Different structure in an organism are specialized to perform different tasks in the organism depending on their makeup. A few examples are:
Heart, veins, arteries are structures forming the cardiovascular system and function is to facilitate transport nutrients and oxygen carried by blood all over the body.
Bones, joints, ligaments and cartilage are structures of the skeletal system and their function is support and protection of the body.
Mouth, esophagus. stomach, large and small intestines are structures of the digestive system and their function is to break down food and absorb nutrients.
The nurse should suspect of a fractured jaw.
The crepitus is a common sign of bone fracture and it's heard when the fractured surfaces of two broken bones rub together.
Also If there is a severe jaw fracture, the patient might experience limited ability to move the jaw or be unable to move it at all.