Neural and Head Development are Intimately Linked

Abstract

Embryonic and post-natal development of the head is dependent on correct neural development. First, closure of the neural plate is essential for formation of the skull whilst patterning along the midline and the rostrocaudal axis is essential for development of the face. If the neural plate does not close, there is an “open brain” phenotype known as exencephaly where the brain is exposed and may be everted. The skull bones also will not develop, a manifestation known as acrania. Failure of the anterior neural plate to divide medially can result in holoprosencephaly whilst defects in rostrocaudal patterning, such as subdivision of the hindbrain into rhombomeres, can result in abnormal development of the neural crest, which not only forms the skeletal structures of the face but gives rise to many connective tissues of the head (see Sect. 3.1). This will affect the development of the face. Signals from the neural tube are also essential for subsequent proliferation and survival of the neural crest cells (see Sects.4.1,4.4). Finally, post-natally, development of the brain is linked to the growth of the skull (see Sect. 6.1). As the brain grows the skull bones are separated, which then continue to grow at suturai edges to fill the gap, a process known as displacement. This growth of the brain, together with development of the eye and paranasal air sinuses, will also contribute to post-natal growth of the face, which at birth is relatively underdeveloped.