Exercise 19 - Mamm Phys Lab

Exam 1

The spinal cord extends from the foramen magnum of the skull to the first or second lumbar vertebra, where it terminates in the:

a. conus medullaris

b. denticulate ligament

c. filum terminale

d. gray matter

conus medullaris

How many pairs of spinal nerves do humans have?

a. 10

b. 12

c. 31

d. 47

31

Which underlined term is correct? In cross section, the gray/white matter of the spinal cord looks like a butterfly or the letter H

Gray

True or False: The cell bodies of sensory neurons are found in an enlarged area of the dorsal root called the gray commissure

False

Which underlined term is correct? Fiber tracts conducting impulses to the brain are called ascending or sensory/motor tracts

Sensory

True or False? Because the spinal nerves arise from fusion of the ventral and dorsal roots of the spinal cord, and contain motor and sensory fibers, all spinal nerves are considered mixed

True

The ventral rami of all spinal nerves except T₂ through T₁₂ form complex networks of nerves known as:

a. fissures

b. ganglia

c. plexuses

d. sulci

Plexuses

Severe injuries to the _______ plexus cause weakness or paralysis of the entire upper limb

a. brachial

b. cervical

c. lumbar

d. sacral

brachial

True or false? The femoral nerve is the largest nerve from the sacral plexus

True

Which underlined term is correct? The sciatic nerve divides into the tibial and posterior femoral cutaneous/common fibular nerves

Common fibular

What is the spinal cord?

continuation of the brain stem; communication center that provides neural pathways to and from the brain

What is the conus medullaris?

Termination of the spinal cord

What is filum terminale?

Fibrous extension of the conus medullaris covered by pia mater

What are denticulate ligaments

Saw-toothed shelves of pia mater that secure the spinal cord to the dura mater

What is the cauda equina?

Collection of spinal nerve roots that travel through vertebral canal before reaching their intervertebral foramina; called this due to similarity to horse’s tail

What is paraplegia/quadriplegia?

Injury to certain spinal cord areas that may result in permanent flaccid paralysis of both legs or of all four limbs

What name is given to the third meninx, and where is it found?

The pia mater, which adheres closely to the surface of the brain and spinal cord

How are the dorsal horns differentiated from the ventral horns?

The dorsal horns are more tapered than the ventral horns

Is the shape of the central canal basically circular or oval?

More oval

Name the type of neuroglia that line the central canal

Lined with ependymal cells; in living specimens, it contains cerebrospinal fluid

What are intercostal nerves?

Ventral rami of spinal nerves T2 through T12 to supply muscles of intercostal spaces and skin/muscles of anterior/lateral trunk

What are nerve plexuses?

The ventral rami of all other spinal nerves form complex networks of nerves

What is the cervical plexus and where does it arise?

Supply muscles of the shoulder and neck; arises from the ventral rami of C1 through C5

What is the major motor branch of the cervical plexus and where does it arise?

The phrenic nerve; arises from C3 through C5 and some of C5

What is the danger of a broken neck?

The phrenic nerve may be severed, which leads to paralysis of the diaphragm and cessation of breathing

Rhyme to remember rami (roots) forming phrenic nerves

C3, C4, C5 keep the diaphragm alive

What is the brachial plexus and where does it arise?

Arises from ventral rami of C5 through C8 and T1

What is the axillary nerve?

Serves the muscles and skin of the shoulder; has the most limited distribution

What nerve is associated with the axillary nerve?

The radial nerve; supplies all extensor muscles of the arm, forearm, and hand and skin along it’s course

How can the radial nerve be injured?

Pressure of a crutch or by hanging one’s arm over the back of a chair

What is the median nerve’s function?

Supply most of the flexor muscles in the forearm and several muscles in the hand; passes down the anteromedial surface

What is the musculocutaneous nerve?

Supplies the arm muscles that flex the forearm and the skin of the lateral surface of the forearm

What is the ulnar nerve?

Travels down the posteromedial surface of the arm

What is the lumbosacral plexus

Serves the pelvic region of the trunk and the lower limbs

What are the two plexuses that make up the lumbosacral plexus?

The lumbar and sacral plexus

What is the lumbar plexus?

Nerves that serve the lower abdominopelvic region and anterior thigh; arises from the ventral rami of L1 through L4

What is the major nerve of the lumbar plexus?

Femoral nerve

What is the sacral plexus?

Arises from L4 through S4; supplies the buttock, posterior surface of thigh, and all sensory/motor fibers of the leg and foot

What is the major nerve of the sacral plexus?

Sciatic nerve; largest nerve in the body

What is sciatica?

Stabbing pain radiating over the course of the sciatic nerve

What is footdrop?

Condition where the leg cannot be flexed and foot drops into plantar flexion

What is most superior boundary of the spinal cord?

Foramen magnum

What is the meningeal extension beyond the spinal cord terminus?

Filum terminale

What is the spinal cord terminus?

Conus medullaris

What is the collection of spinal nerves traveling in the vertebral canal below the terminus of the spinal cord?

cauda equina

What is the neuron type? Neuron type found in dorsal horn

Interneurons

What is the neuron type? Neuron type found in ventral horn

Motor

What is the neuron type? Neuron type in dorsal root ganglion

sensory

What is the neuron type? fiber type in ventral root

Motor

What is the neuron type? Fiber type in dorsal root

sensory

What is the neuron type? fiber type in spinal nerve

Both sensory and motor

Where in the vertebral column is a lumbar puncture generally done?

Between L3 and L4 OR L4 and L5

Why is L3/L4 or L4/L5 the site of choice for a lumbar puncture?

The spinal cord ends at the level of L2; there is little chance of damaging it below that level

In what regions is the spinal cord enlarged?

The cervical and the lumbar regions

What is the significance of the cervical and lumbar region enlargements?

Nerves serving the limbs issue from these regions of the spinal cord

How does the position of the gray and white matter differ in the spinal cord and cerebral hemisphere?

In the spinal cord, the white matter surrounds the gray matter. In the cerebral hemisphere, there is an outer “rind” of gray matter; deep to that is white matter with a few scattered islands of gray matter

What tract might be damaged when the following conditions are observed? Uncoordinated movement

Tectospinal, rubrospinal, and vestibulospinal tract

What tract might be damaged when the following conditions are observed? Lack of voluntary movement

Lateral and ventral corticospinal tract

What tract might be damaged when the following conditions are observed? Tremors, jerky movements

Tectospinal, rubrospinal and vestibulospinal tracts

What tract might be damaged when the following conditions are observed? Diminished pain perception

Lateral spinothalamic tract

What tract might be damaged when the following conditions are observed? Diminished sense of touch

dorsal columns, ventral spinothalamic tract

Compare and contrast meninges of the spinal cord and brain

Both have three meninges: pia mater, arachnoid mater, and dura mater.

Dura mater in brain has two layers (periosteal and meningeal), while spinal cord only has meningeal

In spinal cord, there is an epidural space between vertebral bone and dura, but dura of brain is tightly adhered to skull

How are the cervical nerves numbered?

C1-C8

How are the lumbar nerves numbered?

L1-L5

How are the sacral nerves numbered?

S1-S5

How are the thoracic nerves numbered?

T1-T12

The ventral rami of spinal nerves C1 through T1, and T12 through S4 take part in forming _________, which serve the _________ of the body

plexuses

limbs and anterior trunk

The ventral rami of T2 through T12 run between the ribs to serve the _________.

Intercostal muscles

The dorsal rami of the spinal nerves serve the _________

posterior body trunk

What would happen if the following structure were damaged/transected? Dorsal root of a spinal nerve

Loss of sensory function

What would happen if the following structure were damaged/transected? Ventral root of a spinal nere

Loss of motor function

What would happen if the following structure were damaged/transected? Ventral ramus of a spinal nerve

Loss of both motor and sensory function

What is a plexus?

Complex network of joining and diverging nerves

What is the major nerve that serves the following body areas? Head, neck, shoulders?

Cervical

What is the major nerve that serves the following body areas? Diaphragm

Phrenic

What is the major nerve that serves the following body areas? Posterior thigh

Sciatic

What is the major nerve that serves the following body areas? Leg and foot

Common fibular, tibial, sural, medial and lateral plantar

What is the major nerve that serves the following body areas? Anterior forearm muscles

Median, ulnar

What is the major nerve that serves the following body areas? Arm muscles

Radial, musculocutaneous

What is the major nerve that serves the following body areas? Abdominal wall

Lumbar

What is the major nerve that serves the following body areas? Anterior thigh

Femoral

What is the major nerve that serves the following body areas? medial side of the hand

ulnar