He is listed as Ludwig Kuhn, Company D, 26th Wisconsin, wounded in the right scapula at Gettysburg, the bullet lodging in his thoracic cavity; hospitalized at Satterlee Hospital in Philadelphia on July 9 ... transferred to the Veteran Reserve Corps March 15, 1864 and discharged June 9 at Philadelphia. Reenlisted and mustered into Company I, 214th Pennsylvania on March 29, 1865. [Busey and Busey, Union Casualties at Gettysburg]
His case appears in The Medical and Surgical History of the War of the Rebellion, vol. 3, p. 479. His age is listed as 24 (probably as of July 1863) and the cause of his wound is listed as a "conoidal musket ball" (minie ball).
With the entry listed as the right scapula (shoulder blade), alan polk is correct; the arrow should be pointing in the opposite direction. But in fact the arrow is misleading because minie balls took a variety of paths through the body. I would guess he was shot in the back while retreating, perhaps by a Georgian of Gordon's brigade, or possibly Doles' brigade.