Neurite extension is essential to establish complex neuronal circuits during brain development. Neurons extend their axons in a crowded environment to reach target territories and connect to specific partners. Much work has been performed on cultured isolated neurons, focusing on the response of axon growing ends to chemical guidance cues. However, the cellular mechanisms involved in the growth of axon groups in their natural environment (the brain), are still poorly understood. Our objective is to shed light on collective axon growth and branching processes in a complex environment, considering axon-axon mechanical interactions. To do so, we propose a simple mathematical model for axonal elongation that we simulate embedded in a realistic environment.