Week 9 b
Equine head and neck 2
Facial nerve damage:
- Affected is the buccinators muscle-function of the muscle: to return food back to the oral
- Denervation will cause collection of food in the oral vestibule
- 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
- covered levator labii superioris
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
- 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.
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:
- 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.
New born: last premolar and 1
A) New born to 1month: last
premolar and 1stmolar
B) 1 year-PM4 , M1,M2
M3(premolar and all the
molars) connected the floor
C) 4 to 6 years – molar teeth
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
5) lingual process of basihyiod
8) arytenoids 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.
1) name the four laryngeal cartiages from rostral to caudal
-Thyroid- shield like appearance
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:
intrinsic laryngeal muscle
- role of dorsal cricoarytenoid(CAD) muscle- to abduct the glottis
- role of recurrent laryngeal nerve- to innervate