neck
The French word 'cou' is the equivalent of the English word 'neck'. It refers to the part of the body that connects the head to the torso. 'Cou' is a noun and is used in a similar way to 'neck' in English. For example, you might say 'J'ai mal au cou' (I have a sore neck) or 'Elle a tourné la tête et a regardé par-dessus son épaule avec son cou' (She turned her head and looked over her shoulder with her neck).
I fell on my neck.
This example is a literal sentence referring to a person physically falling down and landing on their neck. It is not a common phrase but is grammatically correct.
He has a sore neck.
This sentence is used when someone is experiencing pain in their neck. 'Mal au cou' is a commonly used phrase in French to express this discomfort.
She wears a scarf around her neck.
This sentence describes a woman who is wearing a scarf around her neck. It's a usual way to depict someone's apparel in French.