Nervous System Quiz-CNS (brain and spinal cord) and ANS

Brain weight

Approximately 3 lbs

Number of neurons in the brain

About 100 billion neurons

Synapses per neuron

Each neuron forms ~1000 synapses with other neurons

Neuroglia in the brain

10-15 trillion neuroglia

Dura mater

Tough, leather-like outer layer of meninges; has 2 layers

Subdural hematoma

Blood vessels passing through dura rupture; blood collects in subdural space between dura and arachnoid; compresses CNS and disrupts brain function

Treatment for subdural hematoma

Drilling a hole in the skull to drain blood

Main parts of the brain

Cerebrum, diencephalon, brainstem, cerebellum

Lobes of the brain

Frontal, parietal, temporal, occipital

Cerebral hemispheres

Right and left halves of cerebrum; form superior brain, 83% of brain mass; have cortex, white matter, and basal nuclei

Cerebrum cortex

Outermost layer of gray matter; 40% of brain mass; contains neuron cell bodies, dendrites, glia, blood vessels; no fiber tracts; enables sensation, communication, memory, understanding, voluntary movement

Hemisphere contralateral control

Each cerebral hemisphere controls the opposite side of the body

Primary motor cortex

Located in precentral gyrus; allows conscious control of precise, skilled, voluntary movements

Primary motor cortex homunculus

Spatial map of body representation; cells controlling foot movement in one place; somatotopy

Premotor cortex

Anterior to precentral gyrus; controls large, repetitive, or patterned movements; coordinates sequential actions; involved in movement planning

Broca's area

Usually left hemisphere; motor speech area directing tongue muscles; active during speech preparation

Frontal eye field

Anterior to premotor cortex, superior to Broca's area; controls voluntary eye movement

Primary somatosensory cortex

Located in postcentral gyrus; receives info from skin and skeletal muscle (proprioceptors); exhibits spatial discrimination

Primary somatosensory cortex homunculus

Most sensitive areas (face, lips, fingertips) have largest sensory cortex representation

Somatosensory association cortex

Posterior to primary somatosensory cortex; integrates sensory info; recognizes size, texture, spatial relationships of objects

Primary visual cortex

Posterior tip of occipital lobe; receives visual info from retinas

Visual association area

Surrounds primary visual cortex; interprets color, form, movement; allows object recognition

Primary auditory cortex

Superior margin of temporal lobe; receives info on pitch, rhythm, loudness, location of sounds

Auditory association area

Posterior to primary auditory cortex; stores sound memories; allows perception of sounds

Wernicke's area

Part of auditory association area; language comprehension

Anterior association area (prefrontal cortex)

Intellect, cognition, recall, personality; working memory; judgment, reasoning, planning

Posterior association area

Recognizes patterns and faces; spatial localization

Limbic association area

Provides emotional impact to stimuli; part of limbic system

Hippocampus

C-shaped structure in medial temporal lobe; involved in learning and memory

Amygdala

Almond-shaped, medial temporal lobe; regulates emotions; processes fear, aggression, facial expression recognition

Lateralization of cortical function

Left hemisphere controls language, math, logic; right controls visual-spatial skills, emotion, artistic skills

Cerebral white matter

Deep myelinated fibers; enables communication between cortex, lower CNS, and other cerebral areas

Types of cerebral white matter

Commissural fibers (connect hemispheres), association fibers (within hemisphere), projection fibers (cortex to lower centers)

Basal nuclei

Gray matter deep in hemispheres; regulate initiation/termination of movements; control subconscious muscle contractions; influence attention, memory, planning, emotional behavior

Thalamus

Gray matter nuclei; sensory relay station; gateway to cerebral cortex; contributes to motor, autonomic, consciousness

Hypothalamus

Inferior to thalamus; controls ANS; regulates hormones, emotions, eating, drinking, body temp, circadian rhythms; connected to pituitary via infundibulum

Epithalamus

Superior and posterior to thalamus; pineal gland secretes melatonin; habenular nuclei involved in olfaction and emotional response to odor

Brainstem

Midbrain, pons, medulla oblongata; controls automatic survival behaviors; pathway for tracts between higher and lower centers; associated with 10 of 12 cranial nerves

Medulla oblongata

Gray matter nuclei; cardiovascular center (heart rate & vessel diameter), respiratory rhythmicity, reflexes (vomiting, coughing, swallowing, hiccuping, sneezing)

Medulla nuclei

Inferior olivary (proprioception to cerebellum), gracile & cuneate (touch, proprioception, vibration); cranial nerves VIII, IX, X, XI, XII

Pons

Connects brain parts; relays voluntary movement signals to cerebellum; respiratory control (pneumotaxic & apneustic); cranial nerves V, VI, VII, VIII

Midbrain (mesencephalon)

Contains tracts & nuclei; cerebral aqueduct connects 3rd & 4th ventricles

Cerebellum

Posterior to medulla & pons, inferior to cerebrum; ~half of brain neurons; coordinates skilled movements, posture, balance

Cerebellar lobes

Anterior, posterior (movement), flocculonodular (balance/equilibrium)

Cerebellar structures

Vermis (central constriction), hemispheres (wings), arbor vitae (white matter tracts), cerebellar nuclei (gray matter outputs)

Blood supply to brain

Internal carotid arteries, vertebral arteries

Blood

brain barrier (BBB) - Protects brain from harmful substances; formed by tight junctions of endothelial cells, thick basement membrane, astrocytes

Cerebrospinal fluid (CSF)

Clear, colorless; protects brain/spinal cord; carries oxygen, glucose, nutrients; circulates through ventricles & subarachnoid space

Brain ventricles

Lateral (one in each hemisphere, separated by septum pellucidum), 3rd (midline, superior to hypothalamus), 4th (between brainstem & cerebellum)

CSF homeostasis functions

Mechanical protection, chemical protection, circulation

Hydrocephalus

CSF backup; ventricles swell; in babies, skull expands; in adults, brain compressed; treated by draining CSF with tube

Spinal cord function

Conduction pathway for sensory input to brain and motor output from brain; >100 million neurons

Spinal cord protection

Vertebrae, meninges, CSF, fat in epidural space

Spinal cord meninges

Dura mater (single layer), epidural space (fat & vessels), subarachnoid space (CSF)

Spinal cord enlargements

Cervical and lumbar regions where nerves for limbs arise

Conus medullaris

Tapered end of spinal cord at L2

Cauda equina

Collection of lumbar & sacral nerve roots below conus medullaris

Filum terminale

Fibrous extension of pia mater anchoring spinal cord to coccyx

Lumbar puncture (spinal tap)

CSF removed from subarachnoid space below S2 for testing

Dermatomes

Skin areas providing sensory input via one spinal nerve pair

Dorsal vs ventral roots

Dorsal = sensory; ventral = motor; fuse laterally to form spinal nerves

Spinal cord white matter directions

Ascending (sensory to brain), descending (motor from brain), transverse (commissural fibers across cord)

Gray vs white matter in spinal cord

Gray = neuron cell bodies/dendrites; White = myelinated axons

Flaccid paralysis

Damage to ventral root/anterior horn; lower motor neurons affected; no voluntary or involuntary control

Spastic paralysis

Upper motor neurons damaged; spinal neurons intact; muscles stimulated irregularly; no voluntary control

Spinal cord transection

Cross-sectioning causes total motor & sensory loss below cut

Paraplegia

Transection between T1-L1

Quadriplegia

Transection in cervical region

Autonomic Nervous System (ANS)

Involuntary impulses to smooth muscle, cardiac muscle, glands; includes sympathetic and parasympathetic divisions

Dual innervation

Most organs innervated by both sympathetic & parasympathetic divisions; balance = autonomic tone

Sympathetic

only structures - Sweat glands, arrector pili muscles, kidneys, spleen, most blood vessels, adrenal medulla

Sympathetic division

Dominates during stress; supports physical activity & ATP production; inhibits energy storage

Fight

or-flight response - Sympathetic activation: dilated pupils, increased heart rate/BP, bronchodilation, vasoconstriction in kidneys/GI, vasodilation in muscles/liver/adipose, glycogenolysis, lipolysis, increased blood glucose

Parasympathetic division

Rest-and-digest; conserves/restores energy; SLUDD: salivation, lacrimation, urination, digestion, defecation; decreases heart rate, airway diameter, pupil diameter

Autonomic reflex components

Receptor (mostly interoceptors), sensory neuron, integrating center (hypothalamus/brainstem), motor neuron, effector (smooth/cardiac muscle, glands), response

Cranial nerves mnemonic

"Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH!"

Cranial nerve I

Olfactory (sensory)

Cranial nerve II

Optic (sensory)

Cranial nerve III

Oculomotor (motor)

Cranial nerve IV

Trochlear (motor)

Cranial nerve V

Trigeminal (both)

Cranial nerve VI

Abducens (motor)

Cranial nerve VII

Facial (both)

Cranial nerve VIII

Vestibulocochlear (sensory)

Cranial nerve IX

Glossopharyngeal (both)

Cranial nerve X

Vagus (both)

Cranial nerve XI

Accessory (motor)

Cranial nerve XII

Hypoglossal (motor)

Gyrus vs sulcus

Gyrus = ridge/fold; sulcus = shallow groove; increases cortex surface area

Central sulcus

Divides frontal (motor, reasoning, personality) and parietal (somatosensory) lobes

Longitudinal fissure

Deep groove separating right & left cerebral hemispheres

Layers of meninges (brain)

Dura mater (tough, 2 layers, subdural space), arachnoid (web-like, subarachnoid space with CSF), pia mater (innermost, delicate)

ANS control center

Hypothalamus

Functions of hypothalamus

Controls ANS; regulates body temp, hunger/thirst, circadian rhythms, consciousness, emotions, hormones

Brain control of heart & respiration

Medulla oblongata (cardiovascular & respiratory centers); pons assists via pneumotaxic & apneustic areas