CORTICAL ANATOMY AND SYNDROMES Peter M' Grossi MD Sept 14, 2004

1
CORTICAL ANATOMY AND SYNDROMESPeter
M. Grossi MDSept 14, 2004
2
GENERAL ANATOMY

• Hemispheres derive from telencephelon
• Gyri and Sulci define the surface
• Sylvian or Transverse sulcus
• Rolandic or Central sulcus

3
GENERAL ANATOMY

• Frontal Lobe
• Temporal Lobe
• Parietal Lobe
• Occipital Lobe
• Insula

4
FRONTAL LOBE

• Two sulci running AP divide into
• Superior Frontal Gyrus
• Middle Frontal Gyrus
• Inferior Frontal Gyrus
• Perpendicular to this is the Precentral Gyrus

5
FRONTAL LOBE

• The inferior frontal convulition is divided into
• pars obitalis anterior
• pars triangularis
• pars opercularis posterior

6
FRONTAL LOBE

• The medial surface is formed by the medial
  surface of the superior frontal gyrus, anterior
  half of the paracentral lobule, and the cingulate
  gyrus
• the cingulate and superior frontal gyri wrap
  around the genu of the CC and the paraterminal
  and paraolfactory gyri sit below the rostrum, in
  front of lamina terminalis

7
TEMPORAL LOBE

• Two transverse sulci divide into
• Superior Temporal Gyrus
• Middle Temporal Gyrus
• Inferior Temporal Gyrus
• Transverse (Heschls) Gyrus runs anterolaterally
  over superior aspect of first temporal Gyrus

8
TEMPORAL LOBE

• Medial surface formed by the rounded medial
  surface of the hippocampal gyrus and uncus
• Three strips
• Parahippocampal gyrus inferior
• Dentate Gyrus medially
• Fimbri of fornix
• The parahippocampal gyrus projects medially along
  edge of tent and forms the basal surface of the
  temporal lobe
• The Uncus is the medially pointing anterior part
  of the parahippocampal gyrus

9
PARIETAL LOBE

• Transverse sulcus divides Parietal Lobe into
• Superior Parietal Lobule
• Inferior Parietal Lobules
• Supramarginal Gyrus around sylvian Fissure
• Angular Gyrus around superior temporal gyrus

10
OCCIPITAL LOBE

• The occipital convexity is not seperated by
  clearly defined sulci
• Most consistent sulcus is the lateral occipital
  sulcus that divided the superior and inferior
  occipital gyri

11
OCCIPITAL LOBE

• Medially, the occipital lobe is seperated from
  the parietal lobe by the parieto-occipital sulcus
• The calcrine fissure extends forward and divides
  the occiptial lobe into the cuneus and
• the lingua

12
MEDIAL HEMISPHERES

• Cingulate Sulcus seperates Cigulate Gyrus from
  the paracentral gyri (lobule)
• Marginal sulcus is a radial sulcus off of the
  cingulate sulcus which seperates the paracentral
  lobule from the Precuneus
• Parietal-occipital sulcus seperates the precuneus
  from the cuneus, the bottom of which is defined
  by the calcrine fissure
• As the cingulate gyrus wraps around the splenium
  of the CC, it blends with the parahippocampal
  gyrus
• Hippocampal gyrus runs anterior laterally
  superiorly to the parahippocampal gyrus,
  seperated by the hippocampal sulcus and
  anteriorly, the two converge to form the uncus

13
MEDIAL HEMISPHERES

• Inferiorly, the orbital surface of the frontal
  lobe
• The gyrus rectus lies medial to the olfactory
  bulb
• Fusiform or occipitotemporal gyrus
• Lingual Gyrus
• Inferior temporal gyrus

14
FRONTAL LOBE LESIONS

• Personality Changes
• Apathetic Dementia Loss of drive, apathy,
  decreasing concern with personal appearance and
  hygeine, loss of concern for family/ business
  affairs
• May lead to legal trouble secondary to
  disinhibiton
• Incontinence
• Abrupt awareness that bladder is full coupled
  with the inability to prevent it from emptying
  immediately
• Seizures associated with frontal lobe lesions
• Adversive Fits head and eyes turn away from
  lesion (Frontal Eye Fields)
• Focal Motor Epilepsy unilateral motor
  convulsions (lesions in or near motor cortex)
• Status 50 of pts who go into status are
  wventually found to have a frontal lobe lesion

15
PARIETAL LOBE LESIONS

• Cortical Sensory Loss or Sensory Neglect
• Dysphysia (Dominant)
• Dyspraxia (Non-Dominant)
• Attention Hemianopia
• Loss of Optokinetic Nystagmus
• Soft Motor Signs- contralateral slighty
  increased reflexes. Mild facial weakness and
  babinski sign

16
LAYERS OF CORTEX

• 1. Molecular horizontal axons, golgi 2 cells
• 2. Ext. Granular granule cells
• 3. Ext. Pyramidal commisural fibers
• 4. Int. Granular stellate cells, ext. band of
• 
  Baillarger
• 5. Int. Pyramidal Largest cells
• 6. Multiform Layer

17
LAYERS OF CORTEX

• 1 2 receive diffuse afferent fibers
• from lower brain to control
• excitability of region
• 3 connect two hemispheres and
• ipsilateral cortico-cortico
• association fibers
• 4 main sensory afferent input
• (in sensory cortex)
• 5 main efferent to brain stem
• and spinal cord
• (in motor cortex)
• 6 efferent fibers to thalamus

18
PRIMARY SENSORY
19
PRIMARY SENSORY

• Postcentral gyrus of parietal lobe
• and posterior paracentral lobule
• Brodman area 1,2,3
• Receives fibers from VPL and VPM
• Convey general sensory- touch, pain, and
  temperature and propriocepition and vibration
• Also receives commisural fibers from
  contralateral Primary sensory cortex through the
  corpus callosum

20
PRIMARY SENSORY

• Sensory homunculus represents contralateral half
  of body
• Disproportionately large representation of face,
  lips, hand, thumb and index finger
• Pharynx, tongue and jaw are most ventreal
• Leg and food on medial surface just above
  cingulate gyrus
• Face and tongue are represented bilaterally

21
PRIMARY SENSORY
22
PRIMARY SENSORY

• Ablation of postcentral gyrus will result in
  immediate loss of all sensory modalities
• But pain and temperature sensations will return-
  thought to be determined on the thalamic level
• Therefore left with complete loss of discrimitive
  touch and proprioception and crude awareness of
  pain, temperature, and light touch

23
SECONDARY SENSORY CORTEX

• Most inferior aspect of postcentral gyrus and
  parietal operculum
• Bilateral body representation, with contralateral
  predominance,
• Organization is reverse to SSI (two face areas
  are adjacent)

24
SECONDARY SENSORY CORTEX

• Lesions produce Asymbolia for pain absence of
  psychic reaction to painful stimuli

25
SENOSRY ASSOC. CORTEX

• In superior parietal lobe- medial Brodmann 5 and
  anterior 7
• Receive inputs from SI
• Reciprocal connections with Pulvinar
• Integration/ Processing of cortical and thalamic
  inputs and multisensory inputs

26
SENOSRY ASSOC. CORTEX
27
SENOSRY ASSOC. CORTEX

• Area 5 necessary for goal-directed voluntary
  movement
• Area 7 role in associating visual and sensory
  stimuli
• Bilateral Lesions of SSA can cause optic apraxia
  inability to mave hand towards object which is
  clearly seen
• Unilateral lesions in non-dominant hemisphere
  produce contralateral sensory neglect

28
PRIMARY VISUAL CORTEX

• Calcrine Gyrus on medial surface of occipital
  lobe on each side of the calcrine sulcus
• Brodmanns 17
• Prominent band of white matter Band of Gennari
  (thickened layer IV)
• Receives fibers from lateral geniculate
• Each visual cortex receives input from
  ipsilateral half of each retina (contralateral
  visual field)

29
PRIMARY VISUAL CORTEX
30
PRIMARY VISUAL CORTEX

• Lesions produce visual field defect in
  contralateral visual field
• e.g. lesion of inferior calcrine cortex
  contralateral quadrantanopsia
• Lesions of the whole visual cortex in one
  hemishpere result in a loss of vision in the
  contralateral visual field
• If lesion is vascular (eg occlusion of PCA)
  results in macular sparing because macula area
  receives collateral blood supply from the MCA

31
SECONDARY VISUAL AREAS

• Adjacent to primary visual areas
• Brodmanns 18 (V2) and 19 (V3)
• V2 is also retinotopically organized
• V3 is associates with form
• Other secondary visual areas are associated with
  color and motion are in variable anatomic
  location sin humans
• Receive primary afferents from primary visual
  cortex (bilateral), but also receive some direct
  input from pulvinar and LGN
• Output is to posterior parietal cortex (area 7)-
  stereopsis and infratemporal cortex (area 20
  21)- form and color

32
SECONDARY VISUAL AREAS

• Area 37 in inferotemporal cortex associated with
  face recognition, and bilateral lesions lead to
  prosopagnosia (inability to recognize faces)
• Projections from 18 and 19 also reach FEFs (area
  8) these play key role in conjugate pursuit
  movements

33
PRIMARY AUDITORY CORTEX

• Transverse Temporal Gyrus of Heschl (areas 41
  42)
• Temporal lobe within sylvian fissure
• Receives fibers from MGN
• Receives input from both ears, predominately
  contralateral
• Cortical organization is columnar based on
  isofrequency stripes
• Important connections include
• Association auditory cortex
• SI
• FEFs
• Brocas Area
• MGN

34
PRIMARY AUDITORY CORTEX
35
PRIMARY AUDITORY CORTEX

• Lesions of Auditory cortex result in
• Impairment of sound localization in space
• Diminution of hearing bilaterally, worse on
  contralateral side

36
AUDITORY ASSOC. CORTEX

• Areas 22 and 24
• Concerned with comprehension of spoken sound
• Area 22 Wernickes
• Connected with Prefrontal cortex via anterior
  commisure and with Prefrontal, premotor, parietal
  and cingulate cortices via corpus callosum

37
GUSTATORY CORTEX

• Cortical receptive area for tase is located in
  parietal operculum, ventral to SI and near the
  sensory areas for tongue and pharynx
• Area 43
• Epileptic foci in this area are associated with
  preictal Gustatory hallucinations
• Receives fibers from VPM of thalamus
• Lesion results in impairment of
• taste contralateral to lesion
• Crude taste can still be perceived
• on a thalamic level

38
OLFACTORY CORTEX

• Piriform Cortex and Periamygdaloid area located
  in tip of temporal lobe
• Receives fibers from Lateral Olfactory Stria
• The only sensory cortex in which fibers reach
  cortex without passing through Thalamus
• Related to surrounding limbic areas

39
OLFACTORY CORTEX

• Area 28 is the entorhinnal cortex which is
  considered an olfactory association cortex
• Epileptic foci in this area are associated with
  preictal Olfactory hallucinations

40
PRIMARY MOTOR CORTEX

• Precentral Gyrus
• Area 4
• Contralateral Half of the Body is represented
  disproportionately in the motor homunculus
• Bilateral representation of EOMs, face, tongue,
  jaw, larynx
• Functions in the initiation of skilled motor
  movements
• Receives fibers from VL, SS cortex, and
  supplementary motor
• Reciprocal connections with SS cortex

41
PRIMARY MOTOR CORTEX
42
PRIMARY MOTOR CORTEX

• Lesion results in flacid paralysis in the
  contralateral half of the body

43
MOTOR CORTEX
44
SUPPLEMENTARY MOTOR

• Located on the Medial surface of the frontal
  lobe, anterior to the primary motor cortex
• Area 6
• Crucial for the temporal organization of
  movement, especially in sequential tasks
• Connected reciprocally with the
• ipsilateral primary motor,
• premotor, and somatosensory
• areas, as well as the contralateral
• supplementary motor area
• Subcortical projections are
• from the basal ganglia via
• the thalamus

45
SUPPLEMENTARY MOTOR
46
SUPPLEMENTARY MOTOR

• Lesions to the SMA result in
• akinesia- global reduction in spontaneous
  movement, particularly on the contralateral side
• Dominant SMA lesion Decreased spontaneous speech
  with preserved repetition
• Deficits generally are transient and resolve
  within a few weeks
• Lesions can also be associated with hypertonia,
  increased reflexes, clonus and babinski reflex

47
PREMOTOR

• In frontal lobe, anterior to primary motor cortex
• Area 6
• Concerned with voluntary motor function dependent
  on sensory inputs
• The premotor area is activated when a new motor
  program is established or changed based on
  sensory input

48
PREMOTOR

• Lesions to Premotor cortex produces an Apraxia- a
  deficit in the execution of learned, complex
  tasks such as walking

49
FRONTAL EYE FIELDS

• Located in the middle frontal gyrus anterior to
  the motor strip
• Area 8
• Triggers voluntary saccades to visible targets in
  the visual environment
• Receives multiple cortical inpurs including from
  the parietoccipital eye field, supplementary eye
  field, and prefrontal cortex
• Has connections to EOM nuclei in the brainstem
  via multiple brain stem reticular nuclei

50
FRONTAL EYE FIELDS

• Seizure activity in the FEF whill deviate eyes
  away from the lesion
• Lesion of the FEF will result in deviation of the
  eyes toward the side of the lesion- this can
  happen following MCA stroke

51
SUPPLEMENTARY EYE FIELD

• In frontal cortex, separate from suppl. motor
• Receives multiple cortical inputs esp from
  prefrontal cortex
• Projects to FEF and to subcortical nuclei
  involved in eye movements
• Plays a role in triggering sequences of saccades

52
PARIETOOCCIPITAL EYE FIELD

• Areas 39, 40 and 19
• Triggers reflexive, visually guided saccades
• Lesions to bilateral POEFs causes
• Balint syndrome inability to direct eyes to
  a certain point despite intact eye movements

53
CORTICAL LANGUAGE AREAS

• Most of the components of the language system are
  located in the the left hemisphere
• Aphasia or Dysphsia disturbances in the ability
  to comprehend, and or produce the symbols
  necessary for communication

54
WERNICKES AREA

• Extensive region including the posterior superior
  temporal gyrus (22) and parietooccipiptotemporal
  junction including the angular gyrus (39)
• Planum Temporale the upper surface of the area
  22 is distinctly larger on the left
• Comprehension of Language
• Sup temporal gyr (22) comprehension of spoken
  language
• angular gyr (39) comprehension of written
  language
• Wernikes Aphasia (sensory, receptive, posterior
  or fluent) pts have difficulty comprehending
  spoken language

55
WERNICKES AREA
56
BROCAS AREA

• Posterior part of the triangular gyrus (45) and
  adjacent opercular gyrus (44) in the inferior
  frontal gyrus of the dominant hemisphere
• Brocas receives inputs from Wernikes via the
  Arcuate Fasciculus
• Within Brocas area a vocalization program is
  formed and transmitterd to mm of face, tongue,
  vocal cords, and pharynx in order to form speech
• Also connected to SMA to initiate speech
• Brocas Aphasia (motor, anterior, expressive,
  nonfluent) inability to expess oneself by
  speech- but are able to comprehend

57
BROCAS AREA
58
ARCUATE FASCICULUS

• A long association fiber bundle that links
  Wernikes and Brocas areas
• Damage is associated with the impairment of
  repetition

59
PREFRONTAL CORTEX

• Frontal pole
• Areas 9,10,11
• Plays a role in affective behavior and judgment

60
PREFRONTAL CORTEX

• Pts with bilateral lesions neglect their
  appearance, act inappropriately, have no
  appreciation of social norms for conduct. They
  are uninhibited and highly distractable
• Perseveration

61
MAJOR ASSOC. CORTEX

• Supramarginal and Angular Gyri in Inferior
  parietal lobule
• Areas 39, 40
• Connected with all sensory cortical areas
• higher-order and complex multisensory perception
• Important in comunication skills

62
MAJOR ASSOC. CORTEX

• Gerstmanns Syndrome Lesion in dominant
  hemisphere
• Receptive and expressive aphasia
• Agraphia inability to write
• Agnosia inability to synthesize, correlate and
  recognize multisensory perceptions
• Left-Right confusion
• Finger agnosia
• Acalculia
• Non dominant lesion
• Constructional apraxia disturbance in drawing
• Pts have trouble drawing for copying a complex
  figure
• Distubance in body image- neglect half of body

63
APHASIA

• Aphasia disorder of language function
• Most frequently encountered in left cortical
  lesions, but can occur with subcortical lesions

64
APHASIA

• TYPE FLUENCY COMPREHESION REPETITION
• BROCAS -
  -
• TRANSCORTICAL -
  -
• MOTOR
• GLOBAL -
  - -
• WERNICKES -
  -
• TRANSCORTICAL -
  
• SENSORY
• CONDUCTION
  -

65
APHASIA
66
BROCAS APHASIA

• Nonfluent or expressive aphasia
• Decreased and labored language
• Dysrhythmic speech (dysprosody)
• Comphresion intact
• Lesion in Brocas area- lower posterior frontal
  lobe
• May occur as result of MCA stroke

67
WERNICKES APHASIA

• Fluent, Receptive
• Normal to supranormal speech output
• Paraphrasia, Substitutions, Neologism,
  Circumlocution
• Empty speech or word-salad
• Cannot comprehend
• Lesion in Wernickes area posterior part of
  Superior Temporal gyrus (22)

68
CONDUCTION APHASIA

• Fluent, paraphrasic speech
• intact comprehension
• poor naming and repetition
• Writing involves use of incorrect letters in
  words
• Lesion in posterior perisylvian reqgion-
  interrputs arcuate fasiculus from Wernickes to
  Brocas

69
GLOBAL APHASIA

• Severe form of aphasia in which all major
  functions of language are severely impaired,
  including
• Verbal output
• Comprehension
• Repetition
• Naming
• Reading
• writing

70
TRANSCORTICAL APHASIA

• Subdivided into motor, sensory, and mixed types
• All have intact repetition
• Transcortical Motor
• Verbal output is nonfluent, comprehension is
  intact, writing is abnl
• Lesion in dominant frontal lober, near Brocas
• Transcortical Sensory
• Speech is fluent and paraphrasic, comprehension
  is poor, therefore associated difficulty in
  reading and writing
• Lesion in border between temporal and parietal
  lobes, near Wernickes
• Mixed Transcortical Aphasia
• Nonfluent speech output, poor comprehension,
  inability to name, read or write
• Lesion usually spares perisylvian area , but
  involves surrounding MCA watershed areas

71
APRAXIA

• Apraxia inability to perform skilled, learned,
  purposeful motor acts correctly despite intact
  motor and sensory systems, and normal attention
  and comprehension
• Ideomotor Apraxia
• Inability to carry out, on verbal command, an
  activity that can be performed spontaneously

Summary of path activated when pt. asked to move
his left hand
72
APRAXIA

• Ideational Apraxia
• Abnormality in the conception of movement so that
  the the pt. has difficulty sequencing the
  different components of a complex motor task
• Lesion in dominant temporo-parieto-occipital area
• Constructional Apraxia
• Inability of the pt to put together or articulate
  component parts to form a single shape or figure,
  eg assembling blocks to form a design
• Can be seen with either dominant or nondominant
  posterior parietal lesions, although more common
  and severe in nondominant lesions

73
ALEXIA

• Alexia inability to comprehend written language
• Pure Alexia may manifest as inability to read
  letters or words, or may be global
• Writing is normal, but pt cannot read what he
  wrote
• Usually a lesion in the left primary visual area
  associated with another lesion in the splenium of
  the corpus callosum
• More commonly alexia without agraphia occurs as a
  result of infarction in the territory of the L
  PCA

74
AGNOSIA

• Agnosia the inability to recognize perceived
  sensory informaton
• Often modality specifiv visual, auditory or
  tactile
• Visual Agnosias
• Visual Object Agnosia inability to recognize
  visually presented objects
• Prosopagnosia inability to recognize faces
• Visual color agnosia inability to recognize
  colors
• Simultanagnosia inability to recognize the whole
• Auditory Agnosias
• Auditory Verbal Agnosia inability to recognize
  spoken language
• Auditory Sound Agnosia inabiltiy to recognize
  non-verbal sounds
• Sensory Amusia inability to recognize music
• Tactile Agnosias
• Astereognosia inability to judge form of object
  by touch

75
GRASP REFLEX

• Grasp at object placed in hand, regardless of
  intention
• Index of frontal lobe pathology
• Can be seen with lesions in other areas but
  usually seen with bilatereal lesions of the
  fromtal lobes

76
BALINTS SYNDROME

• Aka Optic Ataxia, Ocular Apraxia
• Inability to direct eyes to a certain point in
  visual fileld despite intact vision and eye
  movements
• Seen with Bilateral Parieto-Occipital lesions

77
GERSTMANNS SYNDROME

• Right-Left Disorientation
• Acalculia
• Agraphia
• Finger Agnosia
• Due to lesion in left angular gyrus

78
ANTONS SYNDROME

• Cortical blindness
• Denial of blindness
• Most commonly seen in bilateral occipital cortex
  stoke secondary to posterior circulation
  insufficiency

79
KLUVER- BUCY SYNDROME

• Blunted Affect with Apathy
• Psychic Blindness or visual agnosia with
  inability to distinguish between friends and
  strangers
• Hypermetamorphosis hypersensitivity to
  minute/fine visual stimuli
• Hyperorality
• Bulemia or unusual ietary habits
• Hypersexulaitity
• Seen with Bilateral Temporal Lobe Lesions

80
TITLE

• Text