Tsm11: Spinal Cord and Brainstem Anatomy02/10/08

tsm11: Spinal cord and brainstem anatomy02/10/08

Questions

Where does sensory information in the gracile and cuneate fasciculi originate and terminate?
The gracile fasciculus lies medially in the dorsal funiculus and receives sensory information from the lower trunk and lower limbs
The cuneate fasciculus lies laterally in the dorsal funiculus and receives sensory information from the upper trunk, neckand upper limbs
Sensory information travelling through both the gracile and cuneate fasciculi terminates at the primary somatosensory cortex
Do all levels of the spinal cord have both gracile and cuneate fasciculi?
No – sacral and lumbar segments have only gracile fasciculi
The cuneate fasciculus first arises in thoracic segments
Sensory afferents ascend the dorsal columns more laterally at higher levels (somatotopic)
What is the name of this sensory system and what is its point of decussation?
Dorsal column system – decussates at the sensory decussation in the caudal medulla
Where are the cell bodies of origin of the anterolateral system?
The second order neurones that carry sensory information up through the anterolateral funiculushave cell bodies of origin in the contralateral dorsal horn
What is the function of this system and what is its point of decussation?
Conveys sensory information about pain and temperature to the primary somatosensory cortex
Decussates at approximately the same spinal levelfrom which the sensory information originates
What pattern of sensory and motor loss typically occurs in spinal cord hemisection?

This is Brown-Séquard syndrome
Loss or impairmentof touch and proprioception in ipsilateralregions below the lesion
Loss or impairment of pain and temperature sensationincontralateral regions below the lesion
Impairment of motor control (spastic weakness) inipsilateral regions below the lesion

What is the function, location and corresponding sensory system of the chief sensory nucleus of CNV?
The chief sensory nucleus is located in the pons near the entry of the trigeminal nerve
It receives sensory information about touch and pressure from ipsilateral head regions and transmits this via the trigeminothalamic tract to thecontralateralprimary somatosensory cortex
This corresponds in part to the dorsal column system of the spinal cord (see below)
What is the function, location and corresponding sensory system of the mesencephalic nucleus of CNV?
The mesencephalic nucleus is located rostral to the chief sensory nucleus in the midbrain at the level of thesuperior colliculiin the lateral region of the periaqueductal grey matter (see below)
It receives sensory information about proprioception from ipsilateralhead regionsand transmits this to the primary somatosensory cortex as above
With the chief sensory nucleus, this corresponds to the dorsal column system of the spinal cord
What is the function, location and corresponding sensory system of the spinal nucleus of CNV?
The spinal nucleus is located caudal to the chief sensory nucleus in the upper cervical spinal cordcontinuous with the laminar II region in the dorsal horn(substantia gelatinosa)
It receives sensory information about pain and temperature from ipsilateralhead regionsand transmits this to the primary somatosensory cortex as above
This corresponds to the anterolateral system of the spinal cord
What is the function of the periaqueductal grey matter?
The periaqueductal grey matter modulates sensation ofpain– part of the analgesia centre
Stimulation of this region produces profound analgesia
What would be the result of occlusion of the posterior inferior cerebellar artery?
Lateral medullary syndrome, otherwise known as Wallenberg syndrome
Occlusion of this artery prevents blood flow to the lateral medulla and inferiorcerebellum
Loss of pain and temperature sensation in the ipsilateral face and contralateral body
Nausea and vertigo
Ipsilateralataxia[TG1]and paralysis of soft palate, pharynx and vocal cord

[TG1]Shaky, irregular and uncontrolled muscle movements