Functional Anatomy of Cerebral Cortex Flashcards
What are the borders of the frontal lobe?
anterior to the central sulcus
above the lateral sulcus
What proportion of the cortical surface is occupied by the frontal lobe?
40% of the cortical surface area
What are the main subdivisions of the frontal lobe?
- lateral
- medial
- orbital
What is the lateral aspect of the frontal lobe?
aka convex aspect
contains the:
- pre-central gyrus (primary motor area)
- superior frontal gyrus
- medial frontal gyrus
- inferior frontal gyrus
Latter 3 are separated by the superior and inferior frontal sulci
Where is the primary motor area located?
in the pre-central gyrus
located anterior to the central sulcus
Where is the superior frontal gyrus located?
continues onto the medial surface of the hemisphere
separated from the underlying cingulate gyrus (limbic lobe) by the cingulate sulcus
motor strip of lower limbs (below T6) is also found here
Where is the inferior temporal gyrus located?
aka orbital or orbitofrontal
overlies the orbital cavities
What sections are the orbital regions divided into?
divided into 2 areas by the olfactory sulcus/tract
olfactory sulcus contains the olfactory bulb and tract
Medial to the olfactory tract is the straight gyrus/gyrus rectus
remaining orbital region is lateral to the olfactory pathways and is known as the lateral orbital cortex
It contains a poorly define H-shaped orbital sulcus
How can you identify the primary motor cortex?
e.g. on a scan
LOOKING @ SUPERIOR BRAIN SURFACE
look for inverted capital omega shape
this corresponds to the part of the motor cortex that controls the contralateral hand
“motor hand area”
Central sulcus will be just posterior to this
AXIAL (HORIZONTAL) MRI/CT
motor hand area omega-shape will be pointing backwards (towards occipital region)
central sulcus will be immediately behind it
=> often easier to see on LHS for right handed individuals
MID-SAGGITAL SECTION
follow cingulate sulcus posteriorly
most posteriorly it will deflect upwards to the superior margin of the cerebral hemisphere
[-> PARS MARGINALIS]
central sulcus is immediately anterior to this
Where is the inferior frontal gyrus located?
below the inferior frontal sulcus
on the convexity of the frontal lobe
How is the inferior frontal gyrus divided?
divided by 2 branches of the lateral sulcus (Sylvian fissure).
These branches are known as the anterior horizontal or anterior ascending rami
3 portions
gives the overall inferior frontal gyrus an M-shape
What is the part of the inferior frontal gyrus that is closest to the orbit called?
PARS ORBITALIS
What is the portion of the inferior frontal gyrus between the ascending and horizontal rami called?
PARS TRIANGULARIS
this is because it is triangular in shape
What is the portion of the inferior frontal gyrus behind the ascending rams called?
PARS OPERCULARIS
belongs to the opercular region
What is the OPERCULAR REGION near the inferior frontal gyrus?
cortex surrounding the lateral sulcus and overlying insular area
What is the significance of the 3 regions within the inferior frontal gyrus?
the TRIANGULAR and OPERCULARIS regions together constitute BROCA’S AREA
Where is the LATERAL PREMOTOR AREA?
cortex in front of the motor strip
on the convexity of the cerebral hemisphere
What is the SUPPLEMENTARY MOTOR AREA (SMA)?
equivalent to the motor strip on the lateral portion of the frontal lobe
but located on the MEDIAL surface of the frontal lobe
aka MEDIAL PREFRONTAL CORTEX
What is contained within the PREFRONTAL CORTEX?
this describes the remaining non-motor part of the frontal lobe
including entire orbital region
makes up 30% of the total cortical surface area
What is the function of the PREFRONTAL CORTEX?
- cognition
- goal-directed behaviour
- social interactions
- intelligence
- creativity
- Broca’s area is here too (expressive language)
What are the two main regions of the prefrontal cortex?
DORSOLATERAL PREFRONTAL CORTEX
on the convexity of the frontal lobe
ORBITOMEDIAL PREFRONTAL CORTEX
includes both the orbital and medial surfaces
What is the function of the DORSOLATERAL PREFRONTAL CORTEX?
cognitive functions, especially “executive functions”
e.g. organising and planning
contributes to basal ganglia loops that pass through the CAUDATE NUCLEUS
[C = cognition]
regulation of normal thinking
found to be abnormally active in OCD patients
also contains frontal eye fields - controlling attention and gaze and voluntary eye movements
What is the function of the ORBITOMEDIAL PREFRONTAL CORTEX?
regulation of behaviour, personality and social conduct
patients with lessons in this region can become rude, disinhibited and inappropriate
decision-making and judgement are severely impaired
this can lead to rash and imprudent behaviour that may go alongside unconcern or lack of insight
What eye signs may a patient with frontal lobe damage experience?
- attention problems
- impaired eye movement
Where is the PARIETAL LOBE located?
posterior to the central sulcus and superior to the lateral sulcus
What is the boundary between the parietal and occipital lobes?
parieto-occipital sulcus
can only be seen from the medial aspect of the hemisphere
What is contained within the LATERAL PARIETAL REGION?
post-central gyrus or primary SS area
immediately posterior to the motor strip
How is the parietal lobe divided?
divided by the intra-parietal sulcus
forming the INFERIOR and SUPERIOR PARIETAL LOBULES