Spinal Cord Flashcards
What does the CNS consist of?
the forebrain
the brainstem
the spinal cord
What is the forebrain comprised of?
the cerebral hemispheres
the olfactory bulb
the hypothalamus
the diencephalon
What does the brainstem consist of?
the midbrain (mesencephalon)
the hindbrain (rhombencephalon)
What parts of the CNS does the spinal cord contain?
sensory neurons that receive sensation from the sensory receptors
motor neurons that control muscles
long tracts connecting the spinal cord with the brain
the preganglionic nuclei of the autonomic nervous system
pattern generators for complex movements such as running at different speeds
What is the spinal cord?
a long cylindrical structure extending from the base of the skull to the first lumbar vertebra in the human
Where is the spinal cord noticeably thicker?
in the regions that are connected to the upper and lower limb
What is in a transverse section of the spinal cord?
A central butterfly-shaped area of grey matter is surrounded by white matter
The gray matter is divided into:
ventral horn
dorsal horn
The white matter is divided into:
3 funiculi (columns):
the dorsal funiculus
the lateral funiculus
the ventral funiculus
The gray matter can be further subdivided into a series of layers called:
the laminae of Rexed
What layers form the dorsal horn?
Layer 1
Layer 2
Layer 3
Layer 4
What is the dorsal horn related to?
sensory input
What layers form the ventral horn?
Layer 7
Layer 8
Layer 9
What does the ventral horn have functions to?
the motor system
What is located at lamina 9?
the limb and trunk motor neurons
What lamina is found between the ventral and dorsal horns?
lamina 5
What is lamina 5 the site of?
pattern generators for limb movements
What lamina is small and not present at all levels?
lamina 6
What does the spinal cord receive sensory information from?
the skin, joints, and internal organs
The motor neurons in the spinal cord connect with and initiate activity in:
the muscles, blood vessels, and internal organs
The brain sends what to control motor neurons in the SC
nerve fiber bundles (tracts)
The mammalian spinal cord is made up of how many distinct anatomical and functional regions
6
what is the prebrachial anatomical/functional SC region for?
the neck
what is the brachial anatomical/functional SC region for?
the forelimb
what is the postbrachial anatomical/functional SC region for?
sympathetic outflow
what is the crural anatomical/functional SC region for?
lower limb
what is the postcrural anatomical/functional SC region for?
pelvic parasympathetic outflow
what is the caudal anatomical/functional SC region for?
the tail
What is the descending order of the anatomical/functional regions of the SC?
the neck
the forelimb
sympathetic outflow
lower limb
pelvic parasympathetic outflow
the tail
What spinal cord segments does the prebrachial region of the SC extend from?
C1 - C4
What spinal cord segments does the brachial region of the SC extend from?
C5 - T1
What spinal cord segments does the postbrachial region of the SC extend from?
T2 - L2
What spinal cord segments does the crural region of the SC extend from?
L3 - S1
What spinal cord segments does the
postcrural region of the SC extend from?
S2 - S4
What spinal cord segments does the caudal region of the SC extend from?
S5 - coccygeal segments
The spinal cord contains sophisticated pattern generators that can:
initiate different kinds of coordinated movements
Movement patterns generated in the spinal cord include
locomotion, posture, and balancing
Motor neurons in the SC initiate:
muscle fibre contraction and secretion of glands
What do motor neurons in the SC act as a final common pathway for?
motor function’s central and peripheral neural pathways
What are the 2 major functional groups of the motor neurons in the SC?
somatic
autonomic
What do somatic motor neurons innervate?
skeletal (voluntary) muscle
What do autonomic motor neurons innervate?
smooth muscles and glands
Where are somatic motor neurons located in the SC?
the ventral horn of the gray of the SC in lamina 9
What type of neurons are somatic motor neurons in the spinal cord?
large multipolar neurons
What do somatic motor neurons in the spinal cord stain well with?
acetylcholinesterase markers
NeuN markers
Why are lamina 9 motor neurons large?
because they each support a very long axon that runs to supply the striated muscles of the axial skeleton (muscles of the neck, trunk, and tail) and the muscles of the upper and lower limbs
What does the axon of lamina 9 motor neurons supply?
the striated muscles of the axial skeleton (muscles of the neck, trunk, and tail)
the muscles of the upper and lower limbs
The motor neurons innervating axial muscles are present at:
all spinal cord levels
the large motor neurons innervating limb muscles are only present at:
the level of origin of the upper limb nerves (C5 to T1 spinal cord segments in the human)
the level of origin of the lower limb nerves (L3 to S1 spinal cord segments in the human)
The autonomic motor neurons of the spinal cord can be divided into what two separate groups?
the preganglionic motor neurons of the sympathetic nervous system
the preganglionic motor neurons of the pelvic parasympathetic system
the sympathetic preganglionic motor neurons are found where in the SC?
T2 - L2 spinal cord segments
What are the 2 parts of the parasympathetic system in the CNS?
Cranial parasympathetic system
Sacral parasympathetic system