Human Anatomy Week 7 - Outline Notes

Study Notes

Leg Osteology

Tibia:
- Medial and lateral condyles, intercondylar eminence, anterolateral tibial tubercle (Gerdy’s tubercle), tibial tuberosity, facet for fibula, shaft (anterior border and medial surfaces, interosseous border, soleal line), medial malleolus, fibular notch
Fibula:
- Head, neck, lateral malleolus, shaft
Interosseous membrane: Syndesmosis between tibia and fibula (middle tibiofibular joint)
Proximal and distal tibiofibular joints: Planar synovial joints

Leg Fascia

Crural Fascia:
- Continuous with fascia lata
- Surrounds the leg except along medial tibia, attaching to anterior and posterior tibia margins
- Intermuscular septa form anterior and lateral compartments
- Retinacula (superior and inferior extensor retinaculum, flexor retinaculum, fibular retinaculum) prevent tendon bowstringing at the ankle
Compartments of the leg:
- Anterior compartment: bounded by tibia, interosseous membrane, and anterior intermuscular septum
- Lateral compartment: bounded by anterior intermuscular septum, fibula, and posterior intermuscular septum
- Deep posterior compartment: bounded by tibia, interosseous membrane and fibula anteriorly and the transverse septum posteriorly
- Superficial posterior compartment: posterior to the transverse septum
- Clinical Relevance: Compartment syndrome (medical emergency), chronic overuse injuries leading to inflammation and increased pressure

Superficial Posterior Compartment

Overview: Powerful plantar flexors crucial for walking, running, jumping. Plantaris has little function and can be used for surgical repair.
Muscles: gastrocnemius, soleus, plantaris
Neurovascular: Shares posterior tibial artery and tibial nerve with the deep posterior compartment
Clinical Considerations: Achilles tendonitis/rupture (improper training), deep vein thrombosis (DVT) and calf pump

Deep Posterior Compartment

Overview: Long flexors of the foot and toes, controlling the foot during standing and gait.
Muscles: Popliteus, flexor hallucis longus, flexor digitorum longus, tibialis posterior
Neurovascular: Innervation (tibial nerve), vascular (posterior tibial artery)
Clinical Considerations: Pure inversion (tibialis anterior and posterior working together)

Anterior Compartment

Overview: Dorsiflexors (extensors) of the ankle.
Muscles: Tibialis anterior, extensor digitorum longus, extensor hallucis longus, fibularis tertius
Dorsal foot muscles (short toe extensors): extensor digitorum brevis, extensor hallucis brevis
Neurovascular: Innervation (deep fibular nerve), vascular (anterior tibial artery becoming dorsalis pedis artery)
Clinical Considerations: Anterior shin splints (inflammation), compartment syndrome, foot drop

Lateral Compartment

Overview: Evert the ankle, counteracting inversion. Fibularis longus stabilizes arches of the foot
Muscles: Fibularis longus, fibularis brevis
Neurovascular: Innervation (superficial fibular nerve), vascular (fibular artery – NOT in lateral compartment but supplies it via perforating branches)
Clinical Considerations: Superficial fibular nerve injury in lateral ankle sprain.

Neurovascular Overview

Arterial supply: Popliteal artery divides into anterior and posterior tibial arteries, supplying the anterior compartment (with deep fibular nerve) and deep posterior compartment (with fibular artery) respectively.
Superficial veins: Great saphenous (medial) and small saphenous (posterior)
Innervation:
- Tibial nerve in deep posterior compartment.
- Deep fibular nerve in the anterior compartment.
- Superficial fibular nerve in the lateral compartment.

Tibiofibular Joints

Proximal tibiofibular joint:
- Structure: gliding planar joint, ligaments (proximal anterior and posterior tibiofibular ligament).
- Supports: Common peroneal nerve, biceps femoris and popliteus tendons, IT band, origins of PL, EDL, lateral gastrocnemius and soleus.
- Motions: Fibula glides superiorly and posteriorly with dorsiflexion.
- Neurovascular supports: Common peroneal nerve, lateral genicular, anterior tibial, and recurrent tibial arteries.
Middle tibiofibular joint: Syndesmosis (interosseous membrane), motions are accessory with the ankle joint.
Distal tibiofibular joint:
- Structure: fibrous/syndesmosis, ligaments (interosseus, distal anterior and posterior tibiofibular ligament).
- Supports: Transverse tibiofibular ligament (involved in “trimalleolar fx”).
- Neurovascular supports: Deep peroneal, tibial, and saphenous nerves, perforating branches of peroneal, anterior and posterior tibial arteries.
- Motions: Fibula glides superiorly and posteriorly with dorsiflexion.

Clinical Considerations

Tibial fractures (heal slowly due to poor blood supply)
Common fibular nerve injuries (causes foot drop)
Deep venous thrombosis and varicose veins
Compartment syndrome
Shin splints: anterior and medial (anterior discussed above)
Ankle reflex (S1 and S2)

Description

Test your knowledge on the anatomy of the leg, including the tibia and fibula, as well as the surrounding fascia. This quiz covers key features, structures, and compartments within the leg. Perfect for anatomy students and enthusiasts looking to deepen their understanding of lower limb osteology and fascial structures.