Exam 2: Unit V: Spinal Nerves, Cervical Plexus Flashcards
How many pairs of spinal nerves are there and their categories?
31 pairs
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
How are the spinal nerves attached to the spinal cord?
- Anterior (ventral or motor) rootlets (roots)
- Posterior (dorsal or sensory) rootlets (roots)
What are the other names for the anterior rootlets?
ventral or motor
What are the other names for the posterior rootlets?
dorsal or sensory
What type of spinal nerves are the axons carried in that cell bodies reside in the CNS?
located in anterior (ventral) or lateral (if present) horns
How do the anterior roots attach to the spinal cord?
by a series of rootlets
Where are the cell bodies located for the axons carried in the posterior (dorsal or sensory) roots?
in the PNS in DRG (or posterior root ganglion or spinal ganglion)
How do the psoterior roots attached to the spinal cord?
separates into a number of rootlets that attach to the cord at the posterolateral sulcus
Where are spinal ganglion typically located?
inside or just medial to intervertebral foramen, beyond the dura mater (therefore covered by epinerium)
(3 exceptions)
What are the three exceptions to the statement that spinal ganglion are typically located inside or just medial to IVF, beyond dura mater?
- C1 and C2 ganglia are located on their respective vertebral arches
- Sacral ganglion located w/in vertebral canal and beyond dura
- Coccygeal loacted inside dura mater w/in vertebral canal
Where are C1 and C2 ganglia located?
on their respective vertebral arches
Where are sacral ganglion located?
WITHIN the vertebral canal, but still beyond the dura
Where are coccygeal ganglion located?
INSIDE the dura mater WITHIN the vertebral canal
What do the anterior and posterior rootlets combine and form?
a mixed spinal nerve
Shortly after the rootlets form a mixed spinal nerve, what branch is given off?
meningeal (or recurrent meningeal or sinuvertebral) branch
What type of fibers does the meningeal (recurrent meningeal or sinuvertebral) branch carry?
postganglionic sympathetics and somatosensory
T/F. Meningeal (recurrent meningeal or sinuvertebral) branches are present at ALL spinal levels.
True
How do the meningeal nerves re-enter the vertebral canal? Then what happens?
re-enter via IVF
divide into ascending, descending, and transverse branches
What does the meningeal nerve provide somatosensory and post. gang. sympathetics to?
- dura
- blood vessels
- periosteum (vertebral end plates)
- ligaments
- IVDs**
in ant. and lateral portions of canal
What does the mixed spinal nerve divide into?
two (primary) rami
- Posterior (dorsal) primary rami
- Anterior (ventral) primary rami
T/F. The anterior primary rami splits into a lateral and medial branch.
False–the POSTERIOR primary rami does
What does the posterior primary rami split into? Is there an exception?
lateral and medial branches (EXCEPT C1)
T/F. The posterior primary rami is smaller than the anterior primary rami in all cases.
False– yes posterior primary rami is usually smaller, except C1, S4, and S5
What are the exceptions to the posterior primary rami being smaller than the anterior primary rami?
C1, S4. S5
What is the exception, where the posterior primary rami does not split into a lateral and a medial branch?
C1
What does the posterior primary rami have motor supply to? What about sensory innervation?
motor–> deep back muscles
sensory–> skin on either side of spine
What does the anterior primary rami have motor supply to?
- anterior and lateral trunk muscles
- skeletal muscles in extremities
What does the anterior primary rami have sensory supply to?
- skin of extremities
- skin of anterior and lateral trunk
Does the posterior and anterior primary rami contribute to the great plexuses?
anterior primary rami do
Where are the sympathetic chain communications located?
either at or just medial to the bifurcation of the mixed spinal nerve
What type types of communicans does the sympathetic chain consist of?
- white ramus communicans
- gray ramus communicans
What type of axons does the white ramus communicans carry?
myelinated axons that are preganglionic sympathetic fibers
T/F. The anterior primary ramus communicated with the sympathetic chain
true
What type of axons does the gray ramus communicans carry?
unmyelinated postganglionic sympathetic axons
Where are the cell bodies located located for the white ramus communicans?
lateral horn cells at cord levels T1-L2/L3
ass. with sympathetics ONLY–>therefore cannot be found at S2,S3,S4
What are the type options for the preganglionic sympathetic fibers when they enter the sympathetic chain?
- synapse
2. go through and be carried in Splanchnic Nerves (Greater, Lesser, or Least)
What type of fibers do Greater, Lesser, and Least Splanchnic nerves carry?
postganglionic sympathetic fibers
What nerve levels are white ramus communicans ONLY associated with?
T1-L2
What nerve levels are gray ramus communicans ass. with?
each spinal nerve!!!!
Where are the cell bodies located of the gray ramus communicans? Where are these axons going?
sympathetic chain; go to spinal nerve
What are the cervical posterior rami?
C1 (suboccipital nerve)
C2 (splits into medial and lateral branches)
C3 (splits into medial and lateral branches)
C4-C8 (splits into medial and lateral branches)
T/F. It holds true that from C2-C8 of the cervical posterior rami will split into a medial branch carrying sensory and a lateral branch carrying motor.
True
T/F. All of the cervical posterior rami split into a medial and lateral branch.
False- C1 does NOT split
What is another name for the cervical posterior rami of C1?
suboccipital nerve
What cutaneous supply does C1 posterior ramus carry?
none– it only has motor supply (therefore NOT ass. with cutaneous or dermatome level)
What does C1 posterior ramus have motor supply to?
Suboccipital muscles
- Rectus capitus posterior major and minor
- Obliquus capitis superior and inferior
- Semispinalis capitis
What does C2 posterior ramus’ medial branch supply?
sensory to posterior neck and scalp
call Greater occipital nerve
What is another name for the medial branch of C2 posterior ramus?
Greater occiptial nerve
What does the lateral branch of C2 posterior ramus supply?
motor to:
- semispinalis capitis
- longissimus capitis
- splenius capitis
(same as C3’s lateral branch)
What is another name for the medial branch of C3 posterior ramus?
least (third) occipital nerve
What does the medial branch of C3 posterior ramus supply?
sensory for skin of posterior neck
What does the lateral branch of C3 posterior ramus supply?
(Same as C2)–Motor to:
- semispinalis capitis
- longissimus capitis
- splenius capitis
What does the medial branch of the C4-C8 posterior ramus supply?
sensory of skin over posterior neck (same as C3)
What does the lateral branch of the C4-C8 posterior ramus supply?
motor to:
- iliocostalis cervicis
- longissimus cervicis
- capitis
