Orbit and nasal cavity Flashcards
Superior oblique muscle
Extra- ocular muscle responsible for:
- Depression
- Abduction
Innervated by Trochlear nerve
Superior rectus
Extra- ocular muscle responsible for:
- Elevation
- Abduction
Innervated by CN3
Inferior oblique
Extra- ocular muscle responsible for:
- Elevation
Innervated by CN3
Inferior rectus
Extra- ocular muscle responsible for:
- Depression
- Adduction
Innervated by CN3
Medial rectus
Extra- ocular muscle responsible for:
- Adduction
Innervated by CN3
Lateral rectus
Extra- ocular muscle responsible for:
- Abduction
Innervated by CN6- abducens
Levator palpebrae
Muscle responsible for the elevation and retraction of the eyelid.
Orbits of the eye
Vertical
- Abduction and adduction
Transverse
- Elevation
- Depression
Anteroposterior
- Intorsion and extorsion
The natural orbit always leans outwards
Bones of the nose
Frontal
2x nasal
2x maxilla
Septum
Cartilage of the nose
Lateral
Major and minor alar
Internal projections of the nasal cavity
Superior, middle and inferior conchae
- directs flow of air
- warms the air
Lined with epithelium
Olfaction
‘Smelling’
Mechanism:
- Odiferous gases in the air are dissolved in mucosal fluid secreted by epithelium
- Conchae help to direct air
- Odiferous gases are sensed by receptors connected to CN1.
Nervous supply to the nose
- Olfactory, CN1
- CN V1, ophthalmic
- CN V2, maxillary
Blood supply to nose
Supplied by branches from:
- Ophthalmic
- Maxillary
Frontal paranasal sinus
- Drainage
- Innervation
Located on the frontal bone
- Drains into the frontonasal duct–> middle nasal meatus
Innervation
- Supraorbital nerve [from frontal nerve, CN V1]
Ethmoidal air cells
- Drainage
- Innervation
Located within the ethmoidal bone
Drainage:
- Anterior and middle ethmoidal sinus—-> drains into middle meatus
- Posterior—> into superior meatus
Innervation
- Nasocillary nerve [CN V1]
Sphenoid paranasal sinus
- Drainage
- Innervation
Located within the sphenoid bone
- Drains into the spheno-ethmoidal recess–> above the superior concha
Innervation
- Branch of nasocillary nerve [posterior ethmoidal], CN V1
Maxilla paranasal sinus
- Drainage
- Innervation
Located within the maxilla bone
- Drains into middle meatus
Innervation
- Superior alveolar nerve [CN V2]
- Infraorbital nerve [CN V2]
CN II
- Type
- Exit
- Innervation
Optic nerve
- Sensory
Exits- Optic canal
Innervates:
- Vision [transmits visual information from the retina]
Eye anatomy
Outer layer
- Sclera [eye white]
- Cornea [avascular]
Middle:
- Vascular layer
- Iris
Inner:
Retina
Posterior chamber: Below lens
Anterior chamber: Above lens
Bones of the orbit
Nasal Lacrimal Ethmoidal Frontal Sphenoid Temporal-Zygomatic Maxilla
CN III
- Type
- Exit
- Innervation
Oculomotor
- Somatic motor
Exit: Superior orbital fissure
Innervation: Extra-ocular muscles
- Superior rectus
- Medial rectus
- Inferior rectus
- Inferior oblique
Ciliary body and sphincter pupillae
- Via parasympathetic ciliary nerve.
CN IV
- Type
- Exit
- Innervation
Trochlear nerve
- Somatic motor
Exits superior orbital fissure
Innervates superior oblique muscle [Depression + abduction]
CN VI
- Type
- Exit
- Innervation
Abducens nerve
- Somatic motor—-> Lateral rectus [abduction]
Exits superior orbital fissure
Anosmia
Loss of the sense of smell\
Can be temporary [Mucus
filled from a cold] or permanent [Trauma, Parkinson’s abscess].
Blood supply to the eye [3]
Ophthalmic [From Internal carotid]
Infra-orbital [From maxillary]
Central retina [From ophthalmic]
Inability of specific eye movements- clinical consideration
Depression= Problem with CN 3/ CN 4
Elevation= CN3
Abduction= CN 3/6
Adduction = CN3
Pupil dilation [blown pupil]- clinical consideration
Indicates impairment of CN3
- CN3 supplies sphincter pupillae via parasympathetic fibres
Ptosis
Drooping eyelid
Indicates impairment of CN3
- CN3 innervates levator palpebrae [which opens eyelids]
Aneursym in cerebral artery affects CN…
3
An orbital fracture can impair CN…
4
Cavernous sinus lesion can impair CN…
6
Lacrimal apparatus
Enables crying.
- Lacrimal gland secretes lacrimal fluid.
- Lacrimal fluid flows into lacrimal papilla
- Fluid enters lacrimal sac than inferior meatus via naso-lacrimal duct.
Nervous supply to lacrimal apparatus
Secremotor
- Parasympathetic—-> follows CN VII
Vasconstrictive
- Sympathetic—-> follows interal carotid from superior cervial ganglion
Parasympathetic supply to lacrimal gland
Facial nerve at internal acoustic meatus travels
- Joins with lacrimal nerve [CN V1] into gland
CN VII—-> Greater petrosal nerve—-> Deep petrosal nerve [from internal carotid plexus]—–> Nerve of pterygoid canal synapses at ganglion
