Download I. Special Senses: Vision A. Accessory Structures 1. Lacrimal

I. Special Senses: Vision
A. Anatomy of the Eye
1. External Anatomy of the Eye
a. Accessory Structures
1) Palpebrae – Upper and Lower
a) Palpebral fissure
b) Medial Canthus
(1) Lacrimal Caruncle
c) Lateral Canthus
d) Tarsal Plates
(1) Tarsal (Meibomian) glands
e) Levator palpebrae superioris - open
f) Orbicularis oculi - close
2) Eyelashes
a) Ciliary glands
3) Conjunctiva - Palpebral & Ocular (Bulbar)
4) Lacrimal apparatus
a) Lacrimal glands
b) Lacrimal ducts
(1) Tears – Lacrimal fluid
(a) Lysozyme
c) Lacrimal puncta (superior & inferior)
d) Lacrimal canals
e) Lacrimal sac
f) Nasolacrimal duct
5) Extraocular (Extrinsic or External) Eye
Muscles (More detail later with Muscle System)
a) Superior rectus - Oculomotor
b) Inferior rectus - Oculomotor
c) Medial rectus - Oculomotor
d) Lateral rectus – Abducens
e) Superior oblique - Trochlear
f) Inferior oblique - Oculomotor
2. Internal Anatomy of the Eye – Gross Anatomy
a. Fibrous Tunic
1) Sclera
2) Cornea
3) Corneal lumbus
4) Canal or Schlemm (Scleral venous sinus)
b. Vascular Tunic (Uvea)
1) Choroid
a) Tapetum lucidum*
2) Iris
a) Surrounds Pupil
b) Pupillary sphincter (circular) muscles
– Intrinsic Muscle
c) Pupillary dilator (radial) muscles –
Intrinsic Muscle
d) Photopupillary Reflex
3) Ciliary body
a) Ciliary muscle – Intrinsic Muscle
b) Ciliary process
c) Suspensory ligaments (Ciliary
zonule)
c. Neural (Sensory) Tunic – Retina
1) Pigmented (epithelial layer) part
2) Neural (nervous layer) part
3) Ora serrata
d. Lens
e. Cavities
1) Anterior cavity (segment)
a) Anterior chamber
b) Posterior chamber
c) Aqueous humor is formed by
capillaries of the ciliary processes
(1) Intraocular pressure
(2) Reabsorbed by Scleral
venus sinus (Canal of
Schlemm)
2) Posterior cavity (segment)
a) Vitreous (humor) body
(1) Formed before birth
3. Microscopic Anatomy of the Retina
a. Neural Part
1) Photoreceptor cells (layer)
a) Rods
b) Cones
(1) Macula lutea
(2) Fovea (centralis)
2) Bipolar cells (layer)
3) Ganglion cells (layer)
b. Pathway of Light through Eye
1) Light goes through all layers and reflects off
of pigmented part before striking rods & cones
2) Bipolar cells
a) Horizontal cells - inhibit or
facilitate communication
3) Ganglion cells
a) Amacrine cells - enhance
b) Optic disc (Blind spot)
4) Optic nerve
4. Neural Pathway through Brain
a. Optic nerve
b. Optic chiasma
c. Optic tract
d. Thalamus
1) Lateral geniculate nucleus
2) Optic radiation
e. Visual (Optic) Cortex in the Occipital lobe
5. Observation of the Retina
a. Ophthalmoscope
6. Clinical Applications
a. Infections of the eye
1) Sty
2) Conjunctivitis
b. Diseases of the eye
1) Glaucoma
2) Diabetic retinopathy
3) Cataracts
c. Damage to Eye
1) Detached retina
2) Corneal scarring
B. Physiology of the Eye
1. Visual Acuity
a. Snellen eye chart
b. Emmetropic vision
c. Myopic vision
d. Hyperopic vision
2. Astigmatism Test
a. Refracts due to irregularities
1) Lens
2) Cornea
3. Blind spot
4. Accommodation
a. Near-point of vision
1) Clinical Application - Presbyopia
b. Convergence
1) Extrinsic Eye Muscles
2) Clinical Application – Strabismus
3) Clinical Application – Amblyopia
4) Binocular Vision allows Depth Perception
a) Panoramic Vision* in other animals
c. Accommodation Pupil Reflex
5. Electrooculogram (EOG)
a. Voluntary fixation
b. Involuntary fixation
c. Saccades
d. Tracking movements
6. Color Blindness
a. Ishihara Test Plates
1) Deutan (Deuteran) – green cones
2) Protan – red cones
3) Tritan – blue cones
4) – anomaly – deficiency of that cone
5) – anopia – lack of that cone
6) Achromatopia – complete color blindness
7. Mapping of Rods and Cones
8. Afterimages
a. Bleaching of Rhodopsin
1) Retinol (synthesized from Vitamin A)
2) Opsin (several forms)
b. Positive afterimage
c. Negative afterimage
d. Clinical Application – Nyctalopia (Night blindness)
II. Special Senses: Hearing & Equilibrium
A. Anatomy of the Ear
1. Gross Anatomy
a. External (Outer) Ear
1) Auricle (Pinna)
a) Helix
b) Lobule
2) External Auditory Meatus (Canal)
a) Ceruminous Glands
3) Tympanic Membrane – Eardrum
b. Middle Ear – Tympanic Cavity
1) Auditory Ossicles – Study more with bones
a) Malleus – Hammer
b) Incus – Anvil
c) Stapes – Stirrup
2) Auditory (Eustachian or
Pharyngotympanic) Tube
3) Skeletal Muscles
a) Tensor tympani muscle
b) Stapedius muscle
4) Oval Window
5) Round Window
6) Clinical Applications
a) Otitis media
(1) Myringotomy
(2) Tubes
b) Mastoiditis
(1) Mastoidectomy
c. Inner ( Internal) Ear
1) Semicircular Canals - Bony (Osseous) Labyrinth
a) Filled with Perilymph
(1) Orientated perpendicular to one another
(a) Anterior
(b) Posterior
(c) Lateral
(2) Ampulla
(a) Cristae (Crista ampullaris)-Receptors
(b) Cupula
(c) Semicircular Duct-Membranous
Labyrinth
1] Filled with Endolymph
b) Functions in Dynamic Equilibrium
(1) Vestibular branch of Cranial Nerve VIII
(a) Vestibular Ganglia
(2) Senses
(a) Rotation
(b) Acceleration & Deceleration
(c) Rate Change of Movement
(d) Direction Change
2) Vestibule - Bony (Osseous) Labyrinth
a) Filled with Perilymph
(1) Utricle & Saccule - Membranous
Labyrinth
(a) Maculae - Receptors
1] Otoliths
a] Statoconia
b] Gelatinous material
(b) Filled with Endolymph
1] Endolymphatic duct
2] Endolymphatic sac
b) Functions in Static Equilibrium
(1) Vestibular branch of Cranial Nerve VIII
(a) Vestibular Ganglia
(2) Utricle senses changes in horizontal plane
(3) Saccule senses changes in vertical plane
(4) Senses
(a) Gravitational Pull
(b) Linear changes in speed
3) Cochlea - Bony (Osseous) Labyrinth
a) Vestibular duct (Scala vestibule)
(1) Filled with Perilymph
(2) Bordered by Vestibular Membrane
(3) Oval window vibrates when Stapes moves
b) Tympanic duct (Scala tympani)
(1) Filled with Perilymph
(2) Continuous with Vestibular duct at tip of
spiral
(3) Round window dissipates wave energy
c) Cochlear Duct (Scala media) - Membranous Labyrinth
(1) Filled with Endolymph
(2) Spiral Organ (Organ of Corti) - Receptors
(a) Hair Cells
1] Inner Hair Cells
2] Outer Hair Cells
(b) Basilar Membrane
(c) Tectorial Membrane
d) Functions in Hearing
(1) Cochlear branch of Cranial Nerve VIII
(a) Spiral Ganglia
e) Clinical Application - Presbycusis
2. Otoscope
a. Speculum
B. Physiology of the Ear
1. Equilibrium
a. Balance Test
b. Barany Test
1) Nystagmus
2) Vertigo
c. Romberg Test
1) Posterior (Dorsal) White Column
2) Proprioceptors
d. Role of Vision
2. Hearing
a. Sound Localization
b. Frequency Range
1) Hertz
2) Pitch
c. Amplitude
1) Intensity – Loudness
2) Decibels
3) Threshold
d. Weber’s Test
1) Conduction Deafness
2) Nerve (Sensorineural) Deafness
e. Rinne Test
1) Conduction
a) Bone
b) Air
f. Audiometry - Acuity
III. Special Senses: Olfaction (Smell) and Gustation (Taste)
A. Olfaction
1. Olfactory Epithelium
a. Olfactory Receptor Cells
1) Bipolar Neurons
2)Olfactory Cilia (Hairs)
b. Basal Cells – stem cells
c. Supporting (Sustentacular) Cells
2. Lamina propria
a. Olfactory (Bowman’s) Glands
3. Olfactory Nerves
4. Olfactory Bulbs
5. Olfactory Tract
6. Olfactory Cortex – Uncus in Temporal Lobe
7. Some branches of Olfactory Tract go to
a. Hypothalamus
b. Limbic System
8. Olfactory Adaptation
a. Peripheral Adaptation
b. Central Adaptation
B. Gustation
1. Taste Buds
a. Gustatory (Taste) Cells
1) Microvillus (Gustatory Hair)
a) Taste Pore
b. Supporting Cells
2. Papillae
a. Circumvallate (Vallate)
b. Fungiform
c. Foliate
d. Filiform*
3. Taste Categories – Primary Taste Sensations
a. Sour – Acidity – H+
b. Salty – Metallic Ions – Na+
c. Bitter – Alkaloids – Gustducin & Ca+
d. Sweet – Sugars – Gustducin & K+
1) Fructose, Sucrose, Glucose
2) Saccharine
3) Some Amino Acids
e. Umami (Savory) - Glutamate
4. Gustatory Pathway
a. Sensory Information carried by Afferent Fibers of
1) Facial Nerve (VII)
2) Glossopharyngeal Nerve (IX)
3) Vagus Nerve (X)
b. Solitary nucleus of Medulla oblongata
c. Medial lemniscus
d. Thalamus
e. Gustatory Cortex of the Insula & Postcentral Gyrus
5. Taste & Smell & Texture & Temperature & Pain
IV. General Senses
A. Background Overview
1. Receptive Field
2. Labeled Line
3. Sensory Coding
4. Projection
a. Referred Pain
1) Angina pectoris
2) Heartburn
3) Heart Attacks
4) Phantom Limb Pain
5. Sensory Receptors
a. Tonic Receptors
b. Phasic Receptors
B. General Sense Receptors
1. Types of Receptors
a. Thermoreceptors
1) Free Dendritic Endings
b. Chemoreceptors
c. Nociceptors - Pain Receptors
1) Free Dendritic Endings
2) Any Sense Organ
3) Little or NO ADAPTATION - Tonic Receptors
d. Mechanoreceptors
1) Baroreceptors (Pressoreceptors)
2) Proprioceptors
a) Muscle Spindles
(1) Intrafusal Cells (Fibers)
b) Golgi Tendon Organs
3) Tactile Receptors
a) Unencapsulated Receptor Cells
(1) Free (Naked or Dendritic) Nerve Endings
(2) Merkel Cells
(a) Tactile Discs
(3) Root Hair Plexuses (Hair Follicle
Receptors)
b) Encapsulated Receptor Cells
(1) Meissner’s (Tactile) Corpuscles
(a) Phasic Receptors
(2) Pacinian (Lamellated) Corpuscles
(3) Ruffini’s Corpuscles
(4) Krause’s End Bulbs (Mucocutaneous)
C. Receptor Physiology
1. Lab Activities for General Senses
a. Two-point Discrimination Test
b. Distribution of Tactile Receptors
1) Punctate Distribution
c. Distribution of Thermoreceptors
d. Receptor Adaptation
1) Peripheral Adaptation
2) Central Adaptation
e. Referred Pain
D. Clinical Application
1. Brain Freeze