Special Senses

SPECIAL ORGAN: EYE

EYES

Main fUCTIONS 

  • Used to see 

  • Meant to receive light waves 

    • Converted → image by the visual cortex (L: occipital lobe) 

  • Acts as a receptor (receives light → bend light & form focal point) 


Structures 

Allows light to get in via: 

MEDIUM

  • Cornea 

REFRACTIVE MEDIA

  • Aqueous 

  • Vitreous 

  • Lens 

COURSE OF LIGHT WAVE

Happens in split second




Light wave 

↓Bends as it enters

1st bend: Cornea

↓ 

2nd bend: Lens

↓ Light will go to

Focal point = creates image (but DOES NOT UNDERSTOOD THE IMAGE)

↓ Fall in

RETINA 

  • Receive and focus

Receptors located

  • Cones

  • Rods 

↓ From

Eyeball 

↓ sends to 

Visual cortex = understand the image 

  • All signals will sent here


eyeball

2 parts: 

ANTERIOR PART - Anterior ⅙ 

POSTERIOR PART - Posterior 5/6 ; Large part


Layers (3)

Outer fibrous

Vascular 

Inner retinal

OUTER FIBROUS 

Outermost part of the eyeball.

Form 2 anterior structure 

  • Cornea 

  • Sclera





CORNEA

  • Has high refractive power

  • Transparent = light passes

  • Avascular 

  • Refractive 

    • Light pass → bends = create focal point

  • Most problems occur 

  • Perfect sphere 

LAYERS OF CORNEA ( OUTER → INNER)

  1. Corneal epithelium 

  2. Ant. limiting lamina (Bowman’s layer)

  3. Stroma - Thickest 

  4. Posterior limiting lamina (Descement’s membrane)  

  5. Corneal endothelium

CORNEAL EPITHELIUM

  • Outermost part 

  • Nagasgas = scratched easily 

  • Errors of refraction 

    • Due → shape of cornea 

    • Not spherical in shape 

    • Light not refracted properly 

    • Light may fall before or after the retina. 

POST-CORNEA - anterior of iris

[Anterior chamber]

ANT-CORNEA - behind iris

[Posterior chamber]

  • Aqueous Humor

  • Regulates intraocular pressure of the eye w/ ciliary process 

  • Replaceable

  • Produces aqueous flow 

↓ from 

post. Chamber → ant.Chamber

↓drains to 

Canal of schlemm (one direction) 

↓ connected to 

Venous system



  • Canals = clogged → accumulation of fluid 

↓ 

Pressure = goes up 

↓

Retina = tear 

↓ lead to

Blindness 

  • Glaucoma - no adequate drainage of aqueous humor 

SCLERA

  • White part of the eyeball 

  • All race & ethnicity 

  • opaque  = light doesn’t pass through 

  • Edge - connected → bulbar conjunctiva 

    • Attached at edge of sclera 

VASCULAR 

3 parts 

  • Choroid 

  • Ciliary body 

  • iris

IRIS

  • Contracts & dilates 

  • After cornea 

    • Before anterior chamber 

  • Circular structure to the central opening (pupil) 

    • Closes & opens depend on light 

    • Light = smaller pupil 

    • Dark= bigger 

MUSCLES

  • Dilator pupillae - Dilates 

  • Sphincter pupillae  - Constrictor 

  • Ciliary body  - Edges of iris 

    • 2 parts: 

      • Ciliary muscle 

      • Ciliary processes 

        • Produces aqueous humor 

CHOROID 

  • Most vascular part 

  • Provides nutrients 

INNER RETINAL 

Innermost lining 

  • reddish-orange

2 parts: 

Optical part/Retina

  • Receive light 

  • More cones & rods (receptors) 

Non-visual part 

  • Not reach by the light 

  • Devoid rods = don’t have rods

RODS 

  • Low-lit environment

  • Unable to perceive colors 

  • Black & white only 

CONES

  • Allows light = well lit environment 

  • Color perception 

  • Allow to see colors 

  • Common in males: Color blindness 

    • Kulang ng genes to differentiate  Green & red 


LENS

  • Behind posterior chamber 

  • transparent biconcave 

  • Flexible 

  • Refracts light 

  • Lens 0pacifies → When old age = namumuti 

    • Cataract (need to replace lens)

  • Edges of lens: Zonular fibers 

  Zonular fibers 

  • Holds lens in place 

  • Allows lens to be more rounded =

  • Hinila = ninipis lens 

  • Relaxed = kakapal 

  • Refract and create focal point 


 





VITREOUS CHAMBER

  • After the lens 

Vitreous Humor

  • Provide shape of eyeball 

  • Gel-like substance 

  • Not replaceable 

  • Do not flow-steady 



Macula Lutea 

  • Depression in retina 

  • Clearest image produces 


MACULAR DEGENERATION = leads to blindness

FOVEA CENTRALIS

  • Centralis part 

  • Clear image 

  • Sharp 

  • Most no. of cones & rods 


↓ Pass to


OPTIC DISC

  • Collection of nerves from retina 

  • Blind spot of eye 

  • Don’t perceive light 

  • No rods & cones 


↓Leaves signals

OPTIC NERVES

  • Extension of optic disc (outside of eyeball) 

  • Connects eye → brain 

  • Reaches brain via 

↓

Optic chiasma

↓

Visual cortex & occipital lobe 


DIPLOPIA - 2 images seen; double vision 


OUTSIDE STRUCTURES of eye

Ligaments 

  • Holds eyeball in place

SUSPENSORY LIGAMENT

  • Suspend on eyeballs 

  • Nasa ilalim (parang duyan) 

CHECK LIGAMENTS 

  • Lateral check ligament

  • Medial check ligament

  • Holds eyeball in place 

  • Eyeball needs to sync tgt


Extraocular (6)

Rectus (4)

  • Superior - elevate

  • Inferior - depress 

  • Medial - adduction 

  • Lateral - abduction 

    • Innervation: Abducens Nerve


OBLIQUE(2) – not attached to Common tendinous ring

  • Superior oblique - depression & abduction 

    • Innervation: Trochlear nerve 

  • Inferior oblique - elevation, abduction, internal rotation 

  • Levator palpebrae superioris (not considered as part of extraocular)

    • innervation : 

      • MOTOR: Oculomotor nerve

      • SENSORY: Ophthalmic nerve 


Limbus

  • Junction of cornea & sclera 

  • Inseparable 

  • Around cornea 

Avascular – gitnang part of cornea 


Purpose of glasses

  • Bound light in retina 

  • Eyeball = long → errors of refraction
















SPECIAL ORGAN: EARS












Ears

  • Receive soundwaves 

    • Convert into signals in temporal lobe = to make sense 

  • Collector 

  • Maintain  balance 

  • Can heal itself 




3 MAIN PARTS: 

  • External ear 

    • Extend: auricle → tympanic membrane

  • Middle ear 

    • Extend: Posterior of Tympanic membrane → medial wall of middle ear 

  • Internal ear 

    • Medial to middle ear = will find the inner ear 

FOR HEARING: 

EXTERNAL EAR 

AURICLE/EAR LOBE/PINNA 

  • Lateral extension of head 

  • Cartilage except lobule 

  • Elevation and depression 

(pa-search nalang sa grey’s yung meaning nito)

  • Helix 

  • Antihelix 

  • Tragus 

  • Concha 

  • Intertragic notch 

  • Scaphoid fossa 

  • Lobule 

↓ sound wave enters to the ear canal/EAM 

EAR CANAL/External Acoustic Meatus

  • Canal/passageway made into 2 parts: 

    • Lateral - ⅓ = composed of cartilage 

    • Medial - 3rds = composed of bone 

  • Wider laterally than medially 

  • Length: 2.5 cm 

  • Has bends; not straight 

  • Lined w/ skin (as walls) = glands 

    • Sebaceous secretion = ear wax 

  • End of EAM: Tympanic membrane 

↓ to the Eardrum 

Tympanic membrane/ Eardrum

  • Create sound production/sound wave 

  • Border that separates external EAM from middle ear 

  • Thin membrane 

PARTS: 

  • Cone of light - where light is reflected 

    • L: Lower anterior; middle part of tympanic membrane 

    • Loss of cone light:  kapag nasira/scar tissue = hindi masyado mag-vibrate to have an ability to hear

  • Umbo - Central point of attachment/central attached of the handle of malleus

    • Causes to have a concavity because of pull of malleus 

  • Pars tensa - surface is tense = pulled out membrane

    • It has vibrate. 

  • Pars flaccida - loose part; soft 

↓to the middle ear 

MIDDLE EAR

  • Like a “hub” 

    • Just like a box = 6 walls(think of it as a room) 

  • Branches of facial nerve dadaan sa middle ear 

EAR OSSICLES via synovial joint

  • Handle of malleus on ear drum (not the umbo) 

Malleus → Incus → Stapes → stimulus will propagate → to the cochlea (inner ear) 

  • Malleus 

  • Transfers vibrations from the tympanic membrane to the incus.

  • Incus 

    • Articulates with malleus and stapes, acting as a central link in the ossicular chain.

  • Stapes

    • Which transmits vibrations into the oval window, which leads into the cochlea.

BOUNDARIES/ 6 WALLS OF MIDDLE EAR

  • Roof 

  • Floor

  • Lateral 

  • Medial

  • Anterior 

  • Posterior 

MEDIAL aka Labyrinthine wall

  • Separates middle ear & inner ear 

  • Prominence: 

    • Promontory - 1st turn of cochlea 

      • Bulging part 

    • Prominence of Facial nerve 

    • Prominence of lateral semicircular canal 

    • Oval window 

      • Where the footplate of stapes is attached to 

      • L: superior to promontory

    • Round window 

      • Inferior to promontory 

POSTERIOR

  • Entry and exit of mastoid antrum 


Mastoid antrum 

  • Space b/n the mastoid bone 

  • Behind of middle ear 

  • Opening aka aditus = aditus of mastoid antrum 

Nerve to stapedius 

  • Entered Via pyramidal eminence (where the nerve to the stapedius) 

  • After gets through will innervate stapedius muscle to lessen the vibrations

Chorda tympani nerve 

  • Facial canal will enter the middle ear from posterior → anterior wall 

  • After going through posterior wall → traverse to anterior wall (via facial canal) 

ANTERIOR 

Contain: 

  • Tensor tympani 

  • Pharyngotympanic tube 

  • Chorda tympani (exits) 

ROOF

  • Floor of middle cranial fossa 

    • Temporal lobe seats on 

Tegmen tympani 

  • Separates MCF from middle ear


FLOOR 

  • Beneath is the internal jugular vein


LATERAL

  • Contains: Tympanic membrane 

↓to the inner ear 

INNER EAR

  • Contains: 

    • Bony labyrinth - outer covering of membranous 

      • Semicircular canals (SCC)

      • Vestibule (V)

      • Cochlea ©

    • Membranous labyrinth - inside of bony labyrinth 

      • Semicircular duct (SCD)

      • Utricle & saccule (U&S) 

      • Cochlear duct (CD)

BL 

  • Fluid: Perilymph

ML 

  • Fluid: Endolymph 

  1. SCC 

  2. V

  3. C 

  1. SCD (balance)

  2. U&S (balance)

  3. CD (hearing) 

*Kung ano katapat sa (Bony labyrinth), ayun ang laman sa loob (= Membranous) 

  • Lymph - circulate around this structures 

  • All structures connected to each other 


*pagkasunod 


SSC → V → C 

BONY LABYRINTH

COCHLEA 

  • Spiral- like structure 

  • Loops around central conical 

  • Has bony structure = modiolus 

  • Tip of structure = Helicotrema 

  • Spriling structure like a tube 

  • 3 parts: 

    • Scala vestibuli – lower

    • Scala tympani - upper

    • Scala media/Cochlear duct - middle 

MEMBRANOUS LABYRINTH

COCHLEAR DUCT 

  • Within is basement membrane 

Basement membrane – within it: contains organ of corti 


Organ of corti - connects sound wave into electrical impulses 




Vestibulocochlear nerve 

  • Exits: Internal acoustic meatus 

  • 2 nerve: 

    • Vestibule nerve 

    • Cochlear nerve 

      • Innervate cochlea (specifically cochlear duct) 

      • Branches for each cochlea 

      • Connects on the spiral 

      • Will proceed to temporal lobe; auditory cortex → interpret sound from ear 


ORGAN FOR BALANCE

Connects: 

  • Semicircular canal 

  • Vestibule 

SEMICIRCULAR CANAL

  • Series of semicircular canal structures that are right angle to each other 

  • One end of semicircular canal: ampulla (expanded part) 

  • w/in = semicircular duct 

    • Paikot

FLOW FOR BALANCE) 

Semicircular duct

↓

Vestibule 

↓ within: 

Utricle (for balance) 

 & Saccule (for balance): 

Macula of Utricle & saccule 

↓ 

Crista - Little hairs 

  • Occultation of crista  (pick up of maculla) 

  • Fluids will circulate through the hair like 

  • Too much movement = sense of hilo 

↓ will descend 

Cerebellum 

  • Responsible for balance 

  • Sensation 

*Ears = receptors; receiving 

Cerebellum = interpretation 

MUSCLES (no mention of innervation, pero insert ko nalang dito) 

  • Stapedius (posterior wall) 

    • Innervation: facial nerve 

  • Tensor tympani (anterior wall) 

    • Innervation: Mandibular division of the trigeminal nerve

  • Both functions: to dampen the sound wave (if malakas ang sound)