Unit 10 Flashcards
2 functions of the spinal cord
- Essential structural and functional link between brain and torso and limbs. Inputs and outputs. Information goes up and down the spinal cord
- Spinal reflexes. Iniate fastest reaction to stimulus. Ex you touch something hot you immediately take your hand off.
(carries input and output)
Cranial Meninges
Dura mater
Arachnoid mater
Pia mater
Dura Mater
thick, fibrous heavy layer than forms a tough sac that encloses cord. 2 spaces associated, subdural space (internal) and epidural space (external)
Arachnoid mater
up against dura mater. Partially exposed of delicate web. Immediately deep is the subarachnoid space.
Pia Mater
pressed up against the cord supplies nutrients to cord. External, mesh like made up of elastic and collagen fibres
Epidural space
runs outside the dura mater
Subdural space
Between the dura and arachnoid
Subarachnoid space
Between cord and arachnoid mater, where CSF circulates
Gray matter
is formed from neuronal cell bodies and dendrites (no myelin). Functional process center. Resembles an H or a butterfly.
Anterior Gray horn
part of the spinal gray matter which is situated ventral to the central canal. It is motor in function and is the place where motor information exits from the central nervous system through efferent neurons to reach out to the effector organs, including muscles and glands.
Lateral gray horn
the central component of the sympathetic division of the autonomic nervous system.
posterior gray horns
part of the spinal gray matter which is situated dorsal to the central canal. It is sensory in function and is the place where information from the body surface and underlying tissues first reaches the central nervous system.
White matter
formed of aggregations of myelinated axons from many neurons (The lipid part of myelin imparts the white appearance) (fatty substance) (info transmits) (delivering)
Sensory pathways
Nerve signals ascend to the brain in sensory pathways
Primary nerve
First neutron in the chain, Extends from sensory receptors to CNS where it synapses with a secondary neuron
Secondary Neuron
an interferon. It extends from the primary neutron to either tertiary or cerebellum
Teritary
Also interneuron. It extends from the secondary neutron to the cerebellum. Pathways that lead to the cerebellum of non have tertiary neurons
posterior funinculus-medial lemniscal pathway
transmits information about discriminative touch and proprioception (uses 3 chain)
anterolateral pathway
detects crude touch, pressure, pain, and temp. 3 chain.
Spinothalamic tract
a sensory tract that carries nociceptive, temperature, crude touch, and pressure from our skin to the somatosensory area of the thalamus.
Spinocerebellar Pathway
Only uses 2 chains to transmit. The sensory input provides information to the brain (maintain balance and posture)
Motor Pathways
Start in brain and works its way down. Begins in the primary motor areas of the brain
Upper Motor Neurons
connects to the appropriate level in spinal cord. Info tells muscle to start to move.
Lower motor Neurons
descend to innervate skeletal muscle. The entire function of the CNS is manifested through the lower motor neuron.
Endoneurium
surrounds axon
Fascicles
bundles of axon
Perineurium
surrounds fascicles
nerves
bundles of fascicles
Epineurium
surround nerve
Reflex arc
a neural pathway composed of neurons that control rapid, subcutaneous, preprogrammed responses to a stimulus.
Spinal reflexes
a fast, involuntary response to a stimulus. In a spinal reflex the integration takes place in the spinal cord, not the brain
Spinal reflexes involve
stimulus, rapid, preprogrammed, involuntary
monosynaptic
has only a sensory and a motor neurone and lacks an interneuron. There is direct communication between sensory and motor neurons
Polysynaptic
has one or more inter neurons positioned between the sensory and the motor neurons. These reflex arcs are more complicated and not as rapid. Interneurons facilitate sensory-motor communication.
Stretch reflex
causes contraction of a skeletal muscle -Monosynaptic reflex arc. Initated by a muscle spindle.
Steps in stretch reflex
- muscle spindle detects stretch
- muscle stretch stimulates sensory nerve signals to travel to the CNS
- sensory nerve directly stimulates a motor neuron
- motor neurons transmit nerve signals to extramural muscle fibres resulting in contraction of the muscles
- Interneurons synapse with a motor neuron antagonist muscle inhibiting muscle contraction
tendon reflex
(Golgi tendon reflex) Is initiated by Golgi tendon organ proprioceptor
1. muscle contraction increases tension to tendons by Golgi tendon organ
2. nerve signals are propagated along sensory neurones to the CNS
3. sensory neurones stimulate interneurons within the spinal cord
4. Interneruson inhibit a motor neuron to muscle
4b. interneurons stimulate a motor neurons to antagonist muscle
5. muscle relaxes and there is a relief of tension on tendon
5b. Muscle contracts
Withdrawl reflex
often occurs when contracting a body part from a painful stimulus.
Crossed-Extensor reflex
occurs in conjunction with the withdrawal reflex. Usually the lower limbs.
how many pairs of spinal nerves
31
what are all the spinal nerves
8 cervical, c1-c8
12 thoracic, T1-T12
5 lumbar, L1-L5
5 Sacral, S1-S5
1 coccygeal
Anterior root
contains motor neurons that extend to effectors. Relay nerve signals from the spinal cord and control effectors. Does not contain ganglion.
posterior root
houses sensory neurons that extend from sensory receptors relay receptors to the spinal cord. Positioned along the length of the axon. They are located external to spinal cord and form the posterior root ganglion
