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 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)

Thalamus and Hypothalamus (Diencephalon)

• Thalamus – integration center for motor and sensory information in the brain. Relays information between cerebrum and other brain regions.

• Hypothalamus – controls autonomic physiological functions and appetites (thirst, hunger, sex, etc). Produces many hormones and controls the release of pituitary hormones.

Midbrain (Mesencephalon)

• Controls audio and visual reflexes (Corpora quadrigemina). Also, contains the Red nucleus (responsible for limb rhythm during walking) and the Substantia nigra (‘black stuff’ which produces Dopamine).

Cerebellum, Pons and Medulla (Metencephalon)

• Cerebellum – involuntary control and coordination of motor information. Maintains ‘memories’ of learned complex motor skills (bike riding, playing music, etc)

• Pons – Links cerebellum w/other brain areas and contains the nuclei for cranial nerves V-VIII.

• Medulla – Regulation of heart rate, respiration rate and blood pressure. Also contains other involuntary reflex centers.

Brain Ventricle Anatomy-

Lateral ventricles

Third ventricle

Cerebral aquaduct

Fourth ventricle

Median aperature

Central canal of spinal cord

The flow of Cerebrospinal fluid is from Lateral ventricles to Third ventricle to Fourth ventricle and then to the Arachnoid layer & Central canal of the Spinal cord. Remember that CSF is produced by Choroid plexus (a structure of the Pia mater) within ventricles which later gets absorbed from the arachnoid layer at Arachnoid granulations.

Arachnoid granulations are where CSF is absorbed into the blood.

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 superioris 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 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. Autonomic 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

(These are the classic special senses, although as many as nine senses could be listed here…)

Organ of sight-the eye

Major anatomical features of the 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 (meibomian) glands that secrete lipid lubricant for eyelid

-The upper eyelid also contains branching tendon of the levator palpebrae m

Organ of sight-the eye

Anatomical features of the 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. What do you suppose an infection of this layer is called?

• 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.

• *When in the midst of “a good cry”, that’s not just mucous 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 itself is divided internally into anterior and

posterior chambers, with the lens between. The anterior chamber contains aqueous (watery) humor, the posterior chamber contains vitreous (gel-like) humor.

• 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 Optic Retina is made of photoreceptor cells (sensory neurons which communicate via 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, thus providing shape 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 occur – 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 tympani M stabilize the middle ear bones during very loud sounds, preventing damage to them.

• 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 Tympanic membrane

Middle EarEpitympanic recess

Tympanic cavity

Stapedius m

Tensor tympani m

Auditory ossicles

EarThe Middle 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.

• The internal fluid (called perilymph) transmits vibrations produced by the stapes to microscopic hair cells inside the cochlea which move, producing nerve impulses perceived by the brain (via the cochlear part of Vestibulocochlear 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 Vestibulocochlear N to the brain about 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