In emergency tracheostomy all structures are damaged except:
Isthmus of thyroid
Inferior thyroid aery
Thyroid ima
Inferior thyroid vein
Emergency tracheostomy can damage midline structures such as : thyroid isthmus, thyroid ima aery and inferior thyroid vein. Whereas, inferior thyroid aery lies laterally away from midline and so escapes injury.
Neck Triangles and parotid gland