Chapter 13 - The Spinal Cord and Spinal Nerves Flashcards

1
Q

What are the Functions of the Spinal Cord?

A

1- Process reflexes
2- Integrate EPSP and IPSP
3- Conduct sensory impulses to the brain and motor impulses to effectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the Protection of the Spinal Cord?

A

Spinal Cord is protected by:

1- Bone (vertebrae)
2- Connective Tissue (meninges)
3- Fluid (CSF)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are Meninges?

A

The meninges are composed of 3 layers (same for brain):

1- Dura Mater
2- Arachnoid Mater
3- Pia Mater

Epidural space - between Dura and bone
Subdural space - between Dura and Arachnoid
Subarachnoid space - between Arachnoid and Pia, where CSF is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the External Anatomy of the Spinal Cord?

A

The spinal cord begins as an extension of the Medulla Oblongata at the level of the Foramen Magnum
Terminates at the level of L2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the Internal Anatomy of the Spinal Cord?

A

Spinal Nerve (plus Nerve Impulses trajectories)
Anterior Root of Spinal Nerve (plus Axons of Motor Neurons)
Posterior Root of Spinal Nerve
Posterior Root Ganglion (plus Axon of Sensory Neuron)
Anterior Rootlets
Posterior Rootlets

Lateral White Column
Anterior White Column
Posterior White Column

Anterior Gray Horn (plus Cell Body of Somatic Motor Neuron)
Posterior Gray Horn (plus Cell Body of Interneuron)
Lateral Gray Horn (plus Cell Body of Autonomic Motor Neuron)

Anterior Median Fissure
Posterior Median Sulcus
Anterior White Commissure
Gray Commissure
Central Canal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Sensory and Motor Processing?

A

The internal anatomy of the spinal cord allows sensory and motor information to be processed in an organized way:

SOMATIC NERVOUS SYSTEM:

First, Sensory receptors (ex: in skin) send nerve impulses
Second, Nerve impulses travel along sensory neuron to posterior root ganglion
Then one of the following happens:

1- Nerve impulses go to Brain through Sensory (Ascending) Tract
Then back through Motor (Descending) Tract to Somatic Motor Neuron in the Spinal Cord
Then to Effectors (Skeletal Muscles) through Anterior Root of Spinal Nerve

2- Nerve impulses go to Interneuron in Spinal cord
Then go to Brain through Sensory (ascending) Tract
Then back through Motor (Descending) Tract to Somatic Motor Neuron in the Spinal Cord
Then to Effectors (Skeletal Muscles) through Anterior Root of Spinal Nerve

3- Nerve impulses go to Interneuron in Spinal Cord
Then go to Somatic Motor Neuron in the Spinal Cord
Then to Effectors (Skeletal Muscles) through Anterior Root of Spinal Nerve

AUTONOMIC NERVOUS SYSTEM:

Autonomic Motor Neuron in Spinal Cord sends nerve impulses
Nerve impulses go through Anterior Root of Spinal Nerve
Nerve impulses go to another Autonomic Motor Neuron to Effectors (Cardiac Muscle, Smooth Muscles, and Glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the Characteristics of Cervical Segment of the Spinal Cord?

A

Relatively large diameter
Relatively large amounts of White Matter - oval

In upper Cervical segments (C1-C4):
Posterior Gray Horn is large
Anterior Gray Horn is relatively small

In lower Cervical segments (C5 and below)
Posterior Gray Horns are enlarged
Anterior Gray Horns are well developed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the Characteristics of Thoracic Segment of the Spinal Cord?

A

Small diameter due to relative small amounts of Gray Matter
(Except 1st Thoracic segment)

Anterior and Posterior Gray Horns are relatively small
Small Lateral Gray Horn is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the Characteristics of Lumbar Segment of the Spinal Cord?

A

Nearly circular
Very large Anterior and Posterior Gray Horns
Small Lateral Gray Horn is present in upper segments
Relatively less White Matter than Cervical segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the Characteristics of Sacral Segment of the Spinal Cord?

A

Relatively small
Relatively large amounts of Gray Matter
Relatively small amounts of White Matter

Anterior and Posterior Gray Horns are large and thick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the Characteristics of Coccygeal Segment of the Spinal Cord?

A

Resembles lower Sacral spinal segments but much smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are Spinal Nerves?

A

Part of PNS
Spinal Nerves connect CNS to sensory receptors, muscles, and glands

31 Pairs of Spinal Nerves

Anterior and Posterior Roots attach a spinal nerve to a segment of the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the Structure of Spinal Nerves?

A

Epineurium: covers spinal nerve
Fascicles and blood vessels inside spinal nerve

Perineurium: covers each Fascicle
Many Axons inside Fascicle

Endoneurium: covers each Axon
Many Axons covered by Myelin Sheath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are Branches of a Spinal Nerve?

A

Shortly after passing through its intervertebral foramen, a spinal nerve divides into several branches known as Rami

Rami: branches of a spinal nerve

ex:
Anterior Ramus
Posterior Ramus
Meningeal Branch
Rami Communicantes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Dermatome?

A

Certain segments of the skin are supplied by spinal nerves that carry somatic sensory nerve impulses to the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Cervical Plexus?

A

Cervical Plexus: C1-C5

Supplies the skin and muscles of the:
Head
Neck
Superior portion of shoulders and chest
Diaphragm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the Superficial (Sensory) Branches of Cervical Plexus Nerves?

A

Lesser Occipital nerve
Great Auricular nerve
Transverse Cervical nerve
Supraclavicular nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is Lesser Occipital Nerve?

A

Origin:
C2

Distribution:
Skin of scalp posterior and superior to ear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is Great Auricular Nerve?

A

Origin:
C2-C3

Distribution:
Skin anterior, inferior, and over ear
Over Parotid glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is Transverse Cervical Nerve?

A

Origin:
C2-C3

Distribution:
Skin over anterior and lateral aspect of neck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is Supraclavicular Nerve?

A

Origin:
C3-C4

Distribution:
Skin over superior portion of chest and shoulder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the Deep (Largely Motor) Branches of Cervical Plexus Nerves?

A

Superior Root of Ansa Cervicalis nerve
Inferior Root of Ansa Cervicalis nerve
Phrenic nerve
Segmental Branches nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is Superior Root of Ansa Cervicalis Nerve?

A

Origin:
C1

Distribution:
Infrahyoid and Geniohyoid muscles of neck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Segmental Branches Nerve?

A

Origin:
C1-C5

Distribution:
Prevertebral (deep) muscles of neck
Levator Scapulae
Middle Scalene muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
What is Inferior Root of Ansa Cervicalis Nerve?
Origin: C2-C3 Distribution: Infrahyoid muscle of neck
25
What is Phrenic Nerve?
Origin: C3-C5 Distribution: Diaphragm
26
What is Brachial Plexus?
Brachial Plexus: C4- T2 Provides almost the entire nerve supply to the shoulders and upper limbs Subunits of the Brachial Plexus: (Risk Takers Don't Cautiously Behave) 1- Roots 2- Trunks (Superior, Middle, Inferior) 3- Divisions (Anterior and Posterior) 4- Cords (Medial, Posterior, Lateral) 5- Branches
27
What are the Nerves of the Brachial Plexus?
Dorsal Scapular nerve Long Thoracic nerve Nerve to Subclavius Suprascapular nerve Musculocutaneous nerve Lateral Pectoral nerve Upper Subscapular nerve Thoracodorsal nerve Lower Subscapular nerve Axillary nerve Median nerve Radial nerve Medial Pectoral nerve Medial Cutaneous nerve of arm Medial Cutaneous nerve of forearm Ulnar nerve
28
What is Dorsal Scapular Nerve?
Origin: C5 Distribution: Levator Scapulae Rhomboid Major Rhomboid Minor
29
What is Long Thoracic Nerve?
Origin: C5-C7 Distribution: Serratus Anterior (If affected, leads to winged scapula)
30
What is Nerve to Subclavius?
Origin: C5-C6 Distribution: Subclavius muscle
31
What is Suprascapular Nerve?
Origin: C5-C6 Distribution: Supraspinatus Infraspinatus
32
What is Musculocutaneous Nerve?
Origin: C5-C7 Distribution: Coracobrachialis Biceps Brachii brachialis
33
What is Lateral Pectoral Nerve?
Origin: C5-C7 Distribution: Pectoralis Major
34
What is Upper Subscapular Nerve?
Origin: C5-C6 Distribution: Subscapularis
35
What is Thoracodorsal Nerve?
Origin: C6-C8 Distribution: Latissimus Dorsi
36
What is Lower Subscapular Nerve?
Origin: C5-C6 Distribution: Subscapularis Teres Major
37
What is Axillary Nerve?
Origin: C5-C6 Distribution: Deltoid Teres Minor Skin over Deltoid and superior aspect of arm
38
What is Median Nerve?
Origin: C5-T1 Distribution: Flexors of forearm, except Flexor Carpi Ulnaris Ulnar half of Flexor Digitorum Profundus Some muscles of hand (lateral palm) Skin of lateral 2/3 of palm of hand and fingers
39
What is Radial Nerve?
Origin: C5-T1 Distribution: Triceps Brachii Anconeus Extensor muscles of forearm Skin of posterior arm and forearm, lateral 2/3 of dorsum of hand, and fingers over proximal and middle phalanges
40
What is Medial Pectoral Nerve?
Origin: C8-T1 Distribution: Pectoralis Major Pectoralis Minor
41
What is Medial Cutaneous Nerve of Arm?
Origin: C8-T1 Distribution: Skin of medial and posterior aspects of distal third of arm
42
What is Medial Cutaneous Nerve of Forearm?
Origin: C8-T1 Distribution: Skin of medial and posterior aspects of forearm
43
What is Ulnar Nerve?
Origin: C8-T1 Distribution: Flexor Carpi Ulnaris Ulnar half of Flexor Digitorum Profundus Most muscles of hand Skin of medial side of hand, little finger, and medial half of ring finger
44
What is Lumbar Plexus Nerves?
Lumbar Plexus: T12-L5 Roots, Anterior Divisions, Posterior Divisions Iliohypogastric nerve Ilioinguinal nerve Genitofemoral nerve Lateral Cutaneous Nerve of Thigh Femoral nerve Obturator nerve
45
What is Iliohypogastric Nerve?
Origin: L1 Distribution: Muscles of anterolateral abdominal wall Skin of inferior abdomen and buttock
46
What is Ilioinguinal Nerve?
Origin: L1 Distribution: Muscles of anterolateral abdominal wall Skin of superior and medial aspects of thigh, root of penis, and scrotum in male, and Labia Majora and Mons Pubis in female
47
What is Genitofemoral Nerve?
Origin: L1-L2 Distribution: Cremaster Skin over middle anterior surface of thigh, scrotum in make, and Labia Majora in female
48
What is Lateral Cutaneous Nerve of Thigh?
Origin: L2-L3 Distribution: Skin over lateral, anterior, and posterior aspects of thigh
49
What is Femoral Nerve?
Origin: L2-L4 Distribution: Largest nerve arising from Lumbar Plexus Distributed to flexor muscles of hip joint Extensor muscles of knee joint Skin over anterior and medial aspects of thigh and medial side of leg and foot
50
What is Obturator Nerve?
Origin: L2-L4 Distribution: Adductor muscles of hip joint Skin over medial aspect of thigh
51
What is Sacral Plexus Nerves?
Sacral Plexus: L4-S5 Roots, Anterior Division, Posterior Division Superior Gluteal nerve Inferior Gluteal nerve Nerve to Quadratus Femoris and Inferior Gemellus Nerve to Obturator Internus and Superior Gemellus Perforating Cutaneous nerve Posterior Cutaneous Nerve of Thigh Pudendal nerve Sciatic nerve Tibial nerve Medial Plantar nerve Lateral Plantar nerve Common Fibular nerve Superficial Fibular nerve Deep Fibular nerve
52
What is Superior Gluteal Nerve?
Origin: L4-L5 S1 Distribution: Gluteus Minimus Gluteus Medius Tensor Fasciae Latae
53
What is Inferior Gluteal Nerve?
Origin: L5-S2 Distribution: Gluteus Maximus
54
What is Nerve to Piriformis?
Origin: S1-S2 Distribution: Piriformis
55
What is Nerve to Quadratus Femoris and Inferior Gemellus?
Origin: L4-L5 S1 Distribution: Quadratus Femoris Inferior Gemellus
56
What is Nerve to Obturator Internus and Superior Gemellus?
Origin: L5-S2 Distribution: Obturator Internus Superior Gemellus
57
What is Perforating Cutaneous Nerve?
Origin: S2-S3 Distribution: Skin over inferior medial aspect of lower leg
58
What is Posterior Cutaneous Nerve of Thigh?
Origin: S1-S3 Distribution: Skin over anal region, inferior lateral aspect of buttock, superior posterior aspect of thigh, superior part of calf, scrotum in male, Labia Majora in female
59
What is Pudendal Nerve?
Origin: S2-S4 Distribution: Muscles of Perineum Skin of penis and scrotum in male and Clitoris, Labia majora, Labia Minora and Vagina in female
60
What is Sciatic Nerve?
Origin: L4-S3 Distribution: 2 Nerves - Tibial Nerve and Common Fibular Nerve Bound together by common sheath of connective tissue Splits into 2 divisions usually at knee As Sciatic Nerve descends through thigh, it sends branches to Hamstring muscles and Adductor Magnus
61
What is Tibial Nerve?
Origin: L4-S3 Distribution: Gastrocnemius Plantaris Soleus Popliteus Tibialis Posterior Flexor Digitorum Longus Flexor Hallucis Longus Branches of Tibial Nerve in foot are Medial and Lateral Plantar Nerve
62
What is Medial Plantar Nerve?
Origin: L4-S3 Distribution: Abductor Hallucis Flexor Digitorum Brevis Flexor Hallucis Brevis Skin over medial 2/3 of plantar surface of foot
63
What is Lateral Plantar Nerve?
Origin: L4-S3 Distribution: Remaining muscles of foot not supplied by Medial Plantar Nerve Skin over lateral 1/3 of plantar surface of foot
64
What is Common Fibular Nerve?
Origin: L4-S2 Distribution: Divides into Superficial Fibular Nerve and Deep Fibular Nerve
65
What is Superficial Fibular Nerve?
Origin: L4-S2 Distribution: Fibularis Longus Fibularis Brevis Skin over distal 1/3 of anterior aspect of leg and dorsum of foot
66
What is Deep Fibular Nerve?
Origin: L4-S2 Distribution: Tibialis Anterior Extensor Hallucis Longus Fibularis Tertius Extensor Digitorum Longus Extensor Digitorum Brevis Skin on adjacent sides of great and second toes
67
What is Spinal Cord Physiology?
In order to maintain homeostasis, the spinal cord must propagate nerve impulses and integrate information White Matter Tracts conduct nerve impulses to and from the Brain Gray Matter receives and integrates incoming and outgoing information to perform spinal reflexes
68
Where are Sensory Tracts?
Sensory Tracts: 1- Posterior Column: Gracile Fasciculus (medial) Cuneate Fasciculus (lateral) 2- Posterior Spinocerebellar Tract Anterior Spinocerebellar Tract 3- Lateral Spinothalamic Tract Anterior Spinothalamic Tract
69
Where are Motor Tracts?
1- Lateral Corticospinal Tract Anterior Corticospinal Tract 2- Rubrospinal Tract 3- Lateral Reticulospinal Tract Medial Reticulospinal Tract 4- Vestibulospinal Tract 5- Tectospinal Tract
70
What is Reflexes and Reflex Arcs?
A reflex is a fast, involuntary, unplanned response to a particular stimulus Reflexes help maintain homeostasis The Gray Matter of the Spinal Cord serves as the integrating center for spinal reflexes Reflex Arc: Sensory Receptor Sensory Neuron Spinal Cord Motor Nerve Effector
71
What are Reflex Arcs Terms?
Ipsilateral (same side) Contralateral (opposite side) Monosynaptic Polysynaptic Reciprocal Innervation (avoidance of commotion/confusion) Hemiplegia: 1/2 paralysis Monoplegia: 1 limb paralysis Paraplegia: Lower half Paralysis Quadriplegia: 4 limb paralysis -Plegia: Complete death -Paresis: Weakness
72
What is Stretch Reflex?
Causes contraction of a muscle that has been stretched 1- Stretching stimulates sensory receptor (muscle spindle) 2- Sensory neuron excited 3- Within integrating center (spinal cord), sensory neuron activates motor neuron and inhibits motor neuron to antagonistic muscles 4- Motor neuron excited 5- Effector (same muscle) contracts and relieves the stretching
73
What is Tendon Reflex?
Causes relaxation of the muscle attached to the stimulated tendon 1- Increase tension stimulates sensory receptor (tendon organ) 2- Sensory neuron excited 3- Within integrating center (spinal cord) sensory neuron activates inhibitory interneuron, motor neuron to antagonistic muscles is excited, antagonistic muscle contracts 4- Motor neuron inhibited 5- Effector (muscle attached to same tendon) relaxes and relieves excess tension
74
What is Flexor (Withdrawal) Reflex?
Causes withdrawal of a limb to avoid injury or pain 1- Step on tack stimulates sensory receptor (dendrites of pain-sensitive neuron) 2- Sensory neuron excited 3- Within integrating center (spinal cord) sensory neuron activates interneurons in several spinal cord segments 4- Motor neuron excited 5- Effectors (flexor muscles) contract and withdraw leg
75
What is Crossed-Extensor Reflex?
Maintains balance during a withdrawal reflex 1- Step on a tack stimulates sensory receptor (dendrites of pain-sensitive neuron) in right foot 2- Sensory neuron excited 3- Within integrating center (spinal cord) sensory neuron activates several interneurons 4- Motor neurons excited 5- Effector (extensor muscles) contract and extend left leg
76
What are some Spinal Cord and Spinal Nerves Disorders?
Traumatic injuries: Monoplegia Paraplegia Hemiplegia Quadriplegia Damage that results from traumatic injuries depends on : Degree of spinal cord section Or Degree of compression of the segments involved Spinal Cord compression Degenerative disease Shingles: 1st Time chicken pox, goes to dorsal roots of spine and wait until body is weaker, then acts when immune system is weak Poliomyelitis: GI virus, goes to spinal cord