Brain Anatomy -- Midterm 1

bilateral symmetry

When cut down the sagittal plane, the outcome will (pretty much) be mirror images

radial symmetry

When cutting down multiple planes, the outcome will (pretty much) be the same.

cephalization

• Specialized head & brain area

• Concentrated sense organs at anterior end of body

Dorsal

toward the back

ventral

toward the stomach

anterior

toward the front end

posterior

toward the rear end

superior

above another part

inferior

below another part

lateral

toward the side, away from the midline

medial

toward the midline, away from the side

proximal

located close to the point of origin or attachment

distal

located more distant from the point of origin or attachment

ipsilateral

on the same side of the body

contralateral

on the opposite side of the body

rostral

toward the front of the head, towards the nose

caudal

toward the back end, toward the tail end

coronal plane

plane that shows brain structures as seen from the front

sagittal plane

plane that shows brain structures as seen from the side

horizontal plane (transverse plane)

plane that shows brain structures as seen from above

central nervous system (CNS)

brain and spinal cord

peripheral nervous system (PNS)

nerves and ganglia located outside of the brain and spinal cord

somatic nervous system

controls voluntary muscles and conveys sensory information to the CNS

autonomic nervous system

regulates many involuntary processes such as heart rate, blood pressure, digestion, etc.

sympathetic nervous system

response to stressful situations; raises heart beat, slows digestions, dilates pupils, etc. (flight-or-fight system)

parasympathetic nervous system

restores body to original state after stress

ventricles

4 interconnected cerebrospinal fluid-filled cavities within the brain that connect with the central canal of the spinal cord

meninges

membranes the surround the brain and spinal cord (from the outside to inside): dura mater —> subarachnoid mater —> subarachnoid space (with css) —> pic mater —> cerebral cortex

major structures in the hindbrain

medulla, pons, cerebellum

where is the hindbrain located?

just rostral to the spinal cord

what is the hindbrain responsible for?

regulation of many involuntary processes such as breathing and heart rate

nucleus (nucelei)

cluster of cell bodies

ganglion (ganglia)

group of somas (cluster of neuron cell bodies)

major function of ganglia

motor control, motor learning, behaviour and emotions

nerves

grouping of axons that carry electrical impulses between your brain and the rest of your body. impulses help feel sensations and control autonomic nervous system

tract (fibre tract)

neural pathways that connect the brain and the spinal cord; responsible for carrying sensory and motor messages to and from the periphery

afferent nerves

conduct sensory signals from sensory structures to the CNS

efferent nerves

conduct signals from the CNS to target tissues

mixed nerves

contain some afferent axons and some efferent axons

cranial nerve I.

olfactory — smell

cranial nerve II.

optic — vision

cranial nerve III.

oculomotor — control of eye movements, pupil constriction

cranial nerve IV.

trochlear — control or eye movements

cranial nerve V.

trigeminal — skin tensions from most of face; control of jaw muscles for chewing and swallowing

cranial nerve VI.

abducens — control of eye movements

cranial nerve VII.

facial — taste from the anterior two thirds of the tongue; control of facial expressions, crying, salivations, and dilation of the head’s blood vessels

cranial nerve VIII.

statoacoustic — hearing, equilibrium

cranial nerve IX.

glossopharyngeal — taste and other sensations from throat and posterior third of the tongue; control of swallowing, salivation, throat movements during speech

cranial nerve X.

vagus — sensations from neck and thorax; control of throat, esophagus, and larynx parasympathetic nerves to stomach, intestines, and other organs

cranial nerve XI.

accessory — control of neck and shoulder movements

cranial nerve XII. hypoglossal

control of the muscles of the tongue

the pons

• contains the locus coeruleus which produces norepinephrine and plays and important role in arousal, attention, and the stress response

• Contains the nuclei for several cranial nerves

• Contains a portion of the reticular formation

• many fibre tracts pass through the pons — axons from each half of the brain cross to the opposite side of the spinal cord such that the left hemisphere controls the muscles of the right side of the body

the cerebellum

• Extensively folded – an outer cerebellar cortex of grey matter surrounding the white matter

• Helps regulate motor movement, balance, and coordination

• Important for shifting attention between auditory and visual stimuli

• Critical for certain types of learning such as forming procedural memories

what structures make up the brainstem?

Medulla, pons, and midbrain

the divisions of the midbrain

the tectum (dorsal region) and tegmentum (ventral region)

structures in the tectum

• Superior colliculus: processes and integrates sensory information to allow for a rapid response to sensory input from different locations

• Inferior colliculus: processes and integrates sensory information to determine the locations of sound

structures in the tegmentum

• The rostral region of the reticular formation

• Substantia nigra: gives rise to the dopamine containing pathway facilitating readiness for movement

• Ventral tegmental area (VTA): controls certain behaviours such as reward processing, drug addictions, learning and memory, and stress modulation

• Cerebral peduncle (crus cerebri): fibre tracts

• The nuclei for two cranial nerves

two major regions of the forebrain

diencephalon and telencephalon

structures in the diencephalon

thalamus, pineal gland, hypothalamus, and posterior pituitary gland

thalamus

relay station from the sensory organs; receives sensory input from almost all body region; it filters and integrates sensory information (except olfactory/smell) before relaying it to the cerebral cortex. It contains many nuclei, including the lateral geniculate nucleus (LGN) – visual processing

hypothalamus

• Involved in maintaining homeostasis, so regulates many processes, including those affecting water balance, blood pressure, appetite, metabolism, and body temperature

• Associated with behaviours such as eating, drinking, sexual behaviour, and other motivated behaviours

• Regulates the endocrine system by controlling release of hormones from the pituitary gland

nuclei in the hypothalamus

• Mammillary nuclei: spatial and episodic memory function – spatial: places/where an event occurred (where did I put my keys?), positions of things or events in space – episodic: things that have happened (wedding, graduation, etc.)

• Lateral hypothalamus (LH):

  • Stimulates appetite (hunger center), feeding behaviour and arousal – reward pathway

• Paraventricular nucleus (PVN/PVH):

  • One of the most important autonomic control centers in the brain

  • Neurons play essential roles in controlling stress, metabolism, growth, reproduction, immune, and more.

• Supraoptic nucleus:

  • Collection of magnocellular neurosecretory cells located within the anterior hypothalamus

  • Main function of these cells is to produce and secrete the peptide hormone vasopressin (aka antidiuretic hormone ADH and oxytocin) 

• Suprachiasmatic nucleus (SCN):

  • Bilateral structure and the central pacemaker of the circadian timing system and regulates most circadian rhythms in the body

• Medial preoptic area (MPOA):

  • Essential brain region to coordinate sleep and body temperature, and male sexual behaviour

2 regions of pituitary gland

anterior and posterior pituitary gland

anterior pituitary gland

• composed of axons of neurons of the hypothalamus (from the paraventricular nucleus and supraoptic nucleus) that release hormones directly into the blood

  • Produces oxytocin and vasopressin (antidiuretic hormone) for kidneys and water absorption, and dilating/constricting blood vessels

anterior pituitary gland

• composed of endocrine cells that produce hormones, including hormones that regulate hormone production by other glands e.g.,

  • Thyroid stimulating hormone (TSH): target thyroid to secrete thyroid hormone to increase metabolic rate

  • Adrenocorticotropic hormone (ACTH): tells adrenal glands in your kidneys to secrete cortisol

  • Follicle-stimulating hormone (FSH) and luteinizing hormone (LH): testes and ovaries for testosterone, estrogen, and progesterone

pineal gland

• Produces melatonin

• Light inhibits melatonin production

• In many vertebrates, the pineal gland is photosensitive

• In mammals, information about photoperiod is sent from the retina of the eye into the suprachiasmatic nucleus (SCN) of the hypothalamus then via several other regions of the nervous system to the pineal body

the limbic system of forebrain

• Consists of several interlinked structures of the diencephalon and telencephalon that form a border around the brainstem

• Includes the olfactory bulb, hypothalamus, thalamus, hippocampus, amygdala, and cingulate gyrus of the cerebral cortex

• Associated with motivation, emotions, anxiety, aggression, and behaviours such as eating, drinking, and sexual activity

structures in the telencephalon

cerebral cortex, hippocampus, basal ganglia, and olfactory bulbs

olfactory bulb function

olfactory sensory information (smell) is processed here

basal ganglia function

• Associated with planning of motor movement, and with aspects of memory, motivational behaviour, and emotional expression

• Also important for attention, language planning, and other cognitive functions

• Includes the caudate nucleus, the putamen, nucleus accumbens, and blobus pallidus

caudate nucleus function

helps process visual information and control movement

putamen function

learning motor control, including speech articulation, language functions, reward, cognitive functioning, and addiction

nucleus accumbens function

neural interface between motivation and action, plays a key role on feeding, sexual, reward, stress-related, drug self-administration behaviours, etc.

globus pallidus function

primary function is to control conscious and proprioceptive movements

hypothalamus

• A large structure located between the thalamus and cerebral cortex

• Critical for certain types of memory, especially memories for individual events, but also spatial memory and navigation

2 hemispheres of the cerebral cortex

right cerebral hemisphere and left cerebral hemisphere

what divides the cerebral cortex into two halves?

longitudinal fissure

the cerebral cortex

• The cerebral cortex consists of the cellular layers on the outer surface of the two cerebral hemispheres

  • Each side receives sensory information from the opposite (contralateral) side of the body and controls motor movement on the opposite side of the body

  • There are differences in folding of the cerebral cortex in different species of mammals

  • The number of neurons per unit of volume also varies from species to species

• Cells of the cortex are also divided into columns that lie perpendicular to the laminae

what is the outer surface of the cerebral cortex called?

pial surface

4 lobes of the cerebral cortex

occipital, parietal, temporal, frontal

occipital lobe

• Processing of visual sensory information including:

  • Colour

  • Distance and depth perception

  • Space and location

  • Motion

• Receiving visual information from the retina of the eyes via the thalamus (and other structures) and sending processed visual information to the other lobes of the cerebral cortex for further processing

parietal lobe

• Processing sensory information from the somatosensory system to allow for perception of bodily sensations

• Integrating sensory information from most body regions

• Spatial navigation and reasoning, visual mapping

• Coordinating movement, particularly the fine motor movement of the hands required to manipulate objects

temporal lobe

• Processing auditory sensory information (hearing)

• Processing visual information to allow recognition of objects and faces 

• Processing emotions

• Comprehension of language

• Formation of memories, particularly long-term memories, including visual memories, episodic memories, factual memories, verbal memories

frontal lobe

• Cognitive functions including reasoning, planning, making decisions, judgement, problem solving, working memory

• Planning and controlling voluntary movement

• Processing emotions, including understanding and reacting to other people’s feelings

• Producing language

• Formation of long-term memories

• Motivation and control of reward-seeking behaviours

what is 1 called

frontal lobe

what is 2 called

parietal lobe

what is 3 called

occipital lobe

what is 4 called

temporal lobe

what are the bulges of brain tissue in the cerebral cortex

gyri

what are the deep fissures in the cerebral cortex called

sulci

grey matter function & location

processing, outer layer of brain

white matter function

communicating, inner part of brain