ch 12 Flashcards
CNS vs PNS
the central nervous system is the brain and part of the spinal cord.
the peripheral nervous system is the nerves and all the organs they travel to
anatomy of spinal cord
provides a two way conduction pathway to and from the brain
about 18 inches; ends between L1 and L2
bilaterally symmetrical
contain both cervical enlargement (nerves of shoulders and upper limbs) and lumbar enlargement (nerves of pelvis and lower limbs)
at distal end has: conus medullaris, filum terminale, and cauda equina.
31 spinal cord segments.
dura mater
tough and fibrous
fuses with periosteum of occipital bone, and is continuous with cranial dura mater
caudally tapers to dense cord of collagen fibers: filum terminale in coccygeal ligament
arachnoid mater
middle meningeal layer
arachnoid membrane: simple squamous epithelia, covers arachnoid mater
arachnoid trabeculae: delicate network of collagen and elastic fibers.
subdural space: between arachnoid mater and dura mater
subarachnoid space: between arachnoid mater and pia mater, contains arachnoid trabeculae, filled with cerebrospinal fluid: carries dissolved gases, nutrients, and wastes.
lumbar puncture or spinal tap withdraws CSF
pia mater
innermost meningeal layer
a mesh of collagen and elastic fibers, bound to underlying neural tissue
paired denticulate ligaments: extend from pia mater to dura mater, stabilize side to side movement
blood vessels along surface of spinal pia mater, withing subarachnoid space
gray matter vs white matter
white matter is superficial; contains myelinated and unmeylinated axons
gray matter surrounds central canal of spinal cord, contains neuron cell bodies, neuroglia, unmyelinated axons and has projections (gray horns)
dorsal root vs ventral root
white ramus vs gray ramus
dorsal ramus vs ventral ramus
dorsal root contain sensory nuclei and ventral root contains motor nuclei
white ramus: carries visceral motor fibers to sympathetic ganglion of ANS
gray ramus unmyelinated nerves; contains postganglionic fibers return from sympathetic ganglion to rejoin spinal nerve
dorsal ramus: innervates the deep muscles, skin and structures of the posterior surface of the trunk
ventral ramus: larger branch, innervates the muscles, skin and structures of upper and lower limbs of the lateral and anterior surfaces of the trunk (ventrolateral structures and limbs)
4 major principal plexuses:
- cervical plexus: consists of ventral rami of spinal nerves C1-C5
- brachial plexus: consists of ventral rami of spinal nerves C5-T1
- lumbar plexus: consists of ventral rami of spinal nerves T12 - L 4
- sacral plexus: consists of ventral rami of spinal nerves L4 - S4
peripheral nerves
interconnecting branches of spinal nerves
surrounded by same connective tissue sheaths
cervical plexus
innervates skin and muscles of head, neck, superior part of thoracic cavity, diaphragmatic muscles (phrenic nerve)
Phrenic nerve: controls muscle of diaphragm
brachial plexus:
C5-T1 innervates pectoral girdle and upper limbs 4 major groups of brachial: 1. ventral rami 2. trunks 3. divisions 4. cords.
lumbar plexus
includes ventral rami of T12-L4
supplies anterolateral abdominal wall, external genitalia, and part of lower limbs
femoral nerve, obturator
sacral plexus
L4-S4
supplies buttocks, perineum, lower limbs
sciatic nerve, pudenal nerve, common fibular nerve, and tibial nerve.
dermatome map
innervation of skin
area of skin that provides sensory input to cns
bilateral region of skin
monitored by specific pair of spinal nerves: innervated by cutaneous branches of single spinal nerve
each spinal nerve contains sensory neurons that serve specific predictable segment of body
shingles
caused by varicella zoster virus
herpes virus that attacks neurons in dorsal roots and sensory ganglia of cranial nerves
remains dormant within neurons of anterior gray horns
skin eruptions follow the distribution of dermatomal innervation
