What is the Difference Between Acetabulum and Glenoid Cavity

The main difference between the acetabulum and the glenoid cavity is that acetabulum articulates with the head of the femur in the lower limb, whereas the glenoid cavity articulates with the head of the humerus in the upper limb.  

Acetabulum and glenoid cavity are bony cavities that articulate limbs to the axial skeleton.  

Key Areas Covered

1. What is Acetabulum
– Definition, Structure, Function
2. What is Glenoid Cavity
– Definition, Structure, Function
3. Similarities Between Acetabulum and Glenoid Cavity
– Outline of Common Features
4. Difference Between Acetabulum and Glenoid Cavity
– Comparison of Key Differences

Key Terms 

Acetabulum, Glenoid Cavity

What is Acetabulum

Acetabulum or cotyloid cavity is a concave surface of the pelvis. It forms the hip joint with the head of the femur. Also, the hip joint is a ball-socket joint that provides dynamic support to the body’s weight. Additionally, it connects the lower extremities to the central body. Further, the acetabulum is a cup-like depression in the inferolateral aspect of the pelvis. The acetabular labrum is the fibrocartilaginous collar that deepens the acetabulum cavity. The hemispherical head of the femur fits entirely together with the concavity of the acetabulum. On the other hand, the articular cartilage covers both the acetabulum and the head of the femur.

Figure 1: Acetabulum

Furthermore, ligaments of the hip joint increase the stability of the joint. Two groups of ligaments occur in the acetabulum. They are the intracapsular and extracapsular ligaments. The ligament of the head of the femur is the intracapsular ligament which is relatively small. There are three main extracapsular ligaments: the iliofemoral ligament, the pubofemoral ligament, and the iliofemoral ligament. They cover the outer surface of the hip joint capsule. 

What is Glenoid Cavity

The glenoid cavity is the ball-socket joint that articulates the upper limb with the axial skeleton. It occurs in the scapula. Also, it forms the primary articulation of the shoulder girdle. Significantly, the glenohumeral joint is the most mobile joint of the human body. Therefore, the glenoid cavity provides a complex and dynamic articulation between the scapula and the proximal humerus. Notably, the head of the humerus articulates with the scapula, forming the shoulder joint. Additionally, the glenoid cavity contains a glenoid labrum, a fibrocartilaginous rim structurally deepening the glenoid cavity.

Figure 2: Glenoid Cavity

Moreover, the relative size of the humeral head, compared to the shallow glenoidal fossa, is 4:1. Therefore, the ball-socket joint in the shoulder girdle is one of the most dislocating joints in the human body. 

Similarities Between Acetabulum and Glenoid Cavity

• Acetabulum and glenoid cavity are two articulation structures in the limbs.
• They articulate limbs to the axial skeleton.
• They form ball-and-socket joints between limbs and the axial skeleton. 

Difference Between Acetabulum and Glenoid Cavity

Definition

Acetabulum refers to a large socket on the lateral face of the hip bone that articulates with the head of the femur to form the hip joint. In contrast, the glenoid cavity refers to a shallow depression on a bone into which another bone fits to form a joint, especially that on the scapula into which the head of the humerus fits.  

Anatomy

Acetabulum is a large socket on the lateral face of the hip bone that articulates with the head of the femur to form the hip joint, while in the glenoid cavity; glenohumeral articulation involves the humeral head with the glenoid cavity of the scapula. 

Occurrence

The acetabulum occurs in the hip, while the glenoid cavity occurs in the scapula. 

Importance

Acetabulum articulates with the head of the femur in the lower limb, while the glenoid cavity articulates with the head of the humerus in the upper limb.  

Function

Acetabulum connects the pelvis to the lower limb, while the glenoid cavity gives the shoulder joint the highest flexibility compared to other joints.   

Conclusion

In brief, the acetabulum and glenoid cavity are two types of ball-and-socket joints that articulate limbs to the axial skeleton. Acetabulum articulates the lower limb to the axial skeleton. It connects the pelvis to the lower limb. Also, it is a large socket that occurs in the lateral face of the hip bone. In comparison, the glenoid cavity articulates the upper limb to the axial skeleton. It forms the shoulder joint. Therefore, the main difference between the acetabulum and the glenoid cavity is the type of articulation.

References:

1. The hip joint. TeachMeAnatomy. (n.d.). 
2. Chang LR, Anand P, Varacallo M. Anatomy, Shoulder and Upper Limb, Glenohumeral Joint. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.

Image Courtesy:

1. “Pelvic girdle illustration.” By U.S. National Cancer Institute – Own work (CC-BY SA 4.0) via Commons Wikimedia
2. “914 Shoulder Joint.” By OpenStax College – Own Work (CC-BY 3.0) via Commons Wikimedia