gross anatomy of the brain

What are the two main divisions of the human nervous system?

The central nervous system (CNS) and peripheral nervous system (PNS).

What does the central nervous system (CNS) consist of?

The brain and spinal cord.

What is the role of the peripheral nervous system (PNS)?

It connects the CNS to the rest of the body.

What are the two subdivisions of the peripheral nervous system?

The somatic nervous system and autonomic nervous system (ANS).

What does the somatic nervous system control?

Voluntary movements and sensory information

What does the autonomic nervous system (ANS) regulate?

Involuntary processes like heartbeat and digestion

What are the two divisions of the autonomic nervous system (ANS)?

Sympathetic nerves and parasympathetic nerves.

What is the function of sympathetic nerves?

They prepare the body for stress (fight or flight).

What is the function of parasympathetic nerves?

They help the body relax and recover (rest and digest)

What do directional anatomical terms describe?

Positions and directions in the body.

What does the term 'rostral' mean?

Toward the head.

What does the term 'caudal' mean?

Toward the tail.

What does the term 'dorsal' mean?

Posterior (toward the back).

What does the term 'ventral' mean?

Anterior (toward the front)

What does the term 'medial' mean?

Near the midline.

What does the term 'lateral' mean?

Away from the midline.

What does the term 'ipsilateral' mean?

On the same side of the body.

What does the term 'contralateral' mean?

On the opposite side of the body.

What are the main directional planes of the brain?

Frontal (coronal), sagittal, and transverse (horizontal) planes

What is a nucleus in the CNS?

A group of neurons with similar appearance, targets, and functions.

What is a tract in the CNS?

A bundle of axons connecting a nucleus to a target region.

What is a ganglion?

A collection of cell bodies located outside the CNS, in the PNS

What is a nerve in the PNS?

A pathway for sensory and motor information to/from the CNS

What is white matter?

Myelinated axons that increase nerve conduction speed

What is grey matter?

Nerve cell bodies (nuclei) that lack myelination.

What are association fibers in white matter?

Fibers connecting different cortical regions in the same hemisphere

What are commissural fibers in white matter?

Fibers connecting identical cortical regions in both hemispheres

What are projection fibers in white matter?

Fibers linking the cerebral cortex to subcortical centers and the spinal cord.

What is the cerebral cortex?

The brain's outer layer that covers deep nuclei and constitutes part of the forebrain

What is the function of the cerebral cortex?

It processes sensory input, voluntary movement, and higher cognitive functions

How many lobes are in the cerebral cortex?

Four lobes

What is the difference between white matter and grey matter in appearance?

White matter is white due to myelinated axons; grey matter is grey/beige due to nerve cell bodies.

What are the major structures of the forebrain?

Telencephalon and diencephalon

What does the telencephalon include?

Cerebral hemispheres and deep structures

What does the diencephalon include?

Thalamus and hypothalamus

What are sulci in the brain?

Grooves between gyri on the surface of the cerebral hemispheres.

What are gyri in the brain?

Ridges bordered by sulci, named by location or function

Why is the brain highly folded into gyri and sulci?

To increase surface area for higher cognitive capacity

What are primary cortical areas?

Regions that receive sensory input or execute motor tasks with little interpretation.

What are association areas of the cortex?

Regions for higher-order processing and interpreting sensory/motor information

What are Brodmann areas?

Numbered regions of the cerebral cortex based on neuron organization, approximately 52 areas.

What is the largest lobe of the brain?

The frontal lobe.

Where is the primary motor cortex located?

In the precentral gyrus of the frontal lobe.

What is the function of the primary motor cortex?

It executes voluntary motor movements and sends signals to the contralateral side.

What happens if the precentral gyrus is damaged?

It causes weakness on the opposite side of the body (contralateral weakness)

What is the motor homunculus?

A map of body regions represented in the primary motor cortex (Brodmann area 4).

What does the supplementary motor area do?

Contains motor maps for posture and controls trunk/limb movements

What does the premotor area do?

It processes motor information and connects to the basal ganglia and cerebellum.

What are the frontal eye fields responsible for?

Voluntary control of eye movements (Brodmann area 8).

What happens if the frontal eye fields are damaged?

The eyes deviate toward the side of the lesion.

Where is Broca's area located?

In the inferior frontal gyrus of the dominant hemisphere

What is the function of Broca's area?

Motor aspects of speech and tongue movement.

What happens if Broca's area is damaged?

Broca's aphasia, where speech is impaired but language comprehension is preserved.

Where is the prefrontal cortex located?

Anterior to the supplementary motor area.

What are the functions of the prefrontal cortex?

Memory, problem-solving, attention, planning, and cognitive flexibility

What structures connect to the prefrontal cortex?

Sensory/motor cortices, basal ganglia, cerebellum, amygdala, hypothalamus, and brainstem.

What structures are found on the medial surface of the frontal lobe?

Frontal pole, medial frontal gyrus, paracentral lobule, and cingulate gyrus

What is the paracentral lobule responsible for?

Motor and sensory functions of the leg, foot, and urinary bladder

What is the cingulate gyrus, and what does it do?

A limbic system structure involved in emotion, behavior, and memory

What structures are on the lateral surface of the parietal lobe?

-Postcentral gyrus

- superior parietal lobule

- inferior parietal lobule

- supramarginal gyrus

- angular gyrus.

What structures are on the medial surface of the parietal lobe?

Paracentral lobule and precuneus.

What is the function of the postcentral gyrus?

It serves as the primary somatosensory cortex, receiving tactile and kinesthetic information.

The post central gyrus BA

3,1,2

What happens if the postcentral gyrus is damaged?

Contralateral sensory loss

What does the sensory homunculus represent?

The sensory representation of contralateral body parts in the somatosensory cortex.

What separates the superior and inferior parietal lobules?

The interparietal sulcus.

What is the function of the superior parietal lobule (SPL)?

Sensorimotor integration and visuospatial perception.

What is the function of the inferior parietal lobule (IPL)?

Multimodal processing (visuomotor, auditory), language, and math reasoning.

SPL broadmann area:

5 & 7

What is Brodmann area 5 responsible for?

Somatosensory association and visuospatial processing.

What is Brodmann area 7 responsible for?

Visuo-motor coordination and spatial awareness

What happens if areas 5 and 7 are damaged?

Apraxia (inability to perform planned movements).

Where is the supramarginal gyrus located?

Part of the inferior parietal lobule (IPL).

What is the function of the supramarginal gyrus?

Processing of spoken and written language

emotional responses

integration of somatosensory

auditory

visual input

What syndrome is caused by damage to the supramarginal gyrus?

Gerstmann syndrome

what is included in gerstmann syndrome

agraphia, alexia, finger agnosia, and right-left discrimination issues.

What is the function of the angular gyrus?

Language and number processing, memory, and reasoning.

Where is the precuneus located?

On the medial surface of the parietal lobe

What is the function of the precuneus?

Visuospatial imagery and episodic memory retrieval.

What are the main gyri of the temporal lobe?

Superior temporal gyrus

middle temporal gyrus

inferior temporal gyrus

Heschl's gyrus

What are the main sulci of the temporal lobe?

Superior temporal sulcus

inferior temporal sulcus

occipitotemporal sulcus.

What does the superior temporal gyrus house?

The primary auditory cortex (BA 42) and Wernicke's area (BA 22)

What is the function of the superior temporal gyrus?

Auditory processing, role in the visuospatial domain, and receptive language processing.

Where is the primary auditory cortex located?

In the superior temporal gyrus (BA 42) and Heschl's gyrus (BA 41).

What is the function of the primary auditory cortex?

Sound perception, with neurons organized in a tonotopic (frequency) and periodotopic (periodicity of sound) manner.

What happens with unilateral destruction of the primary auditory cortex?

Partial deafness

Where is Wernicke's area located?

Superior temporal gyrus, dominant hemisphere (BA 22).

What happens if Wernicke's area is damaged?

Receptive aphasia – impaired comprehension of speech

What is the function of the middle temporal gyrus?

Detection of motion and receives information from the visual cortex

What is the function of the inferior temporal gyrus?

Face and shape recognition.

Where is the insula located?

Deep within the lateral surface of the brain.

What are the functions of the insula?

Primary gustatory cortex, connections to language areas, visuo-vestibular integration, and autonomic functions.

What are the primary functional areas of the occipital lobe?

Primary visual area (BA 17) and secondary visual association areas (BA 18, 19)

What are key sulci and gyri in the occipital lobe?

Parieto-occipital sulcus, cuneus, and calcarine sulcus.

What is the cuneus, and what does it do?

A wedge-shaped region in the occipital lobe. It processes vision for the inferior quadrant of the visual field. The fibers of the superior optic radiation synapse here

Where is the calcarine sulcus located?

On the medial surface of the occipital lobe

What is the function of the calcarine sulcus?

Divides the visual cortex into two regions:

Below the sulcus – infracalcarine region

Above the sulcus – cuneus

Where is the primary visual cortex located?

In the calcarine fissure region and occipital pole (BA 17)

What is the function of the primary visual cortex?

Visual perception with retinotopic organization, processing visual information from the retina

What happens if the primary visual cortex is damaged?

Visual field deficits (loss of vision in part of the visual field).