Guide to Brain Anatomy

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A Guide to Brain Anatomy, Function and Symptoms

Brain Structure Function Associated Signs and Symptoms

Cerebral Cortex

Ventral View ( From bottom)

The outermost layer of the cerebral hemisphere

which is composed of gray matter. Cortices are

asymmetrical. Both hemispheres are able to

analyze sensory data, perform memory

functions, learn new information, form

thoughts and make decisions.

Left Hemisphere Sequential Analysis: systematic, logicalinterpretation of information. Interpretation and

production of symbolic information:language,

mathematics, abstraction and reasoning.

Memory stored in a language format.

Right Hemisphere Holistic Functioning: processing multi-sensoryinput simultaneously to provide "holistic"

picture of one's environment. Visual spatial

skills. Holistic functions such as dancing and

gymnastics are coordinated by the right

hemisphere. Memory is stored in auditory,

visual and spatial modalities.

Corpus Callosum Connects right and left hemisphere to allow for

communication between the hemispheres.

Forms roof of the lateral and third ventricles.

Damage to the CorpusCallosum may result in "Split

Brain" syndrome.

Frontal Lobe

Ventral View (From Bottom)

Cognition and memory.

Prefrontal area: The ability to concentrate and

attend, elaboration of thought. The

"Gatekeeper"; (judgment, inhibition).

Personality and emotional traits.

Movement:

Motor Cortex (Brodman's): voluntary motor

activity.

Premotor Cortex: storage of motor patterns and

Impairment of recent memory,inattentiveness, inability to

concentrate, behavior

disorders, difficulty in

learning new information.

Lack of inhibition

(inappropriate social and/or

sexual behavior). Emotional

lability. "Flat" affect.

Contralateral plegia, paresis. Expressive/motor aphasia.


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Side View

voluntary activities.

Language: motor speech

Parietal Lobe Processing of sensory input, sensorydiscrimination.

Body orientation.

Primary/ secondary somatic area.

Inability to discriminatebetween sensory stimuli.

Inability to locate andrecognize parts of the body

(Neglect).

Severe Injury: Inability torecognize self.

Disorientation of environmentspace.

Inability to write.

Occipital Lobe Primary visual reception area.

Primary visual association area: Allows for

visual interpretation.

Primary Visual Cortex: loss ofvision opposite field.

Visual Association Cortex:loss of ability to recognize

object seen in opposite field of

vision, "flash of light",

"stars".

Temporal Lobe Auditory receptive area and association areas.

Expressed behavior.

Language: Receptive speech.

Memory: Information retrieval.

Hearing deficits. Agitation, irritability, childish

behavior.

Receptive/ sensory aphasia.

Limbic System

Olfactory pathways:

Amygdala and their different pathways.

Hippocampi and their different pathways.

Limbic lobes: Sex, rage, fear; emotions.

Integration of recent memory, biological

rhythms.

Loss of sense of smell. Agitation, loss of control of

emotion. Loss of recent

memory.


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Hypothalamus.

Basal Ganglia Subcortical gray matter nuclei. Processing link

between thalamus and motor cortex. Initiation

and direction of voluntary movement. Balance

(inhibitory), Postural reflexes.

Part of extrapyramidal system: regulation of

automatic movement.

Movement disorders: chorea,tremors at rest and with

initiation of movement,

abnormal increase in muscle

tone, difficulty initiating

movement.

Parkinson's.

Structures of the Diencephalon (within the cerebrum and continues with themidbrain).


Thalamus Processing center of the cerebral cortex.

Coordinates and regulates all functional

activity of the cortex via the integration of the

afferent input to the cortex (except olfaction).

Contributes to affectual expression.

Altered level ofconsciousness.

Loss of perception. Thalamic syndrome -

spontaneous pain opposite side

of body.

Hypothalamus Integration center of Autonomic Nervous

System (ANS): Regulation of body temperature

and endocrine function.

Anterior Hypothalamus: parasympathetic

activity (maintenance function).

Posterior Hypothalamus: sympathetic activity

("Fight" or "Flight", stress response.

Behavioral patterns: Physical expression of

behavior.

Appestat: Feeding center.

Pleasure center.

Hormonal imbalances. Malignant hypothermia. Inability to control

temperature.

Diabetes Insipidus (DI). Inappropriate ADH (SIADH). Diencephalic dysfunction:

"neurogenic storms".


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Internal Capsule Motor tracts. Contralateral plegia (Paralysisof the opposite side of the

body).

Reticular Activating System(RAS)

Responsible for arousal from sleep,

wakefulness, attention.

Altered level ofconsciousness.

The Cerebellum and the Brain Stem


Cerebellum Coordination and control of voluntary

movement.

Tremors. Nystagmus (Involuntary

movement of the eye).

Ataxia, lack of coordination.

Brain Stem:

Midbrain Nerve pathway of cerebral hemispheres.Auditory and Visual reflex centers.

Cranial Nerves:

CN III - Oculomotor (Related to eye

movement), [motor].

CN IV - Trochlear (Superior

oblique muscle of the eye which rotatesthe eye down and out), [motor].

Weber's: CN III palsy andptosis (drooping) ipsalateral

(same side of body).

Pupils:Size: Midposition to dilated.

Reactivity: Sluggish to fixed.

LOC (Loss of consciousness):Varies

Movement: Abnormalextensor ( muscle that extends

a part).

Respiratory:Hyperventilating.

CN (Cranial Nerve) Deficits:CN III, CN IV.


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Pons Respiratory Center.Cranial Nerves:

CN V - Trigeminal (Skin of face,

tongue, teeth; muscle of mastication),[motor and sensory].

CN VI - Abducens (Lateral rectus

muscle of eye which rotates eye

outward), [motor].

CN VII - Facial (Muscles of

expression), [motor and sensory].

CN VIII - Acoustic (Internal

auditory passage), [sensory].

Pupils:Size: Pinpoint

LOC:Semi-coma

"Akinetic Mute".

"Locked In" Syndrome.

Movement:Abnormal extensor.

Withdrawal.

Respiratory:Apneustic (Abnormal

respiration marked by

sustained inhalation).

Hyperventilation.

CN Deficits: CN VI, CN VII. Medulla Oblongata Crossing of motor tracts.

Cardiac Center.

Respiratory Center.

Vasomotor (nerves having muscular control of

the blood vessel walls) Center

Centers for cough, gag, swallow, and vomit.

Cranial Nerves:

CN IX - Glossopharyneal (Muscles

and mucous membranes of pharynx,

the constricted openings from the

mouth and the oral pharynx and the

posterior third of tongue.), [mixed].

CN X - Vagus (Pharynx, larynx,

heart, lungs, stomach), [mixed].

CN XI - Accessory (Rotation of the

head and shoulder), [motor].

CN XII - Hypoglossal (Intrinsic

muscles of the tongue), [motor].

Movement: Ipsilateral (sameside) plegia (paralysis).

Pupils:Size: Dilated.

Reactivity: Fixed.

LOC: Comatose. Respiratory:

Abnormal breathing patterns.

Ataxic.

Clustered.

Hiccups.

CN Palsies (Inability tocontrol movement):

Absent Cough.

Gag.


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Blood Supply to the Brain

Arteria cerebri

anterior

Arteria cerebrimedia

Arteria cerebriposterior

Arteria chorioidea

anteriorArteria basilaris


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Cerebral angiograms

Carotid angiogram

Anterior view

Carotid angiogram

Lateral View

Vertebral

angiogramAnterior view

Vertebral

angiogramLateral View

Abbreviations:

ACI - internal carotidartery

ACA - anterior cerebralartery

ACM - middle cerebralartery

BA - basilar artery VA - vertebral artery PCA - posterior cerebral artery PICA - posterior inferior

cerebellar artery

More detail

1. Pericallosal artery 2. Callosomarginal artery 3. Anterior cerebral artery 4. Ophthalmic artery 5. Internal carotid artery 6. Anterior choroidal artery 7. Lenticulostrate arteries

Carotid angiogram

Anterior view

Carotid angiogram

Lateral View


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Tracts of the Spinal Cord

1. Fasciculus gracilis (Goll)

2. Fasciculus cuneatus (Burdach)

3. Tractus spinocerebellaris

dorsalis (Flechsig)

4. Tractus corticospinalis lateralis

5. Tractus spinothalamicus

lateralis (Edinger)

6. Tractus spinocerebellaris

ventralis (Gowers)

7. Tractus rubrospinalis

8. Tractus spinotectalis

9. Tractus corticospinalis anterior

10. Tractus olivospinalis

11. Tractus spinoolivaris12. Tractus tectospinalis

13. Tractus reticulospinalis

14. Tractus vestibulospinalis

15. Tractus spinothalamicus

anterior

Syndromes of the Spinal Cord

Extent of lesion Structures damaged Causes

Complete transsection Myelitis

Trauma

Hemisection Brown-Squard syndrome

Central structures

Syringomyelia

Hydromyelia

Tumor

Posterior funiculus

Posterior horn Tabes dorsalis


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Posterior funiculus

Pyramidal tracts Subacute combined degeneration

Posterior funiculus

Pyramidal tracts

Spinocerebellar tracts

Spinocerebellar degeneration

Pyramidal tracts

Ventral horn Amyotrophic lateral sclerosis

Ventral horn Spinal muscular atrophy

Poliomyelitis

Pyramidal tracts (crossed

+ uncrossed) Familial spastic paraparesis

Dorsal one-third Occlusion of the posterior spinal

arteries

Ventral two-thirds Occlusion of the anterior spinal

artery


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Crossed brainstem syndromes

Syndrome Site of lesion Ipsilateral side Contralateral side

Weber(hemiparesis alternans

oculomotoria)

Oculomotor palsy Hemiparesis

Benedikt Oculomotor palsyHyperkinesis (athetosis,chorea)

Rigor

Disturbance of deep sensibility

Raymond-Cestan oral ponsInternuclear

ophthalmoplegia

Hemiparesis

Ataxia

Hypesthesia

Raymond(hemiparesis alternans abducens)

Abducent palsy Hemiparesis

Millard-Gubler(hemiparesis alternans facialis)

Facial paresis Hemiparesis

Brissaud-Siccard Facial hemispasm Hemiparesis

Foville

Facial paresis

Abducent paresis

Horizontal gaze

paralysis

Hemiparesis

Avellis(hemiparesis alternans vaga)

Signs of vagus lesion Hemiparesis

Schmidt(hemiparesis alternans accessoria)

Paresis of m. trapezius

andm.

sternocleidomastoideus

Hemiparesis

Jackson(hemiparesis alternans

hypoglossa)

Hypoglossus palsy Hemiparesis

Djerine Hypoglossus palsyHemiparesis

Disturbance of deep sensibility


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Anatomy and Functional Areas of the Brain

Documents

Guide to Brain Anatomy