Flashcards in Introduction to the Spinal Cord and Spinal Nerves Deck (57):
What two important functions do the spinal cord and its attached spinal nerves have?
1) Is a pathway for sensory and motor impulses.
2) Is responsible for reflexes.
What embryological tissue does the spinal cord develop from?
The spinal cord develops from ectoderm (neuroectoderm/neuroepithelium).
True or False:
The neural groove forms in the neural plate.
Is the notochord on the ventral or dorsal side of the neural plate?
On the ventral side of the neural plate. During the development, the neural tube develops between the notochord and the epidermis.
What does the alar plate develop into?
The alar plate (dorsal plate) develops into the dorsal horn (sensory).
What does the basal plate develop into?
The basal plate (ventral plate) develops into the ventral horn (motor).
What type of nerves originate from the lateral gray column (lateral horns)?
Autonomic (sympathetic and parasympathetic)
What makes up the gray matter?
Is an afferent signal from a sensory or motor neuron?
An afferent signal is from the sensory nerve coming back to wards the spinal cord to synapse with the interneurons of the gray matter.
Is an efferent signal from a sensory or motor neuron?
An efferent signal is from the motor nerve travelling to whichever muscle. This efferent signal was initiated from an afferent signal that was linked to a motor neuron (efferent signal) via an interneuron in the gray matter.
What do interneurons do?
They link the communication between the sensory and motor neurons. Thus, they are located in the gray matter in-between the dorsal and ventral horns.
What makes up the white matter?
axons form white matter
What are the two enlargements of the spinal cord?
How many pairs of spinal nerves are there?
31 pairs of spinal nerves
Are the cervical and lumbar enlargements visible in a 3 month old fetus?
Which two important plexus originate from the cervical enlargement?
Cervical Plexus and Brachial Plexus
From which region of the spine does the intercostal nerves originate?
Which two important plexus originate from the lumbosacral enlargement?
Lumbar Plexus and Sacral Plexus
Which of the 4 regions of the spinal cord have a parasympathetic outflow?
Sacral Region --> which is the sacral parasympathetic outflow.
Which 2 of the 4 regions of the spinal cord has a sympathetic outflow?
The thoracic region (thoracic sympathetic outflow) and the lumbar region (lumbar sympathetic outflow).
Name the 3 meningeal coverings going from superficial to deep.
Dura mater --> Arachnoid mater --> Pia mater
In which space between the meningeal coverings is cerebral spinal fluid found?
In which space do anesthesiologist give pregnant women a nerve block?
Between which two meningeal coverings is the subdural space found?
Dura mater and Arachnoid mater
True of False:
The ventral root goes through a ganglion before joining with the dorsal root to make the spinal nerve.
False --> The dorsal root goes through a dorsal root ganglion before joining the ventral root to make the spinal nerve.
What ligament anchors the spinal cord to the dorsal sac? Also, which meningeal covering is this a continuation from?
This ligament is part of the Pia mater.
Which foramen does the spinal nerves exit through from the spinal cord?
What are the two branches the spinal cord splits into?
Ventral (anterior) and Dorsal (posterior) Ramus
What is the difference between a root and a ramus?
A root carries either sensory or motor neurons (dorsal or ventral root) and a ramus can carry both motor and sensory at the same time.
What is the Filum Terminalis? Also, what is it connected to?
The Filum Terminalis anchors the spinal cord to the sacrum and is a continuation of Pia mater covering the spinal cord. The filum terminalis begins at the conus medullaris, which is where the spinal cord ends.
Between what vertebra does the conus medullaris end in adults, and between what vertebra does it stop in newborns?
Adults --> conus medullaris ends between the 1st and 2nd lumbar vertebra (it can also end between T12 and L1 too, just depends on the person).
Newborns --> conus medullaris ends between the 2nd and 3rd lumbar vertebra.
What is the function of spinal nerves?
To provide a direct link between the CNA and organ systems in the body.
Is the ventral ramus or dorsal ramus smaller in size?
The dorsal ramus is smaller in size.
Which epaxial group of muscles does the dorsal ramus nerves innervate?
The intrinsic muscles of the erector spina group.
How is the sympathetic truck connected to the spinal cord?
By the gray and white rami connumicantes. Thus, the sympathetic truck is a collection of ganglion that are connected to the spinal nerve via the rami communicantes.
What is a dermatome?
An area of skin innervated by the sensory fibers of a single nerve root.
What is a myotome?
an group of muscles that is primarily innervated by the motor fibers of a single nerve root.
What are the 3 main ways in which spinal nerves are distributed in the body?
1) Intercostal nerves (anterior rami)
2) Dorsal rami
3) Nerve Plexuses (anterior rami)
What are the different subunits of intercostal nerves?
* anterior rami
* intercostal spaces
* lateral branches
* anterior branches
* intercostobrachial nerve (T2)
* subcostal nerves (T12)
True or False:
Anterior rami of most spinal nerves form nerve plexuses on both the right and left sides of the body.
What is the basic description of a spinal nerve plexus?
A network of interweaving anterior rami of spinal nerves.
What roots make up the cervical plexus?
C1, C2, C3, and C4
What are the roots of the brachial plexus?
Roots for the brachial plexus C5, C6, C7, C8, and T1.
What's the order of the brachial plexus starting with roots and ending with branches?
Roots -> Trunks -> Divisions -> Cords -> Branches
What are the 5 terminal branches (nerves) of the brachial plexus?
Which 3 terminal branch nerves come together to form the common "M" of the brachial plexus?
*Hint: They come from the anterior division and continue through both the lateral and medial cords where they then join to form the "M" and become terminal branches.
Musculocutaneous nerve, median nerve, and the ulnar nerve.
What are the names of the two terminal branch nerves that come through the posterior division and continue through the posterior cord before splitting into the two terminal branch nerves that lie just deep to the common "M" of the brachial plexus?
Axillary nerve and Radial Nerve
What region are the terminal branches of the brachial plexus in?
The axillary region
Do the roots of the brachial plexus come from the dorsal rami of C5 - T1?
NO, the roots come from the ventral rami of C5 - T1.
What does the lumbosacral trunk do?
It connects the lumbar and sacral plexi.
What vertebral roots make up the sacral plexus?
L4, L5, S1, S2, S3, and S4
Is the pudendal nerve from the anterior division or the posterior division in the sacral plexus.
The anterior division.
What nerves in the sacral plexus are in the posterior division?
superior gluteal nerve
inferior gluteal nerve
nerve to piriformis
common fibular division of the sciatic nerve.
Is the tibial division of the sciatic nerve from the anterior or posterior division in the sacral plexus?
The anterior division in the sacral plexus.
What division is the posterior femoral cutaneous nerve in?
anterior division of sacral plexus.
In normal pathology, does the sciatic nerve exit superior or inferior to the piriformis muscle?
Inferior to the piriformis muscle.