لَهَا مِرْفَقَانِ أَفْتَلَانِ كَأَنَّهُمَا
تَمُرُّ بِسَلْمَي دَالِجٍ مُتَشَدِّدِ
Her two elbows are strong; their outward spread is likened to the two buckets held away from the sides by a powerful water drawer as he moves.
Mirfaqān aftalān describes two especially strong elbow joints. Salm is a water bucket with a particular handle; dālij is the person who draws water from a well and empties it into a trough.
As a strong carrier holds a bucket in each hand, both hang apart from his sides. The comparison draws attention to the camel’s well-spaced, powerful elbows, not to a woman named Salmā.