[10][11] Messner's parents divorced when he was young, and he was raised by his mother and stepfather, Del Pretty,[12] who ran a piano store in Livonia, Michigan.
"[14] He later noted that Pretty "raised me, fed me, spanked me, hugged me, took me to school, wrote me poems, came to all my football games and made me feel like the most important person in the world.
[15] Pretty was diagnosed with lymph node cancer in 1980 and eventually died from the disease in December 1989 when Messner was a rookie with the Los Angeles Rams.
[9][10] He played at the tight end and nose guard positions for Catholic Central in 1982 and 1983 and earned all-state and high school All-American honors as a senior,[17] and graduated in 1984.
"[10] Another writer described him as "a combination Dennis the Menace and Henry David Thoreau, a philosopher with a cowlick" and "Aristotle in a jockstrap.
As a redshirt freshman, he started all 12 games at defensive tackle for the 1985 Michigan Wolverines football team that compiled a 10-1-1 record, was ranked #2 in the final AP Poll, held opponents to 75 points in the regular season (6.8 points per game), and defeated Nebraska in the 1986 Fiesta Bowl.
[21] He was also named the Defensive Player of the Game in the 1986 Fiesta Bowl after he registered nine tackles, forced a fumble, and recovered another.
[24] In his second year, Messner started all 13 games at defensive tackle for the 1986 Michigan team that compiled an 11–2 record, tied for the Big Ten Conference championship, and lost to Arizona State in the 1987 Rose Bowl.
[25] For the second consecutive year, Messner was selected as a first-team defensive lineman on the All-Big Ten team.
[28] At the end of the season, he was selected by the Sporting News as a first-team defensive lineman on the 1987 All-America Team.
[30] Prior to the 1988 season, the Sporting News featured a photograph of Messner and coach Schembechler on the cover of its preseason issue ranking Michigan #1 in the country.
[35][36] Messner was selected in the sixth round (161st overall pick) of the 1989 NFL draft by the Los Angeles Rams.
He was a region vice president for Canon from March 2009 to July 2010 based in Farmington Hills, Michigan.