Brain 1: Spinal cord physiology and brain development and coverings Flashcards
2 main sensory tracts
Spinothalamic tract:
Posterior column:
2 main function of spinal cord
- Propagates nerve impulses (in white matter)
2. Integrates information (in grey matter)
What does spinothalamic tract do
Conveys nerve impulses for sensing pain, temperature, itch, tickle and deep pressure
What is two tracts of posterior column?
Facilicus (leg) and Cunneate fascilicus (arm)
What does posterior column do?
conveys nerve impulses for touch, light pressure, vibration and conscious proprioception
What is conscious proprioception
The awareness of the positions and movements of muscles, tendons and joints
what is 2 main motor tracts
Direct pathways (lateral corticospinal tract, anterior corticospinal tract, corticobulbar tract)
corti- cortex,
spinal -spinal, efferent, motor
bulbar - brainstem
Indirect pathways (rubrospinal, tectospinal, vestibulospinal, lateral reticulospinal, medial reticulospinal tracts)
What is direct pathways of motor tracts
nerve impulses originate in cerebral cortex
cause voluntary movements of skeletal mm
brainstem is considered traveling down
what do indirect pathways of motor tracts do
nerve impulses originate in brain stem
cause automatic movements
helps coordinate body movements with visual stimuli
maintain muscle tone
what is reflex
a fast involuntary unplanned sequence of actions that occurs in response to a particular stimulus
can be in born or learned
4 different reflexes
spinal reflex
cranial reflex
somatic reflex
automatic (visceral) reflexes
spinal reflex is
when integration happens in gray matter in Spinal cord
cranial reflex is
when integration happens in brainstem
somatic reflex is
involves contraction of skeletal muscle
autonomic (visceral) reflexes is
not usually consciously perceived
Invovled responses of smooth mm, cardiac mm and glands
Four somatic spinal reflexes
- The stretch reflex
- Tendon reflex
- Flexor (withdrawal reflex)
- crossed extensor reflex
Stretch reflex
Sensor receptor: muscle spindle Mono synapse Reciprocal innervation: yes ipsilateral reflex intersegmental: no
Tendon reflex
Sensory receptor: G.T.O Poly synapses Reciprocal innervation: yes Ipsilateral reflex Intersegmental: No
Flexor (withdrawal) reflex
Sensory receptor: n/a Poly synapses Reciprocal innervation: Yes Ipsilateral reflex intersegmental: Yes
Cross extensor reflex
Sensory receptor: n/a
poly synapses
reciprocal innervation: yes
Intersegmental: yes
what do brain and spinal cord develop from
ectoderm, arranged in a neural tube
Three primary brain vesicles
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
3-4 week embryo
5 secondary brain vesicles
5 week embryo
Prosencephalon divides to Telencephalon and Dienephalon
Mesencephalon stays as Mesencephalon
Rhombencephalon divides to Metencephalon and Myelencephalon
Adult brain structure (walls and Cavities)
5 week embryo
Telencephalon becomes wall: Cerebrum, Cavities: lateral ventricles
Diencephalon becomes wall: Thalamus, hypothalamus and epithalamus, Cavities: Third ventricle
Mesencephalon becomes wall: Midbrain, cavities: Aqueduct of the midbrain
Metencephalon becomes wall: pons and cerebellum, cavities: upper part of forth ventricle
Myelencephalon becomes wall: Medulla oblongata, cavities: lower part of forth ventricle
what does brain stem have
Continuous with spinal cord
medulla oblongata
pons
midbrain
Where is cerebellum located?
posterior to brain stem
what and where is diencephalon
superior to brain stem
Thalamus
Hypothalamus
epithalamus
Where and what is cerebrum
largest part of the brain
sits on diencephalon
protective coverings of the brain
cranium and cranial meninges surround and protect the brain
cranial meninges - continuous with the spinal meninges (Dura mater, arachnoid mater and pia mater)
What is missing from spinal cord structure
no epidural space around brain
Dura mater of the brain
outer meningeal layer made up of periosteal layer (external) and meningeal layer (internal). These 2 layers are fused together except where they separate to enclose the dural venous sinuses
what is Dural venous sinuse
Endothelial-lined venous channels
Drain blood from the brain and deliver it into internal jugular veins
3 extensions of dura mater
- Falx cerebri: separates the 2 hemispheres of the cerebrum
- Falx cerebelli: separates the 2 hemisphere of cerebellum
3: Tentonium cerebelli: Separates the cerebrum from the cerebellum
Blood flows to brain mainly via
internal carotid, vertebral arteries
Blood flows out of brain via
the dural venous sinuses which drain into the internal jugular veins
