Neurophysiology pdf - D. Noor

بسم هللا الرحمن الرحيم

Lecture 2- Neurophysiology Dr. Noor Jawad

stage sunday

14/10/2018

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Lobes of the Brain

Objective

1. What are the lobes of brain and its functions?

2. What is the cerebellum?

3. Nuclie of cerebellum,its location and functions?

The human brain is the most complex organ in the body. The brain

is divided into four sections, known as lobes .

1. Frontal lobe,

2. Occipital lobe,

3. Oarietal lobe,

4. Temporal lobe

Figure: show lobes of brain

Frontal Lobe

The Frontal Lobe of the brain is located deep to the Frontal Bone
of the skull.

It plays an integral role in the following functions/actions

  Memory Formation
  Emotions
  Decision Making/Reasoning
  Personality

Parietal Lobe

The Parietal Lobe of the brain is located deep to the Parietal Bone

of the skull

It plays an integral role in the following

functions/actions

 Senses and integrates sensation(s)
 Spatial awareness and perception

(Proprioception - Awareness of body/ body parts in space and

in relation to each other).

Occipital lobe

The Occipital Lobe of the Brain is located deep to the Occipital

Bone of the Skull .

Its primary function is the processing, integration, interpretation of

VISION and visual stimuli

Temporal lobe

The Temporal Lobes are located on the sides of the brain, deep to

the Temporal Bones of the skull.

They play an integral role in the

following functions:

 Hearing

 Organization/Comprehension of language.

 Information Retrieval (Memory and Memory

Formation)

Cerebellum

The cerebellum (“little brain”) is part of CNS that is located at the

back of the brain, underlying the occipital and temporal lobes of

the cerebral cortex in posterior cranial fossa . It is a relatively small

portion of the brain -- about ten percent of the total weight, but it

contains roughly half of the brain's neurons, specialized cells that

transmit information via electrical signals.

The cerebellum has been considered a motor structure, because

cerebellar damage leads to impairments in motor control and

posture and because the majority of the cerebellum’s outputs are to

parts of the motor system.

Cerebellar gross anatomy

Anatomically, the cerebellum is divided into three lobes by two

deep fissures, : (1) the anterior lobe, (2) the posterior lobe, and (3)

the flocculonodular lobe been rolled downward from its normally

hidden position. Note, down the center of the cerebellum, a narrow

band called the vermis, which is separated from the remainder of

the cerebellum by shallow grooves. Most cerebellar control

functions for muscle movements of the axial body, neck,

shoulders, and hips are located in this area.

The cerebellar deep nuclei (or cerebellar nuclei) are the sole output

structures of the cerebellum. These nuclei are encased by a highly

convoluted sheet of tissue called the cerebellar cortex, which

contains almost all of the neurons in the cerebellum..

Figure show divisions of cerebellum

Function

The cerebellum is involved in the following functions:

1. Maintenance of balance and posture.

2. Coordination of voluntary movements.

3. Motor learning. The cerebellum is important for motor

learning. The cerebellum plays a major role in adapting and

fine-tuning motor programs to make accurate movements

through a trial-and-error process (e.g., learning to hit a

baseball).

4. Cognitive functions. Although the cerebellum is most

understood in terms of its contributions to motor control, it is

also involved in certain cognitive functions, such as

language.

Cerebellar nuclei

1. The

fastigial nucleus

is the most medially located of the

cerebellar nuclei. It receives input from the vermis and from

cerebellar

afferents

that

carry

vestibular,

proximal

somatosensory, auditory, and visual information. It projects

to the vestibular nuclei and the reticular formation.

2. The

interposed nuclei

: They are situated lateral to the

fastigial nucleus. They receive input from the intermediate

zone and from cerebellar afferents that carry spinal, proximal

somatosensory, auditory, and visual information.

3. The

dentate nucleus

is the largest of the cerebellar nuclei,

located lateral to the interposed nuclei. It receives input from

the lateral hemisphere and from cerebellar afferents that carry

information from the cerebral cortex (via the pontine nuclei).

4. The

vestibular nuclei

are located outside the cerebellum, in

the medulla. The vestibular nuclei receive input from the

flocculonodular lobe and from the vestibular labyrinth. They

project to various motor nuclei and originate the

vestibulospinal tracts.

figure show Cerebellar nuclei

Functional Subdivisions of the Cerebellum

The anatomical subdivisions correspond to three major functional

subdivisions of the cerebellum.

Vestibulocerebellum

. The vestibulocerebellum comprises

the flocculonodular lobe and its connections with the lateral

vestibular nuclei. As its name implies, it is involved in

vestibular reflexes (such as the vestibuloocular reflex) and in

postural maintenance.

Spinocerebellum

. The

spinocerebellum

comprises

the vermis and the intermediate zones of the cerebellar

cortex, as well as the fastigial and interposed nuclei. As its

name implies, it receives major inputs from the

spinocerebellar tract. It is involved in the integration of

sensory input with motor commands to produce adaptive

motor coordination.

Cerebrocerebellum.

The cerebrocerebellum is the largest

functional subdivision of the human cerebellum, comprising

the lateral hemispheres and the dentate nuclei. In addition,

the cerebrocerebellum is involved in the cognitive functions

of the cerebellum

Thank you

References : Guyton and Hall textbook of medical
physiology, thirteen edition