Question: What year did da Vinci collaborate with Marcantonio della Torre?
About the article "Leonardo da Vinci", section "Anatomy".

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Marcantonio della Torre (1481–1511) was a Renaissance Professor of Anatomy who lectured at Pavia and at the University of Padua.
It is believed that della Torre and Leonardo da Vinci, who studied the human anatomy by dissecting corpses, were intending to publish a book, but this did not eventuate as della Torre's life was cut short by plague in 1511.
By this time Leonardo had made over 750 detailed anatomical drawings with annotations.
Both Giorgio Vasari and Paolo Giovio claim that della Torre had written anatomical texts, but none are known to have survived to the modern age. 
Leonardo da Vinci had a number of powerful patrons, including the King of France.
He had, over the years, a large number of followers and pupils.
His patrons included the Medici, Ludovico Sforza and Cesare Borgia, in whose service he spent the years 1502 and 1503, and King Francis I of France.
He had working relations with two other notable scientists, Luca Pacioli and Marcantonio della Torre, and was a close friend of Niccolò Machiavelli.
He had a close, long-lasting friendship with Isabella d'Este, a renowned patroness of the arts, whose portrait he drew while on a journey that took him through Mantua.
The de Predis brothers and collaboration on "Virgin of the Rocks".
Feud with Michelangelo  
As Leonardo became successful as an artist, he was given permission to dissect human corpses at the hospital Santa Maria Nuova in Florence.
Later he dissected in Milan at the hospital Maggiore and in Rome at the hospital Santo Spirito (the first mainland Italian hospital).
From 1510 to 1511 he collaborated in his studies with the doctor Marcantonio della Torre.
""I have removed the skin from a man who was so shrunk by illness that the muscles were worn down and remained in a state like thin membrane, in such a way that the sinews instead of merging in muscles ended in wide membrane; and where the bones were covered by the skin they had very little over their natural size.""
In 30 years, Leonardo dissected 30 male and female corpses of different ages.
Together with Marcantonio, he prepared to publish a theoretical work on anatomy and made more than 200 drawings.
However, his book was published only in 1680 (161 years after his death) under the heading "Treatise on painting".
Among the detailed images that Leonardo drew are many studies of the human skeleton.
He was the first to describe the double S form of the backbone.
He also studied the inclination of pelvis and sacrum and stressed that sacrum was not uniform, but composed of five fused vertebrae.
Leonardo was a physiologist as well as an anatomist, studying the function of the human body as well as examining and recording its structure.
He dissected and drew the human skull and cross-sections of the brain, transversal, sagittal, and frontal.
These drawings may be linked to a search for the "sensus communis", the locus of the human senses, which, by Medieval tradition, was located at the exact physical center of the skull.
Leonardo studied internal organs, being the first to draw the human appendix and the lungs, mesentery, urinary tract, reproductive organs, the muscles of the cervix and a detailed cross-section of coitus.
He was one of the first to draw a scientific representation of the fetus in the intrautero.
Leonardo studied the vascular system and drew a dissected heart in detail.
He correctly worked out how heart valves ebb the flow of blood yet he did not fully understand circulation as he believed that blood was pumped to the muscles where it was consumed.
In 2005 a UK heart surgeon, Francis Wells, from Papworth Hospital Cambridge, pioneered repair to damaged hearts, using Leonardo's depiction of the opening phase of the mitral valve to operate without changing its diameter allowing an individual to recover more quickly.
Wells said "Leonardo had a depth of appreciation of the anatomy and physiology of the body - its structure and function - that perhaps has been overlooked by some.
"Leonardo's observational acumen, drawing skill, and the clarity of depiction of bone structures reveal him at his finest as an anatomist.
However, his depiction of the internal soft tissues of the body are incorrect in many ways, showing that he maintained concepts of anatomy and functioning that were in some cases millennia old, and that his investigations were probably hampered by the lack of preservation techniques available at the time.
Leonardo's detailed drawing of the internal organs of a woman (See left) reveal many traditional misconceptions.
Leonardo's study of human anatomy led also to the design of the first known robot in recorded history.
The design, which has come to be called Leonardo's robot, was probably made around the year 1495 but was rediscovered only in the 1950s. 
  Leonardo da Vinci–Fiumicino Airport, Rome, Italy  Museo della Scienza e della Tecnologia "Leonardo da Vinci", Milan, Italy  Da Vinci, a crater on the Moon  Da Vinci-Broen (Da Vinci Bridge), a small-scale replica of the bridge Leonardo designed to span the Golden Horn, in Ås, Akershus, Norway  Da Vinci Research Park, a science park located in Brussels, Belgium  Da Vinci, a Michelin-starred restaurant in Maasbracht, Netherlands  Da Vinci Tower, a proposed 420-metre (1,378 ft), 80-floor tower in Dubai, United Arab Emirates  
He was the son of Francesco della Torre (brother of Napoleone della Torre) and Giulia Castiglioni,As part of the factional turmoil between the Guelphs and Ghibellines, the conflict of Guido’s Guelph family with the Ghibelline Visconti, led by Ottone Visconti, dominated much of his childhood.
In 1277, after the Battle of Desio, in which he lost his father, he was taken prisoner with his uncle Napoleone, and imprisoned in the castle of Baradello at Como.
He escaped from this castle in 1284, with the help of Loterio Rusca, the Lord of Como and William VII, Marquess of Montferrat.
He fled with his uncle Raimondo della Torre, who was the Patriarch of Aquileia.
In 1287 Guido became Podestà of Treviso.
After his escape from the castle Baradello, Guido led the Guelphs in the riots that took place in Milan in the last years of the thirteenth century.
In 1302, a group of Guelphs, including the Lords of Piacenza and Parma, Alberto Scotti and Ghiberto da Correggio, compelled the Visconti to leave Milan, in 1302.
After twenty-five years of exile, Guido della Torre and his family regained their power in Milan.
Guido then sought to forge new alliances through marriages: Guido married the daughter of Count Filippo Langosco; his eldest son, Francesco, married a niece of Alberto Scotti; finally, his second son, Simone, married a daughter of Pietro Visconti.
Being the head of the della Torre family helped Guido in his election to Milan’s Captain of the People in 1307.
The following year Milan elected him as a perpetual "capitano del popolo".
However, in 1311 Guido entered in conflict with his cousin Cassono della Torre, archbishop of Milan: after an unsuccessful attempt to raise the Milanese against emperor Henry VII, he was forced to flee, first to Lodi, then to Cremona where Guido died in the summer of 1312