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Eyes, ears, nose & throat
30 entries across 2 regions · 138 questions
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Head & Neck
- Cervical lymph nodesHY LymphaticSuperficial and deep nodes of the head and neck, grouped clinically into levels I–VI. Lymphadenopathy is common, and a persistent neck mass in an adult is cancer until proven otherwise.
- Deep neck spacesHY Space / regionPotential spaces between the layers of deep cervical fascia. Infections can track through them from the teeth, tonsils and pharynx into the mediastinum.
- External and middle earHY OrganThe ear canal, eardrum and air-filled tympanic cavity with its three ossicles, connected to the nasopharynx by the pharyngotympanic tube. Otitis externa, otitis media and conductive hearing loss are the key topics.
- External carotid arteryHY ArteryMain artery of the face, scalp and neck outside the skull. It has eight branches (SALFOPSM) and ends in the parotid gland as the superficial temporal and maxillary arteries.
- Extraocular musclesHY MuscleSix muscles that move each eye — four recti and two obliques — supplied by CN III, IV and VI (LR6 SO4, the rest 3). Testing them in the "H" pattern localizes cranial nerve palsies.
- EyeballHY OrganThe globe of the eye — three coats (fibrous, vascular, neural) around the lens and chambers. Acute angle-closure glaucoma, retinal detachment, central retinal artery occlusion and the red eye are its emergencies.
- Inner earHY OrganFluid-filled bony and membranous labyrinth in the petrous temporal bone — the cochlea for hearing and the vestibule and semicircular canals for balance. Sensorineural hearing loss and peripheral vertigo arise here.
- LarynxHY OrganCartilaginous airway organ from C3 to C6 that protects the airway and produces voice. Epiglottitis, croup, vocal cord paralysis from recurrent laryngeal nerve injury and emergency cricothyrotomy are the key topics.
- Mandible BoneThe lower jaw — the largest facial bone and the only movable bone of the skull. As a ring with the skull base, it often fractures in two places, and the inferior alveolar nerve runs through it.
- Muscles of masticationHY MuscleFour muscles derived from the first pharyngeal arch and supplied by the mandibular nerve (V3) — masseter, temporalis and medial pterygoid close the jaw; lateral pterygoid opens and protrudes it.
- Nasal cavityHY Space / regionPaired air passages from the nostrils to the choanae, divided by the septum and lined by the conchae that warm and humidify air. Anterior epistaxis from Kiesselbach plexus is the classic problem.
- OrbitHY Space / regionPyramidal bony cavity holding the eyeball, extraocular muscles, nerves and vessels. Its thin floor and medial wall break in blowout fractures, and infection behind the orbital septum is an emergency.
- Palatine tonsilsHY LymphaticPaired masses of lymphoid tissue in the tonsillar fossae of the oropharynx, part of Waldeyer ring. Streptococcal pharyngitis, peritonsillar abscess and infectious mononucleosis are the key problems.
- Paranasal sinusesHY Space / regionFour paired air-filled cavities — frontal, ethmoid, sphenoid and maxillary — draining into the nasal cavity. Acute sinusitis is usually viral; ethmoid and frontal infections can spread to the orbit and brain.
- Parotid glandHY OrganThe largest salivary gland, in front of the ear, with the facial nerve branching through it. Mumps, bacterial parotitis, stones and tumors (most often pleomorphic adenoma) are its key problems.
- Pharynx OrganFibromuscular tube from the skull base to C6, shared by the airway and the food passage. It is divided into nasopharynx, oropharynx and laryngopharynx, and the site of Zenker diverticulum and nasopharyngeal carcinoma.
- Recurrent laryngeal nerveHY NerveBranch of the vagus that loops under the subclavian artery on the right and the aortic arch on the left, then climbs in the tracheoesophageal groove to supply the larynx. Injury causes hoarseness, a classic thyroidectomy complication.
- Submandibular gland OrganSalivary gland under the body of the mandible that produces most resting saliva. It is the most common site of salivary stones because its duct runs uphill and its saliva is thick.
- Temporomandibular joint JointSynovial joint between the mandibular condyle and the temporal bone, divided by an articular disc into two compartments that allow hinging and gliding. TMJ disorders and anterior dislocation are common.
- TongueHY OrganMuscular organ of taste, speech and swallowing. Its mixed embryologic origin gives it four different nerve supplies, and hypoglossal lesions make it deviate toward the weak side.
- Triangles of the neckHY Space / regionSternocleidomastoid divides each side of the neck into anterior and posterior triangles, and each is subdivided further. Knowing their contents helps localize neck masses and avoid injuring the accessory nerve.
Neuroanatomy
- Abducens nerve (CN VI)HY NerveSupplies the lateral rectus. Its long course along the clivus and through the cavernous sinus makes it the cranial nerve most often affected by raised intracranial pressure, causing horizontal diplopia.
- Facial nerve (CN VII)HY NerveMotor to the muscles of facial expression, with taste from the anterior tongue and parasympathetic supply to the lacrimal and submandibular/sublingual glands. Whether the forehead is spared separates a central (stroke) from a peripheral (Bell) palsy.
- Glossopharyngeal nerve (CN IX) NerveMainly sensory — posterior tongue, oropharynx and middle ear, plus the carotid sinus and body. It is the afferent limb of the gag reflex and supplies the parotid gland (parasympathetic) and stylopharyngeus.
- Oculomotor nerve (CN III)HY NerveSupplies four extraocular muscles, levator palpebrae and the pupillary constrictor. A palsy gives a "down and out" eye with ptosis; a blown pupil signals compression (aneurysm or herniation) rather than diabetic ischemia.
- Olfactory nerve (CN I) NerveSpecial sensory nerve for smell. Its fibers pass through the cribriform plate to the olfactory bulb, so head trauma and anterior fossa tumors cause anosmia.
- Optic nerve and visual pathway (CN II)HY NerveCarries vision from the retina to the occipital cortex through the chiasm, tracts and radiations. The pattern of a visual field defect localizes the lesion, and CN II is the afferent limb of the pupillary light reflex.
- Trochlear nerve (CN IV)HY NerveThinnest cranial nerve and the only one to exit the back of the brainstem. It supplies the superior oblique; a palsy causes vertical diplopia worse on looking down and a compensatory head tilt away from the affected side.
- Vagus nerve (CN X)HY NerveLongest cranial nerve — motor to the palate, pharynx and larynx, and parasympathetic supply to the thoracic and abdominal viscera down to the distal transverse colon. A lesion causes hoarseness, dysphagia and a uvula deviated away from the lesion.
- Vestibulocochlear nerve (CN VIII)HY NerveSpecial sensory nerve for hearing (cochlear part) and balance (vestibular part). It runs with CN VII through the internal acoustic meatus, where a vestibular schwannoma causes unilateral hearing loss.