Sensory Flashcards
Major divisions of the nervous system - afferent
Sensory input:
-cell bodies out of CNS
-cranial nerves (somatic, visual, olfactory, taste, auditory, vestibular)
-spinal nerves (somatic sensation - touch temp and pain) visceral senstation (info from internal organs)
Major divisions of the nervous system - efferent
Motor output:
-Cell bodies out of CNS
-Cranial nerves
-Somatic efferent (innervates skeletal muscle, motor neurons - solely excitatory)
-Autonomic efferent (innervates interneurons, smooth and cardiac muscle - both excitatory and inhibitory)
-Enteric
Division od the spinal cord (top to bottom)
Cervical nerves (upper limbs and neck)
Thoracic “ (upper trunk)
Lumbar “ (lower body)
Sacral “ (digestion and genitals)
Coccygeal “
How many cranial nerves are there?
12
What is a brain edema? result?
Increased intercranial pressure pushes the brain out of the base of the skull (brain swelling)
Compresses the brain stem and the cranial nerves (affects puppillary response
Describe the early development of the nervous system + timeline
Ovum (fertilized egg) - ball of cells - blastocysts - formation of cavities - neural plate (over 3 weeks)
Development of the neural tube + timeframe
Neural plate is compose of 3 things: ectoderm (also known as the neural plate), mesoderm and endoderm
Ectoderm folds up to form the neural groove - closes up to form neural tube
Mesoderm becomes dura
Neural tube becomes CNS
Neural crest becomes PNS
Over week 3 and 4
What develops in the neural tub ine week 4? What is the overall morphology?
Vesicles develop : become the forebrain, midbrain, hindbrain and then a tail (with cavity)
What does the neural tube become?
CNS
Over development what does the forebrain become
Cerebral hemispheres, thalamus
Over development what does the midbrain become
Remains as the midbrain
Over development what does the hindbrain become
Pons, cerebellum, medulla
Over development what does the tail&cavity of the neural tube become
Spinal cord, with the cavity forming the ventricles and the central canal
Ventricles - what, where, what do they contain?
Openings within the brain, containing 150mL of cerebral spinal fluid.
Formation of the cerebrospinal fluid? Where, rate + how is it circulated
Within the choroid plexus
Rate of 500ml/day
Passive
Functions of cerebrospinal fluid?
1) Supports and cushions the CNS (brain) - buyoancy of CSF is the same as CNS
2) Provides nourishment
3)Removal of metabolic waste by the arachnoid villi
Composition of cerebrospinal fluid
Sterile, colorless fluid containing glucose
Circulation of CSF within the CNS?
Formed in choroid plexus in two latera ventricules
Into third ventricule via choroid plexus, down cerebral aqueduct (midbrain) into the fourth ventricule.
Exit process of CSF?
Fgrom the fourth ventricule, passes through 2 foramens of Luksha and one of Magendie (located in the central canal - midbrain) to enter the subarachnoid space
Encounters the arachnoid villi, drains back into the venous blood supply via a cavity in dural sinus
What are the 3 meninges? (def + names)
The three layers of the CNS (protects brain + spinal cord)
Dura matter (1st)
Arachnoid membrane (2nd)
Pia matter (3rd)
Layers from outside into the brain
Skin
Bone
Dura matter
Arachnoid membrane
Subarachnoid space (CSF flow + blood vessel + trabeculae)
Pia matter
Grey matter
White matter
What is the dural sinus? Role + location
Cavity lining central midline of head + opening of dura
CSF return to venous blood supply
Located after the arachnoid villi between the left and righ hemisphere, within the Dura
How does the brain access its glucose requirement?
Glucose is metabolized by neurons, and is transported in by the blood (15% of blood supply)
There is essentially no glycogen (glucose storage in the brain)
How does the blood get from the heart to the brain?
Heart splits into
-aorta (body - 85% of blood)
-carotid artery (brain) into external carotid artery (outside of skull) and internal carotid artery (base of the brain)
-the vertebral artery (x2) join into basilar artery
All joins into the circle of willis into brain