Animal Body Function VIII Audioreceptor system PDF

Master’s Degree in Veterinary Medicine Maria João Soares www.egasmoniz.com/pt 6th February 2024  www.egasmoniz.com/pt...

Master’s Degree in Veterinary Medicine Maria João Soares www.egasmoniz.com/pt 6th February 2024  www.egasmoniz.com/pt Summary This presentation is for educational purposes only - Audioreceptor system - External hear - Middle ear - Internal ear - References Master’s Degree in Veterinary Medicine - Evans, HE, Miller, ME (2013).Miller's Anatomy of the Dog(4th ed.). St. Louis, Missouri: Elsevier. Dyce, KM (2010).Textbook of veterinary anatomy (4)thed.). St. Louis, Missouri: Elsevier. Thomson, C., Hahn, C. (2012). - Mescher, A. (2021). Junqueira’s Basic Histology: Text and Atlas (16th ed.). New York: McGraw-Hill Education - Hans-Georg Liebich. Veterinary histology of domestic mammals and birds (5th Edition). 5m Publishing. 2019. ISBN 9781789180091 - Eurell, J.A., Frappier, B.L. (2006). Dellmann’s Textbook of Veterinary Histology (6th ed.). Blackwell Publishing. ISBN 9780781741484 - Bacha, W.J., Bacha, L.M. (2012). Color atlas of Veterinary Histology (3rd ed.). Wiley-Blackwell. ISBN 9780470958513 Animal Body Function VIII 2023/2024  Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only https://www.youtube.com/watch?v=eQEaiZ2j9oc Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt - The audioreceptor system, or the Ear, is the organ that receive sound waves and transformed it into This presentation is for educational purposes only electrical neural impulses. - Responsible for the sense of hearing and balance External ear (auris externa) - Middle ear (auris media) Master’s Degree in Veterinary Medicine Inner ear (auris interna) - Vestibular organ – balance - Cochlear organ - hearing Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt External ear (auris externa) This presentation is for educational purposes only - Collects and send the sound waves to the middle ear (through the tympanic membrane) - Pinna or auricle (auricula) - External acoustic meatus (meatus acusticus externus) Master’s Degree in Veterinary Medicine - Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricle This presentation is for educational purposes only - Varies greatly in size and shape between species and different breeds; - Is the external visible part of the ear Breedspecific variations are particularly important in dogs - - In most animals is highly mobile → can turned toward the source of the sound Master’s Degree in Veterinary Medicine - The left and right auricle can move independently → each auricle can focus on separate sounds - Is important for the communication between individuals - Formed by: - Auricular cartilage – shaped like a funnel Evans, 2013 - Auricular muscles – allows the localization and collection of the sound - Scutiform cartilage - Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricle – Auricular cartilage This presentation is for educational purposes only - Shaped like a funnel – opens distally and narrows proximally forming a tube that continues as external acoustic meatus - The size and shape of the auricular cartilage determines the appearance - of the auricle Master’s Degree in Veterinary Medicine - Present a convex and a concave surface. Convex surface (caudal) – Regular skin, with hair follicles Concave surface (rostral) – hairs are thin and sparse. Presence of long hairs (tragi) in the entrance to the external acoustic meatus Evans, 2013 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricule - Auricular cartilage This presentation is for educational purposes only - Apex (tip of the ear) - Helix – free margin of the auricle - Medial helix - Lateral helix - Marginal cutaneous sac/cutaneous marginal pouch (dogs and cats) - Convex surface Master’s Degree in Veterinary Medicine - Concave surface: - Scapha – more distally - Conchal cavity (concha) – more proximal to the meatus Evans, 2013 - Anthelix – transverse fold of cartilage. Separates the scapha from the conchal cavity - Tragus – plate of cartilage that projects rostrally to the concha - Antitragus – projection of cartilage lateral to the tragus - Crus of helix – projection of cartilage medial to the tragus Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricule – Auricular muscles This presentation is for educational purposes only - Arranged around the auricle and insert upon it. - Allows the movement of the auricle → Muscles can rotate, move upward and downward the external ear - - Consist in a series of layers of muscles that can differ in size and insertion not only between species and breed but also among different individuals. Master’s Degree in Veterinary Medicine - They can be fixed in the scutiform cartilage or in the skull Scutiform cartilage – a small boot-shape plate of cartilage, place in the rostromedial position of the auricule. Evans, 2013 Innervation: Facial Nerve (VII) Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricule – Auricular muscles This presentation is for educational purposes only - Intrinsic auricular muscles - Helicis muscle - Helicis minor muscle - Tragicus muscle - - Transverse auricular muscle - Oblique auricular muscle Master’s Degree in Veterinary Medicine Action: Narrow the entrance to the conchal canal and make the concha rigid - Extrinsic auricular muscles - Rostral auricular muscles - Dorsal auricular muscles - Caudal auricular muscles Evans, 2013 - Ventral auricular muscles Action: Movement of the pinna Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricule – Auricular muscles This presentation is for educational purposes only - Extrinsic auricular muscles - Rostral auricular muscles - Superficial scutuloauricularis m. - Deep scutuloauricularis m. - - Frontoscutularis m. - Zygomaticoscutularis m. Master’s Degree in Veterinary Medicine - Zygomaticoauricularis m. - Dorsal auricular muscles - Interscutularis m. - Parietoscutularis m - Parietoauricularis m. - Caudal auricular muscles Evans, 2013 - Ventral auricular muscles A. Movement of the pinna Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Pinna or auricule – Auricular muscles This presentation is for educational purposes only - Extrinsic auricular muscles - Rostral auricular muscles - Dorsal auricular muscles - - Caudal auricular muscles - Cervicoscutularis m. Master’s Degree in Veterinary Medicine - Cervicoauricularis superficial m. - Cervicoauricular medius m. - Cervicoauricular profundus m. - Ventral auricular muscles - Styloauricularis m. - Parotidoauricularis m. Evans, 2013 A. Movement of the pinna Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Evans, 2013 Pinna or auricle – Histology This presentation is for educational purposes only - Skin: - Keratinized stratified squamous epithelium - Lamina propria - Convex surface – normal skin with hair follicles Concave surface – less quantity of hair follicles Master’s Degree in Veterinary Medicine Presence of protective hairs (tragi) Sweat and sebaceous glands – increase towards the interior of the external ear - Plate of elastic cartilage - Present perforations to allow the passage of blood vessels Maria Soares Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt External ear (auris externa) This presentation is for educational purposes only - Collects and send the sound waves to the middle ear (through the tympanic membrane) - Pinna or auricle (auricula) - External acoustic meatus (meatus acusticus externus) Master’s Degree in Veterinary Medicine - Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt External acoustic meatus This presentation is for educational purposes only - Starts when the auricular cartilage narrows and forms a tube and end in the tympanic membrane (or eardrum) - Present two portions: Cartilagenous part - Auricular cartilage Annular cartilage – links the osseous part with Master’s Degree in Veterinary Medicine the concha (auricular cartilage) Osseous part Starts at the external acoustic meatus (temporal bone) Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt External acoustic meatus This presentation is for educational purposes only - Starts when the auricular cartilage narrows and forms a tube and end in the tympanic membrane (or eardrum) - Present two portions: - Cartilagenous part - - Auricular cartilage - Annular cartilage Master’s Degree in Veterinary Medicine Konig, 2020 - Osseous part - Temporal bone Carnivores and pigs: cartilaginous part is long and curved, with a initial part directed downward followed by a horizontal part directed medially. Important for the otoscope examination!! https://www.ovrs.com/blog/ears-veterinary-otoscopy/ Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt External acoustic meatus - Histology This presentation is for educational purposes only Lumen – irregular because of the presence of skin folds - Stratified squamous epithelium - Almost absence of hair follicles - - Lamina propria – connective tissue with; - Sebaceous glands; Master’s Degree in Veterinary Medicine - Ceruminous glands - Modified pigmented tubular apocrine sweat glands Cerumen (ear wax) – form by the secretions of the sebaceous and ceruminous gland plus the desquamating stratified squamous epithelial cells. Function – prevent dust from reaching the tympanic membrane Liebich, 2019 - Elastic cartilage in the cartilaginous part - Bone tissue in the osseous part Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt - The audioreceptor system, or the Ear, is the organ that receive sound waves and transformed it into This presentation is for educational purposes only electrical neural impulses. - Responsible for the sense of hearing and balance External ear (auris externa) - Middle ear (auris media) Master’s Degree in Veterinary Medicine Inner ear (auris interna) - Vestibular organ – balance - Cochlear organ - hearing Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Middle ear (auris media) This presentation is for educational purposes only - Sound waves captured by the external ear are transformed into mechanical vibrations and transmitted to the inner ear. - Present inside the temporal bone. - Tympanic membrane (membrana tympanica) Master’s Degree in Veterinary Medicine Tympanic cavity (cavitas tympanica) - Auditory ossicles (ossicula auditus) - Malleus - Incus - Stapes - Auditory tube (tuba auditive; Eustachian tube) Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Tympanic membrane Konig, 2020 This presentation is for educational purposes only - Separates the external from the middle ear - It transmits sound waves into the auditory ossicles of the middle ear Transform a sound wave into a mechanical impulse - - It is a thin, semi-transparent membrane that fills a space lined by the Master’s Degree in Veterinary Medicine tympanic ring (annulus tympanicus) Tympanic ring is interrupted dorsally by a notch Animal Body Function VIII 2023/2024  https://veteriankey.com/examination-of-the-external-ear-canal/ www.egasmoniz.com/pt Tympanic membrane This presentation is for educational purposes only Tympanic membrane is composed by two portions: - Pars tensa (B) – attaches to the tympanic ring https://link.springer.com/chapter/10.1007/978-3-030-98911-8_3 - Pars flaccida (A) – covers the notch of the tympanic ring - It has the handle of the malleus (auricular ossicle) embedded in its Master’s Degree in Veterinary Medicine medial surface → create tension and pulls the tympanic medially → in the external acoustic meatus the tympanic membrane is concave Forms the stria mallearis (light band) - C The tympanic membrane is vascularised and innervated by sensory nerve fibers Dyce, 2018  – www.egasmoniz.com/pt Tympanic membrane - Histology This presentation is for educational purposes only Tympanic membrane is composed by three layers: - Outer layer: epithelium of the external acoustic meatus (squamous epithelium without any glands) - - Middle layer: connective tissue (with collagen and Master’s Degree in Veterinary Medicine elastic fibers) - Important for the attachment to the tympanic ring - Inner layer: squamous to cuboidal epithelial tissue of the tympanic cavity Bacha, 2012 Legend: 2 – Temporal bone (tympanic ring); 3;7 – External acoustic meatus; 10 – Bone tissue (Malleus); 11;15 – Tympanic cavity ; 12;16 – Tympanic membrane;  – www.egasmoniz.com/pt Middle ear (auris media) This presentation is for educational purposes only - Sound waves captured by the external ear are transformed into mechanical vibrations and transmitted to the inner ear. - Present inside the temporal bone. - Tympanic membrane (membrana tympanica) Master’s Degree in Veterinary Medicine Tympanic cavity (cavitas tympanica) - Auditory ossicles (ossicula auditus) - Malleus - Incus - Stapes - Auditory tube (tuba auditive; Eustachian tube) Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Tympanic cavity (cavitas tympanica) This presentation is for educational purposes only - Inside the temporal bone. Air-filled cavity. - Divided into three parts: - Dorsal part or epitympanicum - Contains the auricular ossicles and two muscles - - Middle part or mesotympanicum: - Present the tympanic membrane (laterally) and the Master’s Degree in Veterinary Medicine auditive tube (rostrally) - Ventral part or hypotympanicum - Corresponds to the tympanic bulla Dyce, 2018 Walls - Laterally – tympanic membrane - Rostrally – auditive tube - Medially – Oval vestibular window and cochlear window Histology – tympanic cavity is lined by a simples squamous epithelium that covers the walls (except the auditory tube), ossicles and tympanic membrane; Lamina propria with a rich vascular and nervous supply Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory ossicles (ossicula auditus) This presentation is for educational purposes only The transmission of vibrations from the tympanic membrane to the inner ear is mediated by three bones: - Malleus (hammer) - - Incus (avril) - Stapes (stirrup) Master’s Degree in Veterinary Medicine The bones articulate to each other to form a chain that ends in the vestibular window Dyce, 2018 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory ossicles (ossicula auditus) This presentation is for educational purposes only The transmission of vibrations from the tympanic membrane to the inner ear is mediated by three bones: - Malleus (hammer) – The most lateral (embedded in the tympanic membrane) - - Incus (avril) - Stapes (stirrup) – The base articulates with the fibrocartilaginous ring (annular ligament) that surrounds Master’s Degree in Veterinary Medicine the vestibular window Ligaments and mucosal folds attaches the bones to the tympanic cavity → e.g. Annular ligament Auditory ossicles transmit the vibrations but also magnify them at least by 20 times → is essential to initiate waves in the endolymph (inner ear) - This is dependent of two muscles that are associated with the Konig, 2020 auditory ossicles Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory ossicles (ossicula auditus) This presentation is for educational purposes only Present two muscles associated: - Tensor tympani muscle (6) – insert in the handle (manunbrium) of the malleus; - - A. higher sensitivity of the transmission system - I. tensor tympani nerve (branch of the V3 – mandibular nerve) Master’s Degree in Veterinary Medicine - Stapedius muscle – insert in the head of the stapes - A. attenuating effect on transmission - I. Stapedial nerve (branch of the facial nerve - VII) Chorda tympani nerve (branch from the facial nerve) pass through the tympanic cavity (in the dorsal part) Not related with the auditory apparatus: - preganglionic parasympathetic fibers (salivary A. - Action glands) + special visceral afferent fibers (taste) I. - Innervation Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory tube (tuba auditive; Eustachian tube) This presentation is for educational purposes only Dyce, 2018 - Connects the tympanic cavity with the nasopharynx - Short and narrow lumen → usually collapsed - - Present an osseous part (temporal bone - near the tympanic cavity) and a cartilaginous part (towards the nasopharynx) Master’s Degree in Veterinary Medicine In the tympanic cavity – opening of auditory tube In the nasopharynx – pharyngeal opening of the auditory tube Function: equalization of the pressure on the two sides of the tympanic membranes. The auditory tubes temporarily open with swallowing or yawning. Also drains the secretions of the tympanic cavity. Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory tube (tuba auditive; Eustachian tube) This presentation is for educational purposes only - Connects the tympanic cavity with the nasopharynx - Short and narrow lumen → usually collapsed Histology of the auditory tube: - - Ciliated pseudostratified epithelium with goblet cells (in all the extension, including the opening in the tympanic cavity); Master’s Degree in Veterinary Medicine - Lamina propria – connective tissue with capillaries and nerves and numerous lymphatic cells/lymphatic nodules. - Sheep and carnivore: mixed glands are present in the cartilaginous region - Tubal tonsils – present in the ungulates near the pharyngeal opening of the auditory tube Dyce, 2018 - Cartilage: - Hyaline cartilage near the tympanic cavity; - Elastic cartilage toward the nasopharynx Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory tube (tuba auditive; Eustachian tube) – Guttural pouches This presentation is for educational purposes only - Guttural pouches are an anatomical characteristic of equids Diverticulum of the auditory tube located dorsolaterally to the nasopharynx The stylohyoid bone incompletely divides the pouch into medial and lateral compartments. - Histology: Master’s Degree in Veterinary Medicine - Ciliated pseudostratified epithelium with goblet cells (8) - Lamina propria – elastic fibers, smooth muscle cells and glands (5) - External surface – tunica adventitia Unlike the rest of the auditory tube the guttural pouch do not present a cartilaginous support Function: reduction of the specific weight of the head; Mechanism for cooling the cerebral blood supply Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory tube (tuba auditive; Eustachian tube) – Guttural pouches This presentation is for educational purposes only - Guttural pouches are an anatomical characteristic of equids Several important structures are in close anatomical relationship to the pouch: - - External carotid a. (7); Internal carotid a. (3); Vagus n. (2); Glossopharyngeal n. (11); Hypoglossal n. (1); Cranial cervical ganglion Master’s Degree in Veterinary Medicine Guttural pouch disorders are relatively common in the horse, and often are infections → they may spread to the related structures and lead to important complications! Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Tympanic bulla This presentation is for educational purposes only - Air-filled dilation in the temporal bone - Corresponds to the ventral part of the tympanic cavity Function: not well understood but seems to improve the perception of sounds of very - low and very high frequencies. Master’s Degree in Veterinary Medicine Oval vestibular window (fenestra vestibuli) – located rostrodorsally and is occupied by the base of the stapes - Connects the tympanic cavity with the internal ear. Cochlear window (foramen cochleae) – located more caudally and is round in shape - Leads to the cavity of the cochlea. - Present a secondary tympanic membrane closing the structure Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt - The audioreceptor system, or the Ear, is the organ that receive sound waves and transformed it into This presentation is for educational purposes only electrical neural impulses. - Responsible for the sense of hearing and balance External ear (auris externa) - Middle ear (auris media) Master’s Degree in Veterinary Medicine Inner ear (auris interna) - Vestibular organ – balance - Cochlear organ - hearing Konig, 2020 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - It is the place where the mechanical stimuli produced by sound and by positional changes of the head are converted into nerve impulses. The Inner ear is completely enclosed in the temporal bone (petrosal part). - - Is composed by a system of fluids → perilymph and endolymph Master’s Degree in Veterinary Medicine - Composed by an osseous labyrinth (labyrinthus osseus) that houses the membranous labyrinth (labyrinthus membranaceus) Membranous labyrinth is divided into: - Vestibular apparatus – associated with balance - Cochlear duct – associated with hearing Membranous labyrinth is lined with simple squamous epithelium Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - The membranous labyrinth and the osseous labyrinth are separate by a space – perilymphatic space (spatium perilymphaticum) - - This space is full of perilymph → a fluid similar to the cerebrospinal fluid (CSF) Master’s Degree in Veterinary Medicine - Origin: microvasculature of the periosteum - Drainage: Perilymph is drained via perilymphatic duct to the subarachnoid space (19) - Function: suspend and support the membranous labyrinth from the hard wall of the osseous labyrinth  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - The membranous labyrinth and the osseous labyrinth are separate by a space – perilymphatic space (spatium perilymphaticum) - - This space is full of perilymph → a fluid similar to the cerebrospinal fluid (CSF) Master’s Degree in Veterinary Medicine - Inside the membranous labyrinth the space is fill with endolymph - Endolymph → composition similar to the intracellular fluid - Origin: produce in the membranous labyrinth (sacculus, utriculus and cochlear duct) - Endolymph is drained by the endolymphatic duct (17) into venous sinuses of the dura mater - Endolymphatic sac – in the end of the endolymphatic duct. Important to regulate the pressure and volume of endolymph  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - Osseous labyrinth - Vestibule (11) - Semicircular canals (12) - - Cochlea (18) Master’s Degree in Veterinary Medicine  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - Osseous labyrinth - Vestibule Connects with the semicircular canals caudally and with the - cochlea rostrally Laterally present the vestibular window and the cochlear window Master’s Degree in Veterinary Medicine (communicates with the tympanic cavity) - Semicircular canals - Cochlea Similar in shape to a snail shell  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - Osseous labyrinth - Vestibule - Semicircular canals – SC - - Cochlea Master’s Degree in Veterinary Medicine - Membranous labyrinth Vestibule - Sacculus - Utriculus - Semicircular ducts Cochlea SC - Coclhear duct - Spiral organ/organ of Corti Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) – Membranous labyrinth This presentation is for educational purposes only Membranous labyrinth is lined by simple squamous epithelium - Vestibular apparatus – organ of balance Located in the osseous vestibule: - - Sacculus (14) - Utriculus (15) Master’s Degree in Veterinary Medicine Utriculosaccular duct – connection between the utriculus and the sacculus Located in the semicircular canals: - Three Semicircular ducts (13) with an ampulla - Auditory apparatus (labyrinthus cochlearis) – organ of hearing Located in the cochlea: - Cochlear duct (16) Ductus reuniens – connects the cochlear duct with the sacculus  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) – Membranous labyrinth This presentation is for educational purposes only - Vestibular apparatus – organ of balance Saculus and Utriculus Lumen is lined by simple squamous epithelium and - lamina propria underneath → Place of production of endolymph Master’s Degree in Veterinary Medicine Sensorial parts - macula Maculae - Epithelium Supporting cells (11) Sensory cells (hair cells) - 13 - Lamina propria (3) Thicker with a higher number of blood vessels and nervous fibers bundles Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Membranous labyrinth – Vestibular apparatus – organ of balance This presentation is for educational purposes only Sacculus and Utriculus Maculae - Epithelium - - Supporting cells: columnar cells with basal nucleus and apical microvilli Master’s Degree in Veterinary Medicine - F. supporting the sensorial cells - Sensory cells (hair cells): modified epithelial cells (secondary sensory cells) - Do not contact with the basal lamina - Apical surface: present bundles of stereocilia with a single non-motile kinocilium - Basal surface: synapses with non-myelinated nerve fibers → Vestibular nerve - Can be divided into Type I and Type II Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Membranous labyrinth – Vestibular apparatus – organ of balance This presentation is for educational purposes only Sacculus and Utriculus Maculae - Epithelium - - Supporting cells (11) - Sensory cells (hair cells) (13) Master’s Degree in Veterinary Medicine The hair cells are covered with a gelatinous glycoprotein rich layer → otolithic membrane (7) (where the stereocilia and kinocilia project) Otoliths (statoconia) (6) → calcium carbonate crystals that are located on the surface of the otolithic membrane Function: hair cells receive information regarding the linear movement (vertical or horizontal) Cells are mechanoreceptors (respond to the pressure in the stereocilia)  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) – Membranous labyrinth This presentation is for educational purposes only - Vestibular apparatus – organ of balance Located in the osseous vestibule: - Sacculus - - Utriculus Utriculosaccular duct Master’s Degree in Veterinary Medicine Located in the semicircular canals: - Three Semicircular ducts with an ampulla  – www.egasmoniz.com/pt Membranous labyrinth – Vestibular apparatus (balance) This presentation is for educational purposes only Semicircular ducts Three semicircular ducts – Anterior, Posterior and Lateral semicircular ducts - Arise from the utriculus - - They are enclosed in the semicircular canals (osseous labyrinth) Master’s Degree in Veterinary Medicine Each duct has a dilatation near the junction with the utriculus → Ampulla Histology: epithelial lining similar with the epithelium of the utriculus and sacculus. Ampulla (Ampulla membranacea) - Each ampulla contains a crista ampullaris → the sensorial part of the Semicircular ducts - Sensitive to rotary movements  – www.egasmoniz.com/pt Membranous labyrinth – Vestibular apparatus (balance) This presentation is for educational purposes only Semicircular ducts - Anterior, Posterior and Lateral semicircular ducts Ampulla (Ampulla membranacea) - 1 - Each ampulla contains a crista ampullaris → the sensorial part of the - Semicircular ducts - Sensitive to rotary movements of the head Master’s Degree in Veterinary Medicine Composed by: - Core (3) – Loose connective tissue is thicker, making a projection (ridge) of the epithelium into the lumen - Epithelium – these ridge is lined by a neuroepithelial layer of supporting (11) and sensory cells (9), similar with the cells of the maculae. - Surface of the Crista ampullaris – covered by a layer with a shape of a cupula - Cupula (4) is formed by glycoproteins but do not present crystals in the surface Neural signals are produced by the deformation of the cupula (due to the movement of the endolymph)  – www.egasmoniz.com/pt Membranous labyrinth – Vestibular apparatus (balance) This presentation is for educational purposes only Sacculus and Utriculus Semicircular ducts - Anterior, Posterior and Lateral semicircular ducts - The sensorial cells (hairs cells) of the vestibular apparatus are related to the nerve fibers of the vestibular nerve, that posses a vestibular ganglion within the internal Master’s Degree in Veterinary Medicine acoustic meatus. The vestibular nerve join with the cochlear nerve to form the vestibulocohlear nerve (VIII cranial nerve) Medulla oblongata Cerebellum Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - Auditory apparatus (labyrinthus cochlearis) Osseous labyrinth Cochlea → is a spiral-shaped osseous canal - The spirals wind around a central axis of spongy bone Modiolus Master’s Degree in Veterinary Medicine Spiral canal → space inside the cochlea Membranous labyrinth Cochlear duct  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - Auditory apparatus (labyrinthus cochlearis) Osseous labyrinth Cochlea → is a spiral-shaped osseous canal - The spirals wind around a central axis of spongy bone Modiolus Master’s Degree in Veterinary Medicine The modiolus contains the cochlear nerve and the spiral ganglion. From the modiolus bone laminas are projected – Spiral lamina  – www.egasmoniz.com/pt Inner ear or Internal ear (auris interna) This presentation is for educational purposes only - Auditory apparatus (labyrinthus cochlearis) Cochlea Modiolus – Central axis of spongy bone that encloses the spiral - ganglion and the cochlear nerve Master’s Degree in Veterinary Medicine Spiral lamina – Projections of bone tissue that incompletely divides the lumen (of the osseous labyrinth – spinal canal) into two portions: - Scala vestibuli extend from modiolus and divide cochlea into: - Scala tympani upper part vs lower part Membranous labyrinth - Cochlear duct → in a middle position between the two scala (also called scala media)  – www.egasmoniz.com/pt Auditory apparatus (labyrinthus cochlearis) This presentation is for educational purposes only Spiral lamina – Projections of bone tissue that incompletely divides the lumen (of the osseous labyrinth) into two portions: - Scala vestibuli – upper channel; begins at the base of the - stapes (Vestibular window) Master’s Degree in Veterinary Medicine - Scala tympani – lower channel; passes through the spiral canal to end in the cochlear window Helicotrema – apex of the cochlea, Where the two scala communicate The scala are lined with simple squamous epithelium and are filled with perilymph  – www.egasmoniz.com/pt Auditory apparatus (labyrinthus cochlearis) This presentation is for educational purposes only Spiral lamina – Projections of bone tissue that incompletely divides the lumen (of the osseous labyrinth) into two portions: - Scala vestibuli – upper channel; begins at the base of the - stapes (Vestibular window) Master’s Degree in Veterinary Medicine - Scala tympani – lower channel; passes through the spiral canal to end in the cochlear window Helicotrema – apex of the cochlea, Where the two scala communicate The scala are lined with simple squamous epithelium and are filled with perilymph Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Auditory apparatus (labyrinthus cochlearis) This presentation is for educational purposes only Legend: - 2- Scala media or cochlear duct 5- Modiolus Master’s Degree in Veterinary Medicine 8- Scala tympani 9- Scala vestibuli 10- Spiral ganglion 11- Spiral ligament 16- Cochlea