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Neuro > Structural Organisation Of The Brainstem And Spinal Cord > Flashcards

Structural Organisation Of The Brainstem And Spinal Cord Flashcards

1
Q

The brainstem consists of…

A

Medulla oblongata
Pons
Midbrain

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2
Q

What are the 3 brad functions of the brainstem

A

Connects the tracts to higher centres
Contains reflex centres
Houses nuclei of CNS 3-12

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3
Q

Describe the structure of the brainstem

A

Occupies the posterior cranial fossa of the skull
Stalk like shape
Connects the spinal cord with the cerebral hemispheres and cerebellum and has long tracts of fibres present at all levels
In transverse section can be divided into 4 areas from posterior to anterior:
Tectum (roof over the ventricular system)
Ventricular system
Tegmentum (core of brainstem)
Basal portion (situated most anteriorly)

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4
Q

What are the 4 areas of the brainstem in transverse section

A

Tectum (roof over the ventricular system)
Ventricular system
Tegmentum (core of brainstem)
Basal portion (situated most anteriorly)

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5
Q

Where s the midbrain/mesencephalon

A

Between the Diencephalon and pons

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6
Q

What links the brainstem to the thalami and the cerebrum

A

2 lateral half’s on the anterior side of the cerebral peduncles which are the part of the midbrain that links these

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7
Q

What connects the 3rd and 4th ventricles of the brain

A

The hollow cerebral aqueduct running through the midbrain

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8
Q

What nerves emerge from the midbrain

A

Oculomotor 3
Trochlear 4

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9
Q

What is the function of the red nucleus

A

Relay station and integrator of info

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10
Q

Describe the corpa quadrigemina

A

Contains 4 rounded bodies
2 superior colliculi - control reflex movements of the eyes, neck and head in response to visual stimuli movements
2 inferior colliculi - control reflex movements of the head, neck and trunk in response to auditory stimuli

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11
Q

Describe what th red nucleus contains

A

Numerous blood vessels and receives info form the cerebrum and cerebellum and issues subconscious motor commands concerned with muscle tone and posture

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12
Q

What is lateral to the red nucleus and what is its function?

A

Melanin-containing substantia nigra
Secretes dopamine to inhibit the excitatory neurons of the basal nuclei

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13
Q

Depigmentation of substantia nigra can be indicative of…

A

Parkinson’s disease

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14
Q

Describe the Pons

A

Found between the midbrain and medulla oblongata
Anterior surface - large bulge , basilar pons
Posterior surface cerebral peduncles - Tegmentum

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15
Q

What is the Locus ceruleus

A

Located within the dorsal wall of the upper pons, under the cerebellum in the caudal midbrain, surrounded by the 4th ventricle
Main source of noradrenaline in the brain
Melanin granules contribute to its blue colour

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16
Q

Motor root lies ….. to sensory root

A

Medially

17
Q

What nerves emerge from the groove between the medulla and pons

A

6 7 8

18
Q

What nuceli are involved with respiration

A

Apneustic centre - apneusis sustained gasping inhalation followed by a short inefficient exhalation
Pneumotaxic centres - prevents apneusis by promoting coordinated respiration

19
Q

The pons contains…

A

Sensory and motor nuclei of CNs 5,6,7,8
Nuclei involved with respiration
Nuclei and tracts that process and relay information to and from the cerebellum
Ascending, descending and transverse tracts

20
Q

Describe the function of the medulla oblongata

A

Connects the pons superiority with the spinal cord inferiority
Contains long ascending and descending fibres to higher centres
Allows brain and spinal cord to communicate
Coordinates complex autonomic reflexes
Controls visceral functions

21
Q

Describe the anterior surface of the medulla oblongata

A

Pyramids - contains corticospinal tracts
Decussation of pyramids
Olives - underlying olivary nuceli

22
Q

Describe the posterior surface of the medulla oblongata

A

Gracile tubercle
Cuneate tubercle

23
Q

What is the function of autonomic nuclei

A

Regulate/control a range of visceral activities

24
Q

Describe respiration control by medulla

A

Subset of neurons in the medulla , respiratory pattern generator that sends signals to the cranial and spinal motor nerves that directly innervate the respiratory muscles
Medulla can generate respiratory pattern fine tuned by higher centres

25
Q

Describe the cardiovascular centre of the medulla

A

• Vasomotor area rostral ventrolateral medulla and the inferior olivary complex
• Most afferent fibres from the baroreceptors project to the nucleus tractus solitarii (NTS)
• Inhibitory neurons from the NTS project to the vasomotor area and when stimulated and uninhibited by interneurons produces a vasoconstrictor response
• Therefore an increase in pressure stimulates baroreceptor firing which causes inhibition by vasomotor interneurons causing vasodilation.
•cardioinhibitory area includes the nucleus ambiguus and the dorsal motor nucleus of the vagus nerve
• Excitatory neurons project from the NTS into the cardioinhibitory area
• Neurons in the dorsal motor nucleus of the vagus account for the cardiac component of the baroreceptor reflex (bradycardia). Inhibitory interneurons project from the NTS onto a cardioacceleratory area and stimulation of these causes heart rate and cardiac contractility to increase

26
Q

Describe sensory and relay nuclei

A

• The fasciculus gracilis contains ascending fibres from sacral, lumbar and lower thoracic segments T6-T12 (the lower body). synapse with the ipsilateral gracile nucleus in the medulla.
• It is involved in the mediation of conscious proprioception including kinaesthesia and discriminative touch sensations from the lower body.
• The fasciculus cuneatus exists in thoracic segments above T6 and cervical segments and contains long ascending fibres from the upper body.

27
Q

Describe the reticular formation

A

Extends through brainstem, loose and far-flung neurons, into the cerebral cortex
Reticular activating system-alertness
Filters out repetitive or familiar stimuli
Inhibited by sleep, alcohol, drugs
Severe injury = coma

28
Q

Where does the spinal cord extend from

A

Foramen magnum L1-2

29
Q

How many spinal nerves in SC

A

31 pairs mixed spinal nerves
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

30
Q

Signal nerved C1-7 exit…. To corresponding vertebra

A

Rostrally

31
Q

C8-S5 exit ….. to corresponding vertebra

A

Caudally

32
Q

….. and ….. enlargements in SC

A

Cervical C1-T1 and lumbosacral L1-S3

33
Q

Where do adult cord end

A

L1-L2

34
Q

Where do children’s spinal cord end

A

Caudal end of L3

35
Q

Distal end of the cord …. Emerges ….

A

Conus medullaris
Emerges cauda equina l2-c1

36
Q

What anchors the cord

A

Denticulate ligaments anchors the cord within the dural sac

37
Q

What is the lumbar cistern

A

Caudal end of spinal cord
Suitable for lumbar puncture
Adults - between L3-L4
Children - between L4-L5

38
Q

Describe the internal structure of the spinal cord

A

Gray matter is shaped like a butterfly or an H
At every level the gray matter is capped by a zone of closely packed small neurones, the substantia gelatinosa.
The white matter surrounds the gray butterfly
Consists of the ascending and descending tracts / fasciculi)
The neurons comprising these tracts have similar origins and sites of termination.
A bundle containing one or more tracts or fasciculi is called a funiculus.
Two sides of gray matter connected by gray commissure

39
Q

Name and describe the 3 funiculi in each half of the spinal cord

A

The dorsal (posterior) funiculus, located between the dorsal (posterior) horn and the dorsal (posterior) median septum.
The lateral funiculus which is located between where the dorsal roots enter and the ventral (anterior) roots exit the spinal cord.
The anterior (ventral) funiculus located between the anterior (ventral) median fissure and the site where the ventral roots exit.

Neuro (26 decks)

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