THIS IS A STUDY GUIDE, NOT AN ALL INCLUSIVE REVIEW. THERE MIGHT BE THINGS NOT COVERED BY THIS STUDY GUIDE THAT MIGHT BE ASKED IN YOUR QUIZZES and PRACTICAL TESTS. STUDENTS ARE RESPONSIBLE FOR STUDYING THEIR MANUAL AND FOR ALL THE MATERIAL COVERED DURING THE LABORATORY PERIOD, AS PER THE COURSE SYLLABUS

Lab # 13 and 14 Special Senses (page 333)

External and Accessory Structures of the Eye Medial canthus Lacrimal caruncle Lacrimal gland Lacrimal canals They carry the tears to the lacrimal sac. It produces tears. Lateral canthus Lacrimal sac It collects tears and carries them to the nasolacrimal duct. Nasolacrimal duct It drains excess of tears to the nasal cavity.

Extraocular Muscles It moves the eyeball superiorly Trochlea Superior rectus Superior oblique It moves the eyeball inferiorly and laterally Lateral rectus Medial rectus It moves the eyeball laterally It moves the eyeball medially Inferior oblique Inferior rectus It moves the eyeball superiorly and laterally It moves the eyeball inferiorly

Actions and Innervation of the Extrinsic Muscles of the Eye SUPERIOR RECTUS It moves the eyeball superiorly OCULOMOTOR (III) INFERIOR RECTUS It moves the eyeball inferiorly OCULOMOTOR (III) MEDIAL RECTUS It moves the eyeball medially OCULOMOTOR (III) LATERAL RECTUS It moves the eyeball laterally ABDUCENS (VI) It moves the eyeball inferiorly and laterally SUPERIOR OBLIQUE TROCHLEAR (IV) It moves the eyeball superiorly and laterally INFERIOR OBLIQUE OCULOMOTOR (III)

LAYERS OF THE EYE BALL 1- The fibrous tunic Sclera or white of the eye (protects and gives shape to the eyes) 1- The fibrous tunic Cornea (clear outer part) (It allows the light to come in) Choroid ( vascular layer the nourishes the retina) Ciliary body Ciliary muscle (tension the suspensory ligaments) Ciliary process (produces the aqueous humor) 2- The vascular tunic or uvea Iris (pigmented areas and intrinsic muscles that controls the size of the pupil) Retina Optic nerve 3- Sensory tunic

Layers and Chambers of the Eye Ball Anterior cavity Anterior chamber Posterior chamber It contains aqueous humor Fibrous tunic: Vascular tunic (uvea): Cornea Iris Sclera Lens Ciliary body Suspensory ligaments Choroid Posterior cavity Sensory tunic It contains vitreous humor Retina Fovea centralis Optic disc It contains only cones, which are responsible for the sharpest vision. It is called also blind spot because contains no photoreceptors. Layers and Chambers of the Eye Ball Optic nerve

Weber Test The Weber test is a quick screening test for hearing. It can detect unilateral (one-side) conductive hearing loss and unilateral sensorineural (nerve) hearing loss. The test is named after Ernst Heinrich Weber (1795–1878). In the Weber test a vibrating tuning fork (either 256 or 512 Hz) is placed in the middle of the forehead, chin, head equidistant from the patient's ears. The patient is asked to report in which ear the sound is heard louder. In a normal patient, the sound is heard equally loud in both ears (no lateralization). However a patient with symmetrical hearing loss will have the same findings. Thus, there is diagnostic utility only in asymmetric hearing losses. A patient with a unilateral conductive hearing loss would hear the tuning fork loudest in the affected ear. This is because the conduction problem masks the ambient noise of the room, whilst the well-functioning inner ear picks the sound up via the bones of the skull causing it to be perceived as a louder sound than in the unaffected ear. A patient with a unilateral nerve hearing loss would hear the sound louder in the unaffected ear, because the affected ear is less effective at picking up sound even if it is transmitted directly by conduction into the inner ear.

or or Right ear louder: Left ear louder: Nerve deafness in left ear Nerve deafness in right ear or or Conduction deafness in right ear that masks the ambient noise of the room. Conduction deafness in left ear that masks the ambient noise of the room.

Olfactory and taste Senses page 350 Meatuses: Superior Middle Nasal conchae: Inferior Superior Posterior nasal aperture Middle Inferior Vestibule The Nasal Cavity

Olfactory nerve I: Olfactory bulb Olfactory tract Sensory. It provides for the sense of smell.

Root or Pharyngeal portion They contain taste buds The Tongue Root or Pharyngeal portion They contain taste buds Body or Oral portion They provide friction

Dendrites of sensory neurons Taste Receptors Transitional cells They mature to become gustatory cells. Basal cells They divide to produce daughter cells that mature in stages. Taste pore Taste hairs (microvilli) Dendrites of sensory neurons Gustatory cells Cranial nerves VII (facial), and IX (glossopharyngeal).