Lecture 7 Flashcards
thalamus location
right and left thalami are in the lateral regions of the diencephalon - “sit on top of the brainstem”
diencephalon contains
thalamus
hypothalamus
subthalamus
epithalamus
thalamus blood supply
deep branches of posterior cerebral artery (PCA) and the posterior communicating arteries
thalamus function
relays and regulates all sensory information (except CN1) going to the cortex - “gateway to the consciousness”
thalamus visual function pathway
eye -> thalamus -> area 17 -> secondary/associative visual cortices
thalamus auditory function pathway
ear -> thalamus -> area 41 -> secondary/associative auditory cortices
thalamus somatosensory function pathway
body -> thalamus -> area 3,1,2 -> secondary/associative somatosensory cortices
basal ganglia
relays motor information
cerebellum
relays motor information
limbic system
relays information relating to fear, memory, learning and other human behaviors/needs
reticular connections
relays information that modify and regulate consciousness, sleep/wake cycles, alertness, pain, etc.
thalamic nuclei
specific nuclei that are responsible for relaying information to different regions of the cortex
Medial Geniculate (MGN)
Lateral Geniculate (LGN)
Ventral posterior medial (VPM)
Ventral posterior lateral (VPL)
Ventral lateral (VL)
Medial Geniculate (MGN)
Information coming from: Brainstem
Information going to: Primary Auditory Cortex, Brodmann 41
Location on Thalamus: Posterior small bump, medially
Type of information carried: Auditory
Lateral Geniculate (LGN)
Information coming from: the eye
Information going to: Primary Visual Cortex, Broadman 17
Location on Thalamus: Posterior small bump, laterally
Type of information carried: Visual
Ventral Lateral (VL)
Information coming from: Basal Ganglia (BG) and Cerebellum
Information going to: Primary and Premotor Motor Cortex, Broadman 4,6
Location on Thalamus: Mid thalamus, laterally
Type of information carried: Motor information
Ventral posterior lateral (VPL)
Information coming from: Spinal Cord
Information going to: Primary Somatosensory Cortex – Broadman 3,1, 2
Location on Thalamus: Posterior lateral Thalamus
Type of information carried: Somatosensory Information of Body
Ventral Posterior Medial (VPM)
Information coming from: Cranial Nerves
Information going to: Primary Somatosensory Cortex- Broadman 3,1,2
Location on Thalamus: _Posterior medial
Type of information carried: Somatosensory Information of Head
thalamic pain syndrome (Dejerine-Roussy syndrome)
“lacunar stroke” or “small vessel stroke” occurs in posterior thalamus and damages the somatosensory pathways that transmit information to the cortex
symptoms: contralateral loss of sensation, neuropathic pain
nociceptive pain
“peripheral pain”
non-neural tissue damage/injury produces peripheral pain response
nociception that originates from stimulation in peripheral nerve endings
neuropathic pain
pain caused by disease/injury to the nervous system
the sensation of pain (nociception) that originates from dysfunction of the damaged nervous system structures
thalamic pain syndrome
an example of neuropathic pain
basal ganglia location
in the diencephalon and midbrain (mesencephalon)
basal ganglia lesion
initiation and execution of movement is impaired - “too much or too little” movement
hyperkinetic or hypotonic
cerebellum lesion
motor tone, balance/posture and coordination (synergy) are impaired
basal ganglia structures
caudate nucleus = large horn shaped structure that wraps around other basal ganglia structures, contains amygdala at one end
nucleus accumbens = junction of caudate and putamen, role in pleasure/reward processing
putamen = oval shaped structure located lateral to the globus pallidus nuclei
globus pallidus = 2 structures: external and internal, medial to putamen,
subthalamic nuclei = inferior to the thalamus
substantia nigra = located in the midbrain of the brainstem
basal ganglia blood supply
majority supplied by small penetrating branches of MCA known as lenticulostriate arteries
smaller portion of basal ganglia supplied by ACA
basal ganglia function
initiating and executing movement
basal ganglia pathway
anterior association area -> premotor cortices/motor cortex -> basal ganglia -> thalamus -> premotor/primary motor cortices
basal ganglia motor loop
modifies the motor plan to initiate (activates) and execute movement
premotor/motor cortex send motor plan -> putamen of basal ganglia -> BG sends a copy of plan to direct and indirect pathway -> globus pallidus internus packages finalized plan -> thalamus sends to motor cortex to execute
basal ganglia association (cognitive) loop
learning and choosing the best ways to initiate and execute movement
basal ganglia limbic loop
supplies emotional input to the motor plan and influences how movement is initiated (activated) and executed
hypokinetic disorder
disease/pathology that decrease dopamine
Ach dominates motor plan and suppress movement
person has difficulty initiating and executing movements
hyperkinetic disorder
disease/pathology that decrease Ach
dopamine dominates motor plan and promotes too much movement
person experiences too much movement (constant initiation and execution of abnormal movements)
bradykinesia
slowed movement
rigidity
increased resistance to passive ROM
lead-pipe rigidity = resistance persists throughout the range of movement
cogwheel rigidity = periodic resistance at different points throughout the range of movement
dystonia
involuntary, sustained or intermittent, muscle contractions that cause twisting and repetitive movements, abnormal postures, or both
can affect one muscle, a muscle group, or the entire body i.e. cervical dystonia
athetosis
slow, continuous involuntary writhing movement
writhing twisting movement of limbs (hands/feet), trunk or face
chorea
ongoing random-appearing sequence of one or more discrete involuntary movements or movement fragments
continuous dancelike involuntary movements
choreathetosis
athetosis movements combine with chorea type movements
ballismus
flailing, flinging or rotary movements of proximal limbs
hemi-ballismus = associated with lesion of subthalamic nuclei
tic
repeated, individually recognizable, intermittent movements
tremor
rhythmic back and forth or oscillating involuntary movement
myoclonus
sequence of repeated, often non-rhythmic, brief shock-like jerks due to sudden involuntary contraction or relation of one or more muscles
clonus
muscular spasm involving repeated, often rhythmic, rapid contraction/relaxation
