3. Shoulder joint and arm

Question 1

Where is the anatomical neck of the proximal humerus compared to the surgical neck, and what feature of the bone here can look like a fracture

Answer 1

Anatomical neck spans the two tubercles whereas the surgical neck is more inferior, just under the tubercle.

The epiphysis in the head of the humerus can look like a fracture

Question 2

What structure is at risk when there is mid shaft humeral fracture

Answer 2

The radial nerve because it goes around the back of the mid humerus

Question 3

Where is the coracoid process in relation to the acromion on an AP view of the shoulder joint

Answer 3

The coracoid process is inferior and medial to the acromion, it almost looks like its part of the glenoid fossa which is articulating with the head of the humerus

Question 4

What characterises a normal alignment of shoulder joint in the lateral view

Answer 4

Glenoid is fully surrounded by the head of humerus and

Spine of scapula, coracoid and blade of scapula form a Y

Question 5

What are the telling features of an anterior dislocation of the shoulder joint: most common. How does this happen.

Answer 5

On AP view The humeral head and the glenoid surfaces are not aligned. the humeral head lies below the coracoid rather then in line with it.
Anterior dislocation by abduction and external rotation

Question 6

What are the telling features of an posterior dislocation of the shoulder joint: most common. How does this happen.

Answer 6

On AP view: The glenohumeral joint is widened and the humerus is held in interior rotation, with the contour resembling a lightbulb. On a lateral view can see that head of humerus no longer aligned with glenoid cavity.
This is less common, caused by electrocution and epileptic seizures