The Nasal Cavity and Orbit - Lecture Notes PDF

Module 202 - Theme 2 - Lecture 1 The Nasal Cavity and Orbit A riddle while you wait: I make sense of words, and help with maths The endpoint of two upward paths Processing vibration, touch and position Lesion right, full left omission Join at slido.com #3242461 Module 202 - Theme 2 - Lecture 1...

Module 202 - Theme 2 - Lecture 1 The Nasal Cavity and Orbit A riddle while you wait: I make sense of words, and help with maths The endpoint of two upward paths Processing vibration, touch and position Lesion right, full left omission Join at slido.com #3242461 Module 202 - Theme 2 - Lecture 1 The Nasal Cavity and Orbit Dominic O’Brien MSc, FHEA, PGCert Pronouns: he/she/they Lecturer in Anatomy D.O’[email protected] Join at slido.com #3242461 Join at slido.com #3242461 ⓘ Click Present with Slido or install our Chrome extension to display joining instructions for participants while presenting. Previously on Module 202… Which bone of the skull is the attachment point for the upper row of teeth? ⓘ Start presenting to display the poll results on this slide. Previously on Module 202… Which bone of the skull is the attachment point for the upper row of teeth? A. Frontal B. Occipital C. Mandible D. Maxilla E. Sphenoid The basilar artery bifurcates into which branches of the cerebral arterial circle? ⓘ Start presenting to display the poll results on this slide. Previously on Module 202… The basilar artery bifurcates into which branches of the cerebral arterial circle? A. Anterior cerebral artery B. Anterior communicating artery C. Internal carotid artery D. Middle cerebral artery E. Posterior cerebral artery Outcomes - Describe the anatomy of the nose, nasal cavity and paranasal sinuses - Function - Neurovascular supply - Describe the anatomy of the eye and orbit - Osteology - Extraocular muscles - Neurovascular supply - Explore the nerve supply from cranial nerves I, II, III, IV, V 1 and VI - Olfactory - Optic - Oculomotor - Trochlear - Ophthalmic - Abducens The Nose Primary function is to filter dust entering the respiratory system Blood supply: - Branches from ophthalmic and maxillary arteries - Facial vein Nerve supply: - Olfactory nerve (CN I) - Ophthalmic (V1) - Maxillary (V2) Comprised of bones and cartilage Nasal Cavity Lateral wall of the cavity has three projections: - Superior conchae - Middle conchae - Inferior conchae Superior and middle conchae arise from the ethmoid bone - Inferior concha is an individual bone Spaces beneath the conchae are known as meatuses - Increase the surface area and humidify inspired air Olfaction Fulfilled by the olfactory nerve (CN I) - Special afferent sensory nerve - Arises from the cerebrum - Exits via the cribriform plate Olfactory receptors line the epithelium in the roof and walls of the nasal cavity Mucous allows gases to dissolve into the fluid which are then detected by the olfactory nerves Paranasal Sinuses Paranasal sinuses are air filled extensions of the nasal cavity which can produce mucus They each drain into the nasal cavity: - Frontal sinuses drain through frontonasal duct - Anterior and middle ethmoidal cells drain into middle meatus - Posterior ethmoidal cells drain into superior meatus - Sphenoidal sinuses drain into sphenoethmoidal recess. - Maxillary sinuses drain into middle meatus. Which paranasal sinus is most likely to become infected? ⓘ Start presenting to display the poll results on this slide. Quiz Which paranasal sinus is most likely to become infected? A. Carotid B. Ethmoidal C. Frontal D. Maxillary E. Sphenoidal The Orbit Houses the eye Made up 7 bones: Frontal Ethmoid Sphenoid Palatine Maxilla Lacrimal Zygomatic The Orbit Several openings into the orbit: - Optic canal - CN II and ophthalmic artery Superior orbital fissure - CN III, IV & VI Inferior orbital fissure - CN V2 The Eye Suspended by muscles in the orbit Divided into 3 chambers: - Anterior - Anterior to iris - Aqueous fluid - Posterior - Posterior to iris and anterior to lens - Aqueous fluid - Vitreous chamber - Largest chamber of the eye - Contains set amount of fluid The Eye - Visual Field Visual information received by the retina Impulses carried through CN II (Optic nerve) Lateral visual field is processed by contralateral portion of the occipital lobe The Eye - Visual Field The crossing of visual fields between eyes is important for binocular vision - 3D vision - Depth perception Things are seen backwards and inverted Visual cortex processes the information to “flip” the image The Optic Nerve - CN II Special afferent sensory nerve Exits the skull through the optic canal Develops as extension of the forebrain Medial fibres decussate at the optic chiasm Swelling of which gland can impact on the optic nerve causing disturbances in vision? ⓘ Start presenting to display the poll results on this slide. Quiz - Clinical Correlation Swelling of which gland can impact on the optic nerve causing disturbances in vision? A. Lacrimal B. Pineal C. Pituitary D. Salivary E. Thyroid Audience Q&A Session ⓘ Click Present with Slido or install our Chrome extension to show live Q&A while presenting. Movements of the Eye 7 extraocular muscles: Levator Palpebrae Superior Oblique Superior Rectus Medial Rectus Lateral Rectus Inferior Rectus Inferior Oblique Movements of the Eye Movements occur around 3 axes: - Vertical - ABduction and ADduction - Transverse - Elevation and depression - Anteroposterior - Internal rotation - External rotation The Oculomotor Nerve - CN III Exits through superior orbital fissure Somatic Motor - General somatic efferent - Supplies extraocular muscles - Except superior oblique and lateral rectus Parasympathetic - General visceral efferent via short ciliary nerves to ciliary body and sphincter The Oculomotor Nerve - CN III Exits through superior orbital fissure Somatic Motor - General somatic efferent - Supplies extraocular muscles - Except superior oblique and lateral rectus Parasympathetic - General visceral efferent - via short ciliary nerves to ciliary body and sphincter The Trochlear & Abducens Nerves - CN IV & VI Somatic Motor - General somatic efferent Exits via superior orbital fissure IV - Supplies superior oblique VI - Supplies lateral rectus LR6SO4 A patient presents with ptosis (drooping of the eyelid). Injury to which cranial nerve would cause this sign? ⓘ Start presenting to display the poll results on this slide. Quiz - Clinical Correlation A patient presents with ptosis (drooping of the eyelid). Injury to which cranial nerve would cause this sign? A. CN B. CN C. CN D. CN E. CN I II III IV VI Crying - The Lacrimal Apparatus Lacrimal gland secretes lacrimal fluid - Lubricates, protects and provides nutrients for the eye Lacrimal papilla collects fluid which moves to the lacrimal sac Nasolacrimal duct then drains into the inferior meatus Receives sensory and autonomic innervation Lacrimal Gland Innervation Sensory innervation - Lacrimal nerve (branch of V1) Parasympathetic innervation - Secretomotor function via facial nerve (CN VII) Sympathetic innervation - Vasoconstrictive (sup. cervical ganglion, via internal carotid) The Trigeminal Nerve - CN V(1, 2 & 3) Three divisions: - Ophthalmic / V1 - Exits cranium through superior orbital fissure - Maxillary / V2 - Exits cranium through foramen rotundum - Mandibular / V3 - Exits cranium through foramen ovale Provides somatic sensory and somatic motor to structures developed from 1 st pharyngeal arch. The Ophthalmic Nerve - CN V1 Exits the cranium via the superior orbital fissure Divides into: - Lacrimal - Sensory innervation to lacrimal gland, conjunctiva and upper eyelid - Parasympathetic fibres to lacrimal gland - Nasociliary - Sensory innervation to the eye, bridge of nose and mucous membranes of the paranasal sinuses - Frontal - Sensory innervation to upper eyelid, conjunctiva, forehead & scalp Which nerve does not exit the cranium through the superior orbital fissure? ⓘ Start presenting to display the poll results on this slide. Quiz Which nerve does not exit the cranium through the superior orbital fissure? A. Abducens B. Oculomotor C. Ophthalmic D. Optic E. Trochlear Audience Q&A Session ⓘ Click Present with Slido or install our Chrome extension to show live Q&A while presenting. Further Reading Gray’s Anatomy for Students - Ideal for diagrams and explanations McMinn’s and Abraham’s Clinical Atlas of Human Anatomy - Cadaveric image atlas - great DR prep Neuroanatomy - An Illustrated Colour Text - Concise neuroanatomy explanations with great diagrams However, if you have any questions, concerns or feedback, please feel free to get in touch: D.O’[email protected] or you can provide feedback anonymously through Qualtrics Dominic O’Brien - Qualtrics Feedback Survey I make sense of words, and help with maths The endpoint of two upward paths Processing vibration, touch and position Lesion right, full left omission Parietal Lobe