This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The elbow-joint, like others, is affected with rheumatoid and tuberculous disease. The former frequently causes ankylosis, while the latter frequently causes suppuration. The joint becomes distended and enlarged. The bony prominences of the elbow, while they may not be visible, nevertheless can usually be recognized by palpation. The lateral ligaments are stronger than the anterior and posterior, hence the swelling is most marked in front and behind. As the internal lateral ligament is stronger than the external lateral, swelling will be more marked on the outer side and the medial (internal) condyle will be more easily recognized than the lateral (external).
Pus first works its way posteriorly up behind the tendon of the triceps and then sideways and along the intermuscular septa. As the external supracondylar ridge is nearer the surface than the internal, pus will show itself sooner above the lateral (external) condyle. It may form a protrusion on each side of the triceps tendon and olecranon process.
Later it may show itself anteriorly; when it does so it appears more to the outer than to the inner side, being deflected outwardly through the antecubital space by the attachment of the brachialis anticus to the coronoid process, by the tendon of the biceps and by the bicipital fascia which passes from the tendon over the muscles attached to the medial (internal) condyle.