Hi Class, we’re almost done!• Some advice for these slides:

– The mid-sagittal brain is here so we have the same structures covered in lecture and lab.

– For cranial nerves, know its name, number (roman), whether it is sensory (S) or motor (M) in function (or both), and its basic innervation areas.

– Not all the special senses are covered here. Contact me over the summer and I’ll send you more slides, or come to your house and lecture some more… JOKE!

Brain Midsagittal Anatomy-Cingulate gyrus

Fornix

Thalamus

Interthalamic adhesion

Anterior commissure

Hypothalamus

Septum pellucidum

Mamillary body

Inferior and superior colliculiS

IPineal body

Corpus callosum: head, body, and tail

T

B

H

Arbor vitae of cerebellum

Midbrain

Pons

Medulla

Parieto-occipital sulcus

Infundibulum (descends to Pituitary gland)

The Cranial Nerves Nerves I-XII are numbered in anterior to posterior sequence

S= sensory function(s) M= motor function(s)

• Olfactory N (CN I) – S: the special sense of smell. Fibers innervate mucosa of superior nasal concha.

• Optic N (CN II) – S: the special sense of vision. Fibers innervate rods and cones of the optic retina.

• Oculomotor N (CN III) – M: Innervates 4 of the 6 extrinsic eye MM, as well as the Levator palpebrae M. Also innervates smooth muscle tissue of the lens and iris.

• Trochlear N (CN IV) – M: superior oblique M of eye.

More Cranial NN…• Trigeminal N (CN V) – S: Skin of the face, as well as

cornea, paranasal and nasal sinuses, teeth, etc. M: MM of mastication and soft palate.

• Abducent N (CN VI) – M: lateral rectus M of the eye• Facial N (CN VII) – S: taste from anterior 2/3 of

tongue and some palate. M: MM of facial expression and middle ear, as well as salivary glands.

• Vestibulocochlear N (CN VIII) – S: special sense of hearing via cochlear portion, sense of balance via vestibular portion.

• Glossopharyngeal N (CN IX) – S: taste from post 1/3 of tongue, sensation of external ear canal. M: one pharyngeal constrictor M.

The Last Cranial NN• Vagus N (CN X) – S: visceral sensory sensation

of G.I. Tract and airway (trachea and bronchi). Also, some taste sensation from mouth and sensation from external ear. M: Constrictor MM of pharynx, intrinsic laryngeal MM. Para-sympathetic innervation of heart, G.I. Tract and trachea.

• Spinal Accessory N (CN XI) – M: Sternocleidomastoid M and trapezius M.

• Hypoglossal N (CN XII) – M: MM of tongue

The SPECIAL SENSES

Vision, Taste, Smell, Hearing and Balance

Organ of sight-the eye

Major anatomical features of external eye area

-Upper and lower eyelids

L

U

Organ of sight-the eye-

The eyelid

-Supports orbicularis occuli m

-Reinforced by tarsal plates-tough connective tissue

-Contains tarsal glands that secrete lipid lubricant for eyelid

-Eyelid also contains branching tendon of the levator palpebrae m

Organ of sight-the eye

Anatomical features of external eye

-Lacrimal caruncle

-Lacrimal papilla with lacrimal punctum

-Palpebral conjunctiva

-Medial and lateral canthus

• The external eye has angles (canthi), where upper and lower eyelids meet.

• The medial canthus contains a small mound of soft tissue called the lacrimal caruncle, onto which debris from the eye is flushed by the flow of tears.

• The palpebral conjunctiva is a thin mucosa covering the external eye and the inside of eyelids. Infection of this is?

• Each eyelid has a tiny bump (papilla) on the medial side, in the center of which is a lacrimal punctum. These are openings which drain tears into the nasolacrimal duct.

The flow of tears• “Tears” are a watery solution produced and

drained onto the eye’s surface from the lacrimal gland, located in the upper lateral orbit.

• Tears drain medially across the eye and into lacrimal puncta, then into lacrimal canals which connect with the nasolacrimal duct.

• The nasolacrimal duct drains into the nasal cavity below the inferior nasal concha.

• In the midst of “a good cry”, that’s not just mucus coming out your nose, but also tears…

Don’t try this at home!

Organ of sight-the eyeAnatomy of the eye

CorneaCornea-1° light refractor

IrisIris-contractile diaphragm

Aqueous humorAqueous humor-watery fluid

LensLens-focusing structure

Optic retinaOptic retina

ChoroidChoroid-middle layer

Suspensory ligamentSuspensory ligament

Ciliary bodyCiliary body

ScleraSclera-white of eye

Macula luteaMacula lutea-acute vision

Optic discOptic disc-blind spot

Ora serrataOra serrata

Vitreous bodyVitreous body-support, refracting gel

Internal Eye• The eye is divided internally into anterior and posterior

compartments, with the lens between.• The ciliary body is the mass of smooth muscle which

connects to the lens via the suspensory ligament and changes the shape of the lens for different focal distances.

• The retina is composed of photoreceptor cells (sensory nerve endings of the optic N) called rods and cones. The anterior edge of the retina is the ora serrata. Cones occur in three types and perceive yellow, green and blue light. Rods perceive varying quantities of light, thereby providing information about objects in the environment.

• The ‘blind spot’, where the optic nerve connects, contains no rods or cone cells and so is blind.

• The macula lutea (yellow spot) contains a fovea (pit) in which a huge number of rods and cones occurs – this is the location of greatest visual acuity.

• NEXT SLIDES: THE EAR • The middle ear is deep to the tympanic membrane

(eardrum), and is comprised of spaces above (epitympanic recess) and below (tympanic cavity) the middle ear bones (ossicles).

• The Stapedius M and Tensor tympanic M stabilize the middle ear bones during very loud sounds, preventing damage to structures here.

• The stapes attaches to the ‘oval window’ of the vestibulocochlear organ and transmits vibrations from the tympanic membrane.

Ear

Ear-organ of hearing and balance-divided into three parts:

External EarExternal auditory tube

Auricle (or Pinna)

Separated from middle ear by tympanic membrane

Middle EarEpitympanic recess

Tympanic cavity

Stapedius m

Tensor tympani m

Chorda tympani N (of Facial N, CN VII)

Auditory ossicles

EarMiddle ear

-Within the temporal bone-Tympanic cavity (TC)-Epitympanic recess (ER)

TCTC

ERER ERER-Malleus-Incus-Stapes

-Tensor tympani M

-Stapedius M

Ear

Internal EarMade up of vestibulocochlear organ

• The vestibulocochlear organ is a fluid-filled tubular hollow space inside the temporal bone, made of cochlea (latin: snail) and the vestibule.

• Fluid vibrations produced by the stapes cause microscopic ‘hair cells’ inside the cochlea to move, producing impulses perceived by the brain (via the auditory N – CN VIII) as sounds.

• Fluid movements inside the semicircular canals, caused by movements of the head along 3 axes (up/down, L/R, front/back) affect hair cells here, sending information through the vestibular portion of the auditory N to the brain about body position and balance.

• WE’RE DONE! SEE YOU LATER IN THE WEEK!

Ear

Parts of internal ear

-Oval shaped region -contains oval window

Cochlea of bony labyrinth

Vestibule

Semicircular canals