Lecture 8 - Spinal Cord, Spinal Nerves, and Cranial Nerves Flashcards
(117 cards)
1
Q
How does the organization of grey and white matter differ in the brain and spinal cord?
A
Brain: grey matter on the outside
Spinal cord: white matter on the outside
2
Q
What are the ventral and dorsal horns of the spinal cord?
A
Butterfly like structure that exists in the center of the spinal cord and contains grey matter
3
Q
What is another name for the spinal cord dorsal horns?
A
Sensory horns
4
Q
What is another name for the spinal cord ventral horns?
A
Motor horns
5
Q
What is another name for sensory neurons?
A
Ascending neurons
6
Q
What is another name for motor neurons?
A
Descending neurons
7
Q
How to recognize ventral and dorsal horns?
A
Ventral horns are larger
8
Q
Where is the ascending white matter located in the spinal cord?
A
Dorsal column
9
Q
Where is the descending white matter located in the spinal cord?
A
Lateral and anterior columns
10
Q
What are the 2 major enlargements of the spinal cord? Purpose?
A
- Cervical
- Lumbar
Control over limb and sensory functions resulting from the abundance of cell bodies in the cervical and lumbar vertebrae
11
Q
What is the main function of the thoracic spinal cord? What does this mean for the composition of this part?
A
Posture
Less cell bodies
12
Q
List the 4 parts of the spinal cord from top to bottom.
A
- Cervical
- Thoracic
- Lumbar
- Sacral
13
Q
Describe the input and output of information in the spinal cord.
A
- Dorsal root has afferent sensory fibers with cell bodies in dorsal root ganglia (semiunipolar neurons)
- Ventral root has efferent motor fibers with cell bodies situated in the ventral horn
14
Q
Describe the nature of spinal nerves.
A
Mixed: carry both sensory and motor information
15
Q
How many pairs of spinal nerves?
A
31
16
Q
List the 31 pairs of spinal nerves and their abbreviations. Note?
A
- Cervical nerves: C1-8
- Thoracic nerves: T1-12
- Lumbar nerves: L1-5
- Sacral nerves: S1-5
- Coccygeal nerve: Co
Note: numbered from top to bottom on spinal cord
17
Q
Where do the C1-C7 nerves exit?
A
Superior to the namesake vertebra
18
Q
How many cervical vertebra are there?
A
7
19
Q
Where does the C8 nerve exit?
A
Inferior to C7 vertebrae
20
Q
Where do spinal nerves inferior to C8 exit?
A
Inferior to namesake vertebra
21
Q
What are the 2 ways of classifying the neurons of the spinal cord?
A
- Sensory or motor
2. Somatic or visceral
22
Q
What are nerves?
A
Bundles of neurons
23
Q
What types of neurons does the dorsal root of the spinal cord contain?
A
- Somatic sensory
2. Visceral sensory
24
Q
What types of neurons does the ventral root of the spinal cord contain?
A
- Somatic motor
2. Visceral motor
25
What cell bodies are included in the dorsal horns of the spinal cord?
Cell bodies of interneurons
26
Where are the visceral neurons located compared to the somatic ones?
More central to the spinal cord canal
27
How does each spinal nerve attach to the spinal cord?
Via dorsal and ventral roots
28
Where do the dorsal roots of the spinal cord synapse? Onto what?
In the dorsal horn onto second order sensory neurons
29
Where do the ventral roots of the spinal cord synapse? Onto what?
Project into body to directly or indirectly control muscle
30
Where are the sympathetic chain ganglia located? How many of them?
Parallel to the spinal cord
2: one on each side
31
What is the role of the sympathetic chain ganglia? How?
Control autonomic functions by interacting with the spinal nerves or their anterior rami
32
What does histology of the human spinal cord show? What are these called?
Layers of neurons (Rexed lamina) in both the ventral and dorsal horns:
Dorsal: horizontal layers
Ventral: columns
33
Describe the connective tissue compartmentalization of the PNS nerves.
Endoneurium surrounds individual axon fibers
Perineurium surrounds fascicles = bundles of axon fibers
Epineurium surrounds nerves (which are composed of many fascicles) and the vasculature
34
What are spinal cord nerve rootlets?
Several of them form a dorsal or ventral root
35
What is a spinal nerve root?
Where the dorsal and ventral roots come together
36
What do the spinal nerve roots divide in?
Rami (branches)
37
What do the anterior rami supply?
Limbs and ventral portion of the body
38
What do the posterior rami supply?
Back muscles and skin covering them
39
What do the nerves become after the rami? 3 options
- Anterior rami => plexuses formed by the combination of rami from neighboring anterior rami
- Anterior rami of the thoracic nerves => intercostal nerves
- Posterior rami: directly innervate deep muscles and skin of the back
40
What are the 4 basic plexuses?
1. Cervical
2. Brachial
3. Lumbar
4. Sacral
41
Can nerves get to the body from all levels of plexuses?
YUP
42
Where is the cervical plexus located?
Neck
43
From what anterior rami is the cervical plexus formed?
Anterior rami of C1-C5
44
What 3 parts of the body does the cervical plexus innervate?
1. Back of head
2. Neck
3. Diaphragm
45
Which specific nerves innervates the diaphragm? What 3 cervical nerves does it come from?
2 phrenic nerves (right and left)
Come from C3, C4, C5
46
What happens if you severe one of the 2 phrenic nerves?
Partial diaphragmatic paralysis
47
What happens if you severe both phrenic nerves? Would you loose the ability to breathe completely?
Complete diaphragmatic paralysis
NOPE because you would still have the intercostal muscle functioning
48
What happens if you have an upper cervical cord transection?
Loose all sensory and motor functions caudal to the transection
49
Where is the brachial plexus located?
Muscles of the shoulder
50
From what anterior rami is the brachial plexus formed?
Anterior rami of C5-T1
51
What 2 parts of the body does the brachial plexus innervate?
1. Skin and muscles of upper limbs
| 2. Muscles that help control upper limbs (in back and shoulders)
52
What are the 5 brachial plexus nerves?
1. Axillary nerve
2. Musculocutenous nerve
3. Radial nerve
4. Median nerve
5. Ulnar nerve
53
What 2 parts of the body does the axillary nerve innervate? What 2 cranial nerves does it come from?
1. Deltoid muscle (shoulder)
2. Skin of shoulder
Comes from C5 and C6
54
What 2 parts of the body does the musculocutaneous nerve innervate? What 3 nerves does it come from?
1. Biceps brachii
2. Skin of lateral forearm
Comes from C5, C6, and C7
55
What 3 parts of the body does the radial nerve innervate? What 5 nerves does it come from?
1. Triceps
2. Posterior forarm muscles
3. Overlying skin of both
Comes from C5-C8 and T1
56
What 3 parts of the body does the median nerve innervate? What 5 nerves does it come from?
1. Anterior forearm muscles (flexors)
2. Lateral 2/3rds of the hand
3. Overlying skin
Comes from C5-C8 and T1
57
What 2 parts of the body does the ulnar nerve innervate? What 2 nerves does it come from?
1. Muscles of 4th and 5th digits
2. Overlying skin
Comes from C8 and T1
58
What nerve is affected when you bump your funny bone?
Ulnar nerve
59
What are the 4 types of plexus injuries? Explain each
1. Avulsion = tearing the nerve from the spinal cord
2. Rupture = tearing the nerve, but not at the spinal cord
3. Neuroma = scar tissue when an injured nerve has tried to heal putting pressure on the nerve and disrupting signals to the muscles
4. Praxis = stretching (but no tearing) of the nerve
60
Is the nerve able to heal itself from a praxis?
YUP
61
What are some causes of superior brachial plexus injuries (C5-6)? How do we classify these?
Excessive increase in the angle between the neck and the shoulder: either trauma or obstetrics
62
What is Erb's palsy?
Injury to superior brachial plexus (nerves C5-C6) causing paralysis of limbs which hang by the side with hands flexed upward
63
What is another name for Erb's palsy?
Waiter's tip
64
Can you have Erb's palsy on only one side of your body?
YUP
65
What are causes of inferior brachial plexus injuries (C8-T1)? How do we classify these?
Occurs when upper limb is suddenly pulled superiorly: either trauma or obstetrics
66
What is ulnar claw? What is it caused by?
4th and 5th finger drawn toward the back of the hand at the first knuckle and curled toward the palm at the 2nd and 3rd knuckles
Caused by injury to the inferior brachial plexus
67
What is carpal tunnel syndrome (CTS) caused by? Symptoms?
Injury to the median nerve due to narrowing/inflammation of the carpal tunnel
Symptoms: pain, paresthesia, difficulty moving fingers
68
What is the carpal tunnel?
Narrow, tunnel-like structure in the wrist with median nerve and flexor tendons in the center:
- Dorsal and lateral sides of the tunnel formed by wrist bones
- Ventral side of the tunnel covered by a strong band of connective tissue: transverse carpal ligament
69
What is paresthesia?
Abnormal sensation, typically tingling or pricking (“pins and needles”), caused chiefly by pressure on or damage to peripheral nerves
70
How are the intercostal nerves arranged?
Segmentally between ribs
71
What 2 parts of the body do the intercostal nerves innervate?
1. Skin of thoracic wall
| 2. Muscles of thoracic wall
72
What is the subcostal nerve? Where is it found?
Nerve formed by anterior ramus of T12
Project inferior to 12th rib
73
What rami form the lumbar plexus?
Anterior rami L1-L4
74
Where is the lumbar plexus located?
Underneath the psoas major muscle
75
What 3 parts of the body does the lumbar plexus innervate?
1. Lower limbs
2. Abdominal wall (small branches)
3. Inguinal region (small branches)
76
What can injury to the lumbar plexus cause? What can be the origin?
Deficits in movements and sensation of the lower limbs
Cause: trauma (compression injury to spinal cord) or diabetes
77
What are the 2 nerves of the lumbar plexus?
1. Femoral nerve
| 2. Obturator nerve
78
What 3 parts of the body does the femoral nerve innervate? What 3 nerves does it come from?
1. Quadriceps muscles of anterior thigh
2. Muscles in medial lower leg (toward inside)
3. Overlying skin
Comes form L2-4
79
What 2 parts of the body does the obturator nerve innervate? What 3 nerves does it come from?
1. Adductor muscles of the medial thigh
2. Overlying skin
Comes from L2-4
80
What does adduction mean? What's the opposite?
Movement of a body part toward the body's midline
Opposite: abduction
81
Where is the sacral plexus located?
Caudal to the lumbar plexus
82
What anterior rami form the sacral plexus?
Anterior rami L4-S4
83
What sacral nerve forms the coccygeal nerve?
S5
84
What does the coccygeal nerve innervate?
The muscle of the pelvic floor
85
What 3 parts of the body does the sacral plexus innervate?
1. Pelvis
2. Buttocks
3. Posterior lower limbs
86
What do we call the lumbar and sacral plexuses together?
Lumbosacral plexus
87
What are the 2 nerves of the sacral plexus?
1. Sciatic nerve
| 2. Pudendal nerve
88
What are the 2 branches of the sciatic nerve and what does each innervate?
1. Tibial nerve:
- Muscles of posterior thigh
- Muscles and skin of lower leg (mainly the back of the lower leg)
- Intrinsic muscles and skin of foot (plant of foot)
2. Common fibular nerve:
- Muscles and skin of anterolateral lower leg
- Muscles and skin of top of foot
89
What 4 nerves does the sciatic nerve come from?
L4-S3
90
What 3 parts of the body does the pudendal nerve innervate?
1. Bladder sphincter
2. Rectum sphincter
3. Skin of external genitals
91
What 3 nerves does the pudendal nerve come from?
S2-S4
92
What are dermatomes and myotomes? What can they be used for?
They represent the segmental innervation of the body by somatic fibers (afferent and efferent) in spinal nerves
Can be used as diagnostic tools
93
What is a dermatome?
Area of the skin supplied by a single spinal nerve
94
Where is the chicken pox virus located in the body? In what form?
Dormant in the dorsal root ganglia
95
How are chicken pox and herpes zoster related?
Both are caused by the same virus
| Chicken pox is the primary infection and herpes zoster is a reactivation at a later time
96
What 4 things can cause a herpes zoster outbreak? What is this called? Where does it happen?
HIV, stress, old age, chemotherapy
Happens on a dermatome
Shingles
97
What is referred pain? Example?
Pain that is evident in a visceral organ but the body feels it in the skin or musculature
Example: heart attack will feel pain in left arm because the ganglia that contains heart sensory nerves also innervates that arm
98
What is a myotome?
Collection of skeletal muscles that share a common spinal nerve(s)
99
What can vertical compression of the spinal cord cause?
A disk can bulge out causing nerve pressure, which can cause sciatica and a lot of pain
100
What are cranial nerves numbered according to?
Rostral - caudal extent
101
List the 12 cranial nerves from rostral to caudal.
1. Olfactory
2. Optic
3. Oculomotor
4. Trochlear
5. Trigeminal
6. Abducens
7. Facial
8. Acoustic
9. Glossopharyngeal
10. Vagus
11. Accessory
12. Hypoglossal
102
What cranial nerves are found in the forebrain?
1 and 2
103
What cranial nerves are found in the midbrain?
3 and 4
104
What cranial nerves are found in the pons?
5, 6, 7, and 8
105
What cranial nerves are found in the medulla?
9, 10, 11, 12
106
How to remember the function of each cranial nerve?
Some say marry money but my brother says big brains matter more
```
S: sensory (olfactory nerve - CN I)
S: sensory (optic nerve - CN II)
M: motor (oculomotor nerve - CN III)
M: motor (trochlear nerve - CN IV)
B: both (trigeminal nerve - CN V)
M: motor (abducens nerve - CN VI)
B: both (facial nerve - CN VII)
S: sensory (vestibulocochlear nerve - CN VIII)
B: both (glossopharyngeal nerve CN IX)
B: both (vagus nerve - CN X)
M: motor (spinal accessory nerve - CN XI)
M: motor (hypoglossal nerve - CN XII)
```
107
Cranial nerve mnemonic?
Oh, Oh, Oh, To Touch And Feel A Girls' Vagina and Hymen
108
What are the 3 extraocular nerves and what does each innervate?
1. Abducens nerves innervate lateral rectus muscle which allow side movement
2. Trochlear nerve innervates superior oblique muscles which allows upper eye movement
3. Oculomotor nerve innervates all other extraocular muscles
109
What are the 3 branches of the trigeminal nerve? Where does the branching start? What do they give rise to?
1. Opthalmic branch
2. Maxillary branch
3. Mandibular branch
Branching starts at the trigeminal ganglion
3 dermatomes on the face of the same names
110
What is the external part of the ear known as?
Pina
111
What 2 nerves is the pina innervated by?
1. Vagus nerve
| 2. Facial nerve
112
Where are the efferent somas of the cranial nerves found?
Brainstem nuclei
113
Where are the afferent somas of the cranial nerves found?
Cranial ganglia or sensory epithelium (olfactory epi or retina)
114
What is another name for second order sensory neuron?
Interneuron
115
What is "drop foot"?
Patients with common fibular nerve damage will lose the ability to dorsiflex the foot at the ankle joint. Hence the foot will appear permanently plantarflexed – known as footdrop
116
Nerves affect by superior brachial plexus injuries?
C5 and C6
117
Nerves affect by inferior brachial plexus injuries?
C8 and T1
