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spinal cord

a mass of nerve tissue located in the bertebral canal from which 31 pairs of spinal nerves originate

spinal nerves

one of the 31 pairs of nerves that originate on teh spinal cord from posterior and anterior roots

relfexive responses (REFLEX)

fast reponse to a change (stimulus) in the internal or external environment that attempts to restore homeostasis


That portion of the nervous system that consists of the brain and spinal cord

spinal cord reflexes

when integration takes place in the spinal cord gray matter, example is patellar reflex (knee jerk),

integrating center

one or more regions of gray matter within the CNS act as an integrating center. Symplest type of reflex, it is a single synapse between a sensory neuron and a motor neuron

vertebral column

The 26 vertebrae of an adult and 33 vertebrae of a child; encloses and protects the spinal cord and serves as a point of attachment for the ribs and back muscles AKA backbone, spine, or spinal column

vertebral canal

a cavity within the vertebral column formed by the vertebral foramina of all the vertebrae and containing the spinal cord AKA spinal canal


three membranes covering the brain and spinal cord, called the dura mater, arachnoid mater, and pia mater Singular is meninx

dura mater

the outermost of the three meninges (coverings) of the brain and spinal cord

arachnoid mater

the middle of the three meninges (coverings) of the brain and spinal cord. AKA arachnoid

pia mater

the innermost of the three meninges (coverings) of the brain and spinal cord

subarachnoid space

a space between the arachnoid mater and the pia mater that surrounds the brain and spinal cord through which cerebrospinal fluid circulates

subdural space

a space between the dura mater and the arachnoid mater of the brain and spinal cord that contains a small amount of fluid

denticulate ligaments

******finely toothed or serrated; characterized by a series of small, pointed projections, dense regular connective tissue that attaches bone to bone

cerebrospinal fluid

A fluid produced by ependymal cells that cover choroid plexuses in teh ventricles of the brain; the fluid circulates in the ventricles, the central canal, and the subarachnoid space around the brain and spinal cord


the superficial connective tissue covering around an entire nerve


a small bundle or cluster, especially of nerve or muscle fibers (cells). AKA a fasciculus. Plural is fasciculi


connective tissue wrapping around fascicles in a nerve


connective tissue wrapping around individual nerve axons

cauda equina

a tail-like array of roots of spinal nerves at teh inferior end of the spinal cord

cervical enlargement

when spinal cord is viewed externally, the superior enlargement, extends from the fourth cervical vertebra to the first thoracic vertebra, nerves to and from the upper limbs arise from the cervical enlargement

lumbar enlargement

the inferior enlargement, extends from the ninth to the twelfth thoracic vertebra, nervews to and from the lower limbs arise form the lumbar enlargement

spinal segments

paths of communication between the spinal cord and specific regions of the body, 31 pairs, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 cocygeal nerves

pair of spinal nerves

each pair arises from a spinal segment, no obvious segmentation but the naming of spinal nerves is based on teh segment in which they are located, 8 cervical, 12 thoracic, 5 lumbar, 5 scral, 1 cocygeal nerves

reflex arc

the most basic conduction pathway through the nervous sytem, connecting a receptor and an effector and consisting of a receptor, a sensory neuron, an integrating center in the central nervous sytem, a motor neuron, and an effector

stretch reflex

causes contraction of a skeletal muscle (the effector) in response to stretching of the muscle. this type of reflex occurs via a monosynaptic reflex arc. can occur by activation of a single sensory neuron tha forms one synapse in the CNS with a single motor neuron EX knee jerk

antagonistic muscles

stretches and yields to the effects of the prime mover

describe contributions of the spinal cord and spinal nerves to homeostasis

provide quick, reflexive responses to many stimuli. spinal cord is teh pathway for sensory input to the brain and motor output from the brain

what are reflexive responses

a reflex is a fast, automatic, unplanned sequence of actions that occurs in response to a particular stimulus.

describe the pathway for reflexive responses

Follow a reflex arc (reflex circuit) 1) sensory receptor, is the distal end of a sensory neuron serves as a receptor, responds to a stimulus, Sensory neuron- nerve impulses propagate form the sensory receptor along the axon of teh sensory neuron to the axon terminals, Integrating center- simplest type of reflex, integrating center is a single synapse between a sensory neuron and a motor neuron. Motor Neuron- impulses triggered by the integrating center propagate out of the CNS along a motor neuron to the part of teh body that will respond, Effector- part of teh body taht responds to the motor nerve impulse, action is called a reflex

what is the CNS

the portion of the nervous system that consists of the brain and spinal cord

list and describe the functions of the spinal cord & spinal nerves

control some of your most rapid reactions to environmental changes, reflexes-quick, automatic response to certain kinds of stimuli, besides processing reflexes, the gray matter of the spinal cord also is a site for integration (summing) of excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs), spinal cord has two functions: responder, highway/pathway to the brain (afferent goes toward the brain)

describe the organization of the connective tissue coverings of a spinal nerve.

endoneurium- individual axons within a nerve, whetere unmyelinated or myelinated, are wrapped in this the innermost layer, perineurium- groups of axons with their endoneurium are arranged in bundles called fascicles which are wrapped in this the middle layer, epineurium- outermost covering over the entire nerve

where are the blood vessels located in the connective tissue coverings of a spinal nerve

perineurium and epineurium

how are the connective tissue coverings of a spinal nerve similar to muscle tissue and how dot hey differ

In muscle tissue, perimysium is around the fascicles, and within the fascicles, the sarcolemma holds together myofibrils and mitochondrion, muscle tissue has mitochondrion and sarcoplasm and a nucleus in each fascicle in a spinal nerve the endoneurium is like the myofibrils and many of them are distributed, the perineurium holds all of the endoneuriums together just like the sarcolemma, and the epineurium surrounds all of them with a protective layer just like the perimysium, both have blood supplies

list and describe in sequential order the layers of protection of the spinal cord

vertebral column-provide a sturdy shelter for the ecnlosed spinal cord along with vertebral ligaments, meninges- three connective tissue coverings that encircle the spinal cord and brain, spinal meninges surround the spinal cord, cranial encircle the brain, duramater (most superficial) composed of dense irregular connective tissue forms a sac from the level of the foramen magnum in the occipital bone, to the second sacral vertebra, epidural space- cusion of fat and connective tissue, arachnoid mater- spider web arrangement of delicate colagen fibers and some elastic fibers, between the dura mater and the arachnoid mater is a thin subdural space which has interstitial fluid, innermost meninge is PIA mater- a thin transparaent connective tissue layer thaadheres to the surface of teh spinal cord and brain, many blood vessels, subarachnoid space- between the arachnoid mater and pia mater cerebrospinal fluid and serves as a shock absorber and suspension system , denticulate ligaments- thickenings of the pia mater that project laterally and fuse with the arachnoid mater and inner surface of the dura mater between the anterior and posterior nerve roots of spinal nerves on either side

where is cerbrospinal fluid formed and where does it circulate

formed in the ventricles and circulates through brain and spinal cord

how long is the spinal cord

42-45 cm

describe the structural features of the spinal cord discussed in class, and give the functions of each


list the sequence of events and structures involved in a reflex arc

sensory receptor responds to a stimulus, sensory neuron propogates from the receptor along the axon of the sensory neuron to the axon terminals, integrating center is a either a monosynaptic or polysynaptic reflex arc involves one/many types of neurons and CNS synapse, motor neuron propagate out of the CNS along a motor neuron to the part of the body, Effector responds to the impuse

list the sequence of events and structures involved in the stretch reflex

stretching stimulates sensory receptors called muscle spindes, in response, a muscle spindle generates one or more nerve impulses that travel along a somatic sensory neuron through the posterior root of the spinal nerve and into the spinal cord, in the spinal cord, sensory neuron makes an excitatory synapse with and thereby activates a motor neuron in the anterior gray horn, if excitation is strong enough, one or more nerve impulses are sent to the stimulated muscle, the axon terminals of the motor neuron form neuromuscular junctions with skeletal muscle fibers of the stretched muscle, acetylcholine released by nerve impulses at the NMJs triggers one or more muscle action potentials in the stretched muscle (effector) and the muscle contracts.

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