ENT Flashcards
Label the parts of the tympanic membrane
Describe the blood supply of the external ear
Arterial - branches of external carotid
* Posterior auricular
* Superficial temporal
* Occipital
* Maxillary
Veins follow arteries and drain to external jugular
What are the auditory ossicles? Describe their anatomy and function.
Malleus, incus and stapes
Connect tympanic membrane to oval window, transmit vibrations to detect sound
Muscles attached which contract to prevent vibrations when there is a loud noise to prevent damage to inner ear (acoustic reflex)
Tensor tympani attached to handle of malleus, innervated by tensor tympani nerve from mandibular nerve
Stapedius attached to stapes, innervated by facial nerve
Why is otitis media more common in children?
Eustachian tubes shorter, straighter, ‘floppier’ than in adults, transmit URTIs to ear
Describe the anatomy of the inner ear
Bony labyrinth - contains cochlea, semicircular canals, vestibule
Membraneous labyrinth - within bony labyrinth, contains cochlear duct, semi-circular ducts, utricle and saccule, filled with endolymph
Oval window and round window connect middle ear to inner ear
Vestibular apparatus (balance) = semi-circular ducts, saccule and utricle
Hearing - cochlear duct, containing organ of Corti
Vestibulocochlear nerve innervates
Describe the anatomy of the oral cavity
Vestibule anteriorly - between lips/cheeks and teeth/gums
Roof - hard (bony) palate anteriorly, soft palate posteriorly
Cheeks formed by buccinator muscle
Floor - muscular diaphragm (mylohyoid muscles), geniohyoid muscles, tongue connected by frenulum, salivary glands/ducts
Innervation
Taste - anterior 2/3 is facial nerve, posterior 1/3 is glossopharyngeal nerve
Motor - hypoglossal nerve
Sensation - lingual and glossopharyngeal nerve
Describe the borders of the anterior triangle of the neck
Superior - inferior angle of mandible
Lateral - anterior border of sternocleidomastoid muscle
Medial - sagittal line down midline of neck
Describe the important contents of the anterior triangle of the neck
Muscles - divided into above and below hyoid bone
* Suprahyoid - stylohyoid, digastric, mylohyoid, geniohyoid
* Infrahyoid - omohyoid, sternohyoid, thyrohyoid, sternothyroid
Vascular
* Common carotid artery - bifurcates into internal and external
* Internal jugular vein
Nerves
* Facial
* Glossopharyngeal
* Vagus
* Accessory
* Hypoglossal
Describe the borders of the posterior triangle of the neck
Anterior - posterior border of sternocleidomastoid muscle
Posterior - anterior border of trapezius muscle
Inferior - middle 1/3 of clavicle
Describe the important contents of the posterior triangle of the neck
Muscles
* Omohyoid
* Levator scapulae
* Anterior, medial and posterior scalenes
Vascular
* External jugular vein
* Subclavian vein
* Distal part of subclavian artery which becomes axillary artery as it crosses first rib
Nerves
* Accessory nerve
* Cervical plexus including phrenic nerve
* Brachial plexus
Describe the anatomical location and blood supply of the thyroid gland
Anterior neck, C5-T1 level
Two lobes with central isthmus
In visceral compartment of neck with trachea, oesophagus and pharynx, bound by pre-tracheal fascia
Lies in close proximity to recurrent laryngeal nerve - can be damaged during thyroid surgery
Arterial supply
* Superior thyroid - first branch of external carotid
* Inferior thyroid - thyrocervical trunk from subclavian
Venous drainage - superior, middle and inferior thyroid veins, superior and middle drain to internal jugular and inferior into brachiocephalic
Describe the anatomy of the pharynx
Connect oral cavity and nose to larynx and oesophagus
Begins at base of skull and ends at cricoid cartilage (C6 level)
Nasopharynx (base of skull to soft palate) -> oropharynx (soft palate to epiglottis) -> laryngopharynx (epiglottis to cricoid cartilage)
Adenoid tonsils in posterior nasopharynx
Lingual and palatine tonsils in oropharynx
Circular muscles which constrict to propel food bolus - superior, middle and inferior pharyngeal constrictors
Mainly innervated by vagus and glossopharyngeal nerves
Arterial supply - branches of external carotid
Venous drainage - pharyngeal venous plexus –> internal jugular
Describe the anatomy of the larynx
Anterior compartment of neck, spans C3-C6, from laryngopharynx to trachea
Formed by cartilaginous skeleton held together by ligaments and membranes
Supraglottis (inferior epiglottis to vestibular folds) –> glottis (vocal cords and 1cm below) –> subglottis (inferior glottis to inferior cricoid cartilage)
Vascular
* Arterial - superior and inferior laryngeal arteries
* Venous - superior and inferior laryngeal veins
Innervation
* Recurrent laryngeal nerve and superior laryngeal nerve
Describe the cartilages of the larynx
Unpaired
* Epiglottis - flattens during swallowing to block off larynx and prevent aspiration
* Thyroid - anteriorly forms laryngeal prominence (Adam’s apple)
* Cricoid - signet ring shaped
Paired
* Arytenoid
* Corniculate
* Cuneiform
Describe the clinically important anatomy of the laryngeal soft tissue structures
Cricothyroid ligament - incision made during cricothyroidotomy for upper airway obstruction to insert ET tube and secure airway
Vocal folds (true) - soft tissue folds which move under control of muscles of phonation to control the pitch of sound
Vestibular folds (false vocal cords) - superior to true, protect larynx
List the important anatomical structures which pass through the parotid gland
Facial nerve - splits into terminal branches within parotid (temporal, zygomatic, buccal, marginal mandibular, cervical)
External carotid artery - gives off posterior auricular then splits into terminal branches (maxillary artery and superficial temporal artery)
Retromandibular vein - formed in parotid by convergence of superficial temporal and maxillary veins
List the salivary glands and describe their drainage
Sublingual - smallest, drain via minor sublingual ducts of Rivinus under tongue
Parotid - drain via Stensen duct, opens near second upper molar
Submandibular - drain via Wharton’s duct, opens at base of lingual frenulum
Describe the physiology of swallowing
Voluntary phase - food bolus formed by mastication, moved to pharynx by tongue, stimulated swallowing reflex
Pharyngeal phase - pressure receptors in pharynx stimulated which activate swallowing centre in brainstem to inhibit respiration, raised larynx, close glottis, open upper oesophageal sphincter
Soft palate elevated to block nasopharynx
Bolus moved down via peristalsis of pharyngeal constrictors
Oesophageal phase - larynx lowers to normal position, cricopharyngeus muscle contracts to prevent reflux, respiration begins again
Bolus moved down by peristalsis
Describe the anatomy of the nasal cavity
Superior, middle and inferior turbinates (or conchae) with corresponding meatuses between - slows air flow to allow for humidification
Paranasal sinuses, nasolacrimal duct and Eustachian tube empty into nasal cavity
Cribiform plate forms portion of roof of nasal cavity - where olfactory nerve fibres enter
Vascular supply
Internal carotid branches - anterior and posterior ethmoidal
External carotid branches - sphenopalatine, greater palatine, superior labial, lateral nasal
Lots of anastomoses, anteriorly form Kiesselbach’s plexus, posteriorly form Woodruff plexus
Veins drain to pterygoid plexus, facial vein or cavernous sinus (intracranial spread of infections)
Define stridor
Externally audible, high-pitched sound caused by turbulent airflow due to obstruction of the upper respiratory tract (pharynx, larynx or trachea)
Describe the clinical presentation of acute airway obstruction
Mild
* Hoarse voice
* Intermittent stridor
* Minimal impact on work of breathing
* Good air entry
Moderate
* Tachypnoea
* Stridor
* Prolonged inspiratory time
* Increased work of breathing
* Decreased air entry
Severe to complete obstruction
* Hypoxia
* Slow respiratory rate or marked tachypnoea
* Tripod position
* Agitated or drowsy
* Severe work of breathing
* Markedly reduced or no air movement
* Silent gagging/coughing
* Progresses rapidly to unconsciousness and cardiorespiratory arrest
Describe the immediate management of acute airway obstruction
Suction secretions or remove foreign body from airway if visible
Oxygen - heliox if available
Alert seniors including ENT/anaesthetics
Consider nebulised adrenaline
Consider nebulised salbutamol
Consider dexamethasone oral/IM/IV
Definitive airway management
Endotracheal intubation if able
Emergency cricothyroidotomy if upper airway obstruction
If due to tumour - radiotherapy, laser, stenting
Describe the immediate management of ear foreign bodies
Ask about pain/discharge from ear, hearing loss
Examination - otoscopy to visualise foreign body
Live insects - drown in oil
Remove using Zoelner sucker, crocodile forceps, Jobson-Horne probes, wax hooks etc.
If unable to be removed can be discharged and scheduled for foreign body to be removed under GA (unless button battery which needs to be immediately removed)
Describe the immediate management of a nose foreign body
Ask about issues with breathing and nasal discharge
Examine with Thucidum speculum and a light
Attempt to remove
If distressed or has breathing difficulty - emergency removal under GA