In a blast injury , which of the following organ is least involved

Primary blast injuries result from the rapid overpressure or shock waves produced by an explosion* These injuries result from the dramatic changes in barometric pressure projected from the point of detonation* Primary blast injuries predominantly cause damage to air filled hollow organs of the body from rapid pressure change (barotraumas).\ * Damage to air filled organs includes middle ear, lungs and GIT. * Most sensitive and most frequently injured hollow organ: Tympanic membrane > Lungs* Blast damage to the lungs is the MC cause of life threatening injury following an explosion.