Chapter 14 - brain & cranial nerves

The human brain contains..

98% of the body’s neural tissue

The average brains weighs about..

3 pounds

Cerebrospinal fluid (CSF)

Surrounds all exposed surfaces of CNS

Interchanges with interstitial fluid of brain

Functions of CSF

• Cushions delicate neural structures

• Supports brain (floats brain)

• Transports nutrients, chemical messengers, and waste products

Choroid plexus

Specialized ependymal cells, secrete CSF into ventricles

Lateral ventricles

Each cerebral hemisphere contains 1 large lateral ventricle

Third ventricle

Ventricle of diencephalon, connects with 4th ventricle via (canal)

Cerebral (mesencephalic) Aqueduct

Connects third ventricle to fourth ventricle

Fourth ventricle

Extends into medulla oblongata

Central canal

Continuous with fourth ventricle

How does blood go In the brain?

Internal carotid arteries and vertebral arteries

How does blood go out of the brain?

Internal jugular veins

Stroke or cerebrovascular accident (CVA)

Shuts off blood to portion of brain, neurons die

Astrocytes

Control blood brain barrier by releasing chemicals that control permeability

Blood brain barrier (BBB)

Isolates CNS neural tissue from general circulation

The medulla oblongata

Allows brain and spinal cord to communicate

Functions of the medulla oblongata

• Automatic nuclei (reticular formation)

• Cardiac center and vasomotor center

• Respiratory rhythmicity centers

Autonomic nuclei (reticular formation)

Controls visceral activities

Cardiac and vasomotor center

Adjust HR, heart contractions, and blood flow

Respiratory rhythmicity centers

Regulates respiratory rates

Relay stations of medulla oblongata

• Nucleus gracilis and nucleus cuneatus

• Solitary nucleus

• Olivary nuclei

Nucleus gracilis and nucleus cuneatus

Somatic sensory to the thalamus

Solitary nucleus

Visceral sensory

Olivary nuclei

Somatic motor

Cranial nerves of the medulla oblongata

VIII, IX, X,XI,XII

Pons

Links cerebellum with mesencephalon, diencephalon, cerebrum, and spinal cord

Functions of Pons

• Respiration

• Sensory and motor nuclei of cranial nerves V,VI, VII, VIII

• Nuclei and tracts - process and relay info to and from cerebellum

Midbrain

Mesencephalon

Mesencephalon functions

• corpora quadrigemina

• Superior colliculus

• Inferior colliculus

• Cerebral peduncles

• Tegmentum

Superior colliculus

Visual

Inferior colliculus

Auditory

Cerebral peduncles

Contain descending fibers (motor) to cerebellum and ascending fibers (sensory) to thalamus

Red nucleus

Many blood vessels, subconscious muscle tone

Substantia nigra

Pigmented gray matter, regulates basal nuclei, dopamine

Tegmentum

• red nucleus

• Substantia nigra

Cerebellum

An automatic processing center

Functions of cerebellum

• adjusting the postural muscles

• Programming and fine tuning movements

Folia

Surface of cerebellum, highly folded neural cortex

Cerebellar hemispheres

Left and right separated at midline

Purkinje cells

Found in cerebellar cortex (superficial layer)

Arbor vitae

Highly branched, internal white matter of cerebellum

Cerebellar nucleus

Embedded in arbor vitae, relay info to purkinje cells

Superior cerebellar peduncles

To midbrain and cerebrum

Middle Cerebellar peduncles

To pond

Inferior cerebellar peduncles

Medulla oblongata and spinal cord

Ataxia

Disturbance in muscle coordination