Question | Answer |
How many pairs of spinal nerves are they and how are they named? | 31. named and numbered according to regions of the vertebral column with which they are associated |
What are the types of Spinal Nerves (5) | Cervical Spinal Nerves(8), Thoracic Spinal nerves(12), Lumbar spinal nerves(5), Sacral spinal nerves(5), Coccygeal Spinal nerve(1) |
First pair of spinal nerves that exit between the skull and 1st cervical vertebra | C1 spinal nerves |
Spinal nerves that exit ABOVE corresponding numbered vertebrae via the intervertebral foramina | C2-C7 spinal nerves |
Where does C8 spinal nerve exit? | BELOW the C7 vertebrae |
Where do the thoracic spinal nerves and lumbar spinal nerves leave? | each leaves below its corresponding numbered vertebra |
Spinal nerves that exit through the 4 sacral foramina, one through each foramen | S1-S4 spinal nerves |
spinal nerve that exits through the sacral hiatus below S5 sacral segment | S5 sacral spinal nerves |
Exits below first coccygeal segment | Coccygeal Spinal Nerve |
Besides the coccygeal spinal nerve, no spinal nerves are associated with other what segments? | Coccygeal segments |
What is formed when spinal nerves join or exchange branches with other nerves? | Plexuses |
What are the types of roots of spinal nerves? (2) | Dorsal Roots, Ventral Roots |
Contain sensory(afferent) fibers with cell bodies located in the dorsal root ganglia | Dorsal Roots |
Somatic afferents from skin and skeletal muscles, and visceral afferents from viscera and blood vessels | Sensory(afferent) fibers of dorsal roots |
Contain motor(efferent) fibers with cell bodies located in the spinal cord | Ventral Roots |
What ventral roots contain 2 types of motor fibers? | T1-L2 or L3 and S2-S4 |
What are the types of motor fibers of T1-L2 or L3 and S2-S4 ventral roots | Somatic efferents(voluntary)-->skeletal muscle
Autonomic(visceral) efferents(involuntary)-->autonomic ganglia->smooth muscle, cardiac muscle, or glands |
ventral roots that only have 1 type of motor fiber | all other ventral roots BESIDES T1-L2 or L3 and S2-S4
motor fiber is somatic efferents(voluntary)-->skeletal muscle |
formed by union of dorsal and ventral roots, carries both motor and sensory fibers | Mixed(Complete) Spinal Nerve |
Branches of a typical spinal nerve are? (3) | Meningeal(Recurrent) Branch, Posterior primary division(Dorsal Ramus), Anterior primary division(Ventral Ramus) |
branch that Innervates tissues in vertebral canal(meninges and blood vessels of cords) | Meningeal(Recurrent) Branch |
branch that innervates the intrinsic deep back muscles and skin covering them | Posterior Primary Division(Dorsal Ramus) |
what are the 2 types of Rami communicantes? | White and gray |
attached to T1-L2 or L3 spinal nerves only, contain outgoing(leaving ventral ramus) sympathetic PREganglionic fibers to autonomic ganglia; and incoming visceral afferents | White rami communicant |
attached to ALL spinal nerves, contain incoming(entering ventral ramus) sympathetic POSTganglionic fibers which then supply-->body wall | Gray rami communicantes |
What do the ventral rami form in cervical, lumbar, and sacral regions? | complex plexuses |
In the thoracic region each ventral ramus runs between what? | the internal and external intercostal muscles forming certain nerves |
Nerve of T1-T11 | Intercostal nerves and they run under same rib # |
nerve of T12 | Subcostal nerve |
Branches of intercostal and subcostal nerves (3) | lateral cutaneous nerve, anterior cutaneous nerve which splits into lateral and medial branches, and the muscular branches |
pierces external intercostal muscle then branches into posterior and anterior branches of the lateral cutaneous nerve-->skin lateral back and chest | Lateral cutaneous nerve |
anteriorly the the intercostal nerve terminates between the internal intercostal muscle and pleura. Just before it ends it gives off the what? | Anterior cutaneous nerve |
Anterior cutaneous nerve splits into? | Lateral and Medial branches |
intercostal and or abdominal muscles are innervated by? | Muscular branches |