Joints of the Upper Limbs

Glenohumeral Joint

Notes on the glenohumeral (shoulder) joint:

1. Type

   • Ball and socket joint

2. Articulation

   • Distally it articulates with the head of the humerus

   • Proximally it articulates with the glenoid cavity of the scapula which is deepened by the glenoid labrum

3. Synovial Membrane

   • A synovia membrane lines the capsule and is attached to the articular surfaces

   • Synovial fluid is produced to keep the joint well articulated

   • This membrane extends to form the subscapularis bursa (under the subscapularis)

4. Capsule

   • The joint is enclosed by the fibrous capsule which attaches to the anatomical neck of the humerus and the glenoid labrum of the scapula

   • Inferiorly it is weaker to allow for abduction to occur

5. Cartilage

   • Its articular surfaces are covered by hyaline cartilage

6. Stability

   • In order to permit a wider range of movements, this joint has diminished stability

   • Its stability relies on the tone of the rotator cuff muscles to hold the humerus in place in the glenoid fossa

   • Where the rotator cuff muscles are more deficient (inferiorly) is where this joint is the weakest.

Clinical Notes:

1. Frozen shoulder occurs when adhesive fibrosis and scarring of the capsule (including rotator cuff and deltoid muscles) results in difficulties when abducting the arm.

2. Inferior dislocations commonly occur at this joint due to the stronger carcoacromial arch and rotator cuffs superiorly and the deficiency inferiorly.

Humeroulnar and Proximal Radioulnar Joints

Notes on the humeroulnar and proximal radioulnar joints:

1. Type

   • Humeroulnar - synovial hinge joint

   • Proximal radioulnar - synovial pivot joint

2. Articulation

   • Humeroulnar - Trochlea of ulna, capitulum of humerus, and head of radius

   • Proximal radioulnar - Radius and radial notch of ulna

3. Synovial Membrane

   • A synovia membrane lines the capsule and is attached to the articular surfaces

   • Synovial fluid is produced to keep the joint well articulated

   • Continuous synovial membrane between the two joints

4. Capsule

   • Continuous capsule between the two joints

5. Cartilage

   • Its articular surfaces are covered by hyaline cartilage

Clinical Notes:

1. Fracture of the radial head commonly occurs during a fall on an outstretched hand.

2. Subluxation of the radial head occurs when children are lifted by their upper limbs when their forearm is pronated, potentially causes a tear of the annular ligament.

3. Epicondylitis or tennis elbow might occur when there is a strain on the common flexor and extensor muscle origins on the epicondyles.

Radiocarpal Joint

Notes on the radiocarpal joint:

1. Type

   • Synovial ellipsoid, condyloid joint

2. Articulation

   • Distally - Proximal carpal bones
     (except pisiform)

   • Proximally - Distal end of radius and articular disc of radioulnar joint

3. Synovial Membrane

   • A synovia membrane lines the capsule and is attached to the articular surfaces

   • Synovial fluid is produced to keep the joint well articulated

   • Does not communicate with the distal radioulnar and intercarpal joints

4. Capsule

   • Surrounds the wrist joint and is attached to the distal ends of the ulnar, radius, and proximal carpal bones (except pisiform)

5. Cartilage

   • Its articular surfaces are covered by hyaline cartilage

Other joints in the upper limbs can be briefly summarized as:

1. Interphalangeal - Hinge type

2. Metacarpophalangeal - Condyloid type

3. Carpometacarpal (1st) - Saddle type

4. Carpometacarpal (2n to 5th) - Plane

5. Distal radioulnar - Pivot type

6. Acromioclavicular - Plane type

7. Sternoclavicular - Saddle type