Lesson 10 Flashcards
where does the spinal cord extend from?
the foramen magnum
where and what does the spinal cord terminate as?
conus medullaris, L1 or L2
what does the spinal cord become after L1/L2?
cauda equina
what does cauda equina literally mean?
horse tail
the spinal cord is covered by all three meninges down to the _____ vertebra.
S2
only the _____ mater extends to the posterior coccyx as the _____ _____
pia, filum terminale
the spinal cord is secured to the vertebrae by the _____ _____ of the pia mater
denticulate ligaments
conus medullaris
where the spinal cord tapers off around L1/L2
the “cone” part of conus comes from….
the structure is the three dimensional shape of a cone
what does the filum terminale do?
holds the spinal cord in place at the end of your spine
gray matter
location of neuronal cell bodies
dorsal (posterior) horns
interneurons and sensory fibers from the dorsal root ganglion
ventral (anterior) horns
motor neurons of somatic nervous system that projects fibers through the ventral root
lateral horns
motor neurons of autonomic nervous system (sympathetic) which leaves the cord through the ventral root
gray commissure
connects the left and right horns; surrounds the central canal
white matter
myelinated nerve fibers, bisected by fissures (anterior median fissure and posterior median sulcus)
three primary regions of groupings of axons with the same origin, terminus, and function
- posterior funiculus
- lateral funiculus
- anterior funiculus
posterior funiculus
carries info on joint and muscle position and fine touch
proprioception
the body’s awareness of the limbs even if they aren’t in view
lateral funiculus (2)
- carries info on proprioception, pain, temp, pressure, coarse touch
- used in relaying motor info to control skeletal muscles, posture, visceral muscle functions, muscle tone, and balance
anterior funiculus (2)
- carries info on pain, temp, pressure, and coarse touch
- used in relaying motor info to control skeletal muscle, posture, visceral muscle functions, muscle tone, and balance
how to identify dorsal vs ventral funiculus (2)
- the dorsal median sulcus is more shallow than the central median fissure
- dorsal root is attached to the dorsal root ganglion and the dorsal spinal cord
there are _____ pairs of spinal nerves
31
where do the ventral and dorsal rami branch from?
they branch from the spinal nerve shortly after exiting the spinal column
there are four major plexuses
cervical, brachial, lumbar, and sacral
cervical plexus (4)
- formed from ventral rami of C1-C5
- serves the neck and shoulder
- major motor branch: phrenic nerve in C3/4 and some of 5
- innervates the diaphragm
C1 through C7 spinal nerves emerge above or below the vertebrae they are named after?
above; all other spinal nerves emerge BELOW
where does the C8 spinal nerve emerge from?
between C7 and T1; there is no C8
brachial plexus (2)
- formed from ventral rami of C5 through C8 and T1
- serves the shoulder, arms, and hand
the brachial plexus is arranged into what? (4)
trunks, divisions, cords, and major peripheral nerves
the brachial plexus cords are divided into 5 major peripheral nerves
- axillary
- radial
- median
- musculocutaneous
- ulnar
brachial plexus: peripheral nerves - axillary (2)
- C5 and C6
- serves the shoulder muscles, and the skin of the shoulder area
brachial plexus: peripheral nerves - radial (2)
- C5 through C8 and T1
- serves extensor muscles of the arm, forearm, and hand (on the posterolateral surface of the arm/forearm) thumb side
brachial plexus: peripheral nerves - median (2)
- C8, T1, and C5 through C7
- serves flexor muscles of the forearm, hand (some), and the skin on the lateral surface of the palm in the middle
brachial plexus: peripheral nerves - musculocutaneous (2)
- serves flexor muscle for the forearm and flexion
- serves the skin of the lateral surface of the forearm in the elbow/axillary area
brachial plexus: peripheral nerves - ulnar (2)
- serves the flexor carpi ulnaris, flexor digitorum, and other hand muscles
- skin of the medial third of the anterior/posterior hand (at the pinkie side)
lumbar plexus (3)
- from ventral rami of L1 through L4 (sometimes T12)
- serves lower abdominopelvic region and anterior thigh
- femoral nerve (innervates anterior thigh), branches into the saphenous nerve
sacral plexus (3)
- from the ventral rami of L4 through S4
- serves butt, posterior surface of the thigh, leg, and foot
- major nerve is the sciatic nerve, the largest in the body, which divides into common fibular and tibial nerves
ulnar nerve
on the pinkie finger side of your arm, aka ulnar side
musculocutaneous nerve
usually near the elbow armpit area
median nerve
in the middle of the arm
axillary nerve
in the shoulder ish area
radial nerve
runs along the same side as the radius, aka thumb side/lateral side of your arm
femoral nerve
major nerve at the top of the leg on the front side
saphenous nerve
the big nerve going down your leg after the femoral nerve splits/branches
sciatic nerve
the “starting big nerve” at the top of the back of the leg
tibial nerve
on the medial/big toe side of the leg, on the same side as the tibia
common fibular nerve
on the lateral/pinkie toe side of the leg, same side as the fibula
ANS
autonomic nervous system
what is the ANS?
a subdivision of the peripheral nervous system (PNS) that controls functions not under conscious control
what does the ANS serve? (3)
cardiac muscles, smooth muscle in the viscera and blood vessels, and internal organs
what two motor neurons primarily control the ANS?
- preganglionic neuron
- ganglionic neuron
the preganglionic neuron is where?
in the brain and spinal cord
the ganglionic neuron is where?
in the ganglion outside the CNS
two major divisions of the ANS
sympathetic and parasympathetic
sympathetic division of the ANS (3)
- fight or flight response
- postganglionic axons release norepinephrine
- preganglionic neurons located in the lateral horn of grey matter synapses with ganglionic neurons in the paravertebral ganglion alongside the vertebral column
parasympathetic division of the ANS
- resting, digestion
- postganglionic axons release acetylcholine
- preganglionic neurons located in the brain of cranial nerves III, VII, IX, X, and S2-S4 synapses with ganglionic neurons in the terminal/intramural ganglion close to target
sympathetic trunk
the “chain of nerves” down the back
