Nuroanatomy2

Question 1

Who pioneered phrenology in the early 1800s?

Answer 1

Franz Gall pioneered phrenology in the early 1800s. Even though it was pseudoscience, it provided a first look at localization of brain function.

Question 2

What did Franz Gall believe about bumps on the skull?

Answer 2

Franz Gall believed each bump on the skull represented a unique brain region responsible for some aspect of human attitudes and behaviors. However, this had no scientific basis.

Question 3

What are the two main components of the central nervous system (CNS)?

Answer 3

The brain and spinal cord make up the central nervous system.

Question 4

What is the main difference between the somatic and autonomic nervous systems?

Answer 4

The somatic nervous system controls voluntary functions while the autonomic nervous system controls involuntary functions.

Question 5

What are the two divisions of the autonomic nervous system and what do they control?

Answer 5

The sympathetic nervous system controls “fight or flight” responses while the parasympathetic nervous system controls “rest and digest” functions. They generally have opposing effects.

Question 6

What are the main components inside a cell?

Answer 6

The main cellular components are: cytoplasm (intracellular fluid containing organelles), nucleus (contains DNA), mitochondria (energy production), endoplasmic reticulum (lipid synthesis, protein folding), ribosomes (protein synthesis), Golgi apparatus (processing and packaging proteins and lipids), and lysosomes (digestion of macromolecules and cellular waste).

Question 7

What separates the intracellular and extracellular fluid?

Answer 7

The cell membrane, made of a phospholipid bilayer, separates the intracellular cytoplasm from the extracellular fluid surrounding the cell. It carefully controls what enters and exits the cell.

Question 8

What are the two main compartments of the extracellular fluid?

Answer 8

The extracellular fluid has interstitial fluid that surrounds cells and plasma in which blood circulates. The ECF contains important nutrients like potassium (K+).

Question 9

What are the main parts of a neuron?

Answer 9

The main parts of a neuron are: dendrites (receive signals from other neurons), cell body/soma (contains nucleus and organelles), axon hillock (integrates signals to generate action potential), axon (long projection that transmits electrical signal), myelin sheath (insulating layer that speeds up signal transmission), nodes of Ranvier (gaps in myelin that allow signal to jump), axon terminals (contain synaptic vesicles that release neurotransmitters), and synapse (junction between neurons).

Question 10

What are the functions of dendrites, the cell body, and the axon?

Answer 10

Dendrites receive signals from other neurons and transmit them to the cell body. The cell body contains organelles that keep the neuron alive. The axon transmits the electrical signal to the axon terminals.

Question 11

How does myelin speed up signal transmission down the axon?

Answer 11

Myelin insulates the axon and has gaps called nodes of Ranvier. The electrical signal jumps from node to node, speeding up transmission compared to traveling underneath the sheath.

Question 12

What is the difference between electrical and chemical signaling in neurons?

Answer 12

Within a single neuron (from dendrites to axon terminals), signaling is electrical. Between two neurons (at the synapse), the signal is transmitted chemically via neurotransmitters released from the axon terminal that bind receptors on the next neuron’s dendrites.

Question 13

What are the 12 cranial nerves in order?

Answer 13

The 12 cranial nerves in order are: 1. Olfactory, 2. Optic, 3. Oculomotor, 4. Trochlear, 5. Trigeminal, 6. Abducens, 7. Facial, 8. Vestibulocochlear (formerly auditory), 9. Glossopharyngeal, 10. Vagus, 11. Spinal Accessory, 12. Hypoglossal.

Question 14

What is the mnemonic for remembering the order of the cranial nerves?

Answer 14

The mnemonic is: “On Old Olympus’ Towering Top A Finn And German Viewed A Hawk.”

Question 15

What are the three layers of meninges that protect the brain and spinal cord?

Answer 15

The three meningeal layers from outermost to innermost are: 1. Dura mater - thickest and toughest layer, 2. Arachnoid mater - web-like with subarachnoid space containing cerebrospinal fluid, 3. Pia mater - delicate layer that follows contours of brain.

Question 16

What is the role of the ventricles and choroid plexus in the brain?

Answer 16

The ventricles are interconnected cavities that produce cerebrospinal fluid. CSF is made by the choroid plexus, a network of cells and capillaries. The lateral, third, and fourth ventricles are connected by the cerebral aqueduct to circulate CSF.

Question 17

What are the main anatomical divisions of the brain from rostral (anterior) to caudal (posterior)?

Answer 17

From rostral to caudal, the main brain divisions are: Telencephalon (cerebrum), Diencephalon (thalamus and hypothalamus), Mesencephalon (midbrain), Metencephalon (pons and cerebellum), Myelencephalon (medulla oblongata).

Question 18

What are the three main components of the telencephalon?

Answer 18

The telencephalon contains the cerebral cortex, limbic system, and basal ganglia. It is the most recently evolved part of the human brain.

Question 19

What divides the cerebral cortex into left and right hemispheres?

Answer 19

The longitudinal fissure separates the cerebral cortex into left and right hemispheres. The two hemispheres are connected by the corpus callosum, a large white matter tract.

Question 20

What are the four lobes of the cerebral cortex and their main functions?

Answer 20

The four lobes of the cerebral cortex are: 1. Frontal lobe - attention, planning movement, problem solving, rational thought, speech production, 2. Parietal lobe - integrates sensory information, spatial processing, 3. Temporal lobe - auditory perception, language comprehension, memory, emotion, 4. Occipital lobe - visual processing.

Question 21

Where are Broca’s and Wernicke’s areas located and what are their functions?

Answer 21

Broca’s area is in the left frontal lobe and is critical for speech production. Wernicke’s area is in the left temporal lobe and is involved in language comprehension. Damage to these areas causes different types of aphasia.

Question 22

What case demonstrated the role of the frontal lobes in personality, inhibition, and rational behavior?

Answer 22

Phineas Gage survived an accident where a metal rod went through his frontal lobe. After the injury, his personality changed dramatically - he lost inhibition and rational decision making, even though his intelligence was preserved. This revealed the role of the frontal lobes in regulating appropriate social behavior.

Question 23

What are the main functions of the parietal lobe?

Answer 23

The parietal lobe primarily integrates and processes sensory information like touch, pressure, and spatial awareness. It contains the primary somatosensory cortex. The parietal lobe also has roles in attention, mathematical reasoning, and language processing.

Question 24

What deficits can parietal lobe damage cause?

Answer 24

Parietal lobe lesions can impair sensory processing, leading to difficulties with spatial orientation, writing, and fine motor skills. Patients may also experience contralateral neglect (lack of attention to opposite side of space).

Question 25

What are the main functions of the temporal lobe?

Answer 25

The temporal lobes process auditory information, language comprehension (Wernicke’s area), visual perception, and memory formation. The superior temporal gyrus contains the primary auditory cortex.

Question 26

What are some symptoms of temporal lobe damage?

Answer 26

Damage to the temporal lobes can cause difficulty recognizing faces (prosopagnosia), understanding speech (Wernicke’s aphasia), and forming new memories. Patients may experience changes in sexual behavior, emotional instability, and seizures.

Question 27

What is the primary function of the occipital lobe?

Answer 27

The occipital lobe is primarily responsible for processing visual information. It contains the primary visual cortex which receives sensory input from the eyes and relays it to other areas for higher-order processing.

Question 28

What are the consequences of occipital lobe damage?

Answer 28

Lesions in the occipital lobe can cause visual deficits like blindness, color blindness, inability to recognize objects, and visual hallucinations. The specific impairment depends on the location and extent of the damage.

Question 29

What is the difference between a primary and secondary sensory cortex?

Answer 29

The primary sensory cortex is the first cortical area to receive sensory information from receptors. It detects basic features of the stimulus. The secondary sensory cortex further integrates and processes this information, enabling perception and recognition. It sends information to other brain areas to generate a response.

Question 30

What do the primary and secondary motor cortices control?

Answer 30

The primary motor cortex directly controls the execution of voluntary movements by sending signals to the spinal cord and muscles. The secondary motor cortex helps plan and coordinate complex motor behaviors. They work together to enable precise, goal-directed actions.

Question 31

What are association areas and what do they do?

Answer 31

Association areas are parts of the cerebral cortex that are not primary sensory or motor areas. They integrate information from multiple sensory modalities and are involved in higher cognitive functions like attention, language, memory, emotion, and decision making.

Question 32

How did stimulation studies lead to the incorrect belief that we only use 10% of our brain?

Answer 32

Early researchers electrically stimulated different parts of the brain to map functions. Association areas produced no observable responses when stimulated because they don’t have a primary sensory or motor role. Scientists incorrectly concluded these “silent” areas were unused. In reality, association areas are always active, so further stimulation has no effect on their ongoing processing of complex cognition.

Question 33

What is the limbic system and what are its functions?

Answer 33

The limbic system is a group of structures involved in memory, emotion, motivation, and homeostasis. Its main components are the hippocampus (memory), amygdala (emotion), cingulate gyrus (emotion regulation, error detection), hypothalamus (homeostasis), and pituitary gland (hormone secretion).

Question 34

Why is the hippocampus considered important for memory?

Answer 34

The hippocampus is critical for the formation of new declarative memories - it processes and stores information about facts and events. Damage to the hippocampus results in an inability to form new memories while leaving previous memories intact.

Question 35

What is the main function of the amygdala?

Answer 35

The amygdala is involved in processing emotions, particularly fear, anger, and anxiety. It attaches emotional significance to stimuli and memories. The amygdala triggers the “fight or flight” response by activating the sympathetic nervous system. Damage to the amygdala can lead to fearlessness and reduced aggression.

Question 36

Why is some degree of fear adaptive for survival?

Answer 36

The amygdala allows us to identify potential threats in the environment and respond appropriately. Without any sense of fear, organisms would not avoid dangerous situations and thus have reduced survival. The amygdala’s ability to experience fear and link it to certain stimuli is evolutionarily adaptive - it keeps us safe. However, excessive or inappropriate fear can be detrimental.

Question 37

What is the role of the cingulate cortex?

Answer 37

The cingulate cortex is involved in emotional regulation and processing. It also helps with detecting errors, monitoring conflicts, and learning from mistakes. The cingulate acts like a control center that keeps emotional reactions in check and allows us to adjust our behavior based on negative feedback in order to make better decisions in the future.

Question 38

What are the basal ganglia and what is their main function?

Answer 38

The basal ganglia are a group of subcortical nuclei that are primarily involved in motor control, learning, and executive functions. The main components are the striatum (caudate and putamen), globus pallidus, and nucleus accumbens. The basal ganglia integrate information from the cerebral cortex and thalamus to facilitate the selection and execution of motor programs.

Question 39

What is the role of the striatum and its connections to the substantia nigra?

Answer 39

The striatum (composed of caudate and putamen) receives input from the cerebral cortex and is modulated by dopamine from the substantia nigra pars compacta. This pathway is important for initiating voluntary movements, reward processing, and habit formation. Degeneration of dopamine neurons in the substantia nigra leads to motor deficits seen in Parkinson’s disease.

Question 40

How are the globus pallidus and nucleus accumbens involved in movement and reward?

Answer 40

The globus pallidus is the main output of the basal ganglia, projecting to the thalamus and brainstem to influence movement. Damage to the globus pallidus can cause movement disorders like Huntington’s disease. The nucleus accumbens receives dopaminergic input from the ventral tegmental area and is a key part of the reward system - it reinforces motivating behaviors. Addiction involves changes in the nucleus accumbens.

Question 41

Where is the thalamus located and what is its main function?

Answer 41

The thalamus is located above the brainstem and acts as a relay station for almost all sensory information going to the cerebral cortex (except smell). It processes and directs signals to the appropriate cortical areas for further integration. The thalamus has several nuclei that are specific to each sensory modality.

Question 42

What are some of the important nuclei of the thalamus and their functions?

Answer 42

The lateral geniculate nucleus relays visual information from the retina to the primary visual cortex. The medial geniculate nucleus processes auditory signals and sends them to the primary auditory cortex. The ventral posterior nucleus transmits somatosensory information from the body to the primary somatosensory cortex.

Question 43

What is the location and function of the hypothalamus?

Answer 43

The hypothalamus is a small structure below the thalamus that regulates homeostasis, hormone release, and essential behaviors. It maintains the body’s internal balance by controlling things like temperature, hunger, thirst, sleep, and circadian rhythms. The hypothalamus integrates signals from the nervous and endocrine systems.

Question 44

What are some common symptoms of hypothalamic dysfunction?

Answer 44

Damage to the hypothalamus can disrupt the body’s basic functions and cause a variety of symptoms like abnormal weight gain or loss, disturbed sleep-wake cycles, inability to regulate body temperature, altered sexual function, uncontrolled urine output, and extreme emotional responses.

Question 45

Where is the pituitary gland and what does it do?

Answer 45

The pituitary gland is a pea-sized structure that sits at the base of the brain, just below the hypothalamus. It is considered the “master gland” because it secretes hormones that regulate the function of other endocrine glands throughout the body. The pituitary has an anterior and posterior lobe.

Question 46

How does the hypothalamus control the pituitary gland?

Answer 46

The hypothalamus sends releasing hormones to the anterior pituitary through a special blood supply. These hormones stimulate or inhibit the secretion of pituitary hormones into the bloodstream. The posterior pituitary stores and releases hormones made by the hypothalamus. This interaction allows the hypothalamus to use the pituitary to control endocrine function in the body.

Question 47

Name some important hormones secreted by the pituitary and their functions.

Answer 47

The anterior pituitary secretes: growth hormone (stimulates body growth), prolactin (milk production), ACTH (stimulates cortisol release from adrenal gland), TSH (controls thyroid gland), FSH and LH (regulate reproductive organs). The posterior pituitary secretes: antidiuretic hormone (water retention in kidneys) and oxytocin (uterine contractions, milk let-down).

Question 48

What is the mesencephalon and what are its major components?

Answer 48

The mesencephalon (midbrain) is the most rostral part of the brainstem. It contains two main regions: 1. Tectum - composed of the paired superior and inferior colliculi. Superior colliculus orients head and eye movements toward visual stimuli. Inferior colliculus is a relay station for auditory reflexes. 2. Tegmentum - contains several important nuclei.

Question 49

What is the tegmentum and what are its key nuclei?

Answer 49

The tegmentum is the ventral portion of the midbrain that contains several important nuclei: Periaqueductal gray (PAG) - receives input from the amygdala and is involved in pain modulation, fear responses, and defensive behavior, Substantia nigra - source of dopamine neurons that project to the striatum (nigrostriatal pathway), degeneration leads to Parkinson’s disease, Ventral tegmental area (VTA) - contains dopamine neurons that project to the prefrontal cortex and limbic system (mesolimbic and mesocortical pathways), involved in reward, motivation, and addiction.

Question 50

What does the metencephalon consist of?

Answer 50

The metencephalon is composed of the cerebellum and the pons. The cerebellum is a large structure at the back of the brainstem that coordinates motor control, balance, and sensory processing. The pons contains nuclei involved in sleep, arousal, and motor relay.

Question 51

What are the main functions of the cerebellum?

Answer 51

The cerebellum is critical for fine-tuning motor commands and making movements smooth and coordinated. It uses sensory feedback to adjust ongoing movements and maintain balance and posture. The cerebellum also has roles in motor learning, adaptation, and some cognitive functions like language and attention. Damage leads to disorders of voluntary movement, gait, and motor learning.

Question 52

What are the unique features of cerebellar neurons?

Answer 52

The cerebellum has a highly regular, repeating circuit structure. The outer cortex contains Purkinje cells, which are large inhibitory neurons that integrate input from multiple sources. Purkinje cells are the sole output of the cerebellar cortex, projecting to the deep cerebellar nuclei. The cerebellum also contains granule cells, which are tiny excitatory neurons that receive input from mossy fibers and provide feedforward excitation to Purkinje cells.

Question 53

What are the functions of the pons?

Answer 53

The pons is a bulge on the ventral brainstem that serves as a relay station between the cerebral cortex and the cerebellum. It contains nuclei involved in sleep-wake regulation (REM sleep), arousal, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, and sensations. The pons also plays a role in generating and regulating respiratory rhythms.

Question 54

What are the two major structures in the myelencephalon?

Answer 54

The myelencephalon consists of the medulla oblongata and the reticular formation.

Question 55

What is the medulla oblongata and what are its key functions?

Answer 55

The medulla oblongata is the lowest part of the brainstem, connecting the spinal cord to the pons. It contains vital nuclei that regulate involuntary functions like heart rate, blood pressure, breathing, digestion, and reflexes like vomiting, coughing, and sneezing. Damage to the medulla can be fatal since it controls autonomic functions necessary for survival.

Question 56

What is the reticular formation and what does it do?

Answer 56

The reticular formation is a network of neurons that extends from the medulla through the pons and midbrain. It is involved in modulating arousal, sleep-wake cycles, attention, and consciousness. The reticular activating system (RAS) receives sensory input and projects to the cortex to maintain alertness. Damage to the reticular formation can cause coma, stupor, or hypersomnolence.