DIMS Lectures Lower Limbs Anatomy PDF

Here is the complete pdf lecture of lower limbs anatomy

Lower Limb Anatomy: Clinical Relevance and Functional Importance

The lower limb is essential for locomotion, weight-bearing, and balance, playing a fundamental role in daily activities such as walking, running, and maintaining posture. It consists of the hip, thigh, leg, and foot, each containing complex anatomical structures that contribute to mobility and stability. 

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1. Bones of the Lower Limb

The skeletal framework of the lower limb provides structural support and articulation for movement. The major bones include the hip bone, femur, patella, tibia, fibula, and bones of the foot.

1.1 Hip Bone (Pelvic Bone)

• The hip bone consists of three fused bones: ilium, ischium, and pubis, which meet at the acetabulum, forming the socket for the hip joint.
• The sacroiliac joint connects the pelvis to the spine, transmitting forces between the upper and lower body.
• Clinical relevance:
  • Pelvic fractures commonly occur in high-impact trauma (e.g., road traffic accidents, falls from height) and may be life-threatening due to vascular injury.
  • Acetabular fractures often result in hip dislocations, leading to possible sciatic nerve damage.
  • Hip osteoarthritis leads to pain and reduced mobility, often requiring total hip arthroplasty (hip replacement).

1.2 Femur (Thigh Bone)

• The longest and strongest bone in the human body.
• Proximally articulates with the acetabulum of the hip joint and distally articulates with the tibia and patella at the knee joint.
• Clinical relevance:
  • Femoral neck fractures are common in elderly individuals due to osteoporosis and may cause avascular necrosis of the femoral head due to disruption of the medial circumflex femoral artery.
  • Femoral shaft fractures often result from high-energy trauma and require intramedullary nailing.
  • Supracondylar fractures near the knee can damage the popliteal artery, leading to limb-threatening ischemia.

1.3 Patella (Kneecap)

• A sesamoid bone embedded within the quadriceps tendon.
• Acts as a fulcrum, increasing the leverage of the quadriceps for knee extension.
• Clinical relevance:
  • Patellar fractures impair knee extension and require immobilization or surgical fixation.
  • Patellar dislocation often occurs laterally due to imbalanced quadriceps pull and requires manual reduction and rehabilitation.

1.4 Tibia and Fibula (Leg Bones)

• Tibia: The primary weight-bearing bone of the leg.
• Fibula: Provides lateral stability and serves as an attachment site for muscles.
• Clinical relevance:
  • Tibial plateau fractures can damage the knee joint and menisci, leading to post-traumatic arthritis.
  • Fibular fractures are commonly associated with ankle sprains and Weber fractures.
  • Compartment syndrome is a surgical emergency following tibial fractures, requiring fasciotomy to prevent ischemic necrosis.

1.5 Foot Bones

• The foot consists of 26 bones divided into three regions:
  • Tarsal bones: Talus, calcaneus, navicular, cuboid, and three cuneiforms.
  • Metatarsal bones: Five bones forming the arch of the foot.
  • Phalanges: Toe bones.
• Clinical relevance:
  • Plantar fasciitis results from inflammation of the plantar fascia, causing heel pain.
  • Lisfranc injuries involve dislocation of the midfoot joints and require surgical stabilization.
  • Stress fractures of the metatarsals are common in athletes and military personnel.

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2. Joints of the Lower Limb

The joints of the lower limb facilitate stability, movement, and weight transmission.

2.1 Hip Joint

• Ball-and-socket joint allowing multidirectional movement.
• Ligaments: Iliofemoral (strongest ligament), pubofemoral, ischiofemoral.
• Clinical relevance:
  • Hip dislocations are usually posterior and can damage the sciatic nerve, leading to foot drop.
  • Developmental Dysplasia of the Hip (DDH) is a congenital condition requiring early diagnosis and treatment.

2.2 Knee Joint

• Hinge joint, composed of the femur, tibia, and patella.
• Menisci: Medial and lateral menisci absorb shock and stabilize the knee.
• Ligaments:
  • ACL (Anterior Cruciate Ligament) prevents anterior tibial translation.
  • PCL (Posterior Cruciate Ligament) prevents posterior tibial translation.
• Clinical relevance:
  • ACL injuries are common in athletes, requiring surgical reconstruction.
  • Meniscal tears cause joint locking and pain, treated via arthroscopy.

2.3 Ankle Joint

• Hinge joint formed by the tibia, fibula, and talus.
• Clinical relevance:
  • Lateral ankle sprains involve anterior talofibular ligament (ATFL) injury.
  • Fractures of the ankle need proper reduction to prevent post-traumatic arthritis.

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Clinical Points

• Femoral neck fractures are an orthopedic emergency requiring early surgical intervention.
• ACL injuries are common in sports and necessitate early physiotherapy and surgery.
• Common peroneal nerve injury causes foot drop, requiring splinting and rehabilitation.
• DVT prophylaxis is crucial in immobilized patients.

Case Example:

A 60-year-old female presents with inability to bear weight on her left leg after a fall. Examination reveals shortened and externally rotated leg.

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Diagnosis: Femoral Neck Fracture

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