The lumbar plexus is a collection of nerves, and it originates from the anterior rami of the T12-L5 laterally to the intervertebral foramina. It gives off 6 peripheral nerves, and in the available literature there are a lot of descriptions of each nerve and its possible morphological variations. In some cases, the occurrence of accessory nerve or absence of whole nerve is observed. In other cases, morphological variations regarding the origin, course, or division into more branches are also noticed. Such variations may be associated with some clinical aspects. Understanding the anatomical variations of the lumbar plexus's nerves is essential for procedures involving the lower abdomen, regional anaesthesia, and managing nerve entrapment syndromes. The main aim of this review is to present condensed information on the lumbar plexus based on the available literature. A further aim is to compare the classification systems and the results of previous studies in adults and foetuses. This manuscript also includes information on the most common clinical implications associated with anatomical variations of the individual nerves of the lumbar plexus.