Chapter 19 - Lab

Spinal cord functions - carries sensory information up to the brian, motor commands down from the brain, processes information, and executes various reflexes

Spinal nerves - carries information directly to and from the spinal cord

31 pairs - How many pairs of spinal cords are there?

Neurons - Responds to a stimulus by generating an electrical impulse that will signal another cell and effectors 

Sensory neurons - send signals from the sensory receptors to the central nervous system

Interneurons - send signals from sensory receptors to the central nervous system

Motor neurons - send signals from the central nervous system to effectors

Visceral motor neurons - send signals to glands, cardiac muscles, and smooth muscles cells

Somatic motor neurons - send signals to skeletal muscle cells 

Dendrites, soma, and an axon - Structure of neuron

Dendrites - receive stimuli

Soma - the cell body

Axon - sends an electrical impulse to another cell or cells

Multipolar neurons - has numerous dendrites and a single axon extending from its soma

Axolemma - the plasma membrane of the axon

Axon hillock - the beginning of the axon and the site of action potential initiation

Neurolemmocytes -cells that wrap the Axolemma, and form the myelin sheath

Myelin sheath - wraps around the axon, and protects it, electrically insulating it, and increasing the speed of the action potential 

Neurofibril nodes - gaps between the neurolemmocytes, also known as “nodes of Ranvier”

Endoneurium - layer of connective tissues that wrap the axon and myelin sheath

Telodendria - Branched extensions of axons from other neurons

Axon terminals - ends of telodendria, synapse with the soma and dendrites of other neuron and releases neurotransmitters upon it

Synaptic knobs - 

Schwann cells - cells that wrap their plasma membrane around the axon

Where is the end of a somatic motor neuron axon, along with its telodendria and synaptic knobs, located?

What is a Synapse?

Conus Medullaris - inferior tip of the spinal cord

Cauda equina - structure below the conus medullaris, appears similar to the tail of a horse 

Filum terminale - an extension of the pia mater of the spinal cord, attaches the conus medullaris to the coccyx

Cervical enlargement - where nerves that innervate the upper limbs connect to the spinal cord

Lumbosacral enlargement - where nerves that innervate the lower limbs connect to the spinal cord

Posterior median sulcus - a thin groove that runs longitudinally down the back of the spinal cord

Anterior median fissure - a somewhat wide groove the runs longitudinally down the front of the cord

Anterior rami -  intermingle to form networks called plexuses.

Cervical plexuses - Branches of spinal nerves C1 to C4, innervate certain muscles in the neck along with the skin of the neck and parts of the head and shoulders

Phrenic nerve - nerve that extends from each cervical plexuses innervates the diaphragm and is important for breathing

Brachial Plexuses - Branches of spinal nerves C5 to T1, innervate the pectoral girdles and upper limbs

Lumbosacral plexuses - give rise to various nerves that innervate the lower limbs

Obturator nerves - passes through an obturator foramen to innervate muscles and skin of the medial thigh

Sciatic nerves - largest nerves in the body, they innervate much of the lower limbs

Intercostal Nerves - Travel parallel to each other, between the ribs, from the back to the chest

WHat is the difference between spinal meninges and cranial meninges - The cranial dura mater is made up of two layers, the spinal dura mater is made up of just one layer, the presence of space between the spinal dura mater and the surrounding vertebrae.

Epidural space - space between the spinal dura mater and the surrounding vertebrae, occupied by adipose tissue and blood vessels.

Why is the spinal cord enlarged in two places? They are where spinal nerves that innervate the arms and legs, respectively, join the spinal cord

The lumbosacral enlargement of the spinal cord is located in the lower thoracic region of the spine. Why is it called the lumbosacral enlargement? - The nerves exit the vertebral cavity at the lumbar and sacral regions of the spine

Central canal -

Anterior horn - anterior portion of the butterfly shaped gray matter, contains bodies of somatic motor neurons.

Posterior horn - posterior portion of the butterfly shaped gray matter, contains the bodies of interneurons  

Lateral horn -  contain the bodies of visceral motor neurons 

Gray commissure - portion of gray matter that connects the two wings

Posterior funiculi - posterior portion of the white matter

ANterior funiculi - anterior portion of of the white matter

Lateral funiculi - the lateral portion of the white matter

Ventral roots - nerves that allow motor neuron axons to exit the front of the spinal cord

Dorsal root ganglia - sensory neuron bodies, their axons travel into the back of the cord via nerves called the dorsal root

Dorsal roots - nerves

Ganglion - a structure that houses neuron bodies and lies outside the CNS

In what part of the spinal cord are bodies of somatic motor neurons found? - anterior horns

In what structures are the bodies of sensory neurons found? - dorsal root ganglia

How can you tell the difference between a motor neuron and a sensory neuron? Motor neurons are multipolar and have processes. Sensory neurons are unipolar and have no obvious processes

In what structure are afferent axons found? - dorsal root ganglia and dorsal roots

In what structures are efferent axons found - ventral roots

WHat problem would a person have if all of their ventral roots were cut? - effectors would receive no motor commands

What problem would a person have if all of their dorsal roots were cut? - the spinal cord would receive no sensory information