Leg of Lower Limb Anatomy PDF

Lecture 3: Gross Anatomy of the Leg Course Code: ANA 214 Course Title: Gross Anatomy of Lower Limb Course Lecturer: Adedamola A. FAFURE Learning Objectives: At the end of the class, students should be able to: Describe the osteology of the leg. Learn and appreciate the muscles of the anterior,...

Lecture 3: Gross Anatomy of the Leg Course Code: ANA 214 Course Title: Gross Anatomy of Lower Limb Course Lecturer: Adedamola A. FAFURE Learning Objectives: At the end of the class, students should be able to: Describe the osteology of the leg. Learn and appreciate the muscles of the anterior, posterior, and lateral compartments. Describe the blood and nerve supply to the leg. Describe the popliteal fossa. Introduction: Dermatomes of the Leg Antero-Medially side: Antero-Laterally side: Posteriorly: S2 and S1 Definition: The leg is the region of the lower limb between the knee and the ankle joints. The leg is made up of two important bones: 1. Tibia 2. Fibula The tibia articulates with the condyles of the femur superiorly and the talus inferiorly, transmitting the body’s weight. The fibula mainly functions as an attachment for muscles and is important for ankle joint stability. The shafts of the tibia and fibula are connected by a dense interosseous membrane composed of strong oblique fibers descending from the tibia to the fibula. Tibia: The tibia is the primary weight-bearing bone of the leg. Proximally: Articulates with the condyles of the femur. Distally: Articulates with the talus of the foot. Key Features: Medial condyle: Supports the medial condyle of the femur. Serves as an insertion point for semimembranosus muscles. Lateral condyle: Supports the lateral condyle of the femur. The head of the fibula articulates with its posterior-inferior part. Medial malleolus: Articulates with the medial surface of the talus. Serves as the origin for the deltoid ligament complex. Osteology of the Tibia: Key Features: 1. Tibial tuberosity: An elevation on the proximal anterior aspect of the tibia. Serves as an insertion point for the patellar ligament. 2. Border of the interosseous membrane: The medial attachment point of the interosseous membrane. 3. Nutrient foramen: A small, smooth-walled hole for blood vessels on the posterior surface of the tibia. Entry point for the nutrient artery. 4. Soleal line: A rough diagonal ridge on the posterior surface of the tibia. Serves as part of the soleus muscle origin. Fibula: A long, slim bone located posterolateral to the tibia. Firmly attached to the tibia by the tibiofibular syndesmosis, which includes the interosseous membrane. Key Roles: Has no function in weight-bearing. Serves as an attachment site for muscles. Key Features: 1. Head: Articulates with the lateral condyle of the tibia. Serves as an insertion point for the fibular collateral ligament and biceps femoris. 2. Neck: The common fibular nerve passes along the fibular neck. 3. Lateral malleolus: Stabilizes the ankle joint by limiting eversion. Origin for the lateral ligament of the ankle. Clinical Relevance: Tibial Fracture: Most common site: The shaft at the junction of its middle and inferior thirds. Area has the poorest blood supply, making healing slow. Fibular Fracture: Occurs 2-6 cm proximal to the distal end of the lateral malleolus. Often associated with ankle joint fractures or dislocations. Bone Grafts: The fibula is commonly used for bone grafting. Even after a segment is removed, normal walking, running, and jumping can resume. Fascia of the Leg (Crural): 1. Superficial fascia: Subcutaneous tissue on the medial side of the tibia. 2. Deep fascia: Covers only muscles and thickens around the ankle to form five retinacula. Retinacula: Superior and inferior extensor retinacula. Superior and inferior peroneal retinacula. Flexor retinaculum: Prevents tendons from bowstringing during joint movements. Muscles of the Leg: The leg is divided into compartments: anterior, posterior, and lateral. 1. Anterior compartment: Includes muscles like tibialis anterior and extensor digitorum longus. 2. Posterior compartment: Includes gastrocnemius and soleus muscles. 3. Lateral compartment: Includes fibularis longus and brevis. Continuing from where the previous extraction ended: Extensor Retinacula: Structures Passing Deep to Extensor Retinacula (from medial to lateral): 1. Tibialis anterior 2. Extensor hallucis longus 3. Anterior tibial artery (ATA) 4. Venae comitantes of ATA 5. Deep peroneal nerve (anterior tibial nerve) 6. Extensor digitorum longus 7. Peroneus tertius Peroneal Retinacula: A thickening of the deep fascia located posteriorly and inferiorly to the distal aspect of the fibula. Divisions: 1. Superior Peroneal Retinaculum: Attached anteriorly to the lateral malleolus and posteriorly to the calcaneus. 2. Inferior Peroneal Retinaculum: Attached superiorly and inferiorly to the calcaneus. Structures Passing Deep to Peroneal Retinacula: 1. Peroneus brevis 2. Peroneus longus Flexor Retinaculum: Helps prevent tendon injuries by keeping them in their proper positions. Reduces risks of ruptures, dislocations, or subluxations. Posterior Compartment of the Leg: Superficial Layer: 1. Gastrocnemius: Action: Plantarflexes the ankle and flexes the leg at the knee joint. 2. Soleus: Action: Plantarflexes the ankle. 3. Plantaris: Action: Weakly assists in knee flexion. Nerve Supply: Tibial nerve (S1, S2) Blood Supply: Posterior tibial artery Fibular artery Clinical Conditions: Paralysis of Extensor Hallucis Longus: Results in constant flexion of the big toe due to unopposed flexor muscle action. Tennis Leg: Caused by overstretching the gastrocnemius muscle. Symptoms: Sudden sharp pain in the back of the calf. Achilles Tendonitis: Repetitive strain injury. Symptoms: Pain and bony enlargement at the heel. Popliteal Fossa: Diamond-shaped depression located behind the knee joint. Boundaries: 1. Superolaterally: Biceps femoris. 2. Superomedially: Semitendinosus and semimembranosus, supported by gracilis, sartorius, and adductor magnus. 3. Inferolaterally: Lateral head of the gastrocnemius. 4. Posteriorly (Roof): Deep popliteal fascia, superficial fascia containing the short saphenous vein, and three cutaneous nerves. Contents: 1. Popliteal artery and its branches. 2. Popliteal vein and its tributaries. 3. Tibial and common peroneal nerves. 4. Popliteal lymph nodes. Clinical Relevance: Popliteal Aneurysm: Dilation of the artery greater than 50% of its size. May compress the tibial nerve, leading to weakened plantarflexion or paraesthesia of the foot.