second half of lab 4

1. What are the two main parts of the nervous system and where are they found?

The central nervous system (CNS) is found in the skull and vertebral column. The peripheral nervous system (PNS) is found outside the skull and vertebral column.

1. Which nerves give rise to the two divisions of the autonomic nervous system?

The cranial nerves and sacral spinal nerves give rise to the parasympathetic division, and the lumbar and thoracic spinal nerves give rise to the sympathetic division.

1. Rotate the view to examine the posterior portion and select the dura mater—the protective layer that covers the spinal cord. What are the four regions of the spinal dura mater?

cervial, thoracic , lumbar, sacral

1. Select any nerve of the lumbar plexus and use the arrow in the content box to choose Lumbar plexus (R or L) from the selected structures list, highlighting all the right or left lumbar spinal nerves. What are the three major nerves of the lumbar plexus?

The genitofemoral, lateral femoral cutaneous, and femoral nerves

a. With the cervical plexus highlighted, rotate the view to examine the anterior portion and locate the paired nerves that extend into the thorax. What are these nerves called?

The phrenic nerves

1. List the structures innervated by the sciatic nerve and its branches.

The semimembranosus, semitendinosus, adductor magnus, and muscles of the distal leg and foot.

a. Use the Hide tool to remove the bottom two dura mater regions from the view. Select the cauda equina again and use the book icon to read its definition. Then, select the region of the spine where it originates, which is the ______________________________, found in the _________________ region of the spinal column.

conus medullar is found un lumbar

a. This pair of nerves innervates the ________________________________________________.

diaphragm, pleura, pericardium

a. Locate the point where the two roots of a spinal nerve meet after they exit the spinal column. This short section soon branches into a ____________________________ and a ________________________.

dorsal ramus ventral ramus

1. Rotate the view to examine the dorsal portion and use the Hide tool to remove the cervical region of the dura mater from the view. Observe the four pairs of spinal nerves that are attached to the back of the spinal cord and select any of the finger-like segments that attach them to the spinal cord on either side. These segments are the ____________________________________ of the cervical spinal nerves.

dorsal roots

a. Select any part of the outer protective connective tissue layer surrounding the spinal cord. This layer is called the _____________________________. This tough structure also protects the brain.

dura matter

The spinal cord extends from the upper border of the spinal column (atlas) to the lower border of the first, or upper border of the second, ______________________________ vertebra.

lumbar

1. This large plexus can be divided into two smaller ones. The ______________________________ plexus derives from the spinal nerves ______________________________ and the ______________________________ plexus derives from spinal nerves ______________________________.

lumbar T12--L04 SACRAL L04-S04

a. Select the cauda equina to view its length. Which two regions of the dura mater protect the cauda equina?

lumbar and sacral regions

a. What part of the brain is continuous with the spinal cord?

medulla oblongata

a. The brachial plexus innervates the ___________________________ and ____________________________.

shoulder upper limbs

The part of the cervical plexus that extends into the shoulder is the

supraclavicular nerve

1. The sciatic nerve is the largest nerve in the body. Its two main branches are the _____________________ and the ______________________.

tibial and fibular nerve

a. The spinal nerve segments that connect to the front of the spinal cord are the ________________________________________ of the cervical spinal nerves.

ventral ANTERUOR ROOTS

1. Which spinal nerves contribute to the lumbosacral plexus?

T12-S04

a. The divisions arise from the upper, middle, and lower ______________________________.

TRUNKS

1. Describe how the peripheral nervous system (PNS) is further divided in terms of function.

The PNS is divided into the somatic nervous system (SNS), which controls voluntary movement, and the autonomic nervous system (ANS), which controls involuntary, visceral functions. The ANS is further divided into sympathetic and parasympathetic divisions. The sympathetic division raises heart rate and other body functions in response to an emergency. The parasympathetic division is responsible for rest functions such as digestion.

a. What is the name of this group of nerves? (Hint: It means "horse tail.")

The cauda equina

a. How many pairs of spinal nerves are there?

31

a. These segments are the ______________________________ and ______________________________ divisions of the brachial plexus.

ANTERIOR POSTERIOR

a. Which spinal nerves contribute to the brachial plexus?

C05-C08 AND T01

The divisions unite to form three ______________________________. What are they called

CORDS The lateral cord, medial cord, and posterior cord

a. What is unique about this pair of nerves?

It is the only pair of cervical plexus nerves that is not cutaneous

1. Describe the route taken by the sciatic nerve.

It travels from the lower back through the buttock and down the posterior part of the leg.

s. The two major nerves of the sacral plexus are the __________________________ and the _____________________________.

SCIATIC NERVES PUDENDAL NERVES

a. Which cervical spinal nerves contribute to the cervical plexus?

c01-c04

1. Where does it split into these two branches?

at the knee

a. Why are spinal nerves called mixed nerves?

both sensory and motor fibers

a. The cauda equina innervates the __________ and __________.

pelvis lower limbs

1. List the major plexuses and state which spinal nerves give rise to them.

• The cervical plexus derives from C01-C04. • The brachial plexus derives from C05-C08 and T01. • The lumbosacral plexus derives from T12-S04. Alternately, students could say the lumbar plexus derives from T12-L04 and the sacral plexus derives from L04-S04.