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what is the normal position of the soft palate during breathing

1) free edge rostral to epiglottis in most species
2) soft palate very long in horses, hanging down beneath epiglottis ( ⇒ horses unable to breathe through mouth); sometimes displaced over epiglottis during exercise (causes partial obstruction)
3) brachycephalic dogs - long soft palate rests over epiglottis (⇒ problems with breathing) - excess soft tissues - in constant state of partial obstruction


what occurs during deglutition

raised to stop food entering nasopharynx


auditory tubes what also called, where located, what enter into, what surrounded by, function and when opened

formerly known as Eustachian tubes
• lead from middle ear cavity to open into lateral wall of nasopharynx (respiratory tract)
• partially surrounded by cartilaginous tube
• allow equalization of pressure between middle ear cavity and external environment
• entrance normally closed, but opens during swallowing


what are the 3 parts of the ear and which is air filled

1) external
2) inner
3) middle - air filled


guttural pouches what species found, what are they, what separated into and what lined with

• only in horses
• air-filled diverticula of auditory tubes - left and right pouches
• thin-walled, lined with respiratory mucosa


guttural pouches where located, what do they sit on and what does it divide them into

• medial to mandible between skull and atlas (dorsally) and pharynx and proximal oesophagus (ventrally)
• moulded over stylohyoid bone, which divides each pouch incompletely into lateral and medial


what is the guttural pouches associated with

facial (CNVII), glossopharyngeal (CNIX), vagal (CNX), accessory (CNXI), and hypoglossal (CNXII) nerves (motor innovation for the tongue); sympathetic trunk and internal carotid artery (major supply of blood to the brain), medial retropharyngeal lymph nodes


guttural pouches what is the function, how drain and how to enter through surgery

function unknown, but possibly:
- buffering pressure changes around middle ear
- cooling of blood to brain (internal carotid a.)
• drain via auditory tubes into nasopharynx
• surgical approach through Viborg’s triangle:
- caudal border of mandible
- sternocephalicus tendon
- linguofacial vein


larynx what is the wall formed by and what suspended by

- wall formed by the laryngeal cartilages and muscles
- suspended from skull by hyoid apparatus


List the 6 hyoid bones, which are paired and which are fused in the horse

1) tympanohyoid cartilage - articulates with skull
2) stylohyoid bone - fused
3) epihyoid bone - fused
4) ceratohyoid bone
5) basihyoid bone - unpaired bone - connect the pairs of hyoid bones
6) thyrohyoid bone -


what are the 3 main functions of the larynx and describe

1) connection between pharynx and trachea
2) protection of respiratory tract
- closure during swallowing (epiglottis, vocal folds)
- sensory innervation (⇒ coughing reflex)
3) vocalisation - vocal and vestibular folds - structures that cause vocalisation
- Two components:
○ phonation - production of sound
○ articulation - modification by structures of mouth and sinuses


list the paired and unpaired laryngeal cartilages

• unpaired:
- epiglottis
- thyroid
- cricoid
• paired:
- arytenoid


arytenoid cartilages what position compared to thyroid cartilage, what are the two important structures that come off it, what type of cartilage and what is movement responsible for

- medial
- vocal process (vocal fold)
- muscular process (cricoarytenoideus dorsalis and cricoarytenoideus lateralis)
• part hyaline (more rigid cartilage), part elastic cartilage
• movement of arytenoids (at cricoarytenoid joint) responsible for closure of larynx


circoid cartilage what does it form, where positioned compared to thyroid cartilage, what type of cartilage

- forms a ring and enlarged dorsally to form roof of larynx
- caudal and partially medial to thyroid cartilage
- hyaline cartilage


epiglottis where positioned in larynx, what type of cartilage

- most rostral
- elastic cartilage (flexible)


thyroid cartilage what made of and what form, what is special about it and what type of cartilage

- two lateral plated (wall of larynx) meet ventrally to form floor of larynx
- most rostral part thickened (adams apple) - also largest cartilage
- hyaline cartilage


what are the 5 sturctures that make up the laryngeal cavity

1) laryngeal vestible
2) glottis
3) vocal fold
4) vestibular fold
5) laryngeal ventricle


what is the laryngeal vestible, vestibular fold and laryngeal ventricle

- laryngeal vestibule - open rostral part of larynx
- vestibular fold - parallel to vocal fold, but more rostral
- laryngeal ventricle - pocket of mucosa between vestibular and vocal folds
- depth varies between species (particularly deep in horse)


what is the glottis and what compromised of

where lumen narrows at caudal limit of vestibule
- comprised of arytenoid cartilages (dorsally) and vocal folds (ventrally)


vocal fold what comprised of, where does it run ad function

comprised of m. vocalis and mucosal covering
- runs from vocal process of arytenoid cartilage to floor of thyroid cartilage
- position dependent on position of arytenoids
- position controls diameter of glottis
- air passing over vocal folds leads to phonation


extrinsic laryngeal muscles where extend from and what are the two types and muscles within

• extend from components of larynx to other structures
• Pharyngeal constrictors:
- series of muscles forming walls and roof of pharynx
- most caudal pharyngeal constrictors attached to larynx
• Muscles that move larynx:
- thyrohyoideus
- sternothyroideus (draws larynx caudally)
- hyoepiglotticus (draws epiglottis ventrally)


intrinsic laryngeal muscles name the 3 main ones and what they do

1) cricothyroideus - moves circoid cartilage dorsally - tense vocal folds
2) cricoarytenoideus dorsalis - moves artenoid cartilage pen vocal process - need to breath
3) thyroarytenoideus composed of m. vocalis and m. ventricularis - occupy vocal and vestibular folds


what is the laryngeal innervation

- branches of vagus nerve (CNX) provide sensory innervation (coughing - protection)
1. cranial laryngeal nerve - branches off vagus nerve cranial to caudal nerve
2. caudal laryngeal nerve - from recurrent laryngeal nerve - branches from vagus in abdomen and goes up the neck before becoming the caudal etc


what does the Cranial laryngeal nerve innovate

• motor to cricothyroideus (only one muscle)
• sensory to mucosa cranial to vocal folds


what does the Caudal laryngeal nerve innovate and what are complications with this nerve

• motor to all intrinsic muscles except cricothyroideus
• sensory to mucosa caudal to vocal folds
• damage to caudal laryngeal nerve has serious clinical implications
- Prone due to the tract of the nerve through the abdomen - partially common in horses


what is the larynx in birds supported by and function

• supported by cricoid and paired arytenoid cartilages (i.e. there is no epiglottis or other cartilages)
- not used for vocalisation


glottis in the bird what formed by, how closed and what is missing

- formed by arytenoids
- closed by reflex muscle actin during swallowing
- no vocal folds



cartilage ridge at tracheal bifurcation (branching point)


trachea where bifurcates into what, what supported by, what muscle needed and where located

• bifurcates (branches) into two principal bronchi (left and right) at level of 4th-5th thoracic vertebrae
• supported by cartilage rings:
- incomplete dorsally in mammals (complete rings in birds)
- hyaline cartilage
• trachealis muscle: smooth (involuntary) muscle forming roof of trachea
- carnivores - outside, herbivores within the cartilage ring


bronchi structure, what type of bronchi

- similar structure to trachea but with cartilaginous plates instead of rings
1) principle bronchi - enters each lung - left and right
2) secondary bronchus split from primary etc
2) terminal bronchial - when no further branching