FIBULA: Lateral, smaller bone.

The proximal part can be used as a spare part for bone grafts. The Fibula has no articulation at the knee but some articulation at the ankle joint.

TIBIA: Medial, larger bone.

The anterior part of the tibia has almost no tissue associated with it. So it is the most common place to see an open fracture.

THE KNEE-JOINT (N479): Three groups of ligaments.

Collateral Ligaments

Fibular (lateral) Collateral Ligament -- longitudinal ligament on lateral aspect of Patella.

Tibial (medial) Collateral Ligament

Cruciate Ligaments: They span the Intercondylar Fossa and insert onto the Intercondylar Eminence of the Tibia. They are crucial to knee stability.

Anterior Cruciate Ligament

Posterior Cruciate Ligament

Cartilaginous Ligaments: They provide more articulation space for the condyles of the femur.

Medial Meniscus does connect to the Fibular Collateral Ligament

Lateral Meniscus does not connect to the Tibial Collateral Ligament

So if the Tibial Collateral Ligament is damaged, the Medial Meniscus could easily be damaged with it.

The LATERAL MENISCUS IS MORE MOBILE THAN THE MEDIAL MENISCUS.

The Popliteus Muscle (posterior leg) has an insertion between the lateral meniscus and the joint, creating more room on the lateral side.

COLLATERAL CIRCULATION AROUND THE KNEE (N481):

Superolateral Genicular Artery

Anastomoses with the Lateral Circumflex Artery, all the way from the femur.

Inferolateral Genicular Artery

Superomedial Genicular Artery

Inferomedial Genicular Artery

POPLITEAL ARTERY (N487): Posterior artery around the knee, the continuation of the Femoral Artery, right after it passes though the Adductor Hiatus. It is the

basic blood supply to everything below the knee.

BRANCHES

Posterior Tibial Artery: Comes around the medial malleolus (ankle) and perfuses the sole of the foot.

CLINICAL -- you can test the integrity of the posterior tibial by palpating for a pulse on the sole of the foot.

Anterior Tibial Artery: Comes down through the anterior leg and onto the dorsum of the foot.

Dorsalis Pedis Artery is the continuation of the Anterior Tibial onto the dorsum of the foot.

Common Peroneal Artery

Sural Artery: Terminal branches of the Popliteal Artery, supplying the heads of the gastrocs. They are the exclusive supplier of the Gastrocnemius.

It contains no collateral circulation. If you lose your blood supply there, a lot of cramping of the leg will result.

It can be affected by a femoral artery occlusion, and it is not necessarily fixed by bypass surgery.

CLINICAL -- SUPRACONDYLAR FRACTURE of the distal femur can harm the popliteal artery.

Gastrocnemius Muscle can threaten the popliteal artery at its origin, where it flexes the distal femur. Tearing of the artery would cut blood supply to

entire leg essentially.

A Cast for this fracture should be made with the leg in the flexed position, so pull from the Gastrocnemius on the femur is minimal.

POPLITEAL VEIN: May thrombose, for example, during pregnancy, when the External Iliacs are pinched. The thrombus has potential to break lose and make its

way back to the lungs. Not good as usual.

POPLITEAL FOSSA (N472): The area behind the knee.

Borders:

Lateral border: Biceps Femoris

Medial border: Semimembranosus and semitendinosus muscles.

Inferior border: The lateral and medial head of the gastrocnemius.

CONTENTS:

The origin of the Popliteal Artery and terminus of the Popliteal Vein

The Lesser Saphenous Vein dumps into the popliteal vein at the Popliteal Fossa.

Sciatic Nerve can bifurcate into the Tibial and Common Peroneal as far inferiorly as the popliteal fossa.

The order of things going through Popliteal Fossa, from medial to lateral

ARTERY (popliteal artery)

VEIN (popliteal vein)

NERVE (sciatic or tibial nerve)

ANTERIOR COMPARTMENT OF THE LEG:

Action = Dorsiflexion of foot and some extension of digits

Innervation = Deep Peroneal Nerve

COMMON PERONEAL NERVE:

You can feel it over the head and neck of the fibula.

It divides into:

Deep Peroneal Nerve -- Anterior leg

Superficial Peroneal Nerve -- Lateral leg

CLINICAL -- IT CAN BE INJURED where it lies against the head of the fibula (a fracture of the proximal fibula) or around the lateral knee (the lateral

collateral ligament).

The telling sign for this injury is "foot drop", resulting from damage to the Deep Peroneal Nerve (anterior compartment -- no dorsiflexion of foot).

You will also Varus with this injury, due to injury to the Superficial Peroneal Nerve (lateral compartment -- no eversion of foot)

POSTERIOR COMPARTMENT OF THE LEG:

Action = Flexion of knee, plantarflexion of foot, some flexion of digits.

Innervation = Tibial Nerve.

Sural artery: Sole supplier of the Gastrocnemius, and it has no collateral circulation.

Sural nerve: A SPARE PART. It does not innervate the gastrocs -- the Tibial Nerve does.

Transverse Intermuscular Septum: Separates the superficial and deep compartments of the posterior leg.

Gastrocnemius and Soleus: Both of these muscles are essential for you to push off when you walk, and to change direction.

They are the primary plantar flexors of the foot -- let you stand on your toes.

LATERAL COMPARTMENT OF THE LEG:

Action = eversion of foot

Innervation = Superficial Peroneal Nerve.

JONES' FRACTURE: Pulling off or breaking a piece of the fibula distally, as often occurs with a sprained ankle.

This often results in damage to the Peroneus Brevis muscle, as its origin is on the fibula, which in turn means no eversion of the leg.