Anatomical Sciences Study Guide PDF

Anatomical Sciences Study Guide Week 11 Cranial Nerves CN \# Emergees from --------------- -------------------------------------- I Cerebral hemispheres (telencephalon) II Diencephalon III and IV midbrain V Pons VI, VII, VIII...

Anatomical Sciences Study Guide Week 11 Cranial Nerves CN \# Emergees from --------------- -------------------------------------- I Cerebral hemispheres (telencephalon) II Diencephalon III and IV midbrain V Pons VI, VII, VIII Pontomedullary junction IV and X medulla XI Superior spinal cord XII medulla Trigeminal nerve has 3 divisions / foramen / type of innervation Ophthalmic = V1 = superor orbital fissure = sensory only Maxillary = V2 = foramen rotundum = sensory only Mandibular = V3 = foramen ovale = sensory and motor Dural venous sinuses Superior sagittal and inferior sagittal sinuses run to confluence of sinuses. Superior sagittal goes straight there. Inferior sagittal goes to straight sinus and then to confluence of sinuses. From confluence of sinuses goes to transverse sinus. Then to sigmoid sinus. Then to jugular vein. Posterior blood supply to brain is vertebral artery to basilar artery. Anterior blood supply to brain is common carotid artery to internal carotid artery. Number Name Function Sensory or motor -------- ------------------ ----------------------- ------------------ I Olfcatory smell sensory II optic sight sensory III occulomtor Eye movement motor IV trochlear Eye movement motor V trigeminal Facial sensation both VI abducens Eye movement motor VII Facial Facial expression both VIII vestibulooccular Hearing, balance sensory IX glossopharyngeal Taste, swallow both X vagus Heart rate, digestion both XI accessory moves head motor XII hypoglossal Moves tongue motor Eyelid muscles orbicularis oculi: closes eye CN VII levator palpebrae superioris: CN III Superior tarsal of muller: elevates upper eyelid (sympathetics) Lacrimal gland innervation is parasympathetic. Thinkk about how you relax when you cry. Eye muscles -- superior rectus, lateral rectus, medial rectus, inferior rectus, superior oblique, lateral oblique Opthalmic division of trigemincl CN V1 becomes frontal nerve toward middle of eye, lacrimal nerve our to lacrimal gland on lateral part of eye, abd asocilliary nerev toward nasal area on medial part of eye. The frontal nerve then becomes surpratrochlear and supraorbital. Supratrochlear comes out near medial part of eye near trochlea and surpraorbital comes out more lateral part of eye and innervates forehead. Veins of orbit Facial vein drains to ophthalmic veins which drains into cavernous sinus. In danger zone this is the route that infections could take and cavernous sinus is near brain which can cause issues. Swelling of the eye is one of them. Pupillary constriction with parasympathetics and pupillary dilation with sympathetics. Spinal nerves Cervical -- 8 Thoracic -- 12 Lumbar = 5 Sacral and coccyl When a nerve in the spine is damaged it can cause pain, increased sensitivity, numbness and muscle weakness. Pain can originate from multiple nerve roots. Radicular pain refers to pain that comes from one single nerve root. Each nerve is respobsible for a speciif part of the body. Each nerve contains mixtyre of sensory and motor fibers. Anterior has more motor and dorsal has more sensory nerve fibers. Nevres meet in plexus and innervate certain parts of the body. Preganglionic sympathetics-- preganglionic neurons located inside thoracic and lumbar segments of spinal cord and their fibers. The preganglionic fibers synapse with postganglionic neurons inside the sympathetic trunk. Postganglionic fibers then run from there to affecter organs. Sympathetic run from T1 to L2. Preganglionic fibers can run superior and inferior of that by preganglionic fibers going to sympathetic trunk and running up or down before synapsing with postganglionic sympathetic fiber. White and gray rami communication between spinal nerve and sympathetic chain. Sympathetic is autonomic so 2 neuron system. Preganglionic cells in spinal cord sends axon into spinal cord out to spinal nerve. Takes white ramus communicons to get to sympathetic chain as pre-ganglionic information. Can synapse at level and can get back to spinal nerve by taking gray communicating ramus. From there could go dorsal or ventral ramus pathway to get to effector organ. T1 through L2 for preganglionic sympathetic parts of spinal cord. L4 spinal cord level no sympathetic information leaving that level. Go lateral and find sympathetic chain ganglion, no white communicating ramus bc no preganglionic neuron to get there. Comes from level above and L2 spinal cord sends axon out through dorsal root. Makes its way to right ramus communions but doesn't synapse. Descends to L4 or whatever level it needs on sympathetic chain and then info can synapse with information at L4 level. Only post ganglionic so only gray ramus.   White and gray ramus between T1 and L2. Only gray rami above T1 and below L3. White = pre ganglionic. Pre synaptic info to get into chain Gray = post ganglionic. Post synaptic info to leave chain. White rami moves towards sympathetic chain. Gray rami leaving sympathetic chain. Gray = away they rhyme Gandolph the great leaves. Returns as Gandolph the white. If white comes right into sympathetic chain ganglia. Horner's syndrome is issue with sympathetic sustem. Cold have constricted pupil because sympathetic not working to dilate, droopy eyelid because mullers muscle not working and decreased sweating. Within brainstem goes midbain, pons, medulla. Eye movements Conjugate -- eyes move in same direction Saccadic -- rapid movement: vision moves from target to target Smooth pursuit -- maintains image of moving target fixed on the retina. Vergence -- focus shifts between near ad far objects (eyes move in opposite directions) Convergence -- eyes convergence (near focus) Divergence -- eyes diverge (far focus) 3 cranial nerves innervate the eye Occulomotoer CN III Trochlear CN IV Abducens CN VI Strabismus is misalignment of eye. PPRF controls abducens nerve so when looking right your right eye goes through PPRF to abduct lateral rectus. LMF helps eye adduct and look mediall so when looking right helps left eye look medially. When looking left, PPRF helps abduct eft eye lateral and MLF helps right adduct and look medially. Brainstem gaze centers Horizontal gaze center -- pons Vertical gaze center -- midbrain Vergence gaze center -- midbrain Frontal gaze field -- origin of voluntary saccadic movements. Project to vertical and horizontal gaze centers and to superior colliculus. Parietal gaze center -- influences saccadic movement Temporal gaze center -- influences smooth pursuit. Occipital gaze center -- origin of vergence movements. Focus shift faraway object and near target. Superior oblique responsible for going down and out. Occulomotor nerve 3 controls medial rectus, superior rectus, inferior rectus, and lateral rectus Trochlear nerve 4 controls superioer oblique Abducens nerve 6 controls lateral recturs Superior oblique does intorsion do depress and abduct eye. Inferior oblique does extorsion to elevate and abduct eye. Cranial nerve IV palsy with compensatory head tilt so that vision issue is fixed because eyes don't line up. Week 12 External, middle and inner ear. Sound transmission Sound waves enter external acoustic meatus. This causes tympanic membrane vibrates setting off ossicular chain. Stapes presses on oval windown generating pressure in fluid of cochlea. Receptor hair cells stimulated and send impulses back to brain via vesibulocochlear nerve CN8 where they are interpreted as sound. Tensor tympani innervated by V3 and stapedieus innervated by VII control sound. If not working leads to condition where sounds are louder than normal called hyperacusis. Conduction deafness vs sensorineural deafness Conductionmorew tih external or middle part of ear. Interferes with normal movemnts of ossicular chain. Can be caused by obstruction of external acoustic meatus. Snesorinueral deafness is any lesion in receptor organ (hair cells), the vestibulocochlear nerve CN VIII or its terminus in the brain (low pons). More of an inner ear issue or something further laong process. Middle ear infections can happen. Middle ear infection shapen in children more often because of shorter and more horizontally place auditory tube. Chronic ear infection if lateral or medial walls of middle ear cavity are breached. Middle ear infection can easily spread into mastoid air cells to cause mastoditis. Middle ear infections can produce middle cranial fossa or temporal lobe abscess. Semicircular canals include anterior, posterior, and horizontal. If lesion near top of internal auditory meatus nerve pathway, can have lesions such as facial palsy, taste anterior 2/3 tongue, saslivary glands floor of mouth, skin, dry eye, nasal cavity and palate, loss of hearing and balance. External ear: collect and transmit ound. Includes auricle, external auditory meatus, and tympanic membrane. Middle ear: transmit and ambplify sound signal. Includes malleus, incus, stapes bounds, middle ear cavity, oval window, round window, tensor tympani muscle and stapedius muscle. Inner ear: transformed sound to electric signal. SIncludes scala vestibuli, scala tympani, and cochlear duct or scala media. The organ of corti is an inner ear organ located within the cochlea that contributes to audtion. Includes outer hair cells and inner hair cells. Vibrations caused by sound waves bend sterocilia onthese hair cells via an electromechnaical force. If sterocilia deflected away from longer sterocilia than hair cell membrane ehyperpolarizes and spiral ganglion neurons are inhibited. If sterociliadeflected towards longer sterocilia, hair cell membrane depolarizes and spiral ganglion neurons are excited. Higher frequencies are detected closer to middle ear. Lower tones detected closer to hemicotrema in apex of cochlea. Unilateral lesions of nerve or cochlear nuclei can cause hearing loss-ipsilateral ear. For auditory pathway decussation in pons at trapezoid body. Inferior colliculus prokects to medial geniculate nucleus in the thalamus. MGN then projects t auditory cortex in transverse tempora gyri. Lateral geniculate nucleus for visual information. Medial geniculate nucleus for auditory information. Auditry pathway summary - Spiral ganglia neuron first order neuron sitting inside cochlea. Cochlear nerve t cochlear nuclei. Make connection with cochlear nuclei in medualla. Major crossover of cochlear nuclei structures to contralateral site and make connection with superior olivary nucleus. Infortion here and can synpase orcrossback to contralateral side in pons. Audtitoru pathway fibers bundle together as white matter tracks in later lemnisuc. Bundle together to midbrain to inferior colliculus. Midbrain send fiber to thalmus to medial geniculate nucleus and tehn information sent to auditory cortex to transver temporal gyrus of Heschel. Superior olivary nuclei important because project back to cochlea to inhibit auditory nerve terminals on outer hair cells and regulate hair cell sensitivity. Conductive hearing loss related to mouter and middle ear. Snsory heing loss related to inner ear and auditoy pathway. Air conduction more effective than bonde conduction hearing tests. For weber test, conductive hearing loss louder in affected ear and ensory hearing loss heard better in unaffected ear. Auditory pathways relayed from organ of corti to medualla, pons, midbrain, thalamus, and primary auditory cortex. Vestibular organ in inner ear. Vestibula organ has peilympth fluid in it. Vestibular hair cells transduce head motion into neural activity. When sterocilia bend towards the kinoclium, tip links stretch, opening the chain of channels and allowing ions to enter the cell. Bending sterocilia away from the kinocilium relaxes tip links and encourages ion channels to close, causing hyperpolarization of the cell. Utricle detects horizontal linear motion. Utricle sounds like bicycle so horizontal. Saccule detects vertical linear motion. Saccule like vestibule detects vertical. Linear acceleration detected by macula which is a structure in the utricle and saccule. In the macula is otoliths which create drag due to greater dentisty and bends sterocilia of hair cells. Semicicrular canals have ampullae in them that detects rotational movement. Inside ampullae are cristae which detect rotational movement. Hair cells have stereocilia that extend into a gelatinous layer called a cupula. If cupula is bent towards the utricle, depolarization occurs. Excitation of hair cells when depolarization occurs. Parieto-insular vestibular cortex is a key region involved in processing vestibular information. Vestibulospinal tract helps maintain upright posture and abalnce based on infroamtion from inner ear about changes in head position ex. balance on a moving bus. Originates from vestibular nucle of pons and medulla. Course anterior funiculus of spinal cord. Ends lower motor neurons in the medial ventral horn of the spinal cord. Damage to vestibular system can cause vertigo and nystagmus. Vertigo is a spinning or whirling sensation. Nystagmus is a condition where your eyes make repetivite uncrontrolled movements. Boundaries of anterior triangle of neck -- sternoceliomastoid, border of mandible, midline of neck, and jugular notch. Common cartodi artery in neck branches off to become internal and external carotid arteries. Off of the external cartodi artery is the superior thyroid artery most inferiorly, then the lingual artery, then the facial artery. The internal carotid artery has no branches in the neck. Retropharyngeal space is a potentional highway foran infection to spread from head down into the mediastinum. Infections can spread from pharynx to thorax. There are internal and external branches of superior laryngeal nerve ad arter. If you clamp during thyroid surgery, yo run riskof clamping inferior thyroid artery and recurrent laryngeal nerve. Superior cervical ganglia seen superior to sympathetic chain in neck. Laryngotomy and tracheotomy bpth opening the airway in an emergency procedures. Frontal, parietal, temporal, and occipital 4 lobes in brain. Foramen that each cranial nerve goes through Olfactory nerve I -- cribiform plate Optic nerve II -- optic canal Occulomotoer III, trochlear IV, ophthalmic V1, and abducens VI - Superior orbital fissure Maxillary nerve V2 = Foramen rotundum Mandibular nerve V3 -= Forament Ovale Middle meningeal branch = Formane spinosum Facial nerve VII and vestibuloochlear nerve VIII = Internaal acoustic meatus Glosopharyngeal nerve IX, vagus X, and accessory XI = Jugular foramen Hypoglossa nerve XII = hypoglossal canal Facial nerve branches within parotid gland. Branches innervate muscles of facial expression -- temporal, zygomatic, buccal, marginal mandibular, cervical. Arteries and veins of the face Arteries are branches of external carotid Veins drain into the internal jugular vein. Parotid gland: salivary gland innervated by parasymaptehtcs in CN Ix. Parotid duct located superficial to massester muscles. Opens into oral cavity around upper 2^nd^ molar. Innervatin of parotid gland parasympathetic pathway -- preganglionic axons synapse in otic gangia. Postganglionic axons reach parotid via auriculotemporal nerve V2. Sympathetic to face -- paraganglion cell bodies in lateral horn of upper thoracic spinal cord. Preganglionic axons ascend sympathetic chain and synapse in superior cervical ganglion. Postganglionic axons distribute to face along external carotid artery. Upper horners = loss of sympathetic along internal carotid artery symptoms include loss of sweating in medial forehead, pupillary constriction, a and drooping of upper eyelid. Lower horners= loss of sympathetics along external cartodi artery. Symptoms include loss of sweating to face inferior to orbit and skin off lateral foreheard and temporal fossa. Week 13 Common carotid artery splits off into external more medially and internal carotid artery as you get near madnible of chin. Internal carotid has no branches in the neck. External carotid has branches in the neck. External carotid artery has superior thyroid artery coming off of it. This is most inferior branch and goes straight to the thyroid area from the external carotid artery. Second brnach off of external cartodi located superorly to superior thyroid is the lingual artery which courses deep to that muscle. Third branch off of external carotid most superficial is the facial artery. Goes up to inferior part of mandible. Then maxillary comes off external carotid artery in buccal area of face. Superficail temporal artery comes off of superior part of external carotid artery in the upper forehead area. Carotid sheath contains the internal jugular vein, common carotid artery, and vagus nerve, Superficial muscels of mastication are temporalis which is more superior and closes jaw and masseter which is more infeeior and closes jaw. Deep muscles of mastication located in the infratemporal fossa include lateral pterygid which opens jaw and moves chin towards opposite side and the medial pterygoid which closes jaw. Lateral pterygoid is only main muscle to be jaw opener. Temporalis, masseter, and medial pterygoid close jaw. Because of gravity need more muscles to close jaw. All 4 muscles of mastication are innervated by V3. V3 enters into infratemporal fossa through the foramen ovale. Mandibular nerve branches off to auriculotemporal, inferior alveolar, lingual and long buccal nerves. These are all sensory innervation. 1. Long buccal sensory to check. 2. Lingual sensory to anterior 2/3 tongue. 3. Inferior alveolar sensory to mandibular teeth. 4. Auriculotemporal sensory to region of exernal ear and postganglionic parasympathetic fibers to paooritd gland. Then V3 has motor innervation to muscles of mastication and tensor tympani and tensor veli palatini. Chorda tympani is a branch of cranial nerv 7 and meets up with lingual nerve to give taste sensation from anterior tongue and preganglionic parasympathetic fibers to submandibular and sublingual glands. Cranial nerve V3 also innervaeboth tensor tymapni and tensor veli palatini. Middle meningeal artery branches off from maxillar artery and lies medial to lateral pterygoid muscle. Foramen spinosum -- middle meningeal artery runs through here. Foramne spinosum is posterolateral to foramen ovale. The parasympathetic nerve supply to the parotid gland is mainly from the glossopharyngeal nerve (cranial nerve IX). The preganglionic fibers synapse in the otic ganglion; the postganglionic fibers reach the gland through the auriculotemporal nerve. Stylopharyngeus muscle in neck is innervated by cranial nerve glossopharyngeal nerve. The pharyngeal plexus is controlled by the glossopharyngeal nerve for sensory innervation. The arytenoid cartilages slide medially/laterally on cricoid and rotate around the vertical axis to allow for controlling the vocal folds. Movements of vocal ligaments include tensing vocal ligaments with phonation, abduction for inspiration, adduction for swallowing and holding breath, adduction for phonation, and relaxing vocal ligaments for honation. Muscle of the larynx Innervation Abduct or Adduct -------------------------- ------------------------------------------------ ------------------------------------------------ cricothyroid by external branch of superior laryngeal nerve helps to tense and **adduct** the vocal cords. Posterior cricoarytenoid Recurrent laryngeal nerve **Abducts** vocal ligaments Arytenoids Recurrent laryngeal. nerve **Adducts** the vocal ligaments Lateral cricoarytenoids Recurrent laryngeal nerve **Adducts** the vocal ligaments Thyroarytenoid Recurrent laryngeal nerve **Adducts** and relaxes vocal ligaments All of the muscles of larynx are innervated by recurrent laryngeal nerve except the cricothyroid which is innervated by the external branch of the superior laryngeal nerve of vagus. There are both external and internal branches of superior laryngeal nerve of vagus. The superior laryngeal nerve has two branches: the internal branch, which provides sensory innervation to the supraglottic region, and the external branch, which supplies motor innervation to the cricothyroid muscle. Aditus = opening into larynx Rima glottidis = \[art of laryngeal cavity between the vocal folds. Glottis = reqion of larynx formed by the vocal folds and the intervening rima glottidis. Laryngeal vestibule = part of laryngeal cavity above the vocal forlds. Opening the airway in an emergency can occur as laryngotomy which is more superior or tracheotomy which is more inferior. Confluence of spaces in the head and neck are where infections in one can spread to the other. Contents of masticator space include ramus of mandible and TMJ, 4 muscles of mastication, mandibular division of trigmenial nerve CN V3, chroda tympan branch of CN VII, and maxillary artery and beon including pterygoid plexys. Cotents of parapharyngeal space include fat and deepcervical lympth nodes. Orinetation of tongue muscles -- mylohyoid is most inferior and then geniohyoid and then genioglossus. More laterally and superficial is hyoglossus. Relationship of mandibular teeth root apices to the myohyoid line. Apices of anterior teeth located superor to mylohyoid line and are in the sublingual fascial space. Apices of posterior teeth located inferior to mylohyoid line and are in the submandibular fascial space. Subllingual space infection caused by medial erosion of a periapical abscess of an anterior madnibualr tooth. Results in elevation and displacement of tongue to opposite side. Submandibular space infection caused by medal erosion of a periapical abscess of a posterior madndiblar tooth. Results in swelling in suprahyoid regon of neck becaneath chin and body of mandible. Ludwig's angina is bilateral infection in sublingual and submandibular fascial sapces. Cranial Nerve Madnibular division of trigeminal nerve V3 ------------------ ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -- Name of foramen Foramen ovale Sensory deficits Anterior 2/3 fo tongue just sensory not tste (taste comes from CN 7 chorda tympani), numbness in lower teeth and gums on affected side, loss of feeling of jaw on affected side. Motor deficits Muscles of mastication affected, temporalis, masseter, medial pterygoid, lateral pterygoid. Jaw deviates twowards side of lesion bc muscle intact pulls chin to other side. Palatine tonsil clinical correlation. When you remove tonsils need to be caeful to injure cranial nerve 9. Patients complain about taste after tonsilitis because bleeding and swelling in area which compresses cranial nerve 9 and messes with taste for first ew days after surgery. Goes away after swelling subsides. Tonsils and cranial nerve 9. Part of tongue Cranial nerve and function ------------------------- -------------------------------- Anterior 2/3 tongue taste is CN 7 and pain is CN 5 Posterior 1/3 of tongue taste and pain is CN 9 Epiglottis taste and pain is CN 10 Muscles of the tongue and main action Genioglossus -- protrusion and deviation of tongue. Mneumonic a genius prodtrudes from the crowd. Genius deviates out and works on opposite side. Styloglossus -- retraction and elevation of tongue. Mneumonic retract in style and elevate on platform. Stay in style and work on the same side. Hyoglossus -- depresses tongue. Mnuemonic you pretend to do be on a high but you get depressed and pulls the tongue down. Tensor veli palatini innvervated by cranial nerve V3. Levator veli palatini innvervated by cranial nerve 10. To test if crnail nerve 10 is working, see if there is a cough reflex working. If innervation of mucosa not working could be a cranial 10 issue. Vocal folds and thyroid gland would be paralyzed if damage to cranial nerve 10. To test which cranial nerve is injured for a patient, do a differential diagnosis to see which nerve is affected. Functions of the nasal cavity -- olfaction, warm inspired air, moisten inspired air, filter inspired air. Job of nasal conchae to increase surface area and create turbulent air flow which brings more inspired air in contact with the mucosa. Each meatus is te space lateral to the respective concha. Functons of the paranasal sinuses to lighten the head resonance for ovoice mucous production. 4 sinuses are frontal, sphenoid, ethmoid, and maxillary. Sinus name Drains into where? ---------------------------- ------------------------ Frontal sinus Middle meatus Anerior and middle ethmoid Middle meatus Maxillary Middle meatus Posterio ethmoid Superior meatus Sphenoid Sphenoethmoidal recess Nasolacrmial dusct Inferior meatus Nosebleeds typically occur in kiesselbach's area which includes sphenopalatine (maxillary), greater palatine (maxillary), anterior ethmoidal (ophthalmic), ad septal branch of superior labial (facial). Sensory innvervation to the nasal cavity is converyed mostly via maxillary division of trigmenial nerve. Innervation of maxillary sinus and maxillary teeth through, maxillary V2, zygomatic nerve, superor alveolar nerves, and infraorbital nerves. Postganglionic parasympathteics from pterygopalatine ganglion are secretomotor to glands in the nasal cavity and palate. Innervation of the pterygoplatine ganglion -- preganglionic parasympathetics fro the facial nerve (greater petrosal branch) via the nerve of the pterygoid canal. Flavor is combination of taste, smell, texture, temperature, an dspicyness. Cranial nerves that contribute to flavor include CN 1 olfactory, V trigeminal, VII facial, IX glossopharyngeal, and X vagus. Sensory structures on tongue called papillae. Types of papillae and if they have tastebuds Filiform -- no tastebuds Fungiform- some tastebuds Circumvallate -- many tastebuds Lingual nerve branches off of V3 manibular branch of trigeminal. Lingual nerve meets up with fiacl nerve to give innervatin to tongue. Symmary of lympathic drainage in head and neck Submandibular nodes -- upper lip and corner of mouth, lateral anterior 2/3 of tongue, posterior floor of mouth, maxillar teeth, palate, and palatal gingivae, maxillary and mandibular vestibular gingivae. Submental nodes -- medial lower lip and chin, tip of tongue, anterior floor of mouth Superior deep cervical jugular nodes -- medial anterior 2/3 of tongue, palatine tonisil, posterior 13 of tongue, and mandibular teeth. In the confluence of fascial spaces, parapharyngeal, sublingual, and submandibular spaces all directly communicate. Retropharyngeal space posterior to that area. The cavernous sinus drains posteriorly into the petrosal sinuses (superior and inferior). The superior petrosal sinus connects to the transverse and sigmoid sinus. The inferior petrosal sinus connects to the sigmoid sinus--internal jugular vein (IJV), and basilar plexus--internal vertebral venous plexus.