Nervous system and embryology Flashcards
week 1
Differentiate between visceral and somatic nerve fibres
Visceral
messages from organs, viscera of thoracic and abdominal cavities
Somatic
Impulses from outside body or via movements of muscles and joints
What are the 4 main regions of the brain?
Cerebrum
Cerebellum
Diencephalon
Brain Stem
How many lobes does the cerebrum have and what are their functions?
Frontal: voluntary motor movement, verbal communication and cognitive skills.
Temporal: Hearing, smell, emotion
Parietal: Conscious awareness of sensations. Somatic sensation and integration.
Occipital: Visual awareness and processing
Insula: pain and visceral sensation. Taste and memory.
What are the functions of the cerebellum?
Motor learning
Equilibrium and posture
Smoothens movements
Receives proprioceptive information
Coordinates body position.
What is the general function of the Diencephalon and the functions of its two components?
General function
Relay info from cerebrum to other functional centers
Two components
Hypothalamus: homeostasis
Thalamus: relay station for sensory impulses
What are the general functions of the Brainstem
bidirectional passageway for tracts between the cerebellum and spinal cord
autonomic and reflex centres required for survival
origins of cranial nerves
What are the three components of the brainstem and their functions?
Pons: ascending and descending info,
Medulla Oblongata: Autonomic and respiratory
Midbrain: visual and audio
What are the respective gyrus for the Motor and Sensory Homunculus?
Motor= Pre-central gyrus (primary cortex)
Sensory= postcentral gyrus (somatosensory cortex)
Aspects of Spinal cord structure
31 pairs
Motor and sensory
Forms plexuses (web of nerves)
Exit via interverbal foramen
3 sets of plexuses
Cervical, Brachial
Lumbar, Saccral
Mixed roots
What are the three horns of Grey Matter in the Spinal cord?
Dorsal horn
-somatic sensory axons and interneuron cell bodies
-visceral sensory axons and interneuron cell bodies
Lateral horn
-autonomic motor cell bodies (T1-L2)
Ventral horn
-somatic motor cell bodies
How many pairs of cranial nerves are there?
12
What is neurulation?
Neural plate bends up and then fuses to from hollow tube.
What is a somite?
Transient units that gives rise to repetitive structures including vertebrae, ribs and skeletal muscles.
What is a Sclerotome?
Part of a somite that gives rise to a bone or skeletal tissue
Forms vertebral cartilage
What is a Dermatome?
Forms back of dermis
Area of skin receiving sensory innervation from single spinal nerves dorsal root.
What is myotome?
Group of muscles innervated by single spinal nerve root.
Briefly outline embryological development of musculoskeletal system
1- Notochord forms mesoderm cells after gastrulation
2- signals from notochord cause inward folding of ectoderm at neural plate
3- end of neural plate fuses and disconnects to form a neural tube
Which germ layer does the nervous system develop from
Ectoderm
What embryonic structure do vertebrae develop from
sclerotome
What structure of the spinal cord anchors it securely to the coccyx?
The filum terminale
What type of fibers do the posterior (dorsal) roots contain?
afferent fibers
Trigeminal nerve
largest
arises from pons
sensory innervation of the face
Facial nerve
motor innervation of facial expression
pons and medulla
vagus nerve
main parasympathetic nerve
from medulla
Spinal accessory nerve
motor innervation of two neck muscles
from C1-5/6 and medulla
Hypoglossal
Motor innervation of tongue
from medial aspect of medulla
What are the four main plexuses of the body?
cervical, Brachial, Lumbar and Sacral
what is the function of the primary motor cortexes?
encodes the direction of movement
what is the function of the primary somatosensory cortexes?
processing afferent somatosensory input and contributes to the integration of sensory and motor signals necessary for skilled movement.
Which tract carries impulses between the left and right hemispheres of the brain?
thick tract of nerves called the corpus callosum at the base of the groove.
where are white and grey matter located in the spinal cord
grey = interior
white = surrounds
what type of fibres carry afferent information in the spinal cord?
Dorsal root
what type of fibres carry efferent information in the spinal cord?
Ventral root
Dorsal
on or relating to the upper side or back of an animal, plant, or organ.
ventral
of or relating to the belly : abdominal.
being or located near, on, or toward the lower surface of an animal
posterior
near the rear or end
further back in position
anterior
in front of
proximal
nearer to the center
distal
away from the centre
what is the purpose of the cervical and lumbar enlargements along spinal cord
accomadate for the greater number of nerves and connections necessary to process info from uperr and lower limbs
Moving from brain to coccogeal, what is the order of spinal regions?
Cervical (C1-7)
Thoracic (T1-12)
Lumbar (L1-L5)
Sacral (S1-5)
conus medullaris
distal end of the spinal cord
what are the start and end points of the spinal cord?
- continuouswiththe brainstem at the level of the foramen magnum
- tapers at the conus medullari (continues as the cauda equina) at the level of L1/L2)
what anchors the spinal to the coccyx?
filum terminale
what are the 3 horns of spinal cord grey matter?
dorsal horn
lateral horn
ventral horn
What are the neuron types of the three horns of the spinal cord grey matter?
dorsal
- somatic and visceral sensoryaxons
- interneuroncellbodies
lateral (only sympathetic)
-autonomic motorneuron cellbodies
ventral horn
somaticmotorneuron cellbodies
moving from top to bottom, what are the names of the 5 branches of brachial plexuses?
musculocutaneous
axillary
radial
median
ulnar
what (from top to bottom) are the cords that lead into the branches (plexuses)?
lateral –> musculocutaneous and median
posterior –> axillary and radial
medial –> median and ulnar
What are the 4 main plexuses and their spinal roots?
cervical
-C1-C4
Bracial
- C5-C8, T1
-musculocutaneous
-axillary
-radial
-median
-ulnar
Lumbar
T12-L4
Sacral
-L4-S4
Where are sensory neuron cell bodies located?
within sensory ganglia which may be in the dorsal root of the spinal cord or along cranial nerves.
what is the cauda equina?
a group of axons acting as a continuation of the spinal cord, translates to ‘horsetail’
How are spinal nerves created?
union of the dorsal root (from dorsal rootles) and the ventral root (from ventral rootlets)
What does dorsal roots and rootlets contain?
Dorsal rootlets: somatic and viscera; sensory neuron axons
Dorsal root: sensory neuron axons and ganglion
What does ventral rootlets contain?
somatic and autonomic motor neurons
What foramen do spinal nerves exit from?
interverebrael foramen
proprioception
Awareness of position that requires sensory input from cerebral cortex and cerebellum and motor control.
what are the different types of muscle morphology?
Pennate:
Fusiform
Parallel
Convergent
Circular
What is fusiform and an example.
thick muscle belly that tapers on both sides (bicep brachii)
Gastrulation
Bilaminar embryonic disc –> trilaminar embryonic disc
what does the ectoderm develop into?
Develops into epidermis, epidermal derivatives (hair/ nails) and nervous system.
What are the three strcutures of the mesoderm and what do they develop into?
3 structures that develop into various parts
Notochord: axial skeleton
Paraxial mesoderm: develops into somite forming axial skeleton, muscle, dermis and most CT
Head mesenchyme: CT and musculature of fact
What occurs GENERALLY in first 8 weeks of muscle embryo development?
Gastrulation (halfway wk 2)
Folding of embryonic disc (wk 3)
Neurulation (early wk 4)
Limb development (week 4—8)
MSS embryological development
step 1 (gasturlation)
transformation from a bilaminar to trilaminar embryonic disc
MSS embryological development
2- folding of the embryonic disc
(week 3)
- rapid growth of head and tail causes the folding of the embryonic disc into a tube
MSS embryological development
3- neurulation
(early week 4)
- the notochord stimulates the neural plate to transform into the neural tube
- somites develop and align on either side of the neural tube
-
MSS embryological development
4- limb development
- limb buds, containing a ventral and dorsal muscle mass, form at week 4 (UL before LL)
- rotation of the limbs at weeks 7-8
- UL laterally, moving the elbow posterior
- LL medially, moving the knee anterior
during neurulation, what does sclertome, dermatome and myoterm become?
sclerotome → vertebrae
- myotome → muscle
- dermatome → dermis
