L4. Brainstem And Spinal cord Flashcards
What are the main functions of the brainstem?
- pathway of tracts
- regulatory functions (swallow, breath, sleep, consciousness, etc.)
- reflexes
- origin of cranial nerves
The mid brain’s tectum (roof) has 4 round swellings called?
Corpora Quadrigemina
CN3 and CN4 originates in which part of the brainstem?
Midbrain
What are the functions of the superior colliculi?
- visual and ocular reflexes
- gaze and vergence centers
- connected to LGB
What are the functions of the inferior colliculi?
- auditory reflexes
- sound localization
- connected to MGB
Where is the Edinger-Westphal, oculomotor, and red nucleus found?
Tegmentum
What nucleus is the passageway of ascending tract fibers that connect to the primary motor cortex?
Red nucleus
The Raphe Nuclei extends from the midbrain to the spinal cord and is part of RAS. What are its main functions?
Major site for serotonin-producing neurons at the CNS, Modulates sleep-wake cycle, arousal, and sensory inout (esp. pain)
The Superior Cerebellar Peduncle (midbrain) connects the brainstem to the cerebellum. What is its function?
Main OUTPUT pathway of the cerebellum
What is the major producer of dopamine in the CNS (hint: midbrain)?
Ventral Tegmental Area (VTA) & Substantia Nigra
The pars reticulata of substantia nigra contains what neurotransmitter?
GABA
Which part of the substantia nigra contains dopamine and projects to the striatum, putamen, and the caudate nuclei?
Pars compacta
Which part of the brainstem connects the midbrain and medulla oblongata?
Pons
Which part of the brainstem is also known as the “seat of consciousness”?
Pons
What system and tract is responsible for the overall level of consciousness and the wakeful-sleep states?
Ascending Reticular Activating System (ARAS) and Reticulospinal Tract
Which part of the brainstem is also known as the respiratory and deglutition center?
Medulla Oblongata
Why are olives important?
It’s important for the control of movement
Which part of the medulla oblongata contains motor nerves that innervate ipsilateral muscles of the soft palate, pharynx, larynx, and upper esophagus?
Nucleus Ambiguus
What is the main function of nucleus ambiguus?
Swallowing and speaking + inhibit heart rate
What is the function of nucleus solitarius?
Receive taste, chemoreceptor, and baroreceptor inputs in the aortic arch and carotid body
Which parts of the spinal cord expands laterally?
Cervical and lumbosacral enlargement
What is the terminal end of the spinal cord called?
Conus medullaris
At what level is the conus medullaris found?
L1 or L2 (adult)
What is the bundle of spinal nerves and rootlets that extend down from L2?
Cauda equina (“horsetail”)
What is the pia matter within the equina that extends from the conus to the distal dura sac?
Filum terminale
What structute is found between the dorsal and ventral roots which keeps the spinal cord attached yo the arachnoid and dura matter for stabilization?
Denticulate ligament
What is the function of the meningeal layers?
shock barrier, protects vessels that supply the brain, contain CSF to nourish brain and spinal cord
How many spinal nerve pairs does the coccygeal region have?
1
How many spinal nerve pairs does the cervical region have?
8
Which spinal nerve exits between cervical vertebrae C4 & C5?
C5
Which spinal nerve exits between lumbar vertebrae L4 & L5?
L4
What is the function of the marginal layer (gray matter of spinal cord)?
Responds to noxious stimuli (C/L)
What is the functionnof the nucleus proprius (gray matter of spinal cord)?
Receive information on position and light touch sense
Which layer of Rexed’s Lamina responds to visceral noxious and afferent stimuli (mechanical signals from joints and skin)?
5th layer
Zona intermedia/Clarke’s nucleus gives rise to what?
Posterior spinocerebellar tract
Where are first order neurons at the descending pathway (white matter - spinal cord) located in?
Upper motor neurons in the cerebral cortex/brainstem,
Where are second order neurons found in the descending pathway (spinal cord)?
Interneurons in the spinal cord
Lower motor neurons that innervate the skeletal/visceral muscles at the motor tract is called what?
Third order
What is the function of the lateral corticospinal tract (LCST) and where is it located?
Fine motor functions (controls distal musculature)
Lateral column
A child is buttoning up his shirt, what tract is used to control his fingers in order to perform the task?
Lateral Corticospinal Tract (LCST)
What is the function of the Anterior Corticospinal Tract (ACST) and where is it located?
Gross and postural motor function (proximal and axial musculature)
Anterior Column
What is the function of the vestibulospinal tract (VST) and where is it located?
Postural reflexes and control of antigravity (extensor) musculature
Anterior Column
Which vestibulospinal tract descends ipsilaterally?
Lateral VST
What is the function of the rubrospinal tract (RuST) and where is it located?
Controls distal flexor muscle and tone, inhibits distal extensor muscle, and modulates reflex activity
Lateral Column
What is the function of the reticulospinal tract (ReST) and where is it located?
maintain posture, control autonomic functions, locomotion, and reflex
Ventral & Lateral columns
What is the function of the tectospinal tract (TST) and where is it located?
reflex head turning due to visual or auditory stimuli
Ventral column
What is the function of the Descending Autonomic Tract (DAT) and where is it located?
Modulate autonomic functions (BP, PR, sweating, etc.)
Lateral Column
What is the function of the medial longitudinal fasciculus (MLF) and where is it located?
Coordination of head and eye movements
Ventral column
Where are third order neurons located at the ascending pathway (sensory)?
Thalamus
Where are first order neurons located at the sensory tract/ascending pathway?
Dorsal Root Ganglion
What is the function of the dorsal column medial lemniscus (DCML) and where is it located?
Fine-touch, proprioception, two-point discrimination
Dorsal column
What is the function of the anterior spinothalamic tract (AST)?
Crudely localized touch (aware but no localization)
What is the function of the lateral spinothalamic tract (LST) and where is it located?
Discriminative, can be localized, sharp pain and temperature (A-delta and C-fibers)
Ventrolateral column
What is the function of the dorsal spinocerebellar tract (DSCT) and where is it located?
Generally receives muscle joint information and is responsible for movement and position mechanisms.
Dorsal - coordinates limb and posture
Lateral Column
What should be considered when there are spinal cord lesions?
- What level does abnormality begin (sensory, motor)?
- What tracts are affected?
- Which side are these tracts located?
- What sensory modalities are involved?
What is the function of the anterior spinocerebellar tract (ASCT) and where is it located?
Generally receives muscle joint information and is responsible for movement and position mechanisms.
Anterior - provide information from skin + controlled movement
Lateral column
What is the function of the spinoreticular tract (SRT)?
deep chronic pain + consciousness
These are subconscious stimulus-response mechanisms.
Reflexes
What reflex is described:
Examiner holds one of the baby’s legs extended and applies firm pressure to the sole of the foot of the same leg. The baby’s free leg flexes, adducts and then extends.
Crossed-extensor reflex
What principle is described below:
Flexor AND extensor reflexes of the SAME limb cannot contract simultaneously.
Reciprocal Inhibition (Sherrington’s Law of Reciprocal Innervation)
What happens when the anterior horn pr gray matter downwards are damaged?
Striated skeletal muscle activity is affected and the following may occur:
- Flaccid paralysis
- Muscle atrophy
- Diminished or absent DTR
- Fasciculations and fibrillations
What symptoms can be experienced after damage to the lateral white column occurs?
(hint: S-H-Da-P-D)
- Spastic paralysis
- Hyperactive DTRs
- Disuse atrophy
- Pathologic reflex
- Diminished/absent superficial reflexes
