NeuroAnatomy_Unit3_Lec1 Flashcards
3 divisions of the PNS
3 functional divisions:
- ) Somatic Nervous System (31 pairs of spinal nerves)
- ) Autonomic Nervous System (12 pairs of cranial nerves) (Sympathetic/Parasympathetic)
- ) Enteric Nervous system
spinal nerves exit
intervertebral foramina
spinal cord length
from the base of the skull (foramen magnum) to the superior border of the 2nd lumbar vertebra.
During early development the spinal cord is the entire length of the vertebral column, but the spinal cord grows more slowly than the vertebral column, so it ends up shorter.
conus medullaris
terminal end of the spinal cord (at the 2nd lumber vertebra)
filum terminale
extension of meninges that anchors the spinal cord to the coccyx
cadua equina
bundle of spinal nerves after the conus medullaris
3 meninges
- ) Pia mater-inside
- ) Arachnoid- middle
- ) Dura mater-outside
Dorsal horn
contains sensory neurons that receive input from the periphery
Ventral horn
contains motor neurons that innervate specific muscles
myotome
muscles innervated by the anterior roots of one pair of spinal nerves
Ventral/ Anterior Root
contains the axons of the motor neurons
Dorsal/ Posterior Root
contains the processes of the sensory neurons, the cell bodies of which are found in the dorsal root ganglion.
Dermatome
Area of the skin that provides sensory input to the CNS
there are only 30 dermatomes even though there are 31 pairs of spinal nerves because C1 has no cutaneous terminus
Number of Vertebrae
7 cervical 12 thoracic 5 lumbar 5 fused sacral 4 fused coccyx
number of cervical nerves
8 (because there is one above the C1 and one below C7)
Dorsal/Posterior Ramus
contains motor and sensory nerves for the posterior surface of the trunk and neck
Ventral/Anterior Ramus
contains motor and sensory nerves for the lateral and anterior surface of the trunk and the extremities
Intercostal/ thoracic nerves
The anterior rami of T2-T12 travel in the intercostal spaces and directly connect to the structures they supply.
anterior ramus of nerve T2
innervates the intercostal muscles, the skin of the axilla and posteromedial aspect of the arm.
anterior rami of nerves T3-T6
innervates the intercostal muscles, and skin of the anterior and lateral chest wall
anterior rami of nerves T7-T12
supply the intercostal and abdominal muscles as well as the overlying skin.
Plexus
Network of axons from the anterior rami of the cervical, lumbar, and sacral levels that redistribute instead of directly going into the body structures that they supply.
Cervical plexus
anterior rami of nerves C1-C5 form the cervical plexus which supplies the skin and muscles of the head neck and superior part of the shoulders.
Brachial plexus
formed from anterior rami of C5-T1, supplies shoulders and upper limbs
Lumbar plexus
formed from anterior rami of L1-L4, supplies the anterolateral abdominal wall, external genital, and part of the lower limbs.
Sacral Plexus
formed from the anterior rami of L1-L4 & S1-S4, supplies the buttocks, perineum and lower limbs
Coccygeal Plexus
formed from the anterior rami of S4-S5 and the coccygeal nerve, supplies a small area of skin in the coccygeal region.
Radiculopathy
compressed spinal nerve roots
Symptoms of Sensory Radiculopathy
Sensory loss/deficit (pain, tingling,
numbness) in the dermatomal distribution
of the affected root
Symptoms of Motor Radiculopathy
Motor function loss / deficit (weakness, paralysis) in the
myotomal distribution of the affected root
Plexopathy
A disorder affecting a network of nerves, blood vessels, or lymph vessels. The region of nerves it affects are at the brachial or lumbosacral plexus. Symptoms include pain, loss of motor control, and sensory deficits
