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
guttural pouches where located, what do they sit on and what does it divide them into
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
- 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
circoid cartilage what does it form, where positioned compared to thyroid cartilage, what type of cartilage
epiglottis where positioned in larynx, what type of cartilage
- elastic cartilage (flexible)
thyroid cartilage what made of and what form, what is special about it and what type of 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
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
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
what does the Cranial laryngeal nerve innovate
* sensory to mucosa cranial to vocal folds