Hip

Coxa

Definition

The hip (or the hip joint) is situated laterally to the gluteal region (or buttocks).

Bony framework:

The underlying bony structure consists of the articulation between the head of the femur and the acetabular fossa of the hip bone. The hip joint is a ball and socket type of synovial joint, allowing a wide range of movements, including flexion, extension, adduction, abduction, circumduction, and internal and external rotation of the lower limb.

Capsule, ligaments, and vasculature:

  • A fibrocartilaginous ring, the acetabular labrum, provides stability to the joint by attaching to the margins of the acetabulum and deepening the acetabular cavity.

  • A fibrous capsule is attached to the margins of the acetabulum and the distal part of the femoral neck, with most of neck lying within the joint cavity. It is further reinforced by three surrounding ligaments on the outside: the iliofemoral, ischiofemoral, and pubofemoral ligaments.

  • The ligament of the head of the femur is attached at one end to the head of the femur and the other end to the acetabular notch. A branch of the obturator artery passes through the notch and courses through the ligament of the head of femur to supply blood to the femoral head. A fracture of the femoral neck could lead to avascular necrosis of the femoral head.

  • The vascular supply to the hip joint also comes from branches of the medial and lateral circumflex femoral arteries, which are branches of the profunda femoris artery (a.k.a. deep femoral artery).

Musculature:

Muscles in the hip include the deep and superficial gluteal muscles:

  • The deep muscles of the gluteal region, originating from the hip bone and the sacrum, pass laterally behind the hip joint to insert into the greater trochanter of the femur, causing lateral rotation of the hip joint.

  • The superficial muscles of the gluteal region also extend laterally to cover the hip from the back. They insert into the femur (greater trochanter and shaft) and iliotibial tract to bring about various movements of the hip.

Osteoarthritis of the hip occurs with age, wherein the cartilage on the articulating joint surfaces wears off due to ‘wear and tear’ with age, exposing the underlying bone and thus causing pain.

Hip dislocation is uncommon due to the joint’s stability; however, a traumatic accident may dislocate the femoral head posteriorly and damage the sciatic nerve.

Text written by Muhammad A. Javaid, MD, PhD © 2023 IMAIOS.

  • Drake, R.L., Vogl, A.W. and Mitchell, A.W.M. (2009). ‘Chapter 6: Lower Limb’ in Gray’s anatomy for Students. (2nd ed.) Philadelphia PA 19103-2899: Elsevier, pp.532-547.

  • Barney, J., Piuzzi, N.S. and Akhondi, H. Femoral Head Avascular Necrosis. [Updated 2022 Jul 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546658/

  • Masiewicz, S., Mabrouk, A. and Johnson, D.E. Posterior Hip Dislocation. [Updated 2022 Sep 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459319/


Comparative anatomy in animals

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