Nerve Plexuses Flashcards
Through which root do sensory signals/information go through?
The dorsal root to the spinal cord.
Through which root do motor signals leave the spinal cord?
The ventral root of the spinal cord.
Plexuses are networks of nerves originating from ______________ of the spinal nerves.
Ventral rami.
How many nerve plexuses are there?
Four nerve plexuses.
What are the nerve plexuses?
- Cervical Plexus
- Brachial Plexus
- Lumbar Plexus
- Sacral Plexus
Which two plexuses are sometimes combined and what are they called?
The Lumbar and Sacral plexuses are sometimes combined to form the lumbosacral plexus.
What vertebrae does the Cervical plexus span?
C1-C4, C5
What vertebrae does the Brachial plexus span?
C5-T1
What vertebrae does the Lumbar plexus span?
T12-L4
What vertebrae does the Sacral plexus span?
L4-S4
All plexuses have?
Both sensory and motor nerves.
List the Cervical plexus nerves.
LGTAPSNC
Large gorillas take a piss so newts care.
- Lesser Occipital Nerve
- Great Auricular Nerve
- Transverse Cervical Nerve
- Ansa Cervicalis
- Phrenic Nerve
- Supraclavicular Nerve
- Nerve to Rhomboids and Serratus
- Cranial Nerves
What is special about the cervical plexus?
Has nerves that contribute to cranial nerves.
What is the organization of the brachial plexus?
Branching off the spinal cord:
- Ventral rami (roots)
- Trunks (superior, middle, and inferior)
- Divisions (anterior and posterior)
- Cords (Posterior, lateral, and medial)
- Nerves
All of the nerves of the Brachial Plexus have both _____ and ______ ______.
Sensory and motor nerves. (Specifically within each nerve)
List the Brachial Plexus Nerves.
MAMRU
My aunt makes rainbow undies.
- Musculocutaneous Nerve
- Axillary Nerve
- Median Nerve
- Radial Nerve
- Ulnar Nerve
Nerves in the Brachial Plexus (other)
- Nerve to subclavius
- Dorsal scapular nerve
- Long thoracic nerve
- Suprascapular nerve
- Pectoral nerves (medial and lateral)
- Subscapular nerves
- Thoracodorsal nerve
Clinical applications associated with the Brachial plexus?
Radial nerve damage/compression “wrist drop”
Median nerve issues- wasting of thumb side muscles
Due to pressure/compression
List the Lumbar plexus nerves.
IILGFO
iil getthe fuck out
- Iliohypogastric Nerve
- Ilio-inguinal Nerve
- Lateral femoral cutaneous Nerve
- Genitofemoral Nerve
- Femoral Nerve
- Obturator Nerve
List the Sacral plexus nerves.
PPISS
- Posterior fermoral cutaneous Nerve
- Pudendal Nerve
- Inferior gluteal Nerve
- Sciatic Nerve
- Superior gluteal Nerve
Which nerve is the largest in the body?
Sciatic Nerve.
What does the Sciatic nerve branch into?
The tibial and fibular nerves (motor and sensory nerves for the leg, ankle, and foot).
What causes sciatica?
Compression of the sciatic nerve from the piriformis can cause sciatica.
What are dermatomes?
Specific regions of skin that are supplied by certain spinal sensory nerves. There can be significant overlap between adjacent dermatomes.
Shingles
The rash and pain from shingles typically follow the pattern of the dermatome corresponding to the affected nerve. Each spinal nerve innervates a specific area of the skin, so shingles affects the area served by the reactivated nerve.
What is a reflex?
An immediate involuntary motor response.
What is a reflex arc?
The neural wiring of a single reflex. Begins at a sensory receptor and ends at a peripheral effector.
Is conscious control needed for a reflex arc?
No.
Describe the steps of a reflex arc.
- Stimulation and activation of receptor (hand hits a thumbtack)
- Activation of a sensory neuron, which sends signal through dorsal root to spinal cord.
- Excitatory neuron relays sensation to the brain and motor neuron is stimulated.
- Information processing in CNS leads to the activation of a motor neuron (after signal leaves from ventral root).
- Response by effector (pull arm away).
Describe the steps of a stretch reflex.
- Stimulus activates receptor. Muscle spindle fibers are stretched.
- Activation of a sensory neuron.
- Information processing in CNS (no interneuron).
- Activation of a motor neuron.
- Response by effector. Muscle contracts.
What is an example of a stretch reflex?
Knee-jerk reflex.
The patellar reflex is controlled by muscle spindles in the quadriceps fermoris. The stimulus is a reflex hammer tappung the muscle tendon, stretching the spindle fibers. This results in a sudden increase in the activity of the sensory neurons, which synapse on spinal motor neurons. An action potential is propagated to motor units in the quadriceps femoris. This leads to contraction of the stretched muscle, causing a reflexive kick.
