איוב, פרק ל״א, פסוק כ״ב

Job declares a severe and fitting physical punishment upon himself if he ever abused his power against the weak, such as orphans [מלבי״ם, אלשיך]. Because his arms would have been the instruments of such cruelty, he wishes for those very limbs to be shattered and torn apart as a consequence for misusing his strength [מצודת דוד, ביאור שטיינזלץ].

To convey the totality of this curse, the physical structure of his body is detailed. He asks that the upper part of his arm fall away from his upper back or shoulder width [רש״י, מצודת דוד, מלבי״ם]. To clarify this anatomy, [מלבי״ם] draws a distinction between the sides of the body and the back. While a person has two shoulders on the sides, the center of the upper back is a single area. A burden carried directly on the back rests on this central spot, whereas a load carried on poles rests on the side shoulders. Job wishes for his side shoulder to completely detach from that central back structure.

Continuing the imagery of broken limbs, Job asks for his arm, located below the shoulder, to be snapped off from its connecting bone. The primary approach among commentators is that this connecting piece is the upper arm bone, which is round and resembles a reed plant [רש״י, מצודת דוד]. However, others suggest a different anatomical map, arguing that this reed-like bone is actually located below the arm [מלבי״ם], or that it refers directly to the shoulder blade itself [ביאור שטיינזלץ].