Nasolacrimal duct opens into –
Correct Answer: Inferior
Description: Ans. is 'b' i.e.. Inferior meatus o The nasal conchae or turbinates are curved bony projections directed downwards and medially.The inferior concha is the largest and is an independent bone.The middle concha is also a projection from the medial surface of ethmoiod.The superior concha is the smallest and also arises from the medial surface of the ethmoid.o The meatuses of the nose are passages beneath the overhanging conchae.i) The inferior meatus -Lies underneath the inferior conchaLargestThe nasolacrimal duct opens near its anterior part. The opening is guarded by Hansen's valve,ii) The middle meatus -o Lies underneath the middle concha. It presents the following features :The ethmoidal bulla is a rounded elevation produced by the underlying middle ethmoidal sinuses.The hiatus semilunaris is a deep circular sulcus below the bulla.The infundibulum is a short passage at the anterior end of the hiatusOpening of the frontal sinus is at the anterior end of the hiatusOpening of the maxillary sinus is at the posterior part of the hiatusOpening of the middle ethmoidal sinus is present at the upper margin of the bulla,iii) The Superior meatus -Lies below the superior conchaShortest and shallowest of the 3 meatusesReceives the openings of the posterior ethmoidal air cellsThe sphenoethmidal recess is a triangular fossa just above the superior concha. It receives the opening of the sphenoidal air sinus.Coronal section through the middle cranial fossa showing the relations of the cavernous sinuso Each cavernous sinus is a large venous space situated in the middle cranial fossa on either side of the body of the sphenoid bone. Its interior is divided into a number of trabeculae or caverns,o The floor of the sinus is formed by the endosteal dura mater. The lateral wall, roof and medial wall are formed by the meningeal dura mater.Structures in the lateral wall of the sinus from above downwards:l. Oculomotor nerve2 Trochlear nerveOphthalmic nerve - in the anterior part of the sinus, it divides into the lacrimal, frontal and nasociliary nerve.Maxillary nerve - it leaves the sinus by passing through the foramen rotundum on its way to the pterygopalatine fossa.Trigeminal ganglion - the ganglion and its dural cave project into the posterior part of the lateral wall of the sinus.Structures passing through the centre of the sinus :1. Internal carotid artery with the venous and sympathetic plexus around it.2 Abducent nerve, inferolateral to the internal carotid artery.Part of lateral nasal wallOpeningsInferiorNasolacrimal ductMiddleFrontal sinus, Maxillary sinus, Anterior ethmoidal sinusSuperiorPosterior ethmoidal sinusSphenoethmoidal recessSphenoid sinus
Category:
Anatomy
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