An important issue is to know whether Web ontology languages, meet the expected requirements of expressiveness and reasoning. This paper aims at contributing to this question in evaluating and comparing several languages. After describing the needs of a Semantic Web in medicine, it analyses Protégé and DAML+OIL primitives on a concrete medical ontology, the brain cortex anatomy ontology. It draws conclusions about the requirements that a Web ontology language should meet for the representation of medical taxonomy and axioms. The expressiveness of DAML+OIL or OWL DL seems suited to describe the complex taxonomic knowledge. But rules are required for representing the deductive knowledge (dependencies between relations) and to support several tasks (ontology construction, maintenance, verification, query of heterogeneous distributed information sources). Finally, the paper evaluates the features of the next standard OWL and of an hybrid language CARIN-ALN with respect to these requirements.