Functional Anatomy Of The Spinal Cord Flashcards
Which two sources do motor neurons receive input?
Local sources - segmental reflexes
Descending tracts from brain - voluntary movement
Where does the lateral corticospinal tract decussate?
In the medulla
Where does the anterior corticospinal tract decussate?
At the level at which it leaves the spinal cord
Where in the white matter does the lateral corticospinal tract travel?
Immediately lateral to the dorsal horn
Where in the white matter does the anterior corticospinal tract travel?
Lateral to the anterior median fissure
Which two parts of the brain does the corticospinal tract travel through?
Internal capsule
Cerebral peduncle of the midbrain
Where do the axons of the corticospinal tract form ventral bulges, and what are they called?
In the medulla oblongata
- known as pyramids
What is the difference in function between the lateral and anterior corticospinal tracts?
Anterior - control trunk and proximal limb movement
Lateral - precise, agile and highly skilled movements of hands and feet
What is the function of the corticobulbar pathway?
Controls skeletal muscles of the head
Which two areas of the brain does the corticobulbar tract pass through?
Internal capsule
Cerebral peduncle of the midbrain
Which nine cranial nerve motor nuclei, do axons of the corticobulbar tract terminate in?
Oculomotor Trochlear Trigeminal Abducens Facial Glossopharyngeal Vagus Accessory Hypoglossal
What is the function of the tectospinal pathway?
Maintains balance and posture
Which neurons does tectospinal modulate the activity of?
Alpha and gamma motor neurons innervation muscles of the neck
What is the function of the vestibulospinal pathway?
Maintains balance and posture
What are the two parts of the retculospinal tract?
Pontine (extensor)
Medullary (flexor)
What is the function of the reticulospinal tract?
Maintains balance and posture
What is the function of the rubrospinal tract?
Regulates upper limb muscle tone and movement
Where do the upper motor neurons arise in the rubrospinal tract?
The red nuclei of the midbrain
Where do upper motor neurons of the rubrospinal tract decussate?
Midbrain
Where in the White matter of the spinal cord will you find the dorsal column (medial lemniscus pathway)?
Posterior and medial to the dorsal horn
Why is the dorsal column/medial lemniscus path called this?
Dorsal column of the spinal cord
Medial lemniscus of the brainstem
Where do first order neurons of the dorsal column arise from and terminate at?
Arises from sensory receptors in limbs, trunk, neck, etc
Travels into the spinal cord, ascends up the ipsilateral side and terminates at the medulla (still ipsilaterally)
Where are the cell bodies for the first order neurons of the dorsal column found?
Dorsal root ganglion
What are the two dorsal columns in the white matter - and what sensations are carried in each?
Gracile fasciculus
- touch, pressure and vibration from lower limbs
Cuneate fasciculus
- touch, pressure, vibration and conscious proprioception from the upper limbs, trunk and neck
Where do first and second order neurons synapse in the dorsal column?
In either the gracilis or cuneate nucleus
Where do the second order neurons of the dorsal column arise and terminate?
Arise in the cuneate of gracile nucleus, then decussate (in the medulla still) and enters the medial lemniscus
Terminates in the ventral, posterior nucleus of the thalamus
Where do tertiary axons of the dorsal column arise and terminate?
Arise in the ventral, posterior nucleus of the thalamus
Terminates in the primary somatosensory area of the cerebral cortex
What sensations does the medial lemniscus pathway transmit?
Tactile sensations
Proprioception
Where in the white matter is the spinothalamI c tract located?
Anterio-lateral to the ventral horn
What sensations does the spinothalamic tract carry?
Pain
Temperature
Itch
Tickle
Where do the first order neurons in the spinothalamic tract arise and decussate?
They arise at the receptor (in trunk, limbs, neck, posterior head)
They terminate in the dorsal horn on the ipsilateral side
Where do the second order neurons in the spinothalamic tract arise and decussate?
They arise in the dorsal horn, and then decussate to the contralateral side
They pass up the spinal cord
They terminate in the ventral, posterior nucleus of the thalamus
Where do the third order neurons in the spinothalamic tract arise and decussate?
They arise in the ventral, posterior nucleus of the thalamus and travel to the primary somatosensory area (on the same side as the thalamus)
Where are the pre-ganglionic neurons of the sympathetic nervous system located?
Thoracolumbar region
- T1-L3
Where are the pre-ganglionic neurons of the parasympathetic nervous system located?
The brainstem
- CN III, VII, IX and X
Sacral region
- S2-4
Where are the ganglia of the sympathetic nervous system located?
In the sympathetic trunk - next to the vertebral column from T1 to the coccyx
Where are the ganglia of the parasympathetic nervous system located?
Near the targets organ - in the walls of the viscera they innervate
What is the function of the sympathetic nervous system?
Increased heart rate
Decreases gut activity
Dilates pupils
What is the function of the parasympathetic nervous system?
Decreased heart rate
Increased gut motility
Pupil constriction
Increase in secretions
What organs are only supplies by the sympathies nervous system?
Sweat glands Adrenal medulla Hair follicles Spleen Iris dilator
What organs are only supplies by the parasympathies nervous system?
Ciliary muscles - focusing the eye
Iris sphincter
