Describe Hip Joint under the following headings: Articular surface and Types Ligaments Relations Blood supply and Nerve supply Movement

Articular Surface and Types

The hip joint’s articular surface comprises two main components:

• Acetabulum: This is the socket formed by the fusion of the ilium, ischium, and pubis bones. It’s a hemispherical cavity, deepened by a fibrocartilaginous rim called the labrum acetabuli. The labrum increases the depth and stability of the socket.
• Head of the Femur: This is a roughly spherical projection articulating within the acetabulum. A small pit on the head, the fovea capitis femoris, serves as the attachment point for the ligament of the head of the femur.

The hip joint is classified as a spheroidal synovial joint, specifically a ball-and-socket joint. This classification reflects the spherical shape of the femoral head and the cup-like nature of the acetabulum, allowing for multi-axial movement.

Ligaments

Several ligaments contribute to the stability of the hip joint:

• Iliofemoral Ligament (Y-Ligament): The strongest ligament, extending from the anterior inferior iliac spine to the intertrochanteric line of the femur. It resists hip extension and abduction.
• Pubofemoral Ligament: Runs from the pubic tubercle to the pectineal line of the femur. It resists hip abduction and external rotation.
• Ischiofemoral Ligament: Extends from the ischial tuberosity to the greater trochanter of the femur. It provides posterior stability and resists hip extension.
• Ligament of the Head of the Femur (Ligamentum Teres): A small ligament within the acetabulum, connecting the fovea capitis femoris to the transverse acetabular ligament. It carries a small artery and contributes to nutrient supply.
• Transverse Acetabular Ligament: Bridges the acetabular notch, converting it into a foramen for the passage of vessels and nerves.

Relations

The hip joint has several important relations:

• Anteriorly: Rectus femoris, sartorius, iliopsoas muscles, femoral artery, femoral nerve, and femoral branch of the genitofemoral nerve.
• Medially: Adductor longus, adductor brevis, adductor magnus, obturator nerve and vessels.
• Posteriorly: Gluteus maximus, gluteus medius, gluteus minimus, piriformis, obturator internus, quadratus femoris, sciatic nerve, and superior and inferior gluteal arteries and nerves.
• Laterally: Gluteus medius, gluteus minimus, tensor fasciae latae.

Blood Supply and Nerve Supply

Blood Supply: The hip joint receives its arterial supply primarily from the:

• Medial Circumflex Femoral Artery: Supplies the femoral head and neck.
• Lateral Circumflex Femoral Artery: Supplies the greater trochanter and surrounding tissues.
• Acetabular Branch of the Internal Iliac Artery: Contributes to the capsular blood supply.
• Obturator Artery: Provides some contribution to the joint capsule.

Venous drainage follows the arterial supply, ultimately draining into the internal iliac veins.

Nerve Supply: The hip joint is innervated by:

• Sciatic Nerve: Provides innervation to the posterior aspect of the joint.
• Femoral Nerve: Innervates the anterior aspect of the joint.
• Obturator Nerve: Supplies some of the adductor muscles and contributes to joint sensation.
• Superior Gluteal Nerve: Innervates the gluteus medius and minimus, contributing to hip stability.

Movement

The hip joint allows for a wide range of movements:

• Flexion: Bringing the thigh forward (approximately 120 degrees).
• Extension: Moving the thigh backward (approximately 30 degrees).
• Abduction: Moving the thigh away from the midline (approximately 45 degrees).
• Adduction: Moving the thigh towards the midline (approximately 30 degrees).
• Internal Rotation: Rotating the thigh inward (approximately 40 degrees).
• External Rotation: Rotating the thigh outward (approximately 60 degrees).
• Circumduction: A combination of flexion, extension, abduction, and adduction, resulting in a conical movement.