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Equine Special Senses - Horse Anatomy (view source)
Revision as of 13:36, 22 November 2012
, 13:36, 22 November 2012→Nose
'''Middle nasal meatus''': Between the dorsal and ventral conchae, and communicates with the [[Equine Upper Respiratory Tract - Horse Anatomy#Paranasal Sinuses|paranasal sinuses]].
'''Middle nasal meatus''': Between the dorsal and ventral conchae, and communicates with the [[Equine Upper Respiratory Tract - Horse Anatomy#Paranasal Sinuses|paranasal sinuses]].
'''Ventral nasal meatus''': The main pathway for airflow leading to the [[Pharynx - Anatomy & Physiology|pharynx]], and is positioned between the ventral nasal concha and the floor of the nasal cavity.
'''Ventral nasal meatus''': The main pathway for airflow leading to the [[Pharynx - Anatomy & Physiology|pharynx]], and is positioned between the ventral nasal concha and the floor of the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]].
'''Common nasal meatus''': The longitudinal space on either side of the nasal septum.
'''Common nasal meatus''': The longitudinal space on either side of the nasal septum.
The [[Equine Upper Respiratory Tract - Horse Anatomy#Paranasal Sinuses|paranasal sinuses]] are extensions of the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]].
The [[Equine Upper Respiratory Tract - Horse Anatomy#Paranasal Sinuses|paranasal sinuses]] are extensions of the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]].
===Vasculature===
There is a dense network of blood vessels supplying the nasal mucosa. The '''sphenopalatine artery''' supplies the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]]. The lateral and dorsal '''nasal arteries''', which are branches of the facial artery, itself a branch of the '''external carotid artery''', supply the [[Equine Upper Respiratory Tract - Horse Anatomy#Nose|nose]]. The '''infraorbital artery''' also supplies the [[Equine Upper Respiratory Tract - Horse Anatomy#Nose|nose]].
==Innervation==
Sensory innervation is provided by the '''olfactory nerve''' ([[Equine Cranial Nerves - Horse Anatomy#Olfactory Nerve (I)|CN I]]).
===Olfaction===
[[Image:Olfactory Epithelium.jpg|thumb|right|250px|Olfactory Epithelium - Copyright David Bainbridge]]
The '''olfactory sensory neurones''' are present in the olfactory epithelium. It is the mucous membrane of the dorsal nasal conchae that is sensitive to smell. Here, odourants dissolve in the mucous membrane, and it is these odourants that are recognised by the olfactory sensory receptors. '''Sensory cilia''', that are present on the surface of the olfactory receptors, project into the film of mucous. The mucous also contains antibodies, to prevent infection. This is because the olfactory neurones provide a direct passage, via the olfactory nerve ([[Equine Cranial Nerves - Horse Anatomy#Olfactory Nerve (I)|CN I]]), to the [[Equine Brain - Horse Anatomy|brain]].
===Central Olfactory Pathways===
[[Image:Central Olfactory Pathways.jpg|thumb|right|250px|Central Olfactory Pathways - Copyright David Bainbridge]]
The olfactory receptors are embedded in the mucous membrane within the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]]. They are '''bipolar neurones''', and are covered with cilia (non-motile). It is thought that these cilia contain the active sites for the olfactory transduction process. The axons from the olfactory receptors join together and become the olfactory nerve ([[Equine Cranial Nerves - Horse Anatomy#Olfactory Nerve (I)|CN I]]). The axons pass through the perforations in the '''cribriform plate''' of the ethmoid bone, and enter the '''olfactory bulb'''. Once the axons have entered the olfactory bulb, the olfactory nerve synapses on '''mitral cells'''. The axons from these cells then project into the '''olfactory cortex''' of the [[Equine Brain - Horse Anatomy#Forebrain|cerebral hemispheres]], via the '''olfactory tract'''. The olfactory cortex is the only region within the [[Equine Brain - Horse Anatomy#Forebrain|cerebral hemispheres]] that receives direct sensory input without any information first passing through the [[Equine Brain - Horse Anatomy#Forebrain|thalamus]]. This is because the olfactory system evolved before the [[Equine Brain - Horse Anatomy#Forebrain|thalamus]].
===Vomeronasal Organ===
Click here for information on the [[Vomeronasal Organ]].
==Histology==
Olfactory epithelium is made up of '''olfactory cells''', '''sustentacular cells''' and '''basal cells'''. The olfactory axons and olfactory glands are present in the lamina propria. The first part of the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]], from the nostrils, is lined by keratinised stratified squamous epithelium. Sebaceous glands and hairs are also present in this region. The hairs function to keep dust out of the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]]. The upper part of the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]]is also lined by stratified squamous epithelium, but it is no longer keratinised. The epithelium then becomes pseudostratified columnar, and is ciliated. This is typical of the respiratory system, so this type of epithelium may also be known as respiratory epithelium. Goblet cells, which produce mucous, are present in this region of the nasal cavity. Mucous and serous glands are present in the connective tissue, the lamina propria, which lies underneath the epithelium that covers the nasal conchae. The olfactory region of the nasal cavity is formed by the membrane covering the dorsal nasal conchae. Cilia in this region are formed from olfactory cells, although they are non-motile. It is the membrane that covers these cilia that contains the olfactory receptors that are sensitive to smell, after the odours have been dissolved in the serous membrane covering the epithelium. The axons of these receptors bundle together within the lamina propria. The olfactory cells gain mechanical and metabolic support from the sustentacular cells.
===Links===
Click here for more information on the [[Equine Upper Respiratory Tract - Horse Anatomy#Nasal Cavity|nasal cavity]]
Click here for more information on the [[Equine Upper Respiratory Tract - Horse Anatomy#Paranasal Sinuses| paranasal sinuses]]
Click here for more information on [[Diseases of the nasal cavity and sinuses|diseases of the nasal cavity and sinuses]].
==Gustatory System==
==Gustatory System==