Richmond midfielder Trent Cotchin will miss the AFL club's next four games, after losing a tribunal fight over a charging incident which left North Melbourne's Sam Wright with concussion.

Cotchin could have accepted a three-game ban with an early guilty plea but instead tried to have the suspension reduced to two matches by arguing he had only made contact to Wright's body, not his head.

Video evidence of Sunday's MCG incident was inconclusive, showing Cotchin's right shoulder crashing into Wright's back after arriving late at a marking contest.

Wright's head whipped back sharply but it was unclear whether it moved back far enough to make contact with Cotchin's shoulder.

However, evidence given by North Melbourne club doctor Con Mitropoulos proved decisive.

Mitropoulos told the tribunal that immediately after helping Wright from the field, he asked him where he hurt, with the youngster replying "here" and pointing to his jaw and cheekbone.

Cotchin's advocate Michael Tovey QC argued those sore spots might have been caused by an unrelated incident.

He provided a written submission from Tigers doctor Greg Hickey stating that concussion could occur without direct head contact, a view supported by Mitropoulos.

But that failed to sway the jury, who backed the match review panel's original assessment, meaning Cotchin will not return until the round-21 clash with St Kilda.

Earlier, Port Adelaide forward Daniel Motlop accepted a two-match sanction for engaging in rough conduct against Shaun Higgins of the Western Bulldogs in Saturday's match in Darwin.

Brisbane's Ash McGrath will miss Saturday's trip to Geelong after accepting a one-match ban for engaging in rough conduct against Hawthorn skipper Sam Mitchell.

Adelaide's Michael Doughty, West Coast defender Eric Mackenzie, Carlton utility Andrew Walker and North Melbourne backman Michael Firrito are all free to play this week after accepting reprimands over other weekend offences.

West Coast star Andrew Embley ($1800), Brisbane's Jack Redden and Melbourne's Jordie McKenzie (both $900) have been fined for making negligent contact with umpires.

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