How many thoracic nerve pairs are there?
12
How many pairs of lumbar nerves are there?
5
How many sacral nerve pairs are there?
5
How many coccygeal nerve pairs are there?
1
The 31 pairs of spinal nerves are attached to what structure?
The spinal cord
Which spinal nerve root carries efferent axons from cell bodies located in the anterior (ventral) or lateral horns?
Anterior (ventral or motor) roots
Which spinal nerve root carries axons from cell bodies located in the posterior (dorsal) root ganglion (spinal ganglion)?
Posterior (dorsal or sensory) root
Where, specifically, do the separated rootlets of the spinal nerves’ posterior roots attach to the spinal cord?
At the posterolateral sulcus
Where are spinal ganglia typically located?
Either inside or just medial to the intervertebral foramen, beyond the dura mater
Where are the C1 and C2 spinal ganglia located?
On their respective vertebral arches
What is the location of sacral ganglia?
Within the vertebral canal
What is the location of coccygeal ganglia?
Inside the dura mater
The meningeal branch (recurrent meningeal/sinuvertebral branch) is given off at what spinal levels?
All of them
What is unique about the posterior ramus of C1?
It is one branch and does not split
What is the motor supply for C1 suboccipital nerve?
Rectus capitis posterior major and minor, obliquus capitis superior and inferior, semispinalis capitis
Semispinalis capitis is a part of what muscle group of the back?
Erector spinae
What is the name for the posterior ramus of C1?
Suboccipital nerve
What is the name of the posterior ramus of C2?
Greater occipital nerve
What is the supply of the medial branch of the greater occipital nerve?
Sensory innervation to the posterior neck and scalp
What is the supply of the lateral branch of the greater occipital nerve?
Motor supply to semispinalis capitis, longissimus capitis, and splenius capitis muscles
What is the name for the posterior ramus of C3?
Third (least) occipital nerve
What is the supply of the medial branch of the least occipital nerve?
Sensory supply from skin of posterior neck
What is the supply of the lateral branch of the third (least) occipital nerve?
Motor supply to semispinalis capitis, longissimus capitis, and splenius capitis muscles (same as C2)
What is the supply of the medial branches of the posterior rami of C4-C8?
Sensory supply from the skin of the posterior neck
What is the supply of the lateral branches of the posterior rami of C4-C8?
Iliocostalis cervicis, longissimus cervicis and capitis
When is the meningeal branch given off of spinal nerves?
Shortly after combining into a mixed spinal nerve
The meningeal branch of spinal nerves reenter the vertebral canal through what opening?
Intervertebral foramen
After passing through the intervertebral foramen, the meningeal branch of the spinal nerves divide into what branches?
Ascending, descending, and transverse branches
What do the meningeal branches of the spinal nerves supply?
Dura, blood vessels, periosteum, ligaments, and intervertebral discs in the anterior and lateral portions of the canal (somatosensory and sympathetic supply)
What types of fibers are carried in the meningeal branches of the spinal nerves?
Sympathetic and somatosensory fibers
Mixed spinal nerves divide into what two rami?
Anterior (ventral) and posterior (dorsal) primary rami
What is the only mixed nerve level that does not split into medial and lateral branches?
C1
Which is usually larger: anterior or posterior primary rami of mixed spinal nerves?
Anterior rami
At which mixed nerves is the anterior ramus actually smaller than the posterior (deviation from the norm)?
C1, S4, and S5
The posterior primary rami of mixed spinal nerves have what motor supply?
Deep back muscles
The posterior primary rami have what sensory supply?
To the skin on either side of the spine
What muscles are supplied by the anterior primary rami of mixed spinal nerves?
Anterior and lateral trunk muscles, skeletal muscles in the extremities
What is the sensory innervation of the anterior primary rami of the mixed spinal nerves?
Skin of extremities as well as anterior and lateral trunk
How many pairs of cervical nerves are there?
8
Which rami of the mixed spinal nerves contribute to the great plexuses of the body (cervical, brachial, sacral…)?
Anterior primary rami
What is the location of the sympathetic chain communications?
Either at or just medial to the bifurcation of the mixed spinal nerve
What are the two ways in which preganglionic sympathetic fibers from the white ramus communicans enter the sympathetic chain?
Synapse in the trunk either at the same level or above/below
Pass through trunk and are carried in splanchnic nerves
What “family” of muscles is supplied by the posterior rami of C2 and C3?
Capitis (semispinalis, longissimus, and splenius capitis)
What muscle is supplied by the posterior rami of C2-C8?
Longissimus capitis