Neuroanatomy Exam 2 Ch 7 + 8

Chapters 7 + 8

The learner will list four structures/systems that nourish and protect the brain.

The learner will identify important features of the cerebral hemispheres, including the lobes of the brain.

The learner will describe the phenomenon of hemispheric specialization, especially how it relates to language.

The learner will list and briefly describe causes of damage to the cerebral hemispheres.

The learner will describe the phenomenon of brain plasticity and its principles.

The meninges

the protection, surrounds the delicate brain

what are the parts of the meninges

• Dura mater: most outer layer

• Arachnoid mater: middle layer

Pia mater: inner layer

Where there are layers, spaces result

Potential spaces, and actual space

What is potential spaces and what is actual space

POTENTIAL SPACES - Epidural space: between skull and dura mater

subdural space: between dura mater and arachnoid mater

ACTUAL SPACE: Subarachnoid space: between arachnoid mater and pia mater

What is another way the brain is protected other than the meninges

the blood -brain barrier

what is the function of the blood-brain barrier

protects the brain

-Protects against foreign invaders

-Protects against hormones/neuro-transmitters in rest of body

-Maintains constant environment for brain

what are some (BBB) blood brain barrier problems

•  Hypertension (high blood pressure)

•  Developmental problems with BBB

•  Hyperosmolality (increased movement of particles)

•  Microwaves

•  Radiation

•  Infection

•  Trauma, ischemia, inflammation, pressure

Nourishment: The Cerebral Arteries

• Brain consumes ___ of body’s oxygen

• Blood enters brain through:

  • _______

  • _______

• These feed the _______

• Brain consumes 20% of body’s oxygen

• Blood enters brain through:

  • Carotid arteries

  • Vertebral arteries

• These feed the circle of Willis

Arteries are ____ from the heart

away

arteries pump _____ blood away and veins bring ______- blood back

oxygenated, deoxygenated

The circle of Willis feeds the brain oxygenated blood through

• _______

• _______

• _______

• _______

• Anterior cerebral artery

• Middle cerebral artery

• Posterior cerebral artery

What does the venous system do

moves deoxygenated blood away from the brain , removed through 4 sinuses in meninges

How does the Venous system move deoxygenated blood through 4 sinuses in the meninges

• Superior sagittal

• Transverse

• Occipital

• Sigmoid

  -Superficial and deep cerebral veins then remove

Cerebrum - two cerebral hemispheres (left and right)

Major layers from superficial to deep

• Surface gray matter (cerebral cortex; neuron somas)

• White matter (axons)

• Deep gray matter (e.g., thalamus, basal ganglia)

• Ventricles (4 ventricles)

CEREBRAL CORTEX FEATURES

Cortex means “___”

Features include: ____. ______, ____

• Cortex means “bark”

• Gyri

• Sulci

• Fissures (deep sulci):

  • Longitudinal

  • Central

  • Lateral

Lobes of the brain

• Frontal lobe: reasoning, planning, motor movement

• Parietal lobe: sensory perception and interpretation

• Occipital lobe: vision

• Temporal lobe: memory, receptive language

Interhemispheric connections

corpus callosum is a band of fibers that connects the right and left hemispheres together.

Brodmann Map - Developed by Korbinian Brodmann

Divides brain into 52 area based on - Brain’s gross anatomy and cellular structure of brain —— Brodmann area

Frontal Lobe: prefrontal cortex

occuies BA 9, 10, 11, 12, 45, 46, 47 - Functionally involves with cognition (executive control) personality, decision, making, and social behavior

Frontal Lobe: Frontal Eye Fields

-Occupies BA 8

-Controls eye movements ( up, down, left, and right)

-Damage results in eyes deviating towards the side of injury

Involved in uncertainty and hope

-Sometimes included as part of prefrontal cortex

Frontal Lobe: Broca’s Area

-Occupies BA 44 and 45

-Found on third frontal convolution (inferior frontal gyrus)

-Area 45 is known as pars triangularis, involved in interpretation of language (syntax) and planning/programming of verbal responses

Frontal Lobe: Broca’s area

-Area 44 is known as pars opercularis, involved in coordination of speech organs for language production

-Paul Broca, through observations of Tan, one of first to associate BA 44 45 with speech production

-Impairments to this area my lead to Broca’s aphasia

Frontal Lobe: Premotor

-Occupies BA 6

-Close relationship to BA 44

Involved in selecting and planning of motor movements

-Supplementary motor area (SMA) located at top of BA 6 and s involved in sequencing and “turning on” motor plans

Frontal Lobe: Primary Motor Cortex

-Occupies BA 4

Sends motor plans developed in Ba 6 to the muscles for them to act (e.g., speech muscles)

BA 4 has been mapped to form a homunculus or “little man”

Parietal Lobe: Primary Sensory Cortex

-Occupies BA 1, 2, and 3

-processes somatosensory information such as

• vibration

• proprioception

• Touch

• Stereognosis

  -Homunculus present

Parietal Lobe: Somatosensory Association Cortex

-Occupies BA 5 and 7

-Interprets sensory experience during motor movements

-This sensory experience is used to refine motor action

Involved in the fine movements associated with speech

Plays role in writing sensory and motor experience

Parietal Lobe: Angular Gyrus

Occupies BA 39

-Involved in reading and math abilities

-Damage can lead to alexia and acalculia

-May also be involved in understanding metaphors and our sense of embodiment

Damage can lead to outer body experiences

-Damage can also lead to Gerstmann syndrome

Parietal Lobe: Supramarginal Gyrus

-Occupies BA 40

-Closely rated to the angular gyrus (BA 39)

-Involved in phonological system; stores auditory representations of phonemes (auditory images)

-This helps us sound out words

-Damage can result in phonological dyslexia, difficulty reading new and nonwords

Occipital Lobe: Visual Cortex 1/2

-Occupies BA 17, 18, and 19

-Where information from eyes is received and processed

Occipital Lobe: Visual Cortex 2/2

Two streams of vision

-Dorsal Stream (18, 19, 7 and 39) the where of vision, analyzes motion and spatial relationships

Ventral stream (18, 19, and 37) the what of vision, analyzes forms, colors, and faces

Temporal Lobe: Inferior Temporal Area

-Occupies BA 20 and 21

-Involves in processing of auditory and language information as well as reading facial emotions

May play a role in hallucinations

Temporal Lobe: Parahippocampal Gyrus

-Occupies BA 27, 28, 34, 35, and 36

-Located on medial surface of temporal lobe

• Two structures of note:

  -Hippocampus: associated with declarative memory

• Entorhinal cortex (BA 28 and 34): major input/output relax between the cerebral cortex and the hippocampus

Temporal Lobe: Fusiform Gyrus

-Occupies BA 37

-Also known as occipitemporal gyrus

Important in remembering and naming seen objects

-Functions as a visual lexicon

-Lesions can cause anomia and lexical agraphia

Temporal Lobe: Temporal Pole

-Occupies BA 38

-Involves in language

Left: Semantic processing

Left: speech comprehension

Left: narrative comprehension

Right: integration of emotion into narratives

Right: identifying familiar voices

Both: theory of mind

Both: empathy

Temporal Lobe: primary Auditory Cortex

-Occupies BA 41 and 42 (42 is the secondary cortex, but 41/42 usually discussed as a unit called primary auditor cortex

-Also known as Heschl’s gyrus

Initial cortical region that receives auditory information from the ears via CN VIII and the auditory pathways

-Processes sound intensity and frequency

Organized by tones (tonotopically))

Cingulate Cortex

-Name means ‘band that encircles

-Occupies BA 23- 26, 30, 33

-Sandwiched between corpus callosum and frontal and parietal lobes

Is part of the limbic system and has connections to the prefrontal cortex and hippocampus

Cingulate Cortex

Functionally involved in the following

-Anterior parts: cognitive control, detecting errors, detecting conflicts, and problem solving

-Posterior parts: autobiographical memory, managing risk behavior, and emotional processing

Overall, there appears to be a filter and focus process

-ACC filters out irrelevant information

-PCC detects important information

Insular Cortex

-Located deep in the lateral sulcus

-Also known as insula or island

• Two main parts-

  -Posterior-dorsal area: orofacial programs and emotions (eg. disgust over drinking spoiled milk)

  -Dorsal-caudal area: connections to BA 5 and 7, so involved in integrating sensory feedback into motor behavior (refinement)

Insular Cortex

• Clinical date suggests role in language

• Perhaps plays role in lexical decision making

• May be involved in some cases of global aphasia