Xa umntu ephefumla ngokuqhelekileyo, ikhontrakthi ye-diaphragm kunye ne-contract yangaphandle ye-intercostal muscles.
Xa uphefumla ngamandla, ufuna kwakhona uncedo lokuphefumlela izihlunu ezincedisayo, ezifana ne-trapezius kunye nezihlunu ze-scalene.
Ukucutshungulwa kwezi zihlunu kwenza isifuba sibe banzi Ukuphakamisa, indawo yesifuba iyanda ukuya kumda, ngoko ke kuyimfuneko ukusebenzisa imisipha ekhuthazayo.