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227 .205 (15)

Anatomy equine head and neck

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227 .205
Peter Davie

Anatomy Week 9 b Equine head and neck 2 Kavitha  Facial nerve damage: - Affected is the buccinators muscle-function of the muscle: to return food back to the oral cavity - Denervation will cause collection of food in the oral vestibule Mental foramen- - for mental nerve- innervates the lower lip and the chin -depressor labii inferioris covers. -slip tendon aside to get to the nerve. facial artery and vein - followed by parotid duct Horse and cattle: -facial artery and vein -ventral margin of the mandible and medial side of mandible - opens opposite to cheek teeth Infraorbital foramen - covered levator labii superioris Sinuses Bovine: frontal and maxillary - form cavities of individual bones - named according to the bones - air filled diverticula of nasal cavity - mucus membrane lines sinus- these sinuses have goblet cells and cilia.-secrete mucus so it is always moist. - mucus membranes are similar to nasal cavity. A)paranasal sinuses  air filled diverticula of nasal cavity form cavities within individual bones  lined with mucosa similar to lining of nasal cavity  communicate either directly or indirectly with nasal cavity. So secretions will be drained normally through the nasal cavity. From diagram: 1)conchofrontal sinus 2)caudal maxillary sinus 3) rostral maxillary sinus 4) position of frontomaxillary opening between 1 and 2 Bovine: frontal sinus is divided into two. The caudal and rostral frontal sinus.  there are three important paranasal sinuses: 1)frontoconchal - the “frontal sinus” of the horse is undivided( unlike that of the cattle) -Cattle frontal sinus is divided in to – medial , intermediate , and lateral rostral frontal sinus Horse-Since the “frontal sinus” extends rostrally to communicate with the dorsal nasal concha it is more correctly known as the frontoconchal or conchofrontal sinus. 2)caudal maxillary and 3)rostral maxillary - the rostral maxillary sinus and caudal maxillary sinus are completely separated by a bony septum. - they do not communicate at all. -:rostral and caudal maxillary sinus- no communicate - the importance of the maxillary sinuses lies in their relationship to the check teeth. The floors of the sinuses are molded over the roots of the molars and the premolars. The relationship of the maxillary sinuses to the cheek teeth changes as horses age. Diagram: projection of maxillary sinuses at various ages. In older horses the cheek teeth are more rostrally placed. st New born: last premolar and 1 molar A) New born to 1month: last premolar and 1stmolar B) 1 year-PM4 , M1,M2 M3(premolar and all the molars) connected the floor of C) 4 to 6 years – molar teeth only(M1,M2,M3) D) Older than 12 years  Function of trephination: -To drain fluid from the sinus -To remove an infected tooth -To relieve pressure within the sinus.  entry to the maxillary sinuses -removal of an upper cheek tooth by repulsion following trephination - two structures limit the boundaries for safe surgical entry into the maxillary sinuses: Trephination must be ventral to these structures. i) the nasolacrimal duct and (A) ii) infraorbital nerve(B)  Applied anatomy: boundaries of safe surgical approach to the maxillary sinuses  Margins to drill: must drill within these boundaries. 1) a vertical line dropping from the medial canthus to the facial crest 2) a line from the Facial crestrostrally along the facial crest 3) a oblique line from the facial crest to the infraorbital foramen 4) a line from the infraorbital foramen to the medial canthus of the eye  the usual sites for entry into the A)rostral and B) caudal maxillary sinuses are shown. communication between the paranasal sinuses and the nasal cavity - in all species except the horse the frontal sinus communicates directly with the nasal cavity - instead, in the horse the frontal sinus drains into the caudal maxillary sinus, not directly into the nasal cavity, this means the frontal sinus drains indirectly(“serial drainage”) - the opening between the frontal sinus and caudal maxillary sinus is large(1-2 inches in diameter). It is called the frontomaxillary opening.  in all species the maxillary sinus communicates directly with the nasal cavity. The communication is through a small slit called the nasomaxillary opening.  in the horse therefore, all paranasal sinuses communicate wither directly or indirectly with the middle nasal meatus. the nasogastric tube must be passed into the ventral meatus  frontomaxillary sinus and nasomaxillary sinus. B)Hyiod apparatus of the horse  the equine stylohyoid bone is much larger than that of a dog. - Its role is to divide the guttural pouches into medial and lateral compartments.  The dogs hyoid apparatus: SECT= stylohyiod, epihyiod, ceratohyiod and thyrohyiod.  In the horse, the epihyiod is greatly reduced or absent. 1)cartilage of auditory tube 2)stylohyiod 3)keratohyiod 4)thyrohyiod 5) lingual process of basihyiod 6)epiglottic cartilage 7)thyroid cartilage 8) arytenoids cartilage 9)cricoid cartilage.  applied anatomy: temporohyiod osteoarthropathy -progressive degenerative disease of one or both temporohyiod joints in adult horses. -aetiology: inclide extension od infection from the middle ear or guttural pouch and simple nonseptic osteoarthritis of the temporohyiod joint. - the temporohyiod joint becomes arthritic and enlarged and may ankylose. - with loss of mobility of the articulation. The physiologic forces generated by movement of the tongue and larynx may induce fracture of the petrous temporal bone or stylohyiod bone. - mild or early sings are local pain and inflammation include head tossing, ear rubbing, resentment to taking the bit and resentment to pressure at the base of the ear. c)larynx questions 1) name the four laryngeal cartiages from rostral to caudal -epiglottis-single -Arytenoid -Thyroid- shield like appearance -cricoid 2) two nerves innervate the larynx. Name them. -cranial laryngeal nerve -caudal/recurrent laryngeal nerve 3) both nerves from question 2 are branches of one cranial nerve. Name it. Vagus (CN10) 4) all intrinsic laryngeal muscles constrict the glottis, except one( the CAD= cricoarytenoideus dorsalis), which abduct the glottis. laryngeal cartilages. From diagram: 1)epiglottic cartilage 2)thyroid cartilage 3)cricoids cartilage 4)arytenoid cartilage 5)trachea 6)cricoarytenoid joint 7)cricothyroid joint  intrinsic laryngeal muscle - role of dorsal cricoarytenoid(CAD) muscle- to abduct the glottis - role of recurrent laryngeal nerve- to innervate Diagram: 1)cricothyroideus 2)cricoarytenoideus dorsalis 3)cricoarytenoideus lateralis 4)vocalis
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