Spinal Nerves and Nerve Plexuses Flashcards
How many nerves are in the cervical region?
8
How many nerves are in the thoracic region?
12
How many nerves are in the lumbar region?
5
How many nerves are in the sacral region?
5
Which is smaller, the dorsal ramus or the ventral ramus?
dorsal
What does apaxial mean?
Innervation of back muscles with dorsal rami; they allow the spine to be erect.
What does hypaxial mean?
innervation of upper and lower limbs; they receive info from ventral rami of spinal nerve.
Which rami carries visceral motor components?
ventral
What kind of nerve system forms the sympathetic trunk?
spinal nerve ganglion
The sympathetic trunk is connected to spinal nerves in which regions?
thoracic and upper lumbar.
Where types of nerves are associated with the sympathetic trunk?
visceral motor (autonomic), sympathetic, and grey & white rami communicantes.
what is exteroception?
instant awareness of something painful happening, e.g. snakebite.
What is interoception?
visceral (e.g. nausea) or referred pain.
What is proprioception?
A sense of the surroundings/space around a body, as well as balance.
What is a dermatome?
A area of skin innverated by the sensory fibers of a single nerve root.
What is a myotome?
A group of muscles that is primarily innervated by the motor fibers of a single nerve root.
What are the three ways that spinal nerves are distributed in the body?
intercostal nerves, dorsal rami, and spinal nerve plexuses.
intercostal nerves always extend from whcih rami?
ventral rami (they are hypaxial); they can also extend from dorsal
nerve plexuses extend from which rami?
ventral rami (hypaxial)
What is the intercostalbrachial nerve?
Nerve found around T2; it is responsible for referred pain
What is the subcostal nerve?
A pair of nerves at T12; it innervates the lateral abdominal region. The first lumbar vertebrae are below it.
Where does the dorsal rami innervate?
Back of head to the butt. It also extends laterally (but not very much) along the back.
What are the nerve plexuses?
A network of interweaving ANTERIOR rami of spinal nerves. They are on the right and left sides of the body.
What vertebrae make up the cervial plexus?
C1 - C4
What is the ansa cervicalis?
C2; LOOP of nerves that innervate neck muscles.
What is the phrenic nerve?
C3; nerve that runs from the hyoid to clavicle and scapula.
What spinal nerves innervate the diaphragm?
C3, C4, C5
What vertebrae make up the brachial plexus?
C5 - T1
What are the divisions of the brachial nerves (proximal to distal?)
roots, trunks, divisions, cords, branches
What does the brachial plexus innervate?
clavicle, arm, hand
What vertebrae make up the lumbar plexus?
L1 - L4
What does the lumbar plexus innervate?
femur, hip, lower abdomen, leg
What vertebrae make up the sacral plexus?
L5 - S4
What adoes the sacral plexus innervate?
the gluteal region, shin, calf and foot.
What are reflexes?
Rapid, involuntary reactions of muscles to glands to a stimulus.
What are the three properties of reflexes?
stimulus, rapid response with few neurons and an identical and automatic response every time.
What are ipsliateral reflex arcs?
the receptor and effector organs of the reflex are on the same side of the spinal cord. (e.g. muscles in left arm contract to pull left hand away from a hot object).
What are contralateral reflex arcs?
the sensory impulses from a receptor organ cross over through the spinal cord to activate effector organs in the opposite side limb.
What are monosynaptic reflexes?
reflexes that do not involve neurons. Example is tapping the patellar ligament.
What are polysynaptic reflexes?
reflexes that involve interneurons and more complex pathways. There is a more prolonged delay between stimulus and response. Example is withdrawl reflexes (e.g. hot stove)
What are stretch reflexes?
monosynaptic reflexes that monitor and regulate skeletal muscle length. When a stimulus results in stretching of muscle, the muscle contracts.
What does the golgi tendon reflex do?
prevents skeletal muscle from tensing excessively. It signals interneurons to inhibit the actions of motor neurons. It is a mechanism to prevent excessive tension damage.
Where are Golgi tendon organs?
nerve endings located within tendons near a muscle-tendon junction.
