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===Oculomotor nerve (III)===

===Oculomotor nerve (III)===

The oculomotor nerve is part of the group of cranial nerves responsible for innervating the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Facial_Muscles|muscles of the head]]. The nerves originate from the ventral [[Midbrain_-_Anatomy_%26_Physiology|midbrain]] and is a motor nerve. It is composed of '''general somatic efferent fibres''' and '''general visceral efferent fibres'''. The general somatic efferent fibres of the oculomotor nerve are responsible for the motor function of four of the six [[Eye_-_Anatomy_%26_Physiology#Around_the_Eye|external muscles of the eyeball]]; the 'dorsal rectus', 'medial rectus', 'ventral rectus', 'ventral oblique' and 'levator of the upper eyelid'. The general visceral efferent fibres of the oculomotor nerve are responsible for the control of pupil diameter and therefore control the 'spincter pupillae' muscle and the 'ciliaris' muscle.

The oculomotor nerve is part of the group of cranial nerves responsible for innervating the [[Skull and Facial Muscles - Anatomy & Physiology#Facial_Muscles|muscles of the head]]. The nerves originate from the ventral [[Midbrain - Anatomy & Physiology|midbrain]] and is a motor nerve. It is composed of '''general somatic efferent fibres''' and '''general visceral efferent fibres'''. The general somatic efferent fibres of the oculomotor nerve are responsible for the motor function of four of the six [[Eye - Anatomy & Physiology#Around_the_Eye|external muscles of the eyeball]]; the 'dorsal rectus', 'medial rectus', 'ventral rectus', 'ventral oblique' and 'levator of the upper eyelid'. The general visceral efferent fibres of the oculomotor nerve are responsible for the control of pupil diameter and therefore control the 'spincter pupillae' muscle and the 'ciliaris' muscle.

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The oculomotor nerve has a pre-ganglionic nucleus in the midbrain and the nerve passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''orbital fissure''']], along with the trochlear, abducens and opthalmic branch (V1) of the trigeminal nerve. It synapses in the ciliary ganglion of the eye. During a clinical examination, horizontal eye movements (strabismus) or an abscent [[Neurological_Eye_Examination_-_Horse#The_pupillary_light_reflex_.28PLR.29|pupillary light reflex (PLR)]] may indicate a problem.

The oculomotor nerve has a pre-ganglionic nucleus in the midbrain and the nerve passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''orbital fissure''']], along with the trochlear, abducens and opthalmic branch (V1) of the trigeminal nerve. It synapses in the ciliary ganglion of the eye. During a clinical examination, horizontal eye movements (strabismus) or an absent [[Neurological_Eye_Examination_-_Horse#The_pupillary_light_reflex_(PLR)|pupillary light reflex (PLR)]] may indicate a problem.

===Trochlear nerve (IV)===

===Trochlear nerve (IV)===

The trochlear nerve is part of the cranial nerve group responsible for innervation of the muscles of the head. The trochlear nerve originates from the dorsal mid-brain and is a motor nerve. It is composed of '''general somatic efferent fibres''' and is the smallest of the cranial nerves. The nerve is specifically responsible for the 'dorsal oblique muscle' muscle of the eye and also passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''orbital fissure''']].

The trochlear nerve is part of the cranial nerve group responsible for innervation of the muscles of the head. The trochlear nerve originates from the dorsal mid-brain and is a motor nerve. It is composed of '''general somatic efferent fibres''' and is the smallest of the cranial nerves. The nerve is specifically responsible for the 'dorsal oblique muscle' muscle of the eye and also passes through the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''orbital fissure''']].

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===Trigeminal nerve (V)===

===Trigeminal nerve (V)===

The trigeminal nerve is part of the cranial nerve group responsible for innervation of structures originating from branchial arches. The trigeminal nerve nuclei is in the area of the pons and medulla oblongata and is the nerve of the 1st branchial arch. In general terms the trigeminal represents the sensory nerve of the head but also provides motor fibres to structures also assoicated with the 1st branchial arch. There are three primary branches of the trigeminal nerve; the '''Opthalmic nerve (V1)''', the ''' Maxillary nerve (V2)''' and the '''Mandibular nerve (V3)'''.

The trigeminal nerve is part of the cranial nerve group responsible for innervation of structures originating from branchial arches. The trigeminal nerve nuclei is in the area of the pons and medulla oblongata and is the nerve of the 1st branchial arch. In general terms the trigeminal represents the sensory nerve of the head but also provides motor fibres to structures also associated with the 1st branchial arch. There are three primary branches of the trigeminal nerve; the '''Opthalmic nerve (V1)''', the ''' Maxillary nerve (V2)''' and the '''Mandibular nerve (V3)'''.

 

====Opthalmic nerve (V1)====

====Opthalmic nerve (V1)====

The opthalmic nerve is a sensory nerve composed of '''general somatic afferent fibres''' and passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''orbital fissue''']]. As it enters the orbit of the eye it splits further into the '''lacrimal nerve''', the '''frontal nerve''', the '''nasociliary nerve''' and the '''infratrochlear nerve'''. Therefore the nerve supplies sensory fibres to many aspects of the eye orbit.

The opthalmic nerve is a sensory nerve composed of '''general somatic afferent fibres''' and passes through the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''orbital fissue''']]. As it enters the orbit of the eye it splits further into the '''lacrimal nerve''', the '''frontal nerve''', the '''nasociliary nerve''' and the '''infratrochlear nerve'''. Therefore the nerve supplies sensory fibres to many aspects of the eye orbit.

====Maxillary nerve (V2)====

====Maxillary nerve (V2)====

The maxillary nerve is a sensory nerve composed of '''general somatic afferent fibres'''. The maxillary nerve passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''round foramen''']] and the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''alar canal''']]. It also runs across the wall of the '''pterygopalatine fossa''' and enters the '''infraorbital canal''' via the '''maxillary foramen'''. Whilst in the infraorbital canal the maxillary nerve branch then branches further into the '''infraorbital nerve''' which supplies sensory fibres to the teeth. On exiting the infraorbital canal via the infraorbital foramen, the maxillary nerve branches again into the '''zygomatic nerve''' which supplies sensory fibres to the horn and to the '''pterygopalatine nerve''' supplying sensory fibres to the palate.

The maxillary nerve is a sensory nerve composed of '''general somatic afferent fibres'''. The maxillary nerve passes through the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''round foramen''']] and the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''alar canal''']]. It also runs across the wall of the '''pterygopalatine fossa''' and enters the '''infraorbital canal''' via the '''maxillary foramen'''. Whilst in the infraorbital canal, the maxillary nerve branch then branches further into the '''infraorbital nerve''' which supplies sensory fibres to the teeth. On exiting the infraorbital canal via the infraorbital foramen, the maxillary nerve branches again into the '''zygomatic nerve''' which supplies sensory fibres to the horn and to the '''pterygopalatine nerve''' supplying sensory fibres to the palate.

====Mandibular nerve (V3)====

====Mandibular nerve (V3)====

The mandibular nerve is a mixed sensory '''general somatic afferent fibres''' and motor '''general somatic efferent''' nerves. The mandibular nerve passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''oval foramen''']]. It provides motor branches to the [[Mastication|masticatory muscles]], the [[Larynx_-_Anatomy_%26_Physiology#Intrinsic_Musculature|ventral throat]] and [[Tongue_-_Anatomy_%26_Physiology#Muscles|muscles of the palate]]. The mandibular nerve further branches into the '''masticatory nerve''', the '''masseteric nerve''' and the '''temporal nerve'''. The mandibular nerve provides sensory branches called the '''buccal nerve''', the '''auriculotemporal nerve''', and then itself divides into two smaller branches; the '''lingual nerve''' and the '''inferior alveolar nerve'''. The '''lingual nerve''' receives sensory taste fibres and also connects some sensory taste fibres to parasympathetic salivary glands via the [[Tongue_-_Anatomy_%26_Physiology#Innervation|'''chorda tympani''']]. Via the chorda tympani branch the mandibular branch supplies sensory fibres related to taste to the rostral 2/3 of the tongue. The lingual branch of the glossopharyngeal nerve supplies sensory fibres to the caudal 1/3 of the tongue.

The mandibular nerve is a mixed sensory '''general somatic afferent fibres''' and motor '''general somatic efferent''' nerves. The mandibular nerve passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''oval foramen''']]. It provides motor branches to the [[Mastication|masticatory muscles]], the [[Larynx - Anatomy & Physiology#Intrinsic Musculature|ventral throat]] and [[Tongue - Anatomy & Physiology#Muscles|muscles of the palate]]. The mandibular nerve further branches into the '''masticatory nerve''', the '''masseteric nerve''' and the '''temporal nerve'''. The mandibular nerve provides sensory branches called the '''buccal nerve''', the '''auriculotemporal nerve''', and then itself divides into two smaller branches; the '''lingual nerve''' and the '''inferior alveolar nerve'''. The '''lingual nerve''' receives sensory taste fibres and also connects some sensory taste fibres to parasympathetic salivary glands via the [[Tongue - Anatomy & Physiology#Innervation|'''chorda tympani''']]. Via the chorda tympani branch, the mandibular branch supplies sensory fibres related to taste to the rostral 2/3 of the tongue. The lingual branch of the glossopharyngeal nerve supplies sensory fibres to the caudal 1/3 of the tongue.

===Abducent nerve (VI)===

===Abducent nerve (VI)===

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During a clinical examination, medial deviation stribismus may indicate a problem with this nerve.

During a clinical examination, medial deviation stribismus may indicate a problem with this nerve.

===Facial nerve (VII)===

===Facial nerve (VII)===

The facial nerve is part of the cranial nerve group responsible for the innervation of structures originating from the branchial arches. It originates from the medulla oblongata and from the second branchial arch. It has a common dura sheet with the opthalmic (V1) branch of the trigeminal nerve. The facial nerve is of a mixed composite and is made up of a number of different fibre types. It has a '''general somatic efferent fibre''' within the ear canal, a '''general visceral efferent fibre''' acting under parasympathetic control to some salivary glands, lacrimal glands, nasal cavity and palate, a '''special visceral afferent fibre''' providing taste to the rostral 2/3 of the tongue and finally it has a '''general somatic efferent fibre''' supplying motor function to the muscles of facial expression.

The facial nerve is part of the cranial nerve group responsible for the innervation of structures originating from the branchial arches. It originates from the medulla oblongata and from the second branchial arch. It has a common dura sheet with the opthalmic (V1) branch of the trigeminal nerve. The facial nerve is of a mixed composite and is made up of a number of different fibre types. It has a '''general somatic efferent fibre''' within the ear canal, a '''general visceral efferent fibre''' acting under parasympathetic control to some salivary glands, lacrimal glands, nasal cavity and palate, a '''special visceral afferent fibre''' providing taste to the rostral 2/3 of the tongue and finally it has a '''general somatic efferent fibre''' supplying motor function to the muscles of facial expression.

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The facial nerve enters the petrosal bone via the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Temporal_Bone_.28os_temporale.29|'''internal acoustic meatus''']] along with the vestibulocochlear nerve. The facial nerve also runs inside the '''facial canal'''. There are a number of intermediate branches which seperate from the main facial nerve inside the facial canal including the '''greater petrosal nerve''', the '''stapedial nerve''' (motor) and the '''chorda tympani'''. These then emerges via the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''stylomastoid foramen''']] at the caudoventral aspect of the skull. The chorda tympani of the facial nerve represents the '''special visceral afferent fibre''' supplying taste to the rostral 2/3 of the tongue.

The facial nerve enters the petrosal bone via the [[Skull and Facial Muscles - Anatomy & Physiology#Temporal Bone (os_temporale)|'''internal acoustic meatus''']] along with the vestibulocochlear nerve. The facial nerve also runs inside the '''facial canal'''. There are a number of intermediate branches which separate from the main facial nerve inside the facial canal including the '''greater petrosal nerve''', the '''stapedial nerve''' (motor) and the '''chorda tympani'''. These then emerges via the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''stylomastoid foramen''']] at the caudoventral aspect of the skull. The chorda tympani of the facial nerve represents the '''special visceral afferent fibre''' supplying taste to the rostral 2/3 of the tongue.

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The facial nerve supplies motor innervation to the muscles of facial expression. These are superficial flat, thin muscles that opriginate from bony areas of fascia and then radiate out around the skin. They may also often from sphincters such as around the mouth and eye.

The facial nerve supplies motor innervation to the muscles of facial expression. These are superficial flat, thin muscles that originate from bony areas of fascia and then radiate out around the skin. They may also often from sphincters such as around the mouth and eye.

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