Chapter 14 - Spinal Cord & Spinal Nerves Flashcards
Gross anatomy of spinal cord?
Part of CNS, slender nerve column, 45 cm long, starts at foramen magnum and ends between L1 & L2, and there are 31 pairs of spinal nerves.
Overall structure of spinal cord?
Bilateral symmetry, consist of gray and white matter, central canal (hole down the center of cord continuous with brain ventricles), and 2 grooves.
What are the 2 grooves of the spinal cord?
Anterior median fissure and posterior median sulcus.
What are enlargements?
Swollen regions of the spinal cord.
What are the enlargement regions?
Cervical enlargement and lumbar enlargement.
What is the conus medullaris?
Inferior most tip of spinal cord and it is cone shaped.
What is the cauda equina?
It means horse’s tail, it is a bundle of nerves inferior to spinal cord.
What is the filum terminale?
inferior most spinal nerve.
What is gray matter?
Cell bodies, dendrites, synapses, and projections called horns.
How are the cell bodies organized in gray matter?
Into nuclei.
What are the 2 components of gray matter?
Interior horns and gray commissure.
What are the interior horns?
Posterior horn, anterior gray horn and lateral gray horn.
What are the gray commissures?
Anterior commissure and posterior commissure.
How are the commissures separated?
The central canal.
What are the components of white matter?
Posterior white column, anterior white column, lateral white column, ascending tract (sensory), and descending tract (motor).
What are meninges?
Membranes covering CNS and are similar in brain and spinal cord.
How meninges split?
Into layers called mater.
What are superficial to meninges?
vertebra and epidural space.
What is the epidural space?
Space between meninges and vertebra and contain BVs and adipose.
What are the types of spinal meninges?
Dura mater, arachnoid mater, and pia mater.
Dura mater characteristics?
“Tough mother”, durable, deep to epidural space, superficial to subdural space, and stabilized by coccygeal ligament.
Arachnoid mater characteristics?
“Spidery mother”, superficial to subarachnoid space (contains CSF), and CT looks like a spider web.
Pia mater characteristics?
“Delicate mother”, lightl layer adhering to cord, and forms part of filum terminale.
The layers of the meninges (Vas Eats Daily So Anthony Sees Poop Nuggets?
Vertebra, epidural space, dura mater, subdural space, arachnoid layer, subarachnoid space (with CSF), pia mater, and neural tissue.
How many spinal nerve pairs are there?
31.
Number of pairs per region of spine?
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
2 nerve components?
Dorsal root and ventral root.
Dorsal root characteristics?
Dorsal root ganglion (houses soma) and usually sensory.
Ventral root characteristics?
No ganglion and usually motor.
All roots go through what?
Intervertebral foramina?
Do roots merge?
Yes , they merge to form nerves.
What are the types of connective tissue coverings of nerves?
Epineurium, perineurium, and endoneurium.
What is the epineurium?
Surrounds the entire nerve.
What is the perineurium?
Surrounds bundles of 10 - 100 axons (known as fascicles).
What is the endoneurium?
Surrounds each individual axon of each neuron.
How are spinal nerves organized?
Rami, which are offshoots of a nerve once it exits the vertebra.
What are the types of rami?
Dorsal ramus, ventral ramus, and ramus communicantes.
What are rami communicantes?
Splitting in the ramus separating sensory and motor fibers.
What are the types of rami communicantes?
White ramus communicantes and gray ramus communicantes.
What are dermatomes?
Sensory innervation by specific spinal nerves.
Characteristics of dermatomes?
Spinal cord damage will result in loss of sensation in dermatome and it is the detection method.
What are nerve plexuses?
Braid of ventral rami.
Where are nerve plexuses found?
Cervical, lumbar, sacral regions, and most thoracic nerves are all isolated.
What is the cervical plexus?
C1 - C4 & part of C5.
What does the cervical plexus innervate?
Certain muscles of neck and torso.
Main nerve of cervical plexus?
Phrenic, C3, 4, & 5, goes to diaphragm.
What is the brachial plexus?
C4 - C8 & T1.
What does the brachial plexus innervate?
The chest, upper back, and arm.
What are the nerves of the brachial plexus?
Musculocutaneous, ulnar nerve, median nerve, and radial nerve.
Where does the musculocutaneous nerve go?
To anterior muscles of arms & skin of forearm.
Where does the ulnar nerve go?
To muscles of forearm, hands & skin of hands.
Where does the median nerve go?
To muscles of forearm, hands & skin of hands.
Where does the radial nerve go?
To posterios muscles of arms & skin of forearms & hands.
What is the lumbsacral plexus?
The last thoracic, lumbar, sacral & coccygeal nerves and may be split into lumbar and sacral plexuses?
What does the lumbosacral plexus innervate?
The lower limb regions.
What are the nerves of the lumbosacral plexus?
Obturator nerve, femoral nerve, and sciatic nerve.
Where does the obturator nerve go?
To adductors of leg.
Where does the femoral nerve go?
Motor impulses to leg & thigh & receive sensory from skin of leg & thigh.
Where does sciatic nerve go?
To muscles & skin in thighs, legs & feet.
Characteristics of reflexes?
Rapid automatic involuntary motor response to stimuli, help preserve homeostasis, occur at spinal cord, DO NOT require cerebral processing, and can be modified by cerebral control.
How are reflexes classified?
By development, site of processing, nature of motor response, and complexity of neural circuit.
Types of reflexes based on development?
Genetically (built in) and learned (acquired).
Types of reflexes based on site of processing?
Spinal reflex (impulse goes to spinal cord) and cranial reflex (makes it to brain).
Types of reflexes based on nature of motor response?
Somatics (skeletal movement) and Visceral or autonomic (involluntary movements).
Types of reflexes based on complexity of neural circuit?
Monosynaptic = 1 and polysynaptic = > 1.
What are the steps of a reflex arc (5)?
- The receptor is stimulated by a detectible environmental stimulus.
- The receptor stimulates a sensory neuron that sends a signal to the CNS for processing.
- The information is processed by being transmitted to the appropriate neurons.
- A motor neuron is stimulated and sends response to effector.
- The effector responds to the stimulation.
What is the stretch reflex?
A reflex stimulated by the stretching of a muscle.
What are muscle spindle fobers?
Receptors that detects stretching.
What is the effector of the stretch reflex?
The contraction of the muscle.
What type of reflex is the patellar reflex?
Stretch reflex.
What are the functions of the patellar reflex?
Prevent muscles from being overstrecthed and prevent one from falling forward.
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