Spinal Nerves Flashcards
How many pairs of spinal nerves are there?
31 pair
How many cervical nerve pairs?
8 pair
How many thoracic nerve pairs?
12 pair
How many lumbar nerve pairs?
5 pair
How many sacral nerve pairs?
5 pair
How many coccygeal nerve pairs?
1 pair
Where are the cervical nerves found in relationship to the vertebrae?
found ABOVE the vertebrae
Where are the rest of the spinal nerves found in relationship to its vertebrae?
found BELOW the vertebrae
How are the spinal nerves attached to the cord?
via anterior and posterior roots
What are other names for the anterior roots of the spinal nerves?
ventral or motor
What are other names for the posterior roots of the spinal nerves?
dorsal or sensory
What do the anterior/ventral/motor roots carry?
efferent axons
Where are the cell bodies of the efferent axons found?
anterior (ventral) or lateral (if there) horns
Where are efferent neurons found?
anterior/ventral/motor roots
How are the anterior and posterior roots attached to the cord?
via a series of rootlets
What do the posterior/dorsal/sensory roots carry?
afferent axons
Where are afferent spinal cell bodies found?
posterior (dorsal) root ganglion (spinal ganglion)
Where do the posterior roots attach to the cord?
posterolateral sulcus
Where are the spinal ganglia found?
inside or just medial to the intervertebral foramen, beyond the dura mater
Where are the C1 and C2 ganglia located?
at their respective vertebral arches
Where are the sacral ganglia found?
within the vertebral canal
Where are the coccygeal ganglia found?
inside the dura mater
T/F: the anterior and posterior roots combine to form a mixed spinal nerve?
True
What nerve is given off right after the roots become a mixed spinal nerve?
meningeal (recurrent meningeal/sinuvertebral) branch
What is the 1st branch given off of the mixed spinal nerve?
meningeal branch
Where is the meningeal branch present?
at all spinal levels
Where does the meningeal branch reenter the vertebral canal?
through the IVF
What does the meningeal branch divide into in the IVF?
ascending, transverse, and descending branches
How are the meningeal branches classified?
somatosensory and sympathetic
What do the meningeal branches supply?
dura, blood vessels, periosteum, ligaments and intervertebral discs in anterior and lateral portions of the canal
What area of the canal does the meningeal branches supply?
anterior and lateral portions of the canal
What does the mixed spinal nerve divide into?
posterior (dorsal) primary rami
anterior (ventral) primary rami
What does the posterior/dorsal primary ramus divide into?
lateral and medial branches (except C1)
How is the posterior primary ramus compare in size to the anterior primary ramus?
smaller except at C1, S4 and S5 levels
What does the posterior/dorsal primary ramus innervate?
MOTOR: to deep back muscles “paraspinal musculature”
SENSORY: skin on either side of spine
What does the anterior primary rami innervate?
MOTOR: anterior and lateral trunk muscles, skeletal muscles of the extemities
SENSORY: skin of the extremities as well as anterior and lateral trunk (proprioception too)
What do the anterior primary rami contribute to?
great plexuses (brachial, lumbar, sacral)
Where are the sympathetic chain ganglia found?
either at or just medial to the bifurcation of the mixed spinal nerves
What does the white ramus communicans carry?
myelinated axons
Where are the white ramus communicans cell bodies found?
lateral horn cells at cord levels T1-L2
What kind of fibers enter the sympathetic chain?
preganglionic sympatetic fibers
What do the preganglionic sympathetic fibers do in to sympathetic chain?
1) synapse at the same level (move up/down chain and synapse)
2) pass right on through and synapse in greater/lesser/least splanchnic nerves
What nerves pass right on through the sympathetic chain?
splanchnic nerves
What do the gray ramus communicans carry?
unmyelinated postganglionic sympathetic axons
Where are the cell bodies of the gray ramus communicans found?
sympathetic chain to the spinal nerve
Where is the gray ramus communicans found?
with EVERY spinal nerve
What is the C1 posterior rami called?
suboccipital nerve
How is the C1 suboccipital nerve classified?
exclusively motor
What does the suboccipital nerve supply?
suboccipital muscles: rectus capitis posterior major and minor, obliquus capitis superior and inferior, semispinalis capitis
What makes up the suboccipital nerve?
C1 posterior primary ramus
Does the posterior primary ramus C1 spilt?
NO
Does the suboccipital nerve have a dermatome level?
NO
What does the posterior primary rami of C2 split into?
medial and lateral branches
What is another name for the C2 medial branch?
greater occipital nerve
What sensory information does the greater occipital nerve carry?
posterior neck and scalp
What does the lateral branch of C2 carry?
MOTOR: semispinalis capitis, longissimus capitis, splenius capitis muscles
What branches does the posterior primary rami of C3 have?
medial and lateral branches
What is the medial branch of C3 called
third (least) occipital nerve
What does the least (third) occiptial nerve supply?
SENSORY: skin of posterior neck
What does the lateral branch of C3 supply?
MOTOR: semispinalis capitis, longissimus capitis, splenius captis muscles
What do the C4-C8 posterior primary rami branch into?
medial and lateral branches
What do the medial branches of C4-C8 supply?
SENSORY: skin of posterior neck
What do the lateral branches of C4-C8 supply?
MOTOR: iliocostalis cervicis, lingissimus cervicis, longissimus capitis
