Chapter 13 Spinal cord and Nerves

86 terms by mpcisnero 

Ready to study?
Start with Flashcards

Create a new folder

Advertisement Upgrade to remove ads

List two enlargements

Cervical and Lumbar

Conus Medullaris

End of a spinal cord that ends between the 1st and 2nd lumbar vertebrae in adults

Filum Terminal

Extension of pia mater that extends from the conus medullaries and anchors the spinal cord to the coccyx

Cauda Equina

"Horse's Tail" Formed from the ventral nerved roots that supply the lumber, sacral, and coccygeal regions

Sympathetic Chain Ganglia

Communication point for the two motor neurons in the autonomic nervous system

Sympathetic Chain Ganglia

Located on both sides of the vertebral bodies and are part of the motor division of the autonomic nervous system

Epidural Space

Located between the vertebrae and the duramater; Composed of adipose and blood connective tissue

Dura Mater

Most superficial covering of the spinal cord; composed of dense irregular connective tissue

Subdural Space

Between the dura mater and arachnoid mater; contains interstitial fluid

Arachnoid Mater

Composed of web-like collagen and elastic fibers; is deep to the dura mater

Subarachnoid Space

Deep to the arachnoid mater and contains cerebrospinal fluid

Pia Mater

Thin layer of collagen fibers, elastic fibers and blood vessels that touches the spinal crd

Denticulate Ligaments

Thickenings of the pia mater that stabilize the spinal cord and attach it to the arachnoid mater

Anterior Median Fissure

Deep, wide groove on the anterior (ventral) side

Posterior Median Sulcus

Shallow groove on the posterior side

Gray Mater

Shaped like a butterfly

Gray Matter

Contains interneurons and is the site of integration

Posterior Horns (Dorsal)

Contains axons from the somatic and autonomic sensory neurons

Lateral Gray Horns

Only present in the thoracic and upper lumber regions; contain autonomic preganglionic motor neuron cell

Anterior (Ventral) Horns

Contain the cell bodies of somatic motor neurons and autonomic preganglionic motor neurons

Gray Commissures

Allows communication between the right and left horns

Central Canal

Located within the grey commisure

Central Canal

Small space extending the length of the spinal and is filled with CSF

White Mater

arranged in columns contains ascending sensory and descending motor tracts, which are bundles of axons in the CNS

Sensory (ascending) Tracts

consists of axons that conduct nerve impulses toward the brain

Motor (descending) Tracts

Axons that carry nerve impulses from the brain

Anterior (Ventral) White Columns

Contain tracts involved with spinal cord reflexes

Posterior (Dorsal) White Columns

Ascending sensory tracts for touch, pressure, vibration and voluntary proprioception

Lateral White Columns

Contain both sensory and motor tracts

White Commisure

Allows communication between the right and left anterior columns

Dorsal (Sensory) Root Ganglia

Cell bodies of unipolar sensory neurons

Dorsal (Posterior) Roots

Carry information from the PNS to the CNS

Ventral (Anterior) Roots

Carry information from the CNS-Effector structures

Spinal Nerves

Connect the CNS to the sensory receptors, muscles and glands in all parts of the body

Spinal nerves have

31 pairs

Cervical

C1-C-8

Thoracic

T1-T12

Lumbar

L1-L5

Sacral

S1-S5

What makes up the spinal nerve

Cervical, Thoracic, Lumbar, Sacral, and the Coccygeal

Connective tissue coverings

Each spinal and cranial nerve consists of many individual axons and contains layers of protective __________________.

Endoneurium

Innermost layer; wrap individual axons within a nerve, whether myelinated or unmyelinated

Perineurium

Middle layer; wraps a group of axons with their endoneirium arranged in bundles called fascicles

Epineurium

Outermost covering over the entire nerve

Rami

Branches of the spinal nerve

Posterior Ramus

Dorsal

Anterior Ramus

Ventral

Plexuses

Network of axons from the anterior rami of spinal nerves, except for thoracic nerves T1-T11 form plexuses

Cervical Plexus

Formed by anterior rami of C1-C5

Phrenic Nerves

Important nerves from the cervical plexuses; supply the skin and muscles of the head, neck and superior part of the shoulders and chest

Brachial Plexus

Formed by the anterior rami of C5-C8 and T1; supply the shoulders and upper limbs

Brachial Plexus

Roots --> Trunks --> Divisions --> Cords --> Branches

Important nerves that arise from the brachial plexuses

Axillary, Musculocutaneous, Radial, Median, and Ulnar Nerve

Duchenne Palsy

"Waiter's Tip" Loss of sensation along the lateral side of the arm

Wrist Drop

Inability to extend the wrist and fingers

Median Nerve Palsy

Numbness, tingling and pain in the palm and fingers

Ulnar Nerve Palsy

Inability to abduct or adduct fingers

Winged Scapula

Arm cannot be abducted beyond the horizontal position

Lumbar Plexus

Formed by the anterior rami of L1-L4; supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs

Sacral Plexus

Formed by the anterior rami of L4-L5 and S1-S4; supplies the buttocks, perineum, and lower limbs

Sciatic Nerve

Largest nerve in the body; formed by rami L4-L5 and S1-S4

Coccygeal Plexus

Formed by the anterior rami of S4-S5 and the coccygeal region

Dermatome

Area of the skin that provides sensory input to the CNS via one pair of spinal nerves or the trigeminal nerve serves most of the skin of the face and scalp

Sensory and Motor Tracts

Begins and ends on the white matter

Anterior Corticospinal Tract

Located in the anterior white column; Begins in the cerebral cortex (region in the brain) and ends in the spinal cord

Reflex

Autonomic, sudden, involuntary response to a stimulus

Somatic Reflex

Involve skeletal muscle effectors

Autonomic Reflexes

Involve smooth muscle; cardiac muscle or glands

Reflex Arc

Pathway followed by nerve impulses that produce a reflex

Monosynaptic Reflex Arc

Only one synapse within the gray mater of the CNS

Polysynaptic Reflex Arc

More than one synapse with the gray matter of the CNS

Ipsilateral

reflex when the signal passes from one side to the same side of the spinal cord, the SAME SIDE

Contralateral

Reflex when the signal passes from one side to the opposite side of the spinal cord, OPPOSITE SIDE

A reflex arc includes a

Sensory receptor, Sensory neuron, Integrating center, Motor neuron and Effector

Sensory Receptor

Responds to internal / external stimulus by producing a graded potential that triggers an action potential

Sensory Neuron

Carry the action potential from the receptor to the gray matter of the spinal cord

Integrating Center

One or more regions of gray matter in the CNS composed of interneurons

Motor Neuron

Carries action potentials out of the CNS to the effector organ

Effector

A muscle or gland

Stretch Reflex

Contraction of the skeletal muscle in response to stretching of the muscle; Monosynaptic reflex, ipsilateral; Patellar or knee-jerk reflex

Stretch Reflex

Stretching of a muscle--> activation of muscle spindles--> sensory neurons--> spinal cord--> motor neuron--> contraction of the agonist muscle & relaxation of the agonist muscle

Tendon Reflex

Controls muscle tension by causing muscle relaxation when muscle tension is great

Tendon Reflex

Golgi tendon organs--> tension applied to the tendon--> tendon organ stimulation--> sensory neuron carries information to the gray matter--> integration in the gray matter occurs-->motor neuron carries signal to effector; one motor neuron relaxes the agonist and the other motor neuron causes contraction of the agonist

Flexor (withdrawal) Reflex

Stepping on a tack (stimulus)--> sensory neuron carries signal to spinal cord--> activation of the interneuron to different spinal cord segments--> activation of the motor neuron in several segments of the spinal cord--> muscle contraction--> withdrawal of the leg

Crossed Extensor Reflex

Contraction of the muscles that extend joints in the opposite limb in response to a painful stimulus

Crossed Extension Reflex

Stepping on tack--> Nerve impulse--> Activation of several interneurons--> activation of the motor neurons--> muscle contraction causing flexion of the leg stepping on a tack and extension on the opposite side

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set