BIOL 1408
HANDOUT Chapter 13 (Key)
1 What portion of the spinal cord connects with nerves of the upper limbs?
The cervical enlargement connects with sensory and motor nerves of the upper limbs.
2 What is the difference between a horn and a column in the spinal cord?
A horn is an area of gray matter, and a column is a region of white matter in the spinal cord.
3 Why are all spinal nerves classified as mixed nerves?
All spinal nerves are classified as mixed because their posterior roots contain sensory axons and their anterior roots
contain motor axons.
4 Why does complete severing of the spinal cord at level C2 cause respiratory arrest?
Severing the spinal cord at level C2 causes respiratory arrest because it prevents descending nerve impulses from
reaching the phrenic nerve, which stimulates contraction of the diaphragm, the main muscle needed for breathing.
5 What three important nerves arise from the brachial plexus?
The axillary, musculocutaneous, radial, median, and ulnar nerves are five important nerves that arise from the brachial
plexus.
Critical Thinking: Evalina’s severe headaches and other symptoms were suggestive of meningitis, so her physician
ordered a spinal tap. List the strucdtures that the needle will pierce from the most superficial to the deepest. Why
would the physician order a test in the spinal region to check a problem in Evalina’s head?
The needles will pierce the epidermis, dermis, and subcutaneous layer and then go between the vertebrae through the
epidural space, the dura mater, the subdural space, the arachnoid mater, and into the CSF in the subarachnoid space.
CSF is produced in the brain, and the spinal meninges are continuous with the cranial meninges.