Chapter 19 - Lab

Carries sensory information to the brain, motor commands from the brain, processes information, and executes reflexes.

What is the function of the spinal cord?

Spinal nerves

Carry information directly to and from the spinal cord; there are 31 pairs.

Neurons

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

Sensory neurons

Send signals from 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 muscle, and smooth muscle cells.

Somatic motor neurons

Send signals to skeletal muscle cells.

Neuron structure

Composed of dendrites, soma (cell body), and an axon.

Dendrites

Receive stimuli from the environment.

Soma

The cell body of the neuron.

Axon

Sends an electrical impulse to other cells.

Multipolar neurons

Have numerous dendrites and one axon extending from the soma.

Axolemma

The plasma membrane surrounding the axon.

Axon hillock

The beginning of the axon where action potentials are initiated.

Neurolemmocytes

Cells that wrap the axolemma and form the myelin sheath.

Myelin sheath

Wraps around the axon, protecting, insulating, and increasing the speed of action potentials.

Neurofibril nodes

Gaps between neurolemmocytes, also known as nodes of Ranvier.

Endoneurium

Layer of connective tissue that wraps the axon and myelin sheath.

Telodendria

Branched extensions of axons that synapse with other neurons.

Axon terminals

Ends of telodendria, releasing neurotransmitters at synapses.

Synaptic knobs

Rounded structures at the ends of axon terminals that store and release neurotransmitters.

Schwann cells

cells that wrap their plasma membrane around the axon

Skeletal muscle

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

Junction between two neuron or a neuron and effector cell

What is a Synapse?

Conus Medullaris

The inferior tip of the spinal cord.

Cauda equina

Structure below the conus medullaris, resembling a horse's tail.

Filum terminale

Extension of pia mater that anchors the conus medullaris to the coccyx.

Cervical enlargement

Region where upper limb nerves connect to the spinal cord.

Lumbosacral enlargement

Region where lower limb nerves 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

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.

WHat is the difference between spinal meninges and cranial meninges

Epidural space

Space between the spinal dura mater and surrounding vertebrae filled with adipose tissue.

They are where spinal nerves that innervate the arms and legs, respectively, join the spinal cord

Why is the spinal cord enlarged in two places?

The nerves exit the vertebral cavity at the lumbar and sacral regions of the spine

The lumbosacral enlargement of the spinal cord is located in the lower thoracic region of the spine. Why is it called the lumbosacral enlargement?

Central Canal

Dorsal horn

Anterior part of butterfly-shaped gray matter containing bodies of somatic motor neurons.

Ventral horn

Anterior part of butterfly-shaped gray matter containing bodies of interneurons.

Lateral horn

Contains 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 whose axons travel into the back of the spinal cord.

Dorsal roots

nerves

Ganglion

a structure that houses neuron bodies and lies outside the CNS

Ventral horns

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

dorsal root ganglia

In what structures are the bodies of sensory neurons found?

Motor neurons are multipolar with processes; sensory neurons are unipolar with no obvious processes.

Motor neuron vs. sensory neuron

Effect of cutting ventral roots

Effectors would receive no motor commands.

Spinal cord would receive no sensory information.

Effect of cutting dorsal roots

spinal dura mater

Arachnoid mater

Subarachnoid space

Pia mater

Dorsal root

Dorsal root ganglion

Ventral root

Spinal nerve

Anterior median fissure

Anterior funiculus

Lateral funiculus

Posterior funiculus

Ventral horn

Gray commissure

central canal

Dorsal root ganglion