Anatomy of Lower Limb - Quick Review - Anatomy Review Series

Summary

This video, hosted by Medicosis Perfectionist, offers a comprehensive and engaging review of the anatomy of the lower extremities. It covers the major muscle groups of the thigh and leg, their functions, and the nerves that supply them. The video delves into the lumbosacral plexus, explaining the various nerves, including the femoral, obturator, sciatic, and pudendal nerves. It also discusses arterial and venous supply, lymphatic drainage, and the significance of nerve injuries. With humor and clarity, the host emphasizes how understanding these concepts can make anatomy seem less complex, aiming to help medical students grasp the essentials with ease.

Takeaways

• 😀 The lower extremity functions oppositely to the upper extremity during movement due to embryological development. For example, while the upper arm moves forward during shoulder flexion, the thigh moves backward during hip flexion.
• 😀 The thigh is divided into three compartments: anterior (hip flexion and knee extension), medial (hip adduction), and posterior (knee flexion).
• 😀 The quadriceps and sartorius are located in the anterior compartment, while the adductors like adductor longus and magnus are in the medial compartment.
• 😀 The hamstring muscles, located in the posterior compartment, are responsible for knee flexion. These include biceps femoris, semitendinosus, and semimembranosus.
• 😀 The lumbosacral plexus, which provides motor and sensory innervation to the lower limbs, is made up of the lumbar plexus (femoral and obturator nerves) and the sacral plexus (sciatic and pudendal nerves).
• 😀 The sciatic nerve is actually two nerves: the tibial nerve and the common fibular nerve. The tibial nerve controls the posterior leg muscles, and the common fibular nerve controls the anterior and lateral leg muscles.
• 😀 The lumbar plexus supplies the anterior (femoral nerve) and medial (obturator nerve) compartments of the thigh. The sciatic nerve from the sacral plexus supplies the posterior thigh.
• 😀 The leg is divided into anterior (dorsiflexion), posterior (plantar flexion), and lateral (everting) compartments, with distinct nerve supply: the deep fibular nerve for the anterior compartment, superficial fibular nerve for the lateral compartment, and tibial nerve for the posterior compartment.
• 😀 The deep femoral artery, not the femoral artery, is the main arterial supply to the thigh, providing branches like the medial and lateral circumflex femoral arteries.
• 😀 Venous drainage of the lower limbs is similar to arterial supply, with the greater saphenous vein draining into the femoral vein and lymphatic drainage primarily going to the femoral lymph nodes.
• 😀 A common clinical condition, sciatica, results from injury to the sciatic nerve, causing pain and numbness along the leg. Foot drop and high-steppage gait are typical symptoms of common fibular nerve injury.

Q & A

What is the main difference between the lower limb and the upper limb in terms of movement and rotation during embryological development?

During embryological development, the upper and lower limbs rotate in opposite directions. The upper extremity rotates laterally, while the lower extremity rotates medially, resulting in opposite movements. For example, flexion of the shoulder moves the arm anteriorly, while flexion of the hip moves the thigh posteriorly.

What are the three compartments of the thigh, and what are their primary functions?

The thigh is divided into three compartments: anterior, medial, and posterior. The anterior compartment is responsible for flexing the hip and extending the knee. The medial compartment is responsible for adducting the hip. The posterior compartment contains the hamstring muscles, which flex the knee.

What muscles make up the quadriceps, and what is their primary function?

The quadriceps are made up of four muscles: rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius. Their primary function is to extend the knee.

Which muscles are involved in knee flexion, and what is their anatomical location?

The hamstring muscles, which include the biceps femoris, semitendinosus, and semimembranosus, are responsible for knee flexion. These muscles are located in the posterior compartment of the thigh.

What is the function of the lumbar and sacral plexuses, and which major nerves do they give rise to?

The lumbar and sacral plexuses are networks of nerves that supply motor and sensory innervation to the lower limbs. The lumbar plexus gives rise to the femoral and obturator nerves, while the sacral plexus gives rise to the sciatic and pudendal nerves.

How is the sciatic nerve structured, and what are the two components that make it up?

The sciatic nerve is composed of two separate nerves: the tibial nerve and the common fibular nerve. These two nerves are bundled together to form the sciatic nerve.

What is the role of the femoral nerve, and which compartment does it supply in the thigh?

The femoral nerve supplies the anterior compartment of the thigh, which includes the quadriceps and sartorius muscles. It is responsible for hip flexion and knee extension.

What happens when the tibial nerve is injured, and what is the resulting condition called?

Injury to the tibial nerve results in the inability to plantar flex the foot, leading to a condition called 'tip-toe walking difficulty' or 'calcaneo valgus.' This prevents walking on tiptoes or downhill.

What are the muscles responsible for dorsiflexion and plantar flexion of the foot, and which nerves innervate them?

The muscles responsible for dorsiflexion include tibialis anterior, extensor hallucis longus, and extensor digitorum longus, innervated by the deep fibular nerve. The muscles responsible for plantar flexion include gastrocnemius, soleus, and tibialis posterior, innervated by the tibial nerve.

What is the role of the superior gluteal nerve, and what happens if it is injured?

The superior gluteal nerve innervates the gluteus medius and minimus, which are responsible for stabilizing the pelvis during walking. Injury to this nerve leads to a positive Trendelenburg sign, where the pelvis tilts toward the opposite side during single-leg stance.