Traumatic brain injury is the leading cause of death and disability for those who are under 44. Societal cost is 40-80 billion dollars/year.
Head injury event usually lasts for 200msec.
Three types:
Inertia injury-brain trauma causes diffused axonal injury due to acceleration and deceleration injury
Impact Injury-lead to hematomas
Penetrating Injury-associated with post-traumatic epilepsy.
Glasgow Coma Scale-international grading scale [...]
Reflex inhibition of antagonist muscles leads to reciprocal inhibition of muscles using primary 1a inhibitory interneurons.
Autogenic inhibition of 1b afferents through Golgi Tendon oranges excites inhibitory interneurons leading to inhibition of homonymous and synergistic interneurons.
Crossed Extension Reflex- uses both sides of body to act in response to noxious stimuli; if stimuli is placed on [...]
Ascending reticular activating system maintains a state of wakefulness by indirect projections to cortex.
ARAS… diencephalons… intralaminal nuclei of thalamus… cortex
Hypothalamus… forebrain
ARAS travels in the central tegmental tract after leaving the brainstem.
During wakefulness many pedunculopontine nuclei are active but NOT during sleep.
Electroencephalogram is a gross potential record of the sum of all electrical fluctuations in the [...]
Posterior Pituitary
-called NEUROHYPOPHYSIS because hormones are released directly from axonal endings into circulation
-uses large MAGNOCELLULAR neurons
-hormones are synthesized exclusively in HYPOTHALAMUS but stored in neurohypo.
-made in PARAVENTRICULAR and SUPRAOPTIC nuclei
-releases neurophysin 1 (oxytocin) and neurophysin 2(ADH) co-peptides
-**NEURAL input with HORMONAL output
Oxytocin
-no diurnal rhythm
-controls MILK-LET DOWN reflex upon tactile stimulation by infant
-travels in spino-hypothalamic tract [...]
Olfaction
Olfactory Receptors
- located in a 5 cm2 area of olfactory epithelium.
- well protected by location deep in the nose.
- permanent loss of olfaction can occur as a result of accidental whiplash if the cribriform plate is fractured or as a result of hemorrhaging at the base of frontal lobes that may tear the olfactory filaments.
Olfactory [...]
Most neurological symptoms include syncope (fainting) and seizure (both involve loss on consciousness) Lack of prodrome prior to attack favors syncope over seizure.
Focal transient neurological defect is most commonly due to transient ischemic attack, a cerebro-occusive event.
Low back pain after heavy lifting different from that after a car accident. In lifting concern is with [...]
The motor cortex is the pre-central gyrus (Boardman’s area 4) and is organized somatotopically (i.e. hand is next to wrist is next to arm…etc.)
Areas requiring fine motor control (hand) are overrepresented in the cortex. Representation of body within cortex is called motor homunculus.
M1 is part of precentral gyrus which needs the least amount of [...]
Limbic system consists of: hippocampus, amygdala, septal nuclei, entorhinal cortex, and parahippocampal cortex.
Hippcampusà cornu ammonis or Ammon’s horn
Fornix
-C shaped tract beginning as the alveus
-Alveus-myelinated afferents and efferents to become fibria
-Fimbria- thick rubber band of fibers to split into crura
-Crura- come together to form hippocampal commissure which is mode of communication between the hippocampi
-after comminsureà [...]
Memory is a multi-staged process with 4 distinct levels:
Immediate Memory– 100ms-seconds
Short Term Memory– seconds to minutes
Intermediate Memory– minutes to hours
Long Term Memory– days/weeks/lifetime
Working memory refers to capacity to hold information in order to conduct sequential actions. Multiple sensation modalities.
Declarative memory is a “knowing that” response which involves a conscious collection of facts and events [...]
Area
Location
Function
Damage
Anterior association area
(general)
Prefrontal cortex
Links info from other association areas (massive input from somatosensory, visual and auditory association areas) ; memory, planning, higher-order concept formation; planning motor actions
e.g. prefrontal lobotomy - personality changes, become unreliable, impulsive actions w/little regard for consequences; lack of ability to remember [...]
Depletion-repletion Hypothesis states feeding is controlled by caloric set point. Individuals match energy expenditures with intake without reference to fat storage.
Primed Response Hypothesis states that feeding essentially boils down to idea that animals will eat whenever an opportunity arises unless it is specifically inhibited. Satiety controlled.
Mechanisms of Satiety Control and Satiety Network
Neural signals [...]
Techniques of Examination
Head: Hair = fine — hyperthyroidism, coarse — hypothyroidism
Scalp = Redness + scaling — seborrheic dermatitis, psoriasis
Skull = Enlarged — hydrocephalus, Paget’s disease of bone
Tenderness — trauma
Face = read up on this topic
Skin = Hirsutism (excessive facial hair) in women
Eyes: Visual Acuity:
20/200 — patient can read print at 20 ft. Normal [...]
Endothelium cells in the brain capillaries are the site of the blood-brain barrier.
-continuous tight junctions limit diffusion of molecules
-basement membrane provides structural supportàfoot processes
-transport carrier for glucose and essential amino acids (brain cant make these)
-secondary transport for small molecule
-lots of Na+ on luminal membrane
-”enzymatic” barriers in capillary prevent entry of certain solutes
Outside Blood-Brain barrier: [...]
Introduction
- The routine audiology exam tests the function of the middle ear, inner ear, and cranial nerves VII & VIII.
- Inner ear & CN VIII: hearing & balance
- Sensorineural hearing loss (nerve deafness) can be caused by age, drugs (antibiotics, chemotherapy) and exposure to high-intensity noise. Such hearing losses usually start at high frequencies.
- [...]
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