and the vestibule. The maxillary sinus is supplied by superior alveolar nerves from the maxillary and infraorbital nerves. The frontal sinus is supplied by branches of the supraorbital nerve. The ethmoid sinuses are supplied by anterior and posterior ethmoid branches of the nasociliary nerve. The sphenoid sinus is supplied by the posterior ethmoidal nerves. Movement The muscles of the nose are supplied by branches of the facial nerve. The nasalis muscle is supplied by the buccal branches. It may also be supplied by one of the zygomatic branches. The procerus is supplied by temporal branches of the facial nerve and lower zygomatic branches; a supply from the buccal branch has also been described. The depressor septi is innervated by the buccal branch, and sometimes by the zygomatic branch, of the facial nerve. The levator labii superioris alaeque nasi is innervated by zygomatic and superior buccal branches of the facial nerve. Smell The sense of smell is transmitted by the olfactory nerves. Olfactory nerves are bundles of very small unmyelinated axons that are derived from olfactory receptor neurons in the olfactory mucosa. The axons are in varying stages of maturity, reflecting the constant turnover of neurons in the olfactory epithelium. A plexiform network is formed in the lamina propria, by the bundles of axons that are surrounded by olfactory ensheathing cells. In as many as twenty branches, the bundled axons cross the cribriform plate and enter the overlying olfactory bulb ending as glomeruli. Each branch is enclosed by an outer dura mater that becomes continuous with the nasal periosteum. Autonomic supply The nasal mucosa in the nasal cavity is also supplied by the autonomic nervous system. Postganglionic nerve fibers from the deep petrosal nerve join with preganglionic nerve fibers from the greater petrosal nerve to form the nerve of the pterygoid canal. Sympathetic postganglionic fibers are distributed to the blood vessels of the nose. Postganglionic parasympathetic fibres derived from the pterygopalatine ganglion provide the secretomotor supply to the nasal mucous glands, and are distributed via branches of the maxillary nerves. Development Development of the nose In the early development of the embryo, neural crest cells migrate to form the mesenchymal tissue as ectomesenchyme of the pharyngeal arches. By the end of the fourth week, the first pair of pharyngeal arches form five facial prominences or processes - an unpaired frontonasal process, paired mandibular processes and paired maxillary processes. The nose is