Spinal Nerve and Back Anatomy

Question 1

Sensory/afferent

Answer 1

carries information from body INTO the CNS

Question 2

General somatic afferent (GSA)

Answer 2

sensations from the body such as touch, pain, temperature, proprioception and kinesthesia (perception of position and movement of muscles and joints).

Question 3

general visceral afferent (GVA) / autonomic

Answer 3

sensations that are not usually perceived but monitor basic body functions. may perceive sensations from organs in pain

Question 4

special afferent (SA)

Answer 4

senses of light, smell, hearing, and equilibrium

Question 5

Efferent / motor modality

Answer 5

neurons that carry information FROM the CNS to the body

Question 6

General somatic efferent (GSE)

Answer 6

motor control of skeletal muscle

Question 7

general visceral efferent (GVE) / Autonomic nervous system

Answer 7

motor control of smooth muscle and glands of the viscera, heart and blood vessels, etc

Question 8

Nucleus

Answer 8

A collection of nerve cell bodies within the central nervous system

Question 9

ganglion

Answer 9

collection of nerve bodies outside the central nervous system

Question 10

Components of a spinal cord

Answer 10

The spinal cord have projections of dorsal (sensory) and ventral (motor) rootlets that go on to form their perspective roots.

• Cell bodies for dorsal nerves are located in the dorsal root ganglia (DRG).
• Cell bodies for ventral root motor fibers lie within the spinal cord

Ventral roots and dorsal roots eventually merge forming a spinal nerve.

Spinal nerves (mixed nerve) have dorsal ramus (mixed nerve) and central ramus (mixed nerve) projections.

Question 11

somatic afferent neuronal pathway

Answer 11

Exteroceptive sensation and proprioceptive sensation

Ventral ramus serves the ventrolateral trunk and limbs

Dorsal ramus serves the posterior trunk

the pathway for both ventral and dorsal ramus input goes down the dorsal root, into the Dorsal root ganglion (DRG) then onwards to the dorsal horn of the spinal cord

Question 12

somatic efferent neuronal pathway

Answer 12

pathway starts in cell body located in the ventral horn of the spinal cord.

pathway goes though ventral root into the spinal nerve where it can go through the ventral ramus (ventrolateral thunk and limbs) or dorsal ramus (posterior trunk)

Question 13

Association neurons

Answer 13

reside in the spinal cord and interact with the afferent and efferent spinal nerve neuron.

neurons in ascending pathways transmit sensory information to higher CNS levels

neurons in descending pathways transmit somatic and visceral motor signals from higher levels to motor neurons forming spinal nerve

short interneurons mediate reflexes within the spinal cord

Question 14

intervertebral disc

Answer 14

disc that allows the body of the vertebrae to bend against each other but prevents them from touching

Question 15

zygapophysial joints

Answer 15

bind together the superior articular process and inferior articular process that allows the lumbar vertebrae to from a chain

Question 16

vertebral ligaments

Answer 16

anterior and posterior longitudinal ligaments run the length of the column and are attached to the vertebral bodies and intervertebral discs

ligamentum flava connect adjacent laminae and fill the posterior side of the spinal canal

Question 17

deep back muscle

Answer 17

• involved in powerful extension, lateral bending, and rotation of the back, neck and head
• innervated by the dorsal ramie spinal nerves
• erector spinal: more superficial large muscles

Question 18

Meninges

Answer 18

surround the spinal cord in three layers, these layers also surround the brain

• dura: tough outer layer, reflected out along the spinal nerves and blends into the epineurium
• arachnoid: middle layer with weblike strands extending to the Pia
  pia: thin transparent cover adherent to the cord

space between arachnoid and Pia is filled with cerebrospinal fluid that is made within the brain

Question 19

intervertebral foramen

Answer 19

spinal nerves can exit spinal canal through these and and blood vessels can enter/leave spinal canal

Question 20

Spinal vasculature

Answer 20

Anterior(single) and posterior (paired) spinal arteries run the length of the spinal cord.

In the trunk, these arteries are supplied by the anterior and posterior radicular arteries, which are both branched from the spinal branch. The spinal branch is connected to the intercostal and lumbar branches of the thoracic and abdominal aorta.

Artery of Adamkiewicz originates in the lower thoracic or upper lumbar region. it is much larger than the rest and is a critical supply for the lower spinal cord.

In the neck, branches of the vertebral arteries feed the anterior and posterior spinal arteries

Question 21

cauda equina

Answer 21

Spinal cord ends at L1 vertebrae. Spinal nerves coming off the cord must continue to travel a distance down the spinal canal to reach their foramina and exit. the group of these nerves outside of the cord are called Cauda equina

Question 22

spinal nerves and the caudal equina

Answer 22

a dural sac surround the caudal equina down to the S2 level of the sacrum

film terminale:
pial part: extends from the end of the conus medullar is to the end of the dural sac

dural part: extends from the dural sac to the coccyx. has a Pia sore and dural covering

Question 23

Disc herniation

Answer 23

caused by the weakening of the annulus fibrosus, which leads to the bulging and herniation of part of the vertebral canal. This affects the spinal roots below the bulge. ex: occurs at L4/L5, L5 root will be most affected.

Question 24

Nerve Plexuses

Answer 24

ventral rami merge and exchange fibers to form peripheral nerves consisting of neurons from multiple spinal levels.

cervical plexus: C1-C4
cutaneous and muscular nerves in the neck

brachial plexus: C5-T1
cutaneous and muscular nerves to the upper limb

Lumbar Plexus: L1-L4
Cutaneous and muscular nerves to the abdominal wall and lower limb

Sacral plexus: L4-S4
cutaneous and muscular nerves to the pelvis and lower limb

Question 25

Cutaneous nerves:

Answer 25

Nerves going to the skin of the trunk, neck, and extremities will always contain: - General Somatic Afferent (GSA) Fibers: conducting sensations of touch, pain, heat, and etc from the skin - General Visceral Efferent (GVE) Fibers: controlling capillary beds, sweat glands, and arrector pili muscles

Question 26

Musular Nerves

Answer 26

Nerves going to the skeletal muscles of the trunk, neck and extremities will always contain: - general somatic efferent fibers: driving the contraction of the muscles - general somatic afferent fibers: conducting proprioceptive information from the muscles and tendons, as well as pain sensation - general visceral efferent fibers- controlling capillary beds in the muscles

Question 27

Dermatomes

Answer 27

strip of skin innervated primarily by a single spinal nerve key dermatomes: - face: 3 divisions of cranial nerve V - C1: NO dermatome segment - C2: posterior skull - C6,7 & 8: hand - T4: region of nipple on thorax - T10: region of umbilicus - L1: inguinal region - L4: Big toe - S1: little toe

Question 28

Clinical relevance of dermatomes

Answer 28

- useful in the diagnosis of nerve lesions with a cutaneous sensory deficit - chicken pox can go dormant in DRGs after initial infection and then come back as shingles. it produces a painful rash on the dermatome of the spinal nerve that the chicken pox initially went dominate in.

Question 29

Spinal reflexes

Answer 29

reflex arc is a simple neural pathway linking a receptor, the CNS and an effector all reflex arcs have the following: - a receptor that receives the stimulus - a sensory (afferent) neuron that transmits the impulses away from the CNS to the effector - an effector, a muscle, or gland that carries out the response

Question 30

tendon stretch reflex

Answer 30

simplest type of reflex, requiring a chain of only two neurons. reflex only involves one synapse (monosynaptic) 1) stretching stimulates sensory receptor (muscle spindle) 2) Sensory neuron excited 3) within integrating center (spinal cord), sensory neuron activates motor neuron 4) motor neuron is excited 5) effector (same muscle) contracts and relieves the stretching

Question 31

withdrawal reflex

Answer 31

polysynaptic; requires the participation of the sensory, association, and motor neurons. Think stepping on a nail. foot is flexed/withdrawn to prevent further stepping on it, muscle on leg on the opposite side of the body helps keep balance, signal goes to brain as well.

Question 32

Electromyography

Answer 32

electrical activity in muscle is being tested in used muscle.

Question 33

nerve conduction velocity testing

Answer 33

measures the speed of conduction of impulses through the nerve. can be used to diagnose nerve damage or dysfunction. can differentiate injury to the nerve fiber (axon) from injury (amplitude) to the myelin sheath (velocity) surrounding the never - Sensory nerve action potential (SNAP): nerve field is stimulated and signal is measured proximally to get amplitude and velocity - Combines muscle action potential (CMAP): nerve is stimulated and action potential in the muscles is measured to get amplitude and latency in order to get nerve velocity

Question 34

Somatosensory evoked potential (SEP or SSEP)

Answer 34

determine if sensory information is reaching the CNS sensory nerves are stimulated and electrical activity in the spinal cord or sensory cortex of the brain is monitored by surface electrodes

Question 35

H-reflex test:

Answer 35

helps distinguish between nerve and muscle disease and locales the site of nerve lesions involves stimulating peripheral nerve afferents so that a reflex contraction of muscles results. this is performing a stretch reflex, but bypasses the muscle spindles diminished results show that there is a problem with efferent or afferent limb

Question 36

F-wave analysis

Answer 36

helps distinguish between nerve and muscle disease and locales the site of nerve lesions involves stimulating nerves at a higher intensity so that the signal travels proximally along the motor neurons and elicits a rebound efferent signal that stimulates the muscle tests the motor neuron integrity- without involving the sensory neurons in cases where the stretch reflex is abnormal, this can help determine if the problem is in the afferent or efferent limb of the reflex

Question 37

Which parts of the vertebra would need tone removed to expose spinal cord and caudal equda?

Answer 37

Spinous process and lamina

Question 38

List Meninge levels from superficial to deep

Answer 38

Epidural -> dura mater -> arachnoid -> subarachnoid -> pia -> spinal cord

Question 39

relationship between the spinal cord and meninges

Answer 39

denticulate ligaments anchor the spinal cord to the dural sac

Question 40

phenotypical differences in arteries and veins

Answer 40

- one artery w/ 2 or 3 veins surrounding it - veins are larger, and have one-way valves - arteries have thicker wall and are more tubular

Question 41

muscle action categories

Answer 41

- agonist: muscle doing the action - antagonist: not doing the action/ does opposite of action - fixator: stabilizes action - synergist: works along with agonist

Question 42

Whiplash w/ hyperextension which ligament is most likely injured?

Answer 42

anterior longitudinal ligament