Lab 1 - Bolded Words

Dura Mater

One of the meninges

• the outermost and toughest layer

• surrounded by a fat-filled space, the epidural space

  • common site for the injection of anesthetic during labor and some surgeries

Arachnoid Mater

one of the meninges

• spiderweb-like extensions to the deepest layer

Pia Mater

one of the meninges

• deepest layer

• tightly adheres to the spinal cord, but between it and the arachnoid mater is a fluid-filled cavity, the subarachnoid space

• extends to create the filum terminale and the denticular ligaments

Subarachnoid Space

between the pia mater and the arachnoid mater

• fluid-filled cavity with cerebrospinal fluid (CSF)

• provides a protective cushion around the spinal cord and the brain

Central Canal

narrow passageway in the spinal cord

• CSF is found here

Meninges

three layers: dura, arachnoid, and pia mater

• protect the spinal cord and brain

Epidural Space

surrounds the dura mater

• fat-filled space

• common site for the injection of anesthetic during labor and some surgeries

Cerebrospinal Fluid

fluid that surrounds the spinal cord and brain

Conus Medullaris

cone-shaped termination of the spinal cord

• L1-L2

• since the vertebral column’s growth outpaces the spinal cord, the spinal cord does not extend the full length of the vertebral canal in newborns and adults

Filum Terminale

the pia mater continues past the end of the cord becoming this

• “terminal thread”

• tethers the spinal cord to the sacrum and coccyx

Denticulate Ligaments

around 20 paired lateral extensions along the length of the spinal cord formed by the pia mater

• provides further stability for the spinal cord

Cauda Equina

bundle of spinal nerve roots formed below the conus medullaris

• L2 and lower spinal nerves

• resembles a horse’s tail

• collection of lumbar, sacral, and coccygeal spinal nerves that passed through the vertebral canal on their way to the appropriate body level

Spinal Nerves

cervical, thoracic, lumbar, sacral, and coccygeal, which serve these respective regions of the body

• their roots emerge from the right and left sides of the spinal cord

Anterior Median Fissure

fissure that cuts into the white matter along the entire spinal cord

White Matter

consists of myelinated axons that give it its color and make it distinct from gray matter

Dorsal Column

a bundle of axons running up and down the spinal cord organized into a column on the posterior side of the spinal cord

Lateral Column

a bundle of axons running up and down the spinal cord organized into a column on the lateral side of the spinal cord

Ventral Column

a bundle of axons running up and down the spinal cord organized into a column on the anterior side of the spinal cord

Corticospinal Tract

the largest descending tracts (axons with a similar function organized into large bundles)

• brings motor information from the brain to either the lateral or ventral horn to the appropriate place in the body

• Composed of 2 neurons: 1 peripheral and 1 interneuron

• Decussation of the upper motor neuron occurs in the medullary pyramids of the medulla oblongata

Spinothalamic Tract

ascending tract

• sends non-localized sensations from the entire body to the brain (ex. pain/temperature)

• Composed of 3 neurons

  • 1 peripheral (PNS) - 1st order

  • 2 interneurons (CNS) - 2nd/3rd order

• decussation occurs at the level of the spinal cord where the sensation was felt

Gray Matter

contains the interneurons that allow communication to and from the brain and other regions of the spinal cord

• in cross-section it is shaped like the letter ‘H’ or like a butterfly

• contains portions of sensory and motor neurons that bring signals into or out of the spinal cord

• forms columns that run the spinal cord’s length, containing the cell bodies of neurons that receive sensory information and those that send motor information

Dorsal Horn

a gray matter column that contains cell bodies of neurons that neurons that receive sensory information

• interneurons, not sensory neurons

Somatic Sensory

signals from the skin, skeletal muscles, and bones arrive at the dorsal-most region of the dorsal horn

Visceral Sensory

regions from the internal organs arrive at the central region of the dorsal horn

Somatic Motor

neurons that travel out of the spinal cord to the skeletal muscles have their cell bodies within the ventral horn

Visceral Motor

neurons that travel to glands and smooth or cardiac muscles have their cell bodies within the lateral horn

Ventral Horn

the somatic motor region

• where motor neurons cell bodies are found as they travel out of the spinal cord

Lateral Horn

the visceral motor region

• where motor neurons cell bodies are as they travel to glands and smooth or cardiac muscles

Dermatome

skin’s segments

• one pair of spinal nerves and its branches provide sensory innervation to each of these segments

• no physical boundaries are visible

• numbering scheme corresponds to the numbering of the spinal nerves that innervate them

C / T / L Spinal Nerves

Cervical, Thoracic, and Lumbar Spinal nerves

Cervical Spinal Nerves

there are 8, one more than the number of vertebrae

Thoracic Spinal Nerves

there are 12

Lumbar Spinal Nerves

there are 5

Dorsal Root

contains only sensory neurons that are entering the dorsal horn of the spinal cord

Dorsal Root Ganglion

the sensory neurons’ cell bodies form a swelling within the dorsal root

Ventral Root

contains only axons of motor neurons

• carries all motor information

• no ganglion

Dorsal Ramus

contains somatic motor and somatic sensory neurons headed to or from the skin, muscle, and bones of the back

• information from back of torso/body

Ventral Ramus

carries somatic motor and somatic sensory neurons to the skin, muscle, and bones of the body wall and limbs

• fromt front of torso/body and limbs (all arms/legs)

Communicating Rami

a pair of small branches that carry neurons to the smooth muscle, cardiac muscle, and glands of the body (visceral organs)

Sympathetic Ganglion

the site of synapse and the location of the cell bodies not too far from the communicating rami

Sympathetic Chain

the sympathetic ganglia and connecting branches for this

• a distribution hub for visceral neurons

Intercostal Nerves

ventral rami that travel along the inferior surface of the ribs

• send small branches to the nearby muscles, bones, and skin

Cervical Plexus

formed from ventral rami of cervical spinal nerves, and it innervates many of the neck muscles

Brachial Plexus

formed from ventral rami of C5-T1 spinal nerves, and it supplies the upper appendage

Lumbosacral Plexus

formed from ventral rami of L2-S4 spinal nerves, and it supplies the lower appendage

Withdrawal Reflex

a protective reflex

• suppose you put your hand on a hot stove. the immediate response of your arm is to withdraw from the source of pain

• although your brain may be informed of the pain, the withdrawal happens before you know it’s happening

• the reflex occurs irrespective of the notification to the brain

Polysynaptic Reflex

when at least two synapses are present in the reflex

Vertebral Canal

the pathway that is created by the alignment of each vertebral foramen

• spinal cord runs down

intervertebral foramen

foramina in between the vertebrae

• where spinal nerves emerge

Tract

bundle of neurons with related function

Autonomic Nervous system

aka visceral motor division

• 2 parts: sympathetic nervous system and parasympathetic nervous system

Sympathetic Nervous System

fight or flight

Parasympathetic Nervous System

rest and digest

Monosynaptic Reflexes

sensory neuron synapses directly with motor neuron in ventral horn

• no interneurons involved

• ex. knee-jerk (patellar) reflex

Lower Motor Neuron

peripheral neuron

• synapse in the ventral horn

• corticospinal tract

Upper Motor Neuron

interneuron

• corticospinal tract

1st Order Neuron

peripheral neuron

• goes from stimuli to the dorsal horn and synapses with 2nd order

• spinothalamic tract

2nd Order Neuron

interneuron

• Decussates and enters the white matter tract; synapse in the thalamus with 3rd order

• Spinothalamic tract

3rd Order Neuron

interneuron

• carries signal from thalamus to the cerebral cortex for sensation

• spinothalamic tract

Decussation

when a neuron crosses over to the opposite side of the spinal cord