AP review

Class 7: Lower Leg and Foot

1. Major Muscles of the Lower Leg and Foot & Joints They Cross:

• Anterior Compartment (dorsiflexors): Tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius (cross ankle joint).

• Lateral Compartment (everters): Fibularis longus & brevis (cross ankle joint).

• Posterior Compartment (plantarflexors): Gastrocnemius, soleus, plantaris, tibialis posterior, flexor digitorum longus, flexor hallucis longus (cross knee and ankle joints).

2. Flexor Side vs. Extensor Side:

• Flexor side is generally posterior (back of leg).

• Extensor side is anterior (front of leg).

• The lateral malleolus and interosseous membrane help divide the compartments.

3. Joint Names in the Foot:

• Tarsometatarsal, metatarsophalangeal (MTP), interphalangeal (IP), subtalar, talocrural.

4. Tarsal Bones (7):

• Talus, calcaneus, navicular, cuboid, and 3 cuneiforms (medial, intermediate, lateral).

5. Weight Transfer Pathway:

• Femur → Tibia → Talus → Calcaneus → Forefoot via metatarsals.

6. Anatomy of the Patella:

• Sesamoid bone embedded in quadriceps tendon.

• Increases leverage of quadriceps during knee extension.

7. Muscles That Control the Big Toe and Pinky Toe:

• Big toe (hallux): Flexor/extensor hallucis longus and brevis, abductor/adductor hallucis.

• Pinky toe: Flexor/extensor digiti minimi, abductor digiti minimi.

8. Muscle That Doesn’t Exist in 8–12% of People:

• Plantaris.

9. Achilles Tendon Made Of:

• Tendons from gastrocnemius, soleus, plantaris.

10. Retinacula:

• Thick bands that hold tendons in place at ankle.

• Superior/inferior extensor, flexor, and fibular retinacula.

11. Dorsiflexion vs. Plantar Flexion:

• Dorsiflexion: Lifting foot up (tibialis anterior).

• Plantar flexion: Pointing toes down (gastrocnemius, soleus).

12. Triceps Surae Group:

• Gastrocnemius, soleus, and plantaris.

13. Locked Knee Key Muscle:

• Vastus medialis oblique (VMO) stabilizes and prevents lateral patellar tracking.

14. Other Names for Fibularis Longus/Brevis:

• Peroneus longus/brevis.

15. Muscles That Invert/Evert the Foot:

• Invert: Tibialis anterior & posterior.

• Evert: Fibularis longus, brevis, tertius.

16. ACL, PCL, MCL, LCL:

• ACL: Anterior cruciate ligament – prevents anterior tibial translation.

• PCL: Posterior cruciate ligament – prevents posterior tibial translation.

• MCL: Medial collateral ligament – resists valgus force.

• LCL: Lateral collateral ligament – resists varus force.

• LCL is injured 85% of the time in inversion sprains.

17. Popliteal Artery Location:

• Posterior knee within popliteal fossa.

18. Deltoid Ligament:

• Located on medial side of ankle; very strong, resists eversion.

19. Posterior Tibial and Dorsalis Pedis Arteries:

• Posterior tibial: Felt behind medial malleolus.

• Dorsalis pedis: Felt on dorsum of foot between 1st and 2nd metatarsals.

20. Sesamoid Bones of the Foot:

• Found under head of the 1st metatarsal, embedded in flexor hallucis brevis tendons.