Anatomy of the Brain - Motor Cortex

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Questions and Answers

What is the primary function of the premotor frontal cortex?

To control involuntary movements

To process sensory information

To regulate emotions

To plan and organize the sequence of movement (correct)

What is the significance of the gray matter in the brain?

It is responsible for involuntary movements

It contains neuronal cell bodies (correct)

It is the outer layer of the brain

It contains the cerebral spinal fluid

What is the role of the supplementary motor cortex?

To regulate sensory information

To control voluntary movements

To process visual information

To prepare orientation of the body to execute a particular motor task (correct)

How many pairs of spinal nerves are present in the human body?

36 Signup and view all the answers

What is the function of the association areas?

To integrate sensory inputs, memory, and behavior Signup and view all the answers

Where do motor signals exit the spinal cord?

Ventrally Signup and view all the answers

Where do sensory signals enter the spinal cord?

Dorsally Signup and view all the answers

What is the significance of the cervical and lumbar intumescences?

They contain neurons that innervate the limbs Signup and view all the answers

What is the function of the medulla oblongata?

Regulating heart rate, blood pressure, and breathing Signup and view all the answers

What is the term for an outward fold in the cerebrum?

Gyrus Signup and view all the answers

What is the function of the pons?

Influencing cortex to maintain consciousness and alertness, regulate posture, locomotion and visceral functions Signup and view all the answers

What is the term for the pathways in the midbrain that control voluntary movements?

Brainstem UMN pathways (AKA extrapyramidal tracts) Signup and view all the answers

What is the function of the cerebral cortex?

Cognitive function (learning, memory and intelligent behavior) Signup and view all the answers

What is the term for a deep sulcus in the cerebrum?

Fissure Signup and view all the answers

What is the function of the cerebellum?

Coordinating posture, locomotion, and visceral function Signup and view all the answers

What is the function of the visceral sensory fibers?

To provide information about internal organs Signup and view all the answers

What is the term for the white, myelinated axons in the cerebrum?

White matter Signup and view all the answers

What is the primary route of information transmission to the CNS?

From spinal cord to brainstem to thalamus Signup and view all the answers

Which type of fiber carries motor commands from the CNS to peripheral tissues?

Somatic motor fibers Signup and view all the answers

What is the characteristic of secondary-order neurons?

They conduct impulses from spinal cord to brainstem to thalamus Signup and view all the answers

What is the main function of the dorsal root?

To bring sensory information from receptors to the CNS Signup and view all the answers

What is the difference between somatic sensory and visceral sensory fibers?

Somatic sensory fibers bring information about touch and pressure, while visceral sensory fibers bring information about internal organs Signup and view all the answers

Which type of fiber is responsible for controlling skeletal muscle contraction?

Somatic motor fibers Signup and view all the answers

What is the function of tertiary-order neurons?

They conduct impulses from thalamus to primary somatosensory cortex Signup and view all the answers

What is the function of the ventral root?

To transmit motor signals to peripheral tissues Signup and view all the answers

What is the main function of the peripheral nervous system?

To transmit information between the CNS and peripheral tissues Signup and view all the answers

What is the characteristic of quaternary-order neurons?

They are located in the sensory area of the cerebral cortex Signup and view all the answers

What happens to the impulses before they reach the thalamus?

They cross over to the opposite side Signup and view all the answers

What is the advantage of grouping neurons by function?

It helps to understand the role of neurons in the CNS Signup and view all the answers

What is the main function of the sympathetic trunk?

To give off dorsal communicating branches Signup and view all the answers

What is the primary function of the neurons in the somatosensory cortex?

To process and integrate sensory information Signup and view all the answers

What is the relationship between secondary and tertiary-order neurons?

They are responsible for transmitting information in the same pathway Signup and view all the answers

What type of muscle is under involuntary control and includes adipose tissue?

Smooth muscle Signup and view all the answers

Which of the following is a function of the sympathetic nervous system?

Fight or flight Signup and view all the answers

Where are the cell bodies of lower motor neurons located?

In the central nervous system (CNS) Signup and view all the answers

What type of receptor is involved in the auditory and vestibular system?

Special senses receptors Signup and view all the answers

How many cranial nerves are there in the human body?

12 pairs Signup and view all the answers

Where do axons project via cranial and spinal nerves?

Into the central nervous system Signup and view all the answers

What is the function of primary neurons?

To receive signals and send them to the brain Signup and view all the answers

What is the purpose of complex receptors?

To detect pressure Signup and view all the answers

What type of fibers connect the cerebral cortex with other brain regions?

Projection fibers Signup and view all the answers

Which layers of the cerebral cortex are responsible for sending output signals to other brain regions?

Layers V and VI Signup and view all the answers

What is the function of the association fibers in the cerebral cortex?

Connect regions of the cerebral cortex within one hemisphere Signup and view all the answers

What is the function of the commissural fibers in the cerebral cortex?

Connect cortices from right and left cerebral hemispheres Signup and view all the answers

What is the name of the layer in the cerebral cortex that has a multiform structure?

Layer VI - multiform Signup and view all the answers

What is the primary function of the fibers in the cerebral cortex that originate in the thalamus?

Terminate in the cerebral cortex Signup and view all the answers

Which of the following regions is divided into the telencephalon and diencephalon?

Prosencephalon Signup and view all the answers

Which region is responsible for integrating sensory information?

Thalamus Signup and view all the answers

What is the primary function of the cerebellum?

Control of voluntary movements Signup and view all the answers

Which region connects the brain to the spinal cord?

Brainstem Signup and view all the answers

How many major regions can the CNS be anatomically subdivided into?

7 Signup and view all the answers

What is the term for the lower part of the brain that connects to the spinal cord?

Brainstem Signup and view all the answers

What is the function of the spinal cord?

Transmission of nerve signals between the brain and peripheral tissues Signup and view all the answers

What is the primary function of the corpus callosum?

To connect the two cerebral hemispheres and facilitate their integration Signup and view all the answers

What is the term for the intersection of pathways in the form of an X?

Decussation Signup and view all the answers

What is the function of the basal nuclei?

To execute the initiation and control of movement Signup and view all the answers

Which part of the brain is responsible for planning and preparation for movement?

Premotor cortex and supplementary motor cortex Signup and view all the answers

What is the role of the thalamus in the basal nuclei?

To project output from the basal nuclei to the premotor cortex and supplementary motor cortex Signup and view all the answers

What is the location of the gray matter nuclei of the basal nuclei?

Deep within the white matter of the cerebral hemisphere Signup and view all the answers

What is the primary component of the gray matter in the cerebrum?

Nerve cell bodies and their processes Signup and view all the answers

What is the function of the basal nuclei in the cerebrum?

Regulation of voluntary movement Signup and view all the answers

What is the term for a cluster of neurons cell bodies outside the CNS?

Ganglion Signup and view all the answers

What is the function of the hippocampus in the cerebrum?

Formation of memories Signup and view all the answers

What is the term for a cluster of neurons cell bodies inside the CNS?

Nucleus Signup and view all the answers

What is the function of the amygdala in the cerebrum?

Regulation of emotions Signup and view all the answers

What is the composition of the white matter in the cerebrum?

Myelinated axons Signup and view all the answers

What is the function of the cerebrum in the central nervous system?

Integration of sensory information and control of voluntary movements Signup and view all the answers

Study Notes

Central Nervous System

The brain receives and processes sensory information, initiates responses, stores memories, generates thoughts and emotions.
Cerebrum has two hemispheres: left and right, which are extensively folded, with gyri (outward folds) and sulci (inward folds).
Functions of the cerebrum include conscious experience of sensation and initiation of voluntary movement.
Medulla oblongata regulates heart rate, blood pressure, breathing, walking, sleeping, and swallowing.
Pons influences cortex to maintain consciousness and alertness, and regulates posture, locomotion, and visceral function.

Brainstem

Midbrain is the location of the brainstem UMN pathways and subconscious posture and voluntary skilled/learned movements.

Cerebellum

Cerebellum is responsible for premotor frontal cortex, which plans and organizes the sequence of movement.
Supplementary motor cortex is responsible for preparatory orientation of the body to execute a particular motor task.
Cerebellum integrates and interprets information, producing a specific learned output.

Spinal Nerves

There are 36 pairs of spinal nerves that communicate the spinal cord with sensory receptors, muscles, viscera, and vessels.
Each segment gives rise to paired spinal nerves that exit the vertebral canal via the lateral vertebral foramen of the atlas or via intervertebral foramen.
Neurons innervating the limbs are confined to cervical and lumbar intumescences.

Peripheral Nervous System

Sensory/Afferent system brings information to the CNS from receptors in peripheral tissues and organs.
Motor/Efferent system carries motor commands from CNS to peripheral tissue and systems.
Visceral Sensory provides information about internal organs, while Somatic Sensory provides information about position, touch, pressure, pain, and temperature.
Somatic Motor controls skeletal muscle contraction, while Visceral Motor provides autonomic regulation of smooth muscle, cardiac muscle, glands, and adipose tissue.

Receptors

Receptors are of different types, including free nerve endings, complex receptors, and special senses receptors.

Neurons

Primary (first-order) neurons receive signals and send information to CNS.
Secondary (second-order) neurons conduct impulses from spinal cord to brainstem to thalamus.
Tertiary (third-order) neurons conduct impulses from thalamus to primary somatosensory cortex.
Quaternary (fourth-order) neurons are located in sensory area of cerebral cortex.

Cranial Nerves

There are 12 pairs of cranial nerves that arrive in the brainstem.
Individual nerves have specific sensory and/or motor, somatic and/or autonomic functions.

Cerebrum or Telencephalon

The cerebrum is the largest part of the brain and is divided into two hemispheres.
It is composed of the cerebral cortex, white matter, and subcortical structures.

Cerebral Cortex

The cerebral cortex is a layer of gray matter at the surface of the cerebrum.
It is divided into 6 separate horizontal layers parallel to the surface of the cortex.
The layers are:
- I: Molecular
- II: Outer granular (external granular)
- III: Outer pyramidal (external pyramidal)
- IV: Inner granular (internal granular)
- V: Inner pyramidal (internal pyramidal)
- VI: Multiform
Different distribution of layers according to functional areas.
Most incoming signals are received in layer IV.
Most output signals leave the cortex through layers V and VI.
Layer V sends signals to the brainstem and spinal cord.
Layer VI sends signals to the thalamus.
Layers I, II, and III are involved in intracortical association functions.

White Matter

The white matter is composed of myelinated axons that connect the cerebral cortex with other brain regions.
It is divided into:
- Projection fibers
- Association fibers
- Commissural fibers
Projection fibers leave the white matter and terminate in the basal nuclei, brainstem, or spinal cord.
Association fibers connect regions of the cerebral cortex within one hemisphere.
Commissural fibers connect the cortices from the right and left cerebral hemispheres.

Subcortical Structures

Basal nuclei (Basal Ganglia) are gray matter nuclei located deep within the white matter of the cerebral hemisphere.
They include the Caudate nucleus, nucleus accumbens, putamen, globus pallidum, and claustrum.
The subthalamic nucleus and substancia nigra are also called Basal nuclei.
Basal nuclei project output via the thalamus into the supplementary and premotor cortices.
They are involved in planning and preparation for movement.
They also send output directly to the brainstem.

Brain Regions

The CNS can be anatomically subdivided into 7 major regions:
- 1. Telencephalon or Cerebrum
- 1. Diencephalon (thalamus and hypothalamus)
- 1. Cerebellum
- 1. Mesencephalon or Midbrain
- 1. Pons
- 1. Medulla oblongata
- 1. Spinal cord

Functional Areas

The brain can be divided into 5 major functional areas:
- 1. Cerebrum
- 1. Thalamus
- 1. Hypothalamus
- 1. Cerebellum
- 1. Brainstem (Midbrain, Pons, and Medulla)

Commissures and Decussations

A commissure is a place where fibers cross and connect the two cerebral hemispheres.
Example: Corpus callosum
A decussation is an intersection of pathways in the form of an X.
This accounts for why each side of our brain has control over the opposite side of our body.

Basal Nuclei

Basal nuclei are an accessory motor system that helps execute the initiation and control of movement.
They are responsible for the cognitive control of motor activity.
Studies in monkeys show that changes in neuronal activity of the basal nuclei occur prior to the firing of the neuronal activity of the motor cortex and the movement of body parts.

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Description

Discover the functions of the premotor frontal cortex and supplementary motor cortex in the brain's motor system. Learn about the structure and organization of the brain's gray and white matter.