Posterior nucleus - heating, sympathetic. *If you zap your posterior hypothalamus you become a Poikilotherm (cold blooded).
Suprachiasmatic nucleus -circadian rhythm. * You need sleep to be charismatic(chiasmatic).
What does the posterior pituitary (neurohypophysis) do?
Receives hypothalamic axonal projections from the supraoptic (ADH) and paraventricular (oxytocin) nuclei.
**The Adenohypophysis is the anterior pituitary and releases TSH, GH, LH, FH, etc
What is the function of the thalamus? What are the main nuclei and their details(input, info, and destination?
The thalamus is the major relay for ascending sensory information.
Main nuclei include:
1. VPL (ventral postero-lateral) nucleus - this receives input from the spinothalamic and dorsal columns/medial lemniscus about pain, temperature, position and proprioception. Relays info to the primary somatosensory cortex.
2. VPM (ventral postero-medial) nucleus - this receives input from the trigeminal and gustatory pathway about face sensation and taste and relays it to the primary somatosensory cortex.
3. LGN (lateral geniculate) nucleus - this receives input from CN II about vision and relays it to the calcarine sulcus.
4. MGN (medial geniculate) nucleus - this receives input from the superior olive and inferior colliculus of the pons about hearing and relays to the auditory complex of the temporal lobe.
What structures make up the limbic system? Whare are the main fuctions of the limbic system?
Includes/made up of - cingulate gyrus, hippocampus, fornix, mammillary bodies and septal nucleus.
Responsible for the famous 5 F's - Feeding, Feeling, Fighting, Fleeing and Fucking.
*This is a very primative system.
What is the main function of the cerebellum?
It receives contralateral cortical input via the middle cerebellar peduncle and ipsilateral proprioceptive information via the inferior cerebellar peduncle. (input nerves = climbing and mossy fibers)
Provides stimulatory feedback to contralateral cortex to modulate movement. (output nerves = purkinje fibers output to deep nuclei of cerebellum, which in turn output to cortex via the superior cerebellar peduncle)
What are the deep nuclei of the cerebellum?
Lateral to Medial -> Dentate, Emboliform, Globose, (Emboliform + Globose = Interposed nuclei) and Fastigial.
"Don't Eat Greasy Food"
What is the function of the lateral cerebellum?
Functionally this is the cerebrocerebellum that communicates with the dentate deep nuclei and coordinates voluntary movement of the extremities.
Lateral hemisphere = cerebrocerebellum which communicates to the cerebral cortex.
What is the function of the medial cerebellum?
Functionally this is the spinocerebellum and is made of the vermis and peri-vermal regions. This communicates with the interposed (Enboliform and Globose) and Fastigal deep nuclei to coordinate balance, truncal coordination, ataxia, and the propensity to fall toward the injured (ipsilateral) side.
Medial hemisphere = spinocerebellum which communicates to the spine.
What is the function of the basal ganglia?
This is a system of multiple anatomic structures involved in either inhibiting or disinhibiting each other in different ways.
This is important in voluntary movements and for making postural adjustements.
Receives cortical input and provides negative feedback to the cortex to modulate movement.
What makes up the striatum of the basal ganglia? The lentiform?
Striatum = putamen and caudate
Lentiform = putamen and globus pallidus (internal and external)
What are all of the stuctures involved with the basal ganglia?
Substantia nigra pars compacta (SNc) - normally this inhibits GPi and therefore stimulates movement. In Parkinson's this gets lesioned and therefore causes decreased movement.
Substantia nigra pars reticulata (SNr)
Globus pallidus externus (GPe) - facilitates movement
Globus pallidus internus (GPi) - always inhibits movement when stimulated and always stimulates movement when inhibited
Subthalamic nucleus (STN) - increases GPi therefore it always inhibits
Dopamine D1 receptor (excitatory)
Dopamine D2 receptor (inhibitory)
How does the Direct/excitatory pathway work? How is it affected by Parkinson's disease?
SNc's dopamine binds D1 receptors to stimulate the excitatory path and increase motion.
Loss of dopamine in Parkinson's inhibits the excitatory pathway b/c there is nothing to bind/activate the D1 receptors; this results in loss of motion.
How does the indirect/inhibitory pathway work? How is it affected by Parkinson's disease?
SNc's dopamine binds D2 receptors in the inhibitory pathway which inhibits the inhibitory pathway and increases motion.
Loss of dopamine in Parkinson's excites/disinhibits the inhibitory pathway allowing it to cause inhibition and decreased motion.
What are the 2 most common sites of HTN hemorrhage?
Basal ganglia and the thalamus.
Where does the basal ganglia arterial supply come from?
Lenticulostriate arteries supply the basal ganglia; they come from the MCA
What is the function of the thalamus (VA/VL) and other nuclei?
Stimulates the cerebral cortex
Stimulates the striatum
Gets inhibited by the globus pallidus internus and the SNr.
What is a surgical way to treat Parkinson's disease(w/ movement inhibition)?
Lesion the subthalamic nucleus b/c it will decrease movement inhibition/ increase movement stimulation.
This can be done surgically or with Deep Brain Stimulation(makes it non-functional)
What are the diseases of the basal ganglia?
What are the 2 main types of disease of the basal ganglia?
Excess movement inhibition (ex: Parkinson's)
Excess movement excitation (ex: Hemiballismus)
What is Parkinson's disease? What are the clinical S/S?
Parkinson's disease is a degenerative disorder of the CNS associated with Lewy bodies (alpha-synuclein intracellular inclusions) and depigmentation of the substantia nigra pars compacta (loss of domaminergic neurons).
A decrease in pigmentation shows a decrease in DOPA and therefore a decrease in dopamine which is made from DOPA. This is seen to some degree in 1% of all people >60
Venous sinus path: Superior sagittal sinus (main location of CSF return via arachnoid granulations) --> transverse sinus --> sigmoid sinus (becomes jugular vein once it crosses the jugualr foramen)
Also have cavernous sinus, inferior sagittal sinus, straight sinus, occipital sinus and sphenoparietal sinus.
What is the pathway of the CSF through the ventricular system assuming the lateral ventricle is the start point?
Choroid plexus makes CSF --> lateral ventricle --> (goes through the Foramen of Monro) --> 3rd ventricle --> (goes through the cerebral aquaduct) --> 4th ventricle --> ( splits and goes through the Foremen of Magendie medially and the Foramen of Luschka laterally) --> subarachnoid space --> superior sagittal sinus --> transverse sinus --> sigmoid sinus --> becomes jugular vein.
How many spinal nerves are there? Where do they exit?
There are 31 total spinal nerves; 8 cervical, 12 thoracic, 5 lumbar, 5 saccral and 1 coccygeal.
Nerves C1-C7 exit via intravertebral foramina above the corresponding vertebra; all other nerves exit below.
What is vertebral disk herniation and where does it most commonly occur?
Disk herniation is when the nucleus pulposus herniates through the annulus fibrosus.
Most commonly occurs between L5 - S1
What level does the spinal cord extend down to in adults? Where is a lumbar puncture usually performed in adults? What structure is used to find L4?
SC extends to the lower border of L1-L2 in adults with the subarachnoid space extending to the lower border of S2.
Lumbar puncture is usually performed btwn L3-L4 or L4-L5 interspaces at the cauda equina.
The anterior iliac crest is used to find the level of L4.
What makes up the dorsal colums and what type of information do they carry?
Dorsal columns carry information about pressure, vibration, touch and proprioception.
Made up of the Fasciculus Cuneatus that serves the upper body and extremities, and the Fasiculus Gracilis that serves the lower body and extremities (remember graceful ballerina on her toes)
*Dorsal column is organized as we are with arms on the outside and legs on the inside/medial.
What information is carried in the lateral corticospinal tract?
What information is carried in the spinothalamic tract?
Pain and Temperature
What is the 1st order neuron of the dorsal column, what is its path and where does it synapse/where is the first synapse? Describe the 2nd order neuron and 2nd synapse and the location of the 3rd order neuron.
1st order neuron is in the sensory nerve ending --> cell body in the dorsal root ganglia --> enters the spinal cord, ascends ipsilaterally in the dorsal column --> has 1st synapse on the ipsilateral nucleus cuneatus or gracilis in the medulla.
The 2nd order neuron then decussates in the medulla --> ascends contralaterally in the medial lemniscus --> has 2nd synapse on the VPL of the thalamus.
3rd order neuron is in the sensory cortex
When do ascending tracts synapse?
Before they cross.
What is the 1st order neuron of the spinothalamic tract and where is the 1st synapse? Describe the 2nd order neuron and the 2nd synapse. Where is the 3rd order neuron?
1st order neuron is in the sensory nerve ending (A-delta and C fibers) --> cell body in the dorsal root ganglia --> enters spinal cord --> 1st synapse in the ipsilateral gray matter of the spinal cord.
The 2nd order neuron decussates at the anterior white commisure -->ascends contralaterally --> 2nd synapse in the VPL of the thalamus
The 3rd order neuron goes to the sensory cortex
What is the 1st order neuron of the lateral corticospinal tract and where is the 1st synapse? Describe the 2nd order neuron and the 2nd synapse.
1st order neuron is an UMN: cell body is in the primary motor cortex --> descends ipsilaterally through the internal capsule --> decussates at the caudal medulla (pyramidal decussation) --> descends contralaterally --> 1st synapse in the cell body of the anterior horn of the spinal cord.
2nd order neuron is a LMN: leaves the spinal cord --> 2nd synapse at the neuromuscular junction.
What are the clinically useful landmark dermatomes?
C2- posterior half of a "skull cap"
C3 - high turtleneck shirt
C4 - low collar shirt
T4 - at the nipple (T4 at the Teat Pore)
T7 - xiphoid process
T10 - at umbilicus; useful for early appendicitis referred pain (T10 at the belly butTEN)
L1 - inguinal ligament (L1 is IL-inguinal ligament)
L4 - includes the kneecaps (Down on L4s(all fours))
S2,S3,S4 - erection and sensation of penile and anal zones (S2,S3,S4 keep the penis off the floor)
What are the clinical reflexes?
Biceps = C5 nerve root
Triceps = C7 nerve root
Patella = L4 nerve root (down on L4's(all 4's))
Achilles = S1 nerve root
Babinski = dorsiflexion of the big toe and fanning of other toes; sign of an UMN lesion but normal during 1st year of life
***Reflexes count up in order: S1, S2, L3,L4, C5,C6, C7,C8
What are the primitive reflexes? When are they seen?
Moro Reflex - (the "Oh Shit" reflex)- abduct/extend limbs when startled and then draw together.
Rooting Reflex - movement of head toward one side if cheek or mouth is stroked (nipple seeking)
Sucking Reflex - sucking response when roof of mouth is touched
Palmar and Plantar reflexes - curling of fingers/toes if palms/soles are stroked
Babinski Reflex - dorsiflexion of large toe and fanning of other toes with plantar stimulation.
***These are seen in the first year of life then normally disappear. However, they may reemerge following a frontal lobe lesion or basically any UMN lesion.
What are the purely sensory cranial nerves?
CN I - Olfactory
CN II - Optic
CN VIII - Vestibulocochlear
What are the purely motor cranial nerves?
CN III - Occulomotor
CN IV - Trochlear
CN VI - Abducens
CN XI - Accessory
CN XII - Hypoglossal
Which cranial nerves are both motor and sensory?
CN V - Trigeminal (motor - muscles of mastication, sensory - facial sensation)
CN VII - Facial (motor - expresssion, sensory - taste from anterior 2/3 of tongue, lacrimation, salivation)
CN IX - Glossopharyngeal (motor - swallowing, stylopharyngeus; sensory - taste from posterior 1/3 of tongue, salivation)
CN X - Vagus (motor - swallowing, palate elevation, talking; sensory - taste from epiglottic region)
What CNs have nuclei in the midbrain?
CN III and IV
What CNs have nuclei in the Pons?
CN V, VI, VII, and VIII
What CNs have nuclei in the Medulla?
CN IX, X, XI and XII
What are the cranial nerve reflexes? State the afferents and efferents involved in each.