexor Digitorum) & Harry (Flexor Hallucis)

EHL / EDL

Flexor Digitorum longus

Origin: Mid 1/3 post tibia

Insertion: Base of distal phalanxes toes 2-5, plantar aspect

Action: Flexes toes 2-5 eg in gait, FDL flexes toes in toe-off

Action and function: Flexor digitorum longus flexes the lateral four toes. First the DIP joints, then the PIP and finally the mtp joints. Its course around the medial malleolus means that it contributes to plantar flexion of the ankle. In running, jumping and walking FDL pulls the toes firmly downwards to the floor to give maximum grip in ‘toe off'. It also supports the longitudinal arches of the foot,

Tibialis Anterior

Origin: Upper 2/3s lateral tibial shaft & interosseus Membrane

Insertion: Medial aspect 1st MT and 1st cuneiform

Action: Dorsiflexion and Inversion eg swing phase gait

Action and function: Dorsiflexes the foot at the ankle joint and inverts the foot at the intertarsal joints. It supports the medial longitudinal arch. It works with other muscles of the lower leg to ensure balancing of the body on the foot in weight bearing.

Flexor hallucis longus

Origin: Lower 2/3s posterior aspect fibula

Insertion: Posterior surface base of distal phalanx1st toe

Action: Flexes 1st Toe eg propulsion in toe-off A powerful flexor of the 1^st toe gives its importance to propulsion of the foot in the final stages of toe off as the 1^st toe has the final contact with the ground before the foot is lifted and starts swing through.

FHL is also important in providing support to the medial longitudinal arch.

Extensor Hallucis Longus

Origin: Mid 1/3 anterior aspect fibula & interosseus membrane

Insertion: dorsal aspect of base of distal phalanx 1^st toe

Action: Extends proximal phalanx of big toe e.g. clears big toe during swing phase.

Action and function: Dorsiflexes the foot at the ankle joint, inverts the foot at the intertarsal joint and extends the proximal phalanx of the 1^st toe at the mtp joint.

Important action on swing through, assisting with dorsiflexion of the ankle and extension of the 1^st toe which is the last part to leave the ground at toe off. This action ensures that clearance of the walking or running surface is achieved.

Tibialis posterior

Origin:

Insertion:

Action:

Extensor Digitorum Longus

Origin: Lateral tibial condyle, anterior surface of fibula

Insertion: Middle and distal phlanges of toes 2-5

Action: Extends toes 2-5 eg: extends toes in push-off phase of gait

MSK Foot Surface Anatomy.mp4

Surface markings

Bony points and tendons around the foot & Ankle

TASK Ankle tendons

Now spend some time feeling the tendons around your own foot. As you do this use the video above and other texts. Try to locate:

Peroneus Brevis & Longus (Sometimes Peroneus Tertius) LATERAL
Tibialis Posterior / Flexor Digitorum Longus / Flexor Hallucis Longus (Tom, Dick & Harry) MEDIAL
Extensor Digitorum Longus / Extensor Hallucis Longus / Tibialis Anterior ANTERIOR

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