Select records based on what a field begins with?

I have a database with a table that has identifiers c1, c2, c3..etc..

Instead of writing a query that has a bunch of ORs in it, how can I modify the below query with something that will catch all the records that begin with a certain letter?

SELECT 
    Person.spineinjuryAdmit, 
    tblComorbidity.comorbidityexplanation,
    Count(tblComorbidity.comorbidityexplanation) AS CountOfcomorbidityexplanation

FROM tblKentuckyCounties 
INNER JOIN (tblComorbidity 
            INNER JOIN (Person 
                        INNER JOIN tblComorbidityPerson 
                            ON Person.PersonID = tblComorbidityPerson.personID) 
                ON tblComorbidity.ID = tblComorbidityPerson.comorbidityFK) 
    ON tblKentuckyCounties.ID = Person.County
GROUP BY    Person.spineinjuryAdmit, 
            tblComorbidity.comorbidityexplanation
HAVING (((Person.spineinjuryAdmit)="c1" Or 
         (Person.spineinjuryAdmit)="c2" Or 
         (Person.spineinjuryAdmit)="c3"));