ANATOMY EXAM #2 - CH. 14

CNS - Spinal Cord

What do the brain and spinal cord develop from?

The neural tube

The anterior portion of the neural tube forms which brain vesicles?

3 Primary Brain Vesicles

• Prosencephalon

• Mesencephalon

• Rhombencephalon

Prosencephalon

Forebrain

Mesencephalon

Midbrain

Rhombencephalon

Hindbrain

What do the primary brain vesicles develop into?

5 secondary brain vesicles

• Telencephalon

• Diencephalon

• Mesencephalon

• Metencephalon

• Myelencephalon

What secondary brain vesicles does the prosencephalon develop into?

Telencephalon and Diencephalon

What secondary brain vesicle does the mesencephalon develop into?

Mesencephalon

What secondary brain vesicles does the rhombencephalon develop into?

Metencephalon and Myelencephalon

What is located in the telencephalon?

Cerebrum

What is located in the diencephalon?

Thalamus, hypothalamus, epithalamus

What is located in the mesencephalon?

Midbrain

What is located in the metencephalon?

Pons and cerebellum

What is located in the myelencephalon?

Medulla oblongata

How many neurons are in the brain?

85 billion neurons

How many neuroglia are in the brain?

10-50 trillion neuroglia

What are the 4 subdivisions of the brain?

• Brainstem

  • Medulla oblongata, pons, cerebellum

• Midbrain

• Diencephalon

  • Thalamus, epithalamus, hypothalamus

• Cerebrum

Medulla Oblongata

• Cardiac control center (Heart regulation)

• Vasomotor control center (Arteriolar diameter regulation)

• Medullary respiratory center (Respiration rate regulation)

• Reflexes (Coughing, sneezing, swallowing, vomiting, gagging)

Decussation

• Crossing to opposite side of the body

• Occurs in medulla oblongata for most axons

“Somatic Twist” Hypothesis

• Decussation occured as a consequence of this change in the body plan in early vertebrates

• Inversion introduc

Pons

Pontine respiratory centers (Regulate respiration rate and depth)

Cerebellum

• Coordination and fine-tuning of skeletal muscle movement

• “Muscle memory”

• Adjusts activity of muscles to maintain posture and position

Brain stem

• Typically, sensory info from muscles and joints are sent to cerebellum, then to cerebrum which helps with awareness of state of joints without looking at that part of the body

• Impairment leads to reduced ability to detect sensory information from muscles and joints, decreased muscle coordination and impaired balance

Midbrain

• Cerebral Peduncles

• Red Nucleus

• Substantia Nigra

• Tectum

Cerebral Peduncles

• On anterolateral surfaces of midbrain

• Voluntary motor tracts

Red Nucleus

Reply center to cerebellum, helps in skeletal muscle control and coordination

Substantia nigra

• Lots of melanin, dopaminergic neurons

• Involved in motor control and emotional response, influence activity of cerebral nuclei

• Degeneration of neurons here = Parkinson’s disease

Tectum

• Aka corpora quadrigemina

• 2 superior colliculi, 2 inferior colliculi

• Relay visual and auditory input

Superior colliculi

• Visual reflex centers

• Help visually track moving objects, reflexively turn to look at a moving object

Inferior colliculi

• Auditory reflex centers

• Relay auditory information, identify location of sound and orient the body towards sound

3 components of the diencephalon

• Thalamus

• Epithalamus

• Hypothalamus

Thalamus

• Routes all sensory info except olfactory to appropriate part of the brain

• Info filter - discards unimportant stimuli

• Identifies which sense info is coming from visual, auditory, etc.

• Contains a dozen major nuclei

Epithalamus

• Located above thalamus

• Connects limbic system to rest of brain

• Visceral/emotional response to odor

Pineal Gland

• Located in epithalamus

• Secretes melatonin, regulates sleep/wake cycles

Hypothalamus

• Located below thalamus

• Nervous and endocrine system linkage

• Lots of nuclei

  • Help regulate body temperature

  • Food intake

  • Thirst center

  • Circadian Rhythm

  • Regulates release of hormones from pituitary gland

Cerebrum

• Largest part of the brain

• Home of conscious thought and complex intellectual function

• Divided into lobes

• Gyri/sulci increases surface area 

Cerebral cortex

• Gray matter

• Unmyelinated, lots of space for connections

Gyri

• Single fold = Gyrus

• “Hills”

Sulci

• Single groove = Sulcus

• “Valleys”

White matter

• Deep in cortex

• Myelinated axons

4 lobes of the cerebrum

• Frontal

• Parietal

• Temporal

• Occipital

  • Also insula

Frontal Lobe

• Concentration, decision making, planning, personality

• Also contains primary motor cortex, motor speech area, premotor cortex

• Ex. Phineas Gage

• Precentral Gyrus: Primary motor cortex, Most posterior gyrus

Parietal Lobe

• Postcentral Gyrus

• Primary somatosensory cortex, somatosensory association area

  • Amount designated for motor complex is not proportional to size of body part

• Interpretation of touch, pain, body position (spatial awareness)

Temporal Lobe

• Primary auditory cortex, auditory association area, primary olfactory cortex

• Conscious awareness of odors, interpretation of sound, auditory memory

Occipital Lobe

• Primary visual cortex, visual association area

• Processing, storage, and integration of visual information

• Damage can lead to blindness

Insula

• Deeper than temporal lobe

• Understudied, likely involved with memory and empathy

Language Areas

• 92% ppl only have in left side of brain

• If someone had a stroke in the right hemisphere, they would likely not have the consequences below

Broca’s Area

• Motor speech area, in frontal lobe

• Projects to motor cortex to stimulate muscles to produce speech

Brocha’s Aphasia

• Meaning of language does not change

• Cannot form words, slow and broken speech

• DIfficulty forming long, complex sentences

Wernicke’s Area

• Located more posterior to Brocha’s Area

• Language comprehension (written and spoken)

• First step, sends signals to Broca’s Area

Wernicke’s Aphasia:

• “Fluid Aphasia”

• Word salad

Gabriella Gifford

• Could sing but not speak

• Music exists in both hemispheres of the brain

Cerebral/Basal Nuclei

• Masses of gray matter (cell bodies) in central white matter, inferior to lateral ventricles

• Regulate motor output to decrease unwanted movements

• Initiate directed movements

Caudate Nucleus

• Exists in three-dimensions, arching tube of gray matter

• Parallels curve of lateral ventricles

• Increases speed and accuracy of directed movements like walking

Lentiform Nucleus

• Putamen: Subconscious skeletal muscle movements

• Globus pallidus: Skeletal muscle tone

  • Controls which neural pathways get activated

Claustrum

Subconscious visual processing

Amygdaloid Body

• Aka amygdala

• Mood, expression of emotions, fear

• Integrated with limbic system

• Can lose ability to detect own fear and fear in others

• Codes memories based on emotional perception

• Stress increases stimulation, overstimulation may be a factor in PTSD