Anatomy and Physiology CH 14 (Sadia Ajohda)

6) Abducens (VI) Nerve

•Motor cranial nerve

•Originates from the pons

•Cause abduction of the eyeball (lateral rotation)

7) Facial (VII) Nerve

•Mixed cranial nerve

•Sensory portion extends from the taste buds of the anterior two-thirds of the tongue

•Motor portion deals with facial expression

8) Vestibulocochlear (VIII) Nerve

•Sensory cranial nerve

•Originates in the inner ear

Vestibular branch

•carries impulses for equilibrium

•Cochlear branch

carries impulses for hearing

4 major parts of the brain

brain stem, cerebellum, diencephalon, cerebrum

Brain stem

continuation of the spinal cord; consists of the medulla oblongata, pons and midbrain

Cerebellum

second largest part of the brain

Diencephalon

gives rise to thalamus, hypothalamus and epithalamus

Cerebrum

largest part of the brain

Falx cerebri

membrane that separates 2 hemispheres of the cerebrum

Adult brain

represents 2% of total body weight

Brain and spinal cord develop from _____________ arranged in tubular structure called neural tube

Ectoderm

Mesencephalon

gives rise to midbrain and aqueduct of midbrain

Brain receives approximately ____________ of the total blood supply

20%

Internal carotid and vertebral arteries

carry blood to the brain

Internal jugular veins

return blood from the brain

Blood-brain barrier (BBB)

protects brain from harmful substances and pathogens

What is Cerebrospinal Fluid (CSF)?

A clear fluid

Where does Cerebrospinal Fluid (CSF) circulate?

Through cavities in the brain (ventricles), the spinal cord (central canal), and the subarachnoid space

What is one function of Cerebrospinal Fluid (CSF)?

Absorbs shock and protects the brain and the spinal cord

How does Cerebrospinal Fluid (CSF) assist in nutrient transport?

Helps transport nutrients and wastes from the blood and the nervous tissue

What does Cerebrospinal Fluid (CSF) carry from the blood to neurons?

Chemicals

CSF

filled cavities within the brain

Arachnoid Villus

are fingerlike projections that reabsorb CSF

Lateral ventricles

Located in each hemisphere of the cerebrum

Third ventricle

diencephalon

Cerebral aqueduct

midbrain

Fourth ventricle

brain stem and the cerebellum

Medulla Oblongata

controls heart rate & blood pressure

What is the cardiovascular center responsible for?

Regulating heart rate and blood pressure.

What is the function of the respiratory center?

Regulating breathing rate and depth.

What functions are controlled by centers for vomiting, swallowing, sneezing, coughing, and hiccupping?

These centers coordinate reflex actions related to these processes.

How many pairs of cranial nerves are housed in the vital centers?

Five pairs, specifically cranial nerves VIII (8) to XII (12).

What are pyramids in the context of the medulla?

White matter extensions on the medulla.

What are medulla nuclei?

Masses of gray matter located in the medulla.

What is the function of the pons in relation to respiration?

Responsible for secondary control of respiration

What type of tracts does the pons contain?

Both sensory and motor tracts

What types of impulses pass through the pons?

Motor and sensory impulses

What is the function of the midbrain in relation to loud sounds?

Responsible for somatic (startle) reflexes in response to loud sounds.

What is the role of the substantia nigra?

Controls subconscious muscle activities; loss of neurons here is associated with Parkinson's disease.

What does the red nucleus help control?

Helps control voluntary movements of the limbs.

Which cranial nerves are contained in the midbrain?

Cranial nerves III-IV (3-4).

What is the Reticular Formation?

A netlike region of white/gray matter that extends through the brain maintaining consciousness.

Where does the Reticular Formation extend from?

from the upper part of the spinal cord, throughout the brain stem, and into the lower part of the diencephalon.

What is the Reticular Activating System (RAS)?

A part of the reticular formation that consists of sensory axons projecting to the cerebral cortex.

What role does the Reticular Activating System (RAS) play?

It helps maintain consciousness.

What is the second largest part of the brain?

Cerebellum

What is one function of the cerebellum?

Coordinate smooth movements of skeletal muscle

What aspect of skeletal movement does the cerebellum handle subconsciously?

Subconscious aspects of skeletal movement

What does the cerebellum regulate?

Posture and balance

What is one of the roles of the cerebellum related to equilibrium?

Equilibrium and balance

What is one function of the hypothalamus?

Control of the Autonomic Nervous System (ANS)

What does the hypothalamus produce?

Hormones

What does the hypothalamus regulate?

Emotional and behavioral patterns, eating and drinking, body temperature, and circadian rhythms

What is the location of the epithalamus?

It is a small region superior to the thalamus.

What gland is part of the epithalamus?

The pineal gland.

What hormone does the pineal gland secrete?

Melatonin.

What is the function of melatonin?

It induces sleep.

What role does melatonin play in the body?

It is thought to help set the body's biological clock.

Thalamus

Relays almost all sensory input to cerebral cortex. Plays a role in maintenance of consciousness.

What is the cerebrum often referred to as?

The seat of intelligence

What type of matter makes up the cerebral cortex?

Gray matter

What is the most prominent fissure that divides the brain into left and right halves?

Longitudinal fissure

What are the small grooves and shallow sulcus in the cerebrum called?

Cerebral hemispheres

What are the four lobes of the cerebrum?

Frontal lobe, Parietal lobe, Temporal lobe, Occipital lobe

What structure separates the Frontal and Parietal lobes?

Central Sulcus

What is the primary motor area of the brain?

Precentral gyrus

What is the primary somatosensory area of the brain?

Postcentral gyrus

What are the basal ganglia?

Three nuclei deep within each cerebral hemisphere.

What is one function of the basal ganglia?

Help initiate and terminate movements.

What is another function of the basal ganglia?

Suppress unwanted movements.

What do the basal ganglia regulate?

Muscle tone.

What is the Limbic System?

A ring of structures on the inner border of the cerebrum and floor of the diencephalon.

What structures are included in the Limbic System?

Cingulate gyrus, hippocampus, dentate gyrus, amygdala, mammillary bodies, thalamus, and the olfactory bulb.

What is the Limbic System often referred to as?

The 'emotional brain' as it governs emotional aspects of behavior.

What functions is the Limbic System involved in?

Olfaction and memory.

What is the primary function of the primary somatosensory area?

Responsible for sensing touch and temperature.

Where is the primary visual area located and what is its function?

Located in the occipital lobe, responsible for vision.

What is the primary function of the primary auditory area?

Responsible for hearing.

Where is the primary gustatory area located and what does it sense?

Located at the base of the postcentral gyrus, responsible for taste.

What is the primary function of the primary frontal area?

Responsible for conscious movements of the body.

What is the function of Broca's area?

Responsible for speech.

Where is the primary olfactory area located?

Located in the temporal lobe.

What is another name for the trigeminal nerves?

Cranial nerve V (5).

What is the function of the vagus nerve?

Responsible for regulating visceral activity.

Cranial Nerves

-12 pairs

-Sensory, Motor and Mixed nerves

1) Olfactory (I) Nerve

•Sensory nerve

•Sense of smell

•Carries sensory information to the olfactory area

2) Optic (II) Nerve

•Sensory nerve

•Ganglion cells in the retina of each eye join to form an optic nerve.

•Nerve of vision

3) Oculomotor (III) Nerve

•Motor cranial nerve

•Originates in the midbrain

•Controls movements of the eyeball and upper eyelid

4) Trochlear (IV) Nerve

•Motor cranial nerve

•Smallest of the 12 cranial nerves

•Origin: midbrain

•Controls movement of the eyeball

What is the largest cranial nerve?

Trigeminal Nerve (Cranial Nerve V)

What type of nerve is the Trigeminal Nerve?

Mixed nerve (Sensory & Motor)

What are the three branches of the Trigeminal Nerve?

Ophthalmic, Maxillary, and Mandibular

What sensations does the Trigeminal Nerve deal with?

Touch, pain, and temperature

What do the motor axons of the Trigeminal Nerve supply?

Muscles of mastication

What type of cranial nerve is the Glossopharyngeal (IX) Nerve?

Mixed cranial nerve

What do the sensory axons of the Glossopharyngeal (IX) Nerve carry signals from?

The taste buds of the posterior one-third of the tongue

Where do the motor neurons of the Glossopharyngeal (IX) Nerve arise from?

The medulla

What is the function of the motor neurons of the Glossopharyngeal (IX) Nerve?

They deal with the release of saliva