Anatomy Flashcards
What functions are found in each part of the brain?
Frontal Parietal Temporal Occipital Cerebellum
Frontal:
- rostral: planning, problem solving, short term memory, controlling behavior
- ventral: smell
- Broca area: speech formation
- rostral the motor strip: skilled movement
- motor strip: voluntary
Parietal:
- rostral: sensory perception of self and world
- central: sensory data analyzed
Temporal:
- memory learning,
- visual
- auditory data analyzed
- Wernicke area: language interpretation
Occipital:
- vision
- visual data interpreted
Cerebellum:
- balance
- coordination
Limbic: contains the hippocampus and amygdala. Emotional processing and memory consolidation
What are the 12 cranial nerves and their functions?
- Olfactory: smell
- Optic: vision
- Oculomotor - all eye muscles except superior oblique muscle and external rectus
- Trochlear - superior oblique muscle
- Trigeminal - sensory: face, sinuses, teeth
- motor: muscles of mastication - Abducens - external rectus
- Facial - muscles of the face
- Vestibulocochlear - sensory inner ear
- Glossopharyngeal - pharyngeal musculature
Sensory: posterior part of tongue, pharynx and tonsils - Vagus - heart, lungs, bronchi, trachea, larynx, pharynx, GI tract, external ear
- Accessory - sternocleidomastoid, trapezius
- Hypoglossal - muscles of the tongue
What are the functions of astrocytes
- Form glial membrane (external limiting membrane)
- Component of blood-brain barrier
a. Control K+
b. Modulate vascular tone in the brain, controlling cerebral blood flow. - Remove
a. K+ from extracellular fluid at nodes of Ranvier during action potentials.
b. Neurotransmitters from synaptic clefts (Prevents glutamate excitotoxicity.) - Communicate through gliotransmitters (D-serine, glutamate, ATP) in response to adjacent synaptic activity.
- Produce neurotrophic factors.
- Produce scar tissue in response to CNS injury
What are satellite cells?
Satellite glial cells are the principal glial cells found in the peripheral nervous system, specifically in sensory, sympathetic, and parasympathetic ganglia. They compose the thin cellular sheaths that surround the individual neurons in these ganglia.
SGCs have been found to play a variety of roles, including control over the microenvironment of sympathetic ganglia. They are thought to have a similar role to astrocytes in the central nervous system (CNS). They supply nutrients to the surrounding neurons and also have some structural function. Satellite cells also act as protective, cushioning cells. Additionally, they express a variety of receptors that allow for a range of interactions with neuroactive chemicals.
What are the components of spinal nerves?
- Motor efferents to muscle
- Sensory afferents from skin, muscle, joints, visceral receptors.
- Autonomic efferents to viscera*
- sympathetic in the thoracic and upper lumbar
- parasympathetic in the sacral
What are the vertebrae and nerves of the spinal cord?
Vertebrae - C1-C7 *
T1-T12
L1-L5
S
Nerves, C1-C7, C8*. So the spinal nerves exit in the intervertebral foramen above the vertebraes. So C8 vertebrae does not exist but the nerve does. All the other nerves exit in a foramen below so T1-T12, L1-L5, S1-S5
The conus medullaris is around L1
Describe the spinothalamic tract
A unipolar primary sensory neuron synapses with a secondary sensory neuron in the dorsal horn. The tract neuron crosses the midline (decussation) and travels up to the brain via the anterolateral pathway aka spinothalamic and synapses at the thalamus where an interneuron that takes the signal to the primary somatosensory cortex
A major sensory tract fro the spinal cord to the cortex, crosses in the spinal cord, so the representation is in the opposite brain.
Describe the stretch reflex circuit
A muscle sensory receptor detects stretch in the extensor muscle. Too much stretch and it travels up the afferent axon, synapses in the grey matter of the spinal cord, with help from interneurons, and then inhibit the extensor while stimulating the flexor using efferent axons.
Describe the features of the brain stem
The brain stem - features long pathways, and cranial nerves instead of spinal nerves.
They are important for functions the head can do like facial expression, ingestion, respiration
–keep in mind the flexure when taking locations—
from rostral to caudal - midbrain, pons, medulla oblongata
Midbrain: cerebral peduncle
- Cranial, only 3 and 4
- visual reflexes, visual motor control
- **has dopamine projections to corticol areas significant for movement and “reward”
Pons - balloon aka “big bridge to cerebellum”
Cranial nerves - 5,6,7,8
Function - balance, sound localization, eye movement coordination
Medulla -pyramid
Cranial nerves - 9,10,11,12
Function:
-regulation of body homeostasis/heart rate, respiration, vasomotor tone, gastric secretions
-vomiting, coughing, sneezing, swallowing, gagging
Damage to medulla is death
Describe the RAS-reticular activating system
Major component: reticular formation—
Nuclei and neuronal circuits
• Net-like appearance
• Through the core of the brainstem. • Include projections to the cortex or spinal cord.
RAS - beings in the reticular formation
Rostral projections from the pons and midbrain (pontomesencephalic)
• Projection controls attention, arousal, sleep and wakefulness.
• Includes several neurotransmitters systems
What is contained in the cross sections of these three
midbrain
pons
medulla
Midbrain:
- Cerebral peduncle (ventral)
- Cerebral aqueduct
- Colliculi (lil bumps dorsally)
Pons
- large round base (ventral)
- 4th ventricle
- Cerebellum
Medulla
- Pyramid
- 4th ventricle
Describe the corticospinal tract:
Corticospinal tract: Major motor pathway from the cortex to the spinal cord. Upper motor neuron crosses in the medulla to control contralateral muscles.
Projects to the spinal cord from the primary motor cortex as all do,
- crosses at the medulla “pyramid decussation
- travels through the lateral corticospinal tract
- synapses in the anterior horn with the lower motor neuron which synapses on skeletal muscle
There are 6 layers of grey matter *cerebral cortex surrounding the white matter in the brain. What do each do?
Layers 2-3 contain neurons that project mainly to other areas of cortex
Layer 4 is sensory inputs from the thalamus (thalamocortical)
Layer 5 is motor output, projecting mostly to subcortial structures other than the thalamus such as brainstem, spinal cord and basal ganglia.
Association cortex: thick 2,3
Primary motor cortex: thick 5
Primary somatosensory cortex: thick 4
Electrical synapses - pros and where are they found?
They have faster, and more preserved event transfer between neurons.
direct physical connection allows flow of ions between cells
through gap junctions
• transmit depolarizing & hyperpolarizing currents
• gap junctions are composed of many individual channels
between cells
• each connexon is composed of a pair of hemi-channels (one
presynaptic, one post-synaptic)
low-resistance (high-conductance) pathway • near instantaneous (very short latency) transmission
*they do not regenerate their action potentials, the transmission diffuses all the way through
Coordinated connection of large groups of neurons
Found - retina, glial cells, astrocytes, enteric nervous system, cardiac
Describe and distinguish between the components of the blood-CSF and blood-brain
barrier.
Blood-CSF
- choroid plexus which produces CSF and is found in all the major ventricles
- blood vessels entering the choroid plexus
- Endothelial wall of the choroidal capillaries: No barrier– are
fenestrated. - Scattered pial cells.
- Choroidal epithelial creates a blood-CSF barrier by tight junctions
– active transport, ion exchange mechanisms to determine
flow of molecules (e.g., Na+, K+, Cl-, Mg++, folates)
Blood-brain barrier
-blood vessels in subarachnoid space meeting brain tissue
-is formed by tight junctions between the brain capillary endothelial cell. Astrocyte foot processes surround the capillary but are not part of the barrier. They can control blood flow
Controls ionic environment–neurotransmission
Protects brain from toxins
Prevents drugs from entering brain Contains transporters for some critical molecules (glucose and proteins)
The blood-brain barrier may be disrupted by infections, tumors or trauma, causing
“vasogenic edema”
Describe the function of CSF
Is in the subarachnoid space around the brain and within the ventricles
*CSF provides bouyancy! and protects against sudden movements
- Maintains constant intracranial pressure
- Some antibacterial properties
- Controls the extracellular fluid of the brain
- Possible role in clearing metabolic wastes and toxins from interstitial space (especially during sleep)
