Chpt 14 The Brain

Elevated ridges

Gyri

Deep grooves

Fissures

What are the six regions of the brain?

1. Cerebrum (lateral ventricles)

2. Cerebellum

3. Diencephalon (slit like cavity)

4. Mesencephalon (same as midbrain)

5. Pons

6. Medulla oblongata

The ventricles of the brain are filled with what?

CSF

Each cerebral hemisphere contains what and is separated by what?

One large lateral ventricle

Separated by a thin medial partition (septum pellucidum)

The lateral ventricles communicate with the third ventricle via what?

Interventricular foramen (foramen of Monro)

The third ventricle is the ventricle of what?

The diencephalon

Which ventricle extends into the medulla oblongata, is continuous with the central canal of the spinal cord, and connects with the third ventricle?

Fourth ventricle

What cavities are connected by the cerebral aqueduct (Sylvius)?

Third and fourth ventricles

What are the three layers of cranial meninges and what do they protect the brain from?

1. Dura mater

2. Arachnoid mater

3. Pia mater

Protect the brain from cranial trauma

This cranial meninges layer has an inner fibrous layer (meningeal layer) and an outer fibrous layer (endosteal layer) fused to the periosteum with venous sinuses (big veins in cranium filled with blood) between the two layers

Dura mater

What are the folded inner layers of dura mater that extend into and divide the cranial cavity while stabilizing and supporting the brain and contain collecting veins (dural sinuses)?

Dural folds

What are the three largest dural folds?

1. Falx cerebri: extension of dura matter between left + right cerebral hemispheres

2. Tentorium cerebelli: Like tent over cerebellum

3. Falx cerebelli

Fluid goes in this sinus

Transverse sinus

This sinus passes through the jugular foramen

Sigmoid sinus

This mater is spider-like, covers the brain, contacts the meningeal layer of dura mater, and holds subarachnoid space

Arachnoid mater

This space is filled with serous fluid

Subdural space

This mater is attached to the brain’s surface by astrocytes and fused with tissue of the brain to supply blood

Pia mater

This surrounds all exposed surfaces of the CNS (including in cavities and the subarachnoid space) and interchanges with the interstitial fluid of the brain

Cerebrospinal Fluid (CSF)

What are the three main functions of CSF?

1. Cushions delicate neural structures

2. Supports brain (absorbs trauma to head, protection)

3. Transports nutrients, chemical messengers, and waste products

What is CSF produced by?

The choroid plexus of each ventricle

This barrier is one of two that isolates the CNS neural tissue from general circulation, is formed by tight junctions, and allows for diffusion of lipid-soluble compounds (O2, CO2), steroids, and prostaglandins?

Blood ECF Barrier

What controls the blood-brain barrier by releasing chemicals that control the permeability of the endothelium?

Astrocytes

This barrier is formed by special ependymal cells (tight junctions), surrounds capillaries of choroid plexus, limits movement of compounds transferred, and allows chemical composition of blood and CSF to differ

Blood-CSF Barrier

Does CSF have any proteins or blood cells in it?

No

How is the medulla oblongata connected to the spinal cord, pons, and cerebellum?

Inferiorly connected is the spinal cord

Superiorly connected is pons

Posterior to it is the cerebellum

What are the superficial structures (5) of the medulla oblongata?

Pyramids/decussation of pyramids (descending tracts)

Olives (somatic motor relay)

Fasiculus gracilus (lateral) and cuteatus (medial)(sensory, ascending tract)

Inferior cerebeller peduncle (fibers that connect medulla to cerebellum)

What are the three nuclei groups of the medulla oblongata?

Autonomic nuclei

Sensory nuclei

Motor nuclei

The cardiovascular center (heart rate + how strong heart beats), the respiratory center (how deep + fast you breathe), and the reticular formation (alertness) are all part of which nuclei?

Autonomic

Cranial nerves VIII(8), IX(9), X(10), XI(11), and XII(12) along with relay stations belong to which nuclei?

Sensory and motor

Pons involved what sensory and motor nuclei of cranial nerves?

V, VI, VII, VIII

The apneustric center and pneumotaxic center of pons function to do what?

Modify respiratory rhythmicity center activity sent by medulla

Nuclei of pons process and relay information to and from where?

Cerebellum

Along with ascending and descending fibers, these fibers link pontine nuclei with opposite cerebellar hemisphere?

Transverse

This connects the cerebellum, pons, and medulla

Middle cerebellar peduncle

This is the posterior portion of the midbrain with two pairs of sensory nuclei (corpora quadrigemina)

Tectum

What is the difference between the superior colliculus and the inferior colliculus of tectum?

Superior colliculus is visual, associated with the reflex of turning your head away from a bright light

Inferior colliculus is auditory, associated with the reaction of turning your head with a loud noise

The tegmentum of the midbrain contains what two structures?

Red nucleus (many blood vessels)

Substantia nigra (pigmented gray matter)

These are nerve fiber bundles on ventrolateral surfaces that contain descending fibers

Cerebral peduncles

*NOT to be confused with “cerebellar”, leads to spinal cord

These are ridges that are narrow and highly folded on the surface of the cerebellum

Folia

The cerebral aquaduct is present where?

In the midbrain

Cerebellar hemispheres are separated at the midline by what?

Vermis

Anterior and posterior lobes of the cerebellum are separated by what?

Primary fissure

The narrow band of the cortex (cerebellum)

Vermis

Below the fourth ventricle, 3rd lobe

Flocculonodular lobe

This is the outer, darker layer in the cut section of the cerebellum

Cortex

These are large, branched cells of the cortex that receive input from up to 200,000 synapses

Purkinje cells

This structure is seen in the cut section of the cerebellum to relay information to Purkinje cells

White matter or Arbor vitae (“tree of life”)

Embedded in arbor vitae with clusters of cell bodies (unmyelinated)

Cerebellar nuclei

Tracks link cerebellum with brain stem, cerebrum, and spinal cord

Superior, middle, and inferior regions

Cerebellar peduncles

This cerebellar peduncle goes from the cerebellum to the cerebrum

Superior

This cerebellar peduncle goes from muscle contraction to the cerebellum

Inferior

This cerebellar peduncle goes from the stimulus to the cerebellum

Middle peduncle

What are the two functions of the cerebellum?

1. Adjusts postural muscles

2. Fine-tunes conscious and subconscious movements

This is a disorder of the cerebellum that results in damage from trauma or stroke, intoxication (temporary impairment), and disturbs muscle coordination

Ataxia

What structures are included in the diencephalon?

Thalamus, epithalamus, and hypothalamus

The pineal gland is found here and it secretes melatonin

Epithalamus

This structure filters ascending sensory information for primary sensory cortex (over 90%), relays information between basal nuclei and cerebral cortex, and is made up of multiple thalamic nuclei

Thalamus

What are the 7 functions of the hypothalamus?

1. Controls autonomic function (Confused)

2. Coordinates activities of nervous and endocrine systems (Cats)

3. Secretes hormones (ADH and OT)(Steal)

4. Produces emotions and behavioral drives(Pizza)

5. Coordinates voluntary and autonomic functions(Causing)

6. Regulates body temperature (ex. chills, preoptic area)(Random)

7. Controls circadian rhythms (suprachiasmatic nucleus, SAD)(Chaos)

Supraoptic nucleus of the hypothalamus

ADH

Paraventricular nucleus of the hypothalamus

OT

The feeding and thirst centers are controlled by what structure?

Hypothalamus

The preoptic area is part of the hypothalamus to do what?

Regulate body temperature

The suprachiasmatic nucleus is part of the hypothalamus to do what?

Control circadian rhythms

What is the largest part of the brain?

The cerebrum

This structure controls all conscious thoughts and intellectual functions and processes somatic sensory and motor information

The cerebrum

This is found in the cerebral cortex and basal nuclei

Gray matter

This is found deep to the cortex and around the basal nuclei

White matter

Increases the surface area with a number of cortical neurons including pre-central and post-central and cingulate

Gyri of neural cortex

Shallow depressions in between gyri including central, calcarine, and parieto-occipital

Sulci

Deep depressions including longitudinal, transverse, and lateral

Fissure

Divisions of hemispheres including frontal, parietal, occipital, temporal, and insula

Lobes

How many pairs of cranial nerves are connected to the brain?

12

What are the classifications of cranial nerves?

• Sensory

  • Somatic sensory: touch, pressure, vibration, temperature, and pain

  • *Special sensory: taste, smell, sight, hearing, balance

• Motor: axons of somatic motor neurons

• Mixed: mixture of motor and sensory fibers

Cranial nerve I

Olfactory (smell)

Cranial nerve II

Optic (smell)

Cranial nerve III

Oculomotor (motor)

Cranial nerve IV

Trochlear (motor)

Cranial nerve V

Trigeminal (mixed)

Cranial nerve VI

Abducens (motor)

Cranial nerve VII

Facial (mixed)

Cranial nerve VIII

Vestibulocochlear (smell)

Cranial nerve IX

Glossopharyngeal (tongue, mixed)

Cranial nerve X

Vagus (mixed)

Cranial nerve XI

Accessory (sternocleidomastoid, trapezius, motor)

Cranial nerve XII

Hypoglossal (motor)

Association fibers are found where?

White matter of the cerebrum

These fibers are connections within one hemisphere on the same side that are arcuate (short) and longitudinal (longer)

Association fibers

Commissural fibers are found where?

White matter of the cerebrum

These fibers connect the two hemispheres

Commissural fibers

Where are projection fibers found?

White matter of the cerebrum

These fibers connect with the cerebrum in lower areas

Projection fibers

What are the two major basal nuclei (or basal ganglia)?

Caudate nucleus and lentiform nucleus

This nucleus is a curving, slender tail in a “C” shape

Caudate nucleus

This nucleus is found more internally including the globus pallidus and putamen

Lentiform nucleus

What are the four functions of the basal nuclei?

1. Subconscious control of skeletal muscle tone (Sally)

2. Functionally linked with substantia nigra (Fixed)

3. The coordination of learned movement patterns (walking, lifting, rhythmic movement)(The)

4. Dysfunction may lead to Parkinsonism (inhibited, abnormal) and Chorea (sudden movements, impulse)(Drain)

What sulcus separates motor and sensory areas?

Central sulcus

What is the gyrus of the primary motor cortex and what does it do?

Precentral gyrus including voluntary movements (facial, hands, etc.)

What are the cells of the primary motor cortex?

Pyramidal cells including neurons with axons to brain stem to spinal cord

What are the three motor areas of the cerebrum?

Primary motor cortex (voluntary movements)

Premotor cortex

Frontal eye field (for eye movement)