341 Spinal Cord & Brainstem Organization

spinal cord segment

a cross section of spinal cord giving rise to a spinal nerve on each side

posterior

Is the dorsal side of the spinal cord anterior or posterior?

anterior

Is the ventral side of the spinal cord anterior or posterior?

ventral

Which term describes the anterior side of the spinal cord: dorsal or ventral

dorsal

Which term describes the posterior side of the spinal cord: dorsal or ventral

posterolateral sulcus

Through what sulcus do dorsal rootlets enter the spinal cord?

2

How many posterolateral sulci are there in one spinal cord segment?

roots

Dorsal rootlets merge into dorsal _____. 

anterolateral sulcus

Through what sulcus do ventral rootlets exit the spinal cord?

2

How many anterolateral sulci are there in one spinal cord segment?

dorsal

Are dorsal or ventral rootlets associated with the posterolateral sulcus?

ventral

Are dorsal or ventral rootlets associated with the anterolateral sulcus?

roots

Ventral rootlets merge into ventral _____. 

nerve

A dorsal root and a ventral root join to form a spinal _____.

dorsal

Which roots are associated with sensory (afferent) functions: dorsal roots or ventral root

ventral

Which roots are associated with motor (efferent) functions: dorsal roots or ventral roots

sensory

Are dorsal roots associated with sensory (afferent) or motor (efferent) functions? 

motor

Are ventral roots associated with sensory (afferent) or motor (efferent) functions? 

dorsal root ganglion (DRG)

collection of cell bodies of sensory fibers entering the spinal cord; located just proximal to where the dorsal and ventral roots join to form the spinal cord

ganglion

Each dorsal root contains a dorsal root _____.

31

How many spinal cord segments are there?

8, 12, 5, 5, 1 

There are 31 spinal cord segments 

• _____ cervical  

• _____ thoracic

• _____ lumbar  

• _____ sacral 

• _____ coccygeal 

8

How many cervical spinal cord segments are there?

12

How many thoracic spinal cord segments are there?

5

How many lumbar spinal cord segments are there?

5

How many sacral spinal cord segments are there?

1

How many coccygeal spinal cord segments are there?

31

How many spinal cord nerve pairs are there?

8, 12, 5, 5, 1

There are 31 spinal nerve pairs

• _____ cervical  

• _____ thoracic

• _____ lumbar  

• _____ sacral 

• _____ coccygeal 

8

How many cervical spinal nerve pairs are there?

12

How many thoracic spinal nerve pairs are there?

5

How many lumbar spinal nerve pairs are there?

5

How many sacral spinal nerve pairs are there?

1

How many coccygeal spinal nerve pairs are there?

C1-C8

What are the abbreviations for the cervical spinal cord segments and spinal nerve pairs?

T1-T12

What are the abbreviations for the thoracic spinal cord segments and spinal nerve pairs?

L1-L5

What are the abbreviations for the lumbar spinal cord segments and spinal nerve pairs?

S1-S5

What are the abbreviations for the sacral spinal cord segments and spinal nerve pairs?

Co1

What is the abbreviation for the coccygeal spinal cord segment and spinal nerve pair?

~33

How many vertebrae does an adult human have in the spinal column (also known as the vertebral column, spine, or backbone)?

7, 12, 5, 5, ~4 

There are ~33 vertebrae in the adult human spinal column (also known as the vertebral column, spine, or backbone)

• _____ cervical  

• _____ thoracic

• _____ lumbar  

• _____ sacral 

• _____ coccygeal 

false

True or false: There are the same number of spinal cord segments, spinal nerve pairs, and vertebrae in an adult human. 

7

How many cervical vertebrae are there?

12

How many thoracic vertebrae are there?

5

How many lumbar vertebrae are there?

5

How many sacral vertebrae are there?

~4

How many coccygeal vertebrae are there?

false

True or false: There are the same number of cervical spinal cord segments, spinal nerve pairs, and vertebrae in an adult human. 

true

True or false: There are the same number of thoracic spinal cord segments, spinal nerve pairs, and vertebrae in an adult human. 

true

True or false: There are the same number of lumbar spinal cord segments, spinal nerve pairs, and vertebrae in an adult human. 

true

True or false: There are the same number of sacral spinal cord segments, spinal nerve pairs, and vertebrae in an adult human. 

false

True or false: There are the same number of coccygeal spinal cord segments, spinal nerve pairs, and vertebrae in an adult human. 

dermatome

area of skin innervated by a single spinal cord segment (more specifically, a single dorsal root ganglion)

sensory

Is the dermatome related to sensory or motor innervation?

motor

Is the myotome related to sensory or motor innervation?

C2, T4, T10, S5

What are the four dermatomes to remember?

C2

Which dermatome’s landmark is the back of head?

T4

Which dermatome’s landmark is the nipple line?

T10

Which dermatome’s landmark is the umbilicus?

S5

Which dermatome’s landmark is the anal area?

back of head

What is the landmark for dermatome C2?

nipple line

What is the landmark for dermatome T4?

umbilicus

What is the landmark for dermatome T10?

anal area

What is the landmark for dermatome S5?

C2, T4, T10, S5

Which dermatomes area associated with the following landmarks:

• back of head

• nipple line

• umbilicus

• anal area

back of head, nipple line, umbilicus, anal area

What are the landmarks for the following dermatomes:

• C2

• T4

• T10

• S5

myotome

group of muscles innervated by a single spinal cord segment

false

True or false: most muscles are innervated by a single spinal cord segment. 

C5, C6, C7, C8, T1

What are the upper extremity myotomes used to test for motor function of spinal cord segments?

C5, C6, C7, C8, T1

Which upper extremity myotomes are associated with the following muscle group actions:

• elbow flexion

• wrist extension

• elbow extension

• finger flexion

• pinky abduction

C5

Which upper extremity myotome is associated with elbow flexion?

C6

Which upper extremity myotome is associated with wrist extension?

C7

Which upper extremity myotome is associated with elbow extension?

C8

Which upper extremity myotome is associated with finger flexion?

T1

Which upper extremity myotome is associated with pinky abduction? 

elbow flexion

What muscle group action is myotome C5 associated with?

wrist extension

What muscle group action is myotome C6 associated with?

elbow flexion

What muscle group action is myotome C7 associated with?

finger flexion

What muscle group action is myotome C8 associated with?

pinky abduction

What muscle group action is myotome T1 associated with?

L2, L3, L4, L5, S1

What are the lower extremity myotomes used to test for motor function of spinal cord segments?

L2, L3, L4, L5, S1

Which lower extremity myotomes are associated with the following muscle group actions:

• hip flexion

• knee extension

• ankle dorsiflexion

• long toe extension

• ankle plantar flexion

L2

Which lower extremity myotome is associated with hip flexion?

L3

Which lower extremity myotome is associated with knee extension?

L4

Which lower extremity myotome is associated with ankle dorsiflexion?

L5

Which lower extremity myotome is associated with long toe extension? 

S1

Which lower extremity myotome is associated with ankle plantar flexion?

hip flexion

What muscle group action is myotome T2 associated with?

knee extension

What muscle group action is myotome L3 associated with?

ankle dorsiflexion

What muscle group action is myotome T4 associated with?

long toe extension

What muscle group action is myotome L5 associated with?

ankle plantar flexion

What muscle group action is myotome S1 associated with?

shorter

Is the spinal cord shorter or longer than the vertebral column?

cervical enlargement, lumbar enlargement

What are the two enlargements of the spinal cord?

cervical enlargement

region of spinal cord that gives rise to the spinal nerves that supply the upper extremities (C5-T1)

C5, T1

The cervical enlargement extends from spinal cord segment ____ to spinal cord segment ____. 

lumbar enlargement

region of spinal cord that gives rise to the spinal nerves that supply the lower extremities (L2-S3)

L2, S3

The lumbar enlargement extends from spinal cord segment ____ to spinal cord segment ____. 

conus medullaris

cone-shaped caudal end of the spinal cord located around vertebral level L1-L2

L1-L2.

The conus medullaris is located around vertebral level ____.