Anatomy - Ch 17 (Spinal cord)
polysynaptic reflex
A reflex invovling one or several interneurons.
Epineurium
Dense connective tissue that surrounds entire nerve including fascicles and blood vessels.
rootlets
Spinal nerves initially arise from the spinal cord as
gray and white commissures
axons that cross from one side of the spinal cord to the other
fascicle or fasciculi
bundle of muscle fibers
sensory nerve
dorsal root (enters)
Median nerve injury
opponens splint, C-bar or thumb post splint
Which of these is NOT a region of the spinal cord?
pelvic
spinal reflexes
simple pathways in the nervous system that rapidly generate muscle contractions
posterior (dorsal) gray horn has 2 parts:
somatic (skeletal muscle) portion visceral (organs) portion
anterior (ventral) white column
somatic motor tracts, anterior (ventral) surface of spinal cord
conus medullaris
tapered end of spinal cord
motor nerve
ventral root (exits)
autonomic reflexes
(visceral) regulate the activity of smooth muscles, the heart, and glands
dorsal root ganglion
- cell bodies of sensory neurons - glial cells here are satellite cells
mixed spinal nerve
- nerve that is formed of dorsal and ventral roots - sensory (afferent) = brings sensory to the CNS -motor (efferent) = brings commands way from CNS to visceral (organs)
length of adult spinal cord
42-45 cm (16-18 in)
reflex arc
A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus, often without conscious brain involvement.
denticulate ligaments
Specializations of the pia mater that anchor the spinal cord to the dura mater and limit the movement of the cord.
filum terminale
anchors spinal cord to coccyx
In the spinal cord, the somas (cell bodies) of the lower motor neurons are found in the:
anterior horns
Dermatomes
are skin segments that relate to sensory innervation regions of the spinal nerves
The nerve branching off of C5 can belong to both the _________ and ________ plexuses.
cervical; brachial
Ulnar nerve injury
claw hand
Perineurium
connective tissue that bundles fibers into fascicles
motor (descending) tracts
consist of axons that carry nerve impulses from the brain and away
sensory (ascending) tracts
consist of axons that conduct nerve impulses toward the brain
arachmoid mater
contains CSF in the middle
Endoneurium
delicate connective tissue around each axon
The following helps prevent lateral and inferior movement of the spinal cord:
denticulate ligaments
The ____________ is the outermost meninx, and forms supportive and protective partitions between some portions of the brain.
dura mater
Meninges
dura mater, arachnoid mater, pia mater
Lumbar Plexus (L1-L4)
femoral nerve
Further you go down the spinal cord what gets larger?
gray matter
superior trunk
roots: C5 & C6 cords: posterior & lateral nerves: musculocutaneous & median
middle trunk
roots: C7 cords: posterior & lateral nerves: axillary & radial
inferior trunk
roots: C8 & T1 cords: posterior & medial nerves: ulnar & median
posterior (dorsal) ramus
serves the deep muscles and skin of the posterior surface of the trunk
long thoracic nerve injury
winged scapula
Radial nerve injury
wrist drop
components of a reflex arc
1. sensory receptor 2. sensory neuron 3. integration center 4. motor neuron 5. effector
pia mater
Innermost layer of the meninges (delicate mother)
monosynaptic reflex
Reflex pathway with only one synapse between the sensory and motor neurons (ex: knee-jerk).
Cutaneous Fields
Regions of skin supplied by a specific nerve arising from a plexus
Sacral Plexus (L4-S4)
Superior gluteal nerve Inferior gluteal nerve Sciatic nerve • Tibial nerve • Common fibular (peroneal) nerve
Erb-Duchenne palsy
Superior trunk brachial plexus injury ("waiter's tip")
somatic reflexes
activation of skeletal muscles
Which cord is formed by all trunks?
posterior
all trunks form what?
posterior cord
cervical plexus
C1-C5
The superior trunk originates from the branches of which cervical nerve?
C5 and C6
brachial plexus
C5-C8, T1
The middle trunk arises from which cervical nerve(s)?
C7
phrenic nerve
innervates the diaphragm C3-C5
plexus
large, interlacing network of nerves
lateral white column
lateral part of white matter function: tissue through which messages pass between different areas of gray matter
lateral gray horn
located only in thoracic and lumbar segments, contains visceral motor nuclei -visceral portion
lumbar enlargement
nerves of pelvis and lower limbs (TII-L1)
dura mater
thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord (hard mother)
The longest nerve that innervates the digestive system is the:
vagus
The motor command leaves through the:
ventral root
spinal cord protected by
vertebral column and meninges
cranial reflexes
reflexes mediated by cranial nerves
central canal
CSF passes through
spinal cord
a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain. (31 segments)
anterior (ventral) gray horn
a section of gray matter that extends towards the anterior part of spinal cord, has motor neurons -somatic (skeletal muscle)
posterior (dorsal) gray horn
a section of gray matter that extends towards the posterior part of spinal cord, has sensory neurons -somatic (skeletal muscle) & visceral (organs)
patellar reflex (knee jerk)
reflex triggered by the knee tap 1. stretching stimulus sensory receptor (muscle spindle) 2. sensory neuron excited 3. within integrating center (spinal cord), sensory neuron activates motor neuron 4. motor neuron excited 5. effector (same muscle) contracts and relieves the stretching
anterior (ventral) ramus
serves the muscles and structures of the upper and lower limbs and the skin of the lateral and anterior surfaces of the trunk
Where in the spinal cord is the cerebrospinal fluid located?
subarachnoid space
cervical enlargement
supplies nerves to the shoulder and upper limbs (C4-T1)