Nakamura Human Anatomy Ch 13.2

Question 1

The thalamus

Answer 1

Makes up 80% of the diencephalon
•Contains approximately a dozen major nuclei
•Send axons to regions of the cerebral cortex
•Nuclei act as relay stations for incoming sensory messages (ascending)
•Afferent impulses converge on the thalamus
–Synapse in at least one of its nuclei
•Is the “gateway” to the cerebral cortex (relay center)
•Nuclei organize and amplify or tone down signals

Question 2

The hypothalamus

Answer 2

-Lies between the optic chiasm(cross section for optic nerve) and the mammillary bodies
•Pituitary gland projects inferiorly
•Contains approximately a dozen nuclei
•Main visceral (inside/internal) control center of the body

Question 3

Functions of the hypothalamus

Answer 3

–Control of the autonomic nervous system
–Control of emotional responses
–Regulation of body temperature
–Regulation of hunger and thirst sensations
–Control of behavior
–Regulation of sleep-wake cycles (works with epithalamus)
–Control of the endocrine system (hormones): body growth, repro system, digestive system
–Formation of memory

Question 4

The epithalamus

Answer 4

Consists of a tiny group of nuclei
•Includes the pineal gland (pineal body)
–Secretes the hormone melatonin (is linked to both the sleep-wakefulness and light-dark cycles)
–Under influence of the hypothalamus

Question 5

The brain stem

Answer 5

Includes the midbrain, pons, and medulla oblongata
•Several general functions
–Produces automatic behaviors necessary for survival (life center)
–Passageway for all fiber tracts (both ascending and descending) running between the cerebrum and spinal cord
–Heavily involved with the innervation of the face and head
•10 of the 12 pairs of cranial nerves attach to it

Question 6

The midbrain

Answer 6

Lies between the diencephalon and the pons
•Contains the nuclei of cranial nerves III and IV
•Cerebral peduncles located on the ventral surface of the brain
–Contain pyramidal (corticospinal) tracts
•Superior cerebellar peduncles
–Connect midbrain to the cerebellum
Also contains red nucleus(cell body) and substantia nigra, which is related to Parkinson’s disease

Question 7

Central cavity

Answer 7

Located in the midbrain
•contains the cerebral aqueduct (which separates the 3rd and 4th ventricles
•Periaqueductal gray matter surrounds the cerebral aqueduct
–Involved in two related functions
•Fright-and-flight reaction
•Mediates response to visceral pain

Question 8

The Diencephalon

Answer 8

Forms the center core of the forebrain
•Surrounded by the cerebral hemispheres
•Composed of three paired structures:
–Thalamus, hypothalamus, and epithalamus
•Border the third ventricle
•Primarily composed of gray matter

Question 9

The pons

Answer 9

Located between the midbrain and medulla oblongata
•Contains the nuclei of cranial nerves V, VI, and VII
•Two general groups of cranial nerve nuclei
–Motor nuclei
–Sensory nuclei

Question 10

Cerebellum

Answer 10

Located dorsal to the pons and medulla
–Smoothes and coordinates body movements
–Helps maintain equilibrium

Question 11

The medulla oblongata

Answer 11

Most caudal level of the brain stem
–Continuous with the spinal cord
–Choroid plexus lies in the roof of the fourth ventricle (also in the third ventricle) and produces cerebrospinal fluid (CSF).
–Cranial nerves VIII-XI attach to medulla
- core of the medulla contains much of the reticular formation

Question 12

Pyramids of the medulla

Answer 12

Lie on its ventral surface

Decussation of the pyramids: crossing over of motor tracts

Question 13

The reticular formation

Answer 13

-nuclei influence autonomic functions (sympathetic and parasympathetic)
-area/region within medulla oblongata that sparks stimulation (spans the brain stem)
-Widespread connections
–Ideal for arousal of the brain as a whole
•Reticular activating system (RAS) (another name)
–Maintains consciousness and alertness
–Functions in sleep and arousal from sleep

Question 14

Functions of the medulla oblongata

Answer 14

Visceral centers of the reticular formation include:
•Cardiac center: increase cardiovascular center
•Vasomotor center: increase blood pressure in vessels
•The medullary respiratory center: increased breathing
•Centers for hiccupping, sneezing, swallowing, and coughing

Question 15

Functional brain systems

Answer 15

Networks of neurons functioning together
–The limbic system – spread widely in the forebrain
–The reticular formation – spans (reach over)
the brain stem

Question 16

Forebrain

Answer 16

Includes telencephalon (cerebral cortex)
Diencephalon

Question 17

Hindbrain

Answer 17

Pons, medulla, cerebellum

Question 18

The limbic system

Answer 18

Location
–Medial aspect of cerebral hemispheres
–Also within the diencephalon
•Composed of:
   Amygdala
   Septal nuclei
   Cingulate gyrus.
   Hippocampus.
•The fornix and other tracts link the limbic system together

Question 19

Protection of the brain

Answer 19

The brain is protected from injury by
–The skull
–Meninges: connective tissue 
–Cerebrospinal fluid: brain floats in this
–Blood-brain barrier (BBB) : vessels

Question 20

Cerebrospinal fluid

Answer 20

-Provides a liquid cushion for the brain and spinal cord
•The brain “floats” in CSF
-Formed in choroid plexuses in the brain ventricles

Question 21

Blood brain barrier

Answer 21

-Prevents most blood-borne toxins from entering the brain
–Structure: impermeable capillaries
•Not an absolute barrier
–Nutrients such as oxygen pass through
–Allows alcohol, nicotine, and anesthetics through

Question 22

The spinal cord

Answer 22

-Runs through the vertebral canal
•Protected by bone, meninges, and CSF
•Dura mater of the spinal cord
•The spinal dural sheath – only one layer
-Two deep grooves run the length of the cord
–Posterior median sulcus
–Anterior median fissure

Question 23

Cervical and lumbar enlargements

Answer 23

Where nerves for upper and lower limbs arise from the spine

Question 24

Conus medullaris

Answer 24

the inferior end of the spinal cord

Question 25

Cauda equina

Answer 25

Collection of nerve roots in the spinal cord

Question 26

Film terminale

Answer 26

Long filament of connective tissue | -attaches to the coccyx inferiorly

Question 27

Denticulate ligaments

Answer 27

Anchor spinal cord to vertebrae

Question 28

Ventral, dorsal, and lateral horns

Answer 28

``` Gray matter of spinal cord Lateral horn: Cell bodies are autonomic (sympathetic and parasympathetic) Ventral horn (anterior): somatic motor and visceral motor Dorsal horn (posterior): somatic sensory and Visceral sensory ```

Question 29

Foramen magnum

Answer 29

•the spinal cord extends from the foramen magnum to the level of the vertebra L1 or L2 -the large opening in the basal part of the occipital bone through which the spinal cord becomes continuous with the medulla oblongata

Question 30

Gray matter of the spinal cord and roots

Answer 30

Shaped like the letter H •Gray commissure : contains the central canal •Anterior horns:contain cell bodies of motor neurons •Posterior horns: consist of interneurons •Gray matter: divided according to somatic and visceral regions

Question 31

White matter of the spinal cord

Answer 31

Composed of myelinated and unmyelinated axons •Three types of fibers –Ascending (sensory) –Descending (motor) –Commissural (communicating between the two)

Question 32

Ascending sensory pathways

Answer 32

Conduct general somatic sensory impulses •Chains of neurons composed of: –First-, second-, and third-order neurons (connections between these called synapses)

Question 33

Four main ascending pathways

Answer 33

–Dorsal column pathway –Spinothalamic pathway –Posterior spinocerebellar pathway –Anterior spinocerebellar pathway

Question 34

Descending (motor) pathways

Answer 34

Deliver motor instructions from the brain to the spinal cord •Divided into two groups –Pyramidal, or corticospinal, tracts

Question 35

Other motor pathways

Answer 35

Other motor pathways •Tectospinal tracts (from the midbrain to the spinal cord) •Vestibulospinal tract (from the medulla oblongata to the spinal cord) •Rubrospinal tract (from the midbrain to the spinal cord)

Question 36

Look at pathway diagrams

Answer 36

.