Anatomy of the Upper Respiratory System PDF

26/01/24 Anatomy of the upper Respiratory System: Learning objective: describe the anatomy of the nose and the de ning characteristics of the nasal cavities. Learning objective: describe the paranasal sinuses and how they link to the nasal cavity. Learning objective: describe the vascular supply and...

26/01/24 Anatomy of the upper Respiratory System: Learning objective: describe the anatomy of the nose and the de ning characteristics of the nasal cavities. Learning objective: describe the paranasal sinuses and how they link to the nasal cavity. Learning objective: describe the vascular supply and inner vation of the nose, including a brief overview of the pathway of smell. The upper tract: Nasal cavity: Functions of the nasal cavities: 1. Adjust temperature. 2. Adjust humidity. 3. Trap and remove particulate matter. 4. Drains paranasal sinuses. Olfaction is controlled by the olfactory nerve. Olfaction is the same as smelling. The nasal cavity is the rst part of the upper respiratory tract. It can be subdivided into 2 regions: 1. External nose- located at the centre of the midface. 2. Internal chamber- located centrally within the cranium. The nasal cavity extends from anterior openings ( nostrils ) to posterior apertures ( choanae ). Separated from oral cavity below by the hard palate. Divided from the cranial cavity above by frontal, ethmoid and sphenoid bones. Left and right nasal cavities divided by the nasal septum. Nares Anterior Nasal openings ate store palate External nose: This is the anterior opening of the nasal cavity which is supported by a framework of cartilage and bone ( becomes more boney as you move more posterior towards the midface ). Regions of the nasal cavity: Lateral wall of the nasal cavity: Characterised by three cur ved shelves of bone known as conchae or turbinates projecting off the lateral wall. Superior concha. Middle concha. Inferior concha. Anterior end of each concha curves medially to form a lip overlying the meatus. Inferior Meatus Between inferior Concha and floor 4 air channels are created within each cavity, increasing surface area for contact with inspired air. Paranasal sinuses: Four paranasal air sinuses named in relation to the bone they are found within. Develop as outgrowths from nasal cavities eroding into surrounding bone. Lined by ciliated, mucus secreting respiratory mucosa. They lighten the skull as replaces space with air rather than bone. They also act as shock absorbers and give your face resonance. Drainage of paranasal sinuses: Mucus produced by mucus membrane is moved by ciliary action and by siphon action created during blowing up your nose. Blood supply: Little’s area: Important site of extensive anastomosis on nasal septum. Consists of: Anterior ethmoidal artery. Greater palatine artery. Sphenopalatine artery. Superior labial artery. Olfaction: 9Fr9E This is smelling and is controlled by cranial nerve I ( olfactory ). Ethmoid sphenoid Olfactory nerve: Olfactory receptors embedded within olfactory epithelium at the apex of each naval cavity. Receptors are peripheral processes of bipolar sensory neurons, with cell bodies deeper in epithelium. Axons of rst order bipolar neurones pass through the cribriform plate to synapse with second order neurons in the olfactory bulb. Note: rst order is picking up info from the nasal cavity and taking it back up to the olfactory bulb. Olfactory bulb: Olfactory tract: The lateral stria goes directly back to the unilateral temporal lobe. The medial stria provides connections bet ween the left and right hemispheres. Anosmia: This is damage to the sense of smell. Temporary: infection or common cold. Permanent: head injury, or tumours which occur in the olfactory groove. Progressive: neurodegenerative conditions I.e Parkinson’s or Alzheimer’s.