The Knee and Lower Leg

• The articulation between the femur and the tibia
• Uniaxial synovial joint
• Modified hinge joint due to the differences between the lateral and medial femoral condyles
• 2 menisci
• 4 primary ligaments
• 13-15 bursae
• Joint capsule

• Semitendinosis/Semimebranosis
• Biceps femoris
• Medial head of gastrocnemius
• Lateral head of gastrocnemius

• Medial Collateral Ligament (MCL)
• Lateral Collateral Ligament (LCL)
• Anterior Cruciate Ligament (ACL)
• Posterior Cruciate Ligament (PCL)

Origin: Medial epicondyle of the femur

Insertion: Medial tibial plateau

Action: Resists valgus stress

• *Inserts slightly deeper and superior to pes anserine*
• *Longer of two collateral ligaments and therefore more prone to injury*
• *Located 3 fingers below the joint line*

Origin: Lateral epicondyle of the femur

Insertion: Fibular head

Action: Resists varus stress

*Shorter and therefore sturdier than the medial collateral ligament*

Origin: Anterior intercondylar eminence (tubercle) of tibia

Insertion: Posterior lateral femoral condyle

Action: Resists external rotation, anterior displacement of tibia on femur, and hyperextension

Origin: Posterior intercondylar eminence (tubercle) of tibia

Insertion: Anterior medial femoral condyle

Action: Resists external rotation, posterior displacement of tibia on femur, and hyperflexion

• *The PCL is not as long as the ACL and therefore does not get injured quite as frequently*
• *Both the ACL and PCL are intracapsular structures*

• They are more competitive than before
• Hips are wider
• Shallower intercondylar notches

• "C" shaped
• Fibrocartilage discs that lie between the femur and tibia in the knee
• Contains both medial and lateral menisci
• Joined in the middle by two ligaments: coronary and transverse ligaments
• Can be injured by twisting or rotation in which case swelling (effusion) would occur 24-48 hours after the injury

• Absorb shock/cushion
• Provide smooth articulation
• Add stability (menisci are slightly thicker on lateral aspect, which helps form a little fossa; like a saucer)

Attaches the meniscus to the tibial condyle

Attaches meniscus to meniscus

• Located on the medial aspect
• Larger and more "C" shaped
• Firmly attached to the tibial condyle and therefore more prone to injury

• Fatter (because the medial femoral condyle is longer, the lateral meniscus compensates to prevent unevenness)
• More "O" shaped
• Not as firmly attached to tibial condyle

• Small fluid-filled sacs
• Cushion and reduce friction
• Lubricate articulating surfaces
• Injured by extreme force

• *Suprapatellar bursa is the largest bursa in the knee*
• *Prepatellar bursa is one of the most commonly injured bursa in the knee*

The name given to the bursa located in the popliteal fossa, which contains lymph fluid

*Commonly injured with an ACL injury*

• Femur displaces posteriorly
• Tibia displaces anteriorly

• Femur displaces anteriorly
• Tibia displaces posteriorly

• Anterior Cruciate Ligament
• Medial/Lateral meniscus
• Medial Collateral Ligament

• Varus stress
• Valgus stress

Swelling within the joint capsule

Swelling outside of the joint capsule

Osgood Schlatter's; when a muscle is stronger than a bone

• 26 bones between the knee and toes
• Tibia
• Fibula
• 4 compartments (surrounded by synovial tissue)

• Tarsals (14)
• Metatarsals (10)
• Phalanges (28)

• 14 total
• Calcaneus (heel)
• Talus
• Navicular
• Cuboid
• Lateral (3rd) cuneiform
• Intermediate (2nd) cuneiform
• Medial (1st) cuneiform

• 28 total
• Proximal
• Distal
• Middle

*The great toe (hallux) has only 2, while others have 3*

Lateral Compartment

Origin: Shaft and head of the fibula

Insertion: Base of the 1st metatarsal

Action: Ankle eversion

*Runs posterior and lateral to lateral malleolus and inserts at the base of plantar surface of the 1st metatarsal*

Lateral Compartment

Origin: Inferior 2/3 of the fibula

Insertion: Base of the 5th metatarsal (styloid process)

Action: Ankle eversion

Anterior Compartment

Origin: Lateral condyle and shaft of tibia

Insertion: Medial cuneiform and 1st metatarsal

Action: Ankle dorsiflexion and ankle inversion

Anterior Compartment

Origin: Anterior shaft of fibula

Insertion: Base of distal phalanx of great toe

Action: Dorsiflexion of the great toe (hallux) and very little ankle dorsiflexion

Anterior Compartment

Origin: Lateral tibial condyle

• Insertion: Middle and distal phalanges of digits 2-5
• Action: Dorsiflexion of toes and very little ankle dorsiflexion

Superficial Posterior Compartment

• Origin: Lateral head - Lateral femoral condyle
• Origin: Medial head - Medial femoral condyle

Insertion: Posterior surface of calcaneus (posterior calcaneal tubercle)

Action: Ankle plantarflexion (pulls on posterior aspect)

• *If you exercise the gastrocnemius with feet internally rotated, you will work the lateral head more*
• *If you exercise the gastrocnemius with feet externally rotated, you will work the medial head more*

Superficial Posterior Compartment

Origin: Posterior shaft of tibia and fibula

Insertion: Posterior sruface of calcaneus

Action: Ankle plantarflexion

By incorporating knee flexion; example: seated calf raises

Triceps surae

Superficial Posterior Compartment

Origin: Lateral femoral supracondylar line

Insertion: Posterior surface of calcaneus

Action: Assists the gastrocnemius in ankle plantarflexion

*NOT a part of the triceps surae*

Deep Posterior Compartment

Origin: Posterior surface of tibia and fibula

Insertion: Navicular, cuneiforms (3), and cuboid

Action: Ankle inversion and very weak ankle plantarflexion

Yes, but just a little

Ruptured achilles tendon

Deep Posterior Compartment

Origin: Posterior tibial shaft

Insertion: Middle and distal phalanges of digits 2-5

Action: Plantarflexion of digits 2-5; very weak ankle plantarflexion

Deep Posterior Compartment

Origin: Inferior 2/3 of fibula

Insertion: Base of distal phalanx of great toe

Action: Plantarflexion of the great toe; very weak ankle plantarflexion

Swelling in a compartment; muscle loss, foot drop and can cause lower blood flow

• Medial tibial stress syndrome (MTSS)
• Muscle (perimysium) pulls away from the bone

• Peroneus Longus
• Peroneus Brevis

• Anterior Tibialis
• Extensor Hallucis Longus
• Extensor Digitorum Longus

• Gastrocnemius
• Soleus
• Plantaris

• Tibialis Posterior
• Flexor Digitorum Longus
• Flexor Hallucis Longus