Ascending Spinal Pathways

Where does the spinal cord end?

L1-L2 vertebral level

What comprises the cauda equina?

the lumbosacral nerve roots extending inferior to the spinal cord

How many pairs of spinal nerves are there?

31

Levels of cervical enlargement

C5-T1

Position of lateral column

T1-L2

Position of lumbosacral enlargement

L2-S3

Lamina I-II

the axons carrying the noxious and temperature impulses from the peripheral receptors synapse here

Lamina I name

marginal zone

Lamina II name

Substantia gelatinosa

Lamina III-IV

aid in processing of vibration and pressure touch sensation and carry conscious proprioceptive impulses to cerebral cortex via the dorsal medial lemniscus pathway

Lamina V

sensory afferents received from cutaneous, muscle, mechanical, and visceral nociceptors

Lamina VI

processes the flexion reflex or reflex withdrawal from painful stimuli and receives information from the muscle spindles and functions with Lamina VIII to coordinate spinal reflexes within spinal cord

Lamina III and IV correspond to…

nucleus proprius

What is a fasciculus purpose?

carry a specific modality from the periphery to the brain

Fasciculus gracilis

trunk from T6 and below and lower extremity

Medial Lemniscus (dorsal column)

conveys information about vibrations, light touch, conscious proprioception, two point discrimination

What are the two fasciculi in the medial lemniscus?

fasciculus gracilis and fasciculus cuneatus

Fasciculus cuneatus

trunk above T6 and upper extremities

Proprioception

integration of sensory signals from mechanoreceptors that allow determination of body segment position and movements in space

Kinesthesia

detecting the speed, direction, and extent of body movement

Force perception

gauging how much tension, resistance, or effort is needed to life or hold an object

Unconscious proprioception

the automated sensory process that monitors body position and movement without conscious thought to maintain posture and balance

Conscious proprioception

the awareness of the body’s position in space, allow for conscious perception and control of the body’s posture and actions

Dorsal column first order enuron

conveys information from the receptors to the medulla (nucleus gracilis and nucleus cuneatus)

Dorsal column second order neuron

medulla crosses to form medial lemniscus and terminates in the thalamus (ventral posterolateral)