0312 - Spinal cord and peripheral nerves - EG Flashcards
What is a spinal segment?
A section of spinal cord that carries sensory information from, and motor information to, a predictable and discrete body region.
What are the two major sensory pathways within the spinal column and what type of information does each convey?
dorsal column - fine touch and proprioception; spinothalamic tract - pain and temperature
What are the two major motor pathways within the spinal column and what type of information does each convey?
lateral corticospinal tract - contralateral information; ventral corticospinal tract - ipsilateral information.
What is a sensory territory also known as?
a dermatome. dorsal rami of C1 does not have a cutaneous representation.
What is a motor territory also known as?
a myotome. Segments from upper part of a plexus innervate proximal muscle groups and segments from lower parts of a plexus innervate distal muscle groups.
Does the ventral primary ramus contain sensory, motor, or mixed nerves?
mixed nerves.
Does the ventral root contain sensory, motor, or mixed nerves?
motor nerves
Does the dorsal root contain sensory, motor, or mixed nerves?
sensory nerves
Describe the numbering of spinal nerves to vertebrae
C1-C7 n’s exit at the vertebral level above corresponding vertebrae, C8 n exits below C7 vertebrae, T1-S5 exit below pedicles of corresponding vertebrae.
What cervical n does the radial n derive from?
C6
What cervical n does the median n derive from?
C7
What cervical n does the ulnar n derive from?
C8
The brachial plexus is comprised of which nerves?
ventral primary rami of C5 to T1
At what vertebral level down the spinal cord end in an adult? What is the end of the spinal cord known as? What is below this level?
L1, end called conus medullaris, post which is cauda equina
What helps anchor the spinal cord within the spinal column?
The denticulate ligaments and the phylum terminale, both extensions of the pia mater that anchor to the lateral and inferior respectively.
Describe the cross-sectional appearance of a cervical, thoracic, lumbrosacral spinal cord section.
Cervical: large ventral horn with cell bodies of motor neurons supplying upper limb and large proportion of white matter; thoracic: prominent lateral horn of sympathetic neurons; lumbosacral: large ventral horn for motor neurons supplying lower limb, minimal white matter.
Describe the simple reflex arc in the withdrawal reflex from a pinprick in a finger.
sensory dermatome (thumb C6, index-ring C7, little finger C8), pinprick sensation sent via sensory nerve into dorsal root, enters spinal cord to interneuron - initiates motor reflex to cause movement of the wrist (C6,7) and fingers (C7,8) away from insulting object.
