Chapter 13 Spinal Cord
processes reflexes
Spinal cord funct
Conducts sensory impulses to the brain and motor impulses to the effector
Spinal cord funct
Integrated EPSPs and IPSPs
Spinal cord funct
Process Reflex
quick, automatic response-only involves spinal cord and spinal nerves
Integrated EPSPs and IPSPs
graded potential produce when neurotransmitter interact at synapse with receptors in spinal cord-gray matter of spinal cord
Conduct sensory impulses
white matter of the spinal cord contains motor and sensory input to the brain and motor output from the brain to muscle and other effectors
Subarachnoid Space
between the arachnoid and pia matter filled with cerebospinal fluid which provide some shock absorption
Cervical Enlargement
nerves of the upper extremities emerge
Lumbar Enlargement
nerves to the lower extremities emerge
filum terminale
an extension of the pia mater arising from the conus medullaris that fuses with the arachnoid and dura maters to anchor the spinal cord to the coccyx
Anterior (ventral) roots/rootlets
contains axons of motor neurons that conduct impulses from the CNS to effector
Posterior (dorsal) root/rootlets
contains only sensory neurons conducting impulses from sensory receptors in the skin, muscles, and internal organs to the CNS
each root has a root ganglion containing cell bodies of the sensory neurons
Posterior (dorsal) root/rootlets
resembles a "horse tail"
Cauda equina
Cauda equina
nerve roots that angle inferiorly along the filum terminale
Gray commissure
connect the two sides of gray matter
Central Canal
small space in the gray commisure that contains cerebrospinal fluid
Gray Matter (Horns)
divided on either side of spinal cord into regions
Posterior (dorsal) gray horns
sensory neurons
Anterior (ventral) gray horns
motor neurons
Lateral gray horn
autonomic motor nuclei
Anterior (ventral) white column (funiculus)
White matter region
Posterior (dorsal) white column (funiculus)
White matter region
Lateral white column (funiculus)
White matter region
Mixed Nerve
spinal nerve because it contains both sensory and motor axons
Endoneurium (Spinal Nerve C.T.)
surrrounds each axon within a nerve, whether its myelinated or unmyelinated
Perineurium (Spinal Nerve C.T.)
groups of axons are bundled into fasicles which are surrounded by the perineurium connective sheath
Epineurium (Spinal Nerve C.T.)
surrounds entire nerve
Conus Medullans
where the spinal cord terminates inferiorly to the lumbar enlargement and ends at the intervertebrae disc L1 and L2
a conical structure
Conus Medullans
Posterior (dorsal) ramus (spinal nerve branch)
serves deep muscles and skin of posterior trunk
Anterior (ventral) ramus (spinal nerve branch)
serves muscles/structures of upper and lower limbs and skin of anterior and lateral trunk
Meningeal Branch (spinal nerve branch)
reenters vertebral cavity and supplies vertebrae, meninges and vertebral ligaments
Rami Communicantes
component of the ANS
Dermatomes
segments of the skin that are supplied by spinal nerves that carry somatic sensory nerve imulses to the brain
Motor Output
from the spinal cord to skeletal muscles involves somativ motor neurons of the anterior gray horn
Intercostal (thoracic) nerves
anterior rami of spinal nerves T2-T12; doesnt form plexus
supply structures in the intercostal spaces
Intercoastal (thoracic) nerves
Plexus
networks with anterior rami adjacent nerves
Cervical Plexus
supplies the skin and muscles of the head and neck, superior portion of shoulders and chest, diaphragm
Brachial plexus
provides almost the entire nerve supply to the shoulder and upper limbs
Lumbar plexus
supplies the anterclateral abdominal wall, external genitalia, and part of the lower limbs
Sacral Plexus
supplies the buttocks, perineum, and lower limbs
Direct Motor Pathways (pyramidal pathways)
convey impluses from cerebral cortex of brain to cause voluntary movements of skeletal muscles
Indirect Motor Pathways (extrapyramidal pathways)
convey impulses from the brain stem of the brain to cause autonomic movements and help the body coordinate body movements with visual stimuli
Reflex Arc
pathway which nerve impulse follows to produce reflex
Sensory receptor (reflex arc)
responds to a stimulus by producing a generator or receptor potential
Sensory Neuron (reflex arc)
axon conducts impulses from receptorto integrating center
Integrating Center (reflex arc)
one or more regions within CNS that relay impulses from sensory to motor neurons
Motor Neuron (reflex arc)
axon conduct impulses from integrating center to effector
Effector (reflex arc)
muscle or gland that responds to motor impulses
Reciprocal Innervation
neural circuit when one muscle contracts and its antagonist relaxes at the same time
Shingles
acute infections of the nervous system cause by herpes zoster (chicken pox), lays in posterior root ganlion, occurs when immune sytem is weakened
Poliomyelitis
can cause paralysis due to virus destroying cell bodies of motor neurons
Tendon reflex
causes relaxation of the muscle attached to the stimulated tendon
prevents muscle force from becoming strong enogh to tear tendon and can override the stretch reflex when tension is too great
Tendon reflex