The 31 pairs of human spinal nerves arise from the fusions of what 2 roots of the spinal cord?

1. Ventral roots of spinal cord

2. Dorsal roots of spinal cord

The spinal nerves are what type of nerves?

Mixed nerves

Mixed nerves consist of what 2 fiber types?

1. Motor fibers

2. Sensory fibers

What are the 5 types of spinal nerves?

1. Cervical nerves

2. Thoracic nerves

3. Lumbar nerves

4. Sacral nerves

5. Coccygeal nerves

How many pairs of cervical nerves are there?

8

What are the cervical nerves (in term of numbering)?

C1-C8

How many pairs of thoracic nerves are there?

12

What are the cervical nerves (in term of numbering)?

T1-T12

How many pairs of lumbar nerves are there?

5

What are the lumbar nerves (in term of numbering)?

L1-L5

How many pairs of sacral nerves are there?

5

What are the sacral nerves (in term of numbering)?

S1-S5

How many pair(s) of coccygeal nerves are there?

1

What is/are the coccgeal nerves (in term of numbering)?

Co₁

1. The first pair of spinal nerves leaves which canal and between which 2 body parts?

2. Where do the rest of the spinal nerves leave then?

1. Leaves the vertebral canal between the base of the skull and the atlas

2. Through the intervertebral foramina

The first through seventh pairs of cervical nerves emerge where in regard to their respective vertebra?

Emerge above the vertebra for which they are named

The C8 spinal nerve emerges between which 2 vertebra?

1. C7

2. T1

The remaining spinal nerve pairs emerge where in regard to their respective vertebra?

Emerge from the spinal cord area below the same-numbered vertebra

After emerging, each nerve divides into what 2 rami?

1. Dorsal rami

2. Ventral rami

How long is each spinal nerve?

About 1 or 2 cm long

The rami, like the spinal nerves, contain what 2 fiber types?

1. Motor

2. Sensory

The dorsal rami serve what 2 body features?

1. Skin

2. Musculature of the posterior body trunk

The ventral rami T2-T12 pass anteriorly as what type of nerves?

Intercostal nerves

1. The intercostal nerves T2-T12 supply which 3 body parts?

1. muscles of intercostal spaces

2. skin

3. muscles of anterior and lateral trunk

2. The ventral rami of all other spinal nerves, except for thoracic nerves, form what complex networks?

Nerve plexuses

What are the 4 nerve plexuses?

1. Cervical plexus

2. Brachial plexus

3. Lumbar plexus

4. Sacral plexus

The nerve plexuses serve what 2 body features?

1. Muscles of the limbs

2. Skin of the limbs

The fibers of the ventral rami unite at which features?

Plexuses

After the fibers of the ventral rami unite at the nerve plexuses, they diverge again to form what type of nerves?

Peripheral nerves

The peripheral nerves that result from the fibers diverging from the plexuses contain fibers from how many nerves?

More than one spinal nerve

The cervical plexus arises from the ventral rami of what cervical nerves?

C1-C5

The cervical plexus supplies muscles of which 2 body parts?

1. Shoulder

2. Neck

What is the major motor branch (nerve) of the cervical plexus?

Phrenic nerve

The phrenic nerve arises from the ventral rami of which cervical nerves?

C3-C5

The phrenic nerve innervates which body part?

Diaphragm

What is the primary danger of a broken neck (in regard to which nerve being damaged)?

The phrenic nerve may be severed

If the phrenic nerve is severed, what 2 dangerous conditions could occur?

1. Paralysis of the diaphragm

2. Cessation of breathing

The brachial plexus arises from the ventral rami of what cervical and thoracic nerves?

C5-T1

The brachial plexus after being rearranged consecutively into trunks, divisions, and cords, finally becomes subdivided into what 5 major peripheral nerves?

1. axillary nerve

2. radial nerve

3. median nerve

4. musculocutaneous nerve

5. ulnar nerve

The axillary nerve arises from the ventral rami of what cervical nerves and corresponding cord?

C5-C6 (posterior cord)

The axillary nerve serves what what 2 features (muscles and general feature of a certain body part)?

1. Muscles of the shoulder

2. Skin of the shoulder

Give an example of a muscle served by the axillary nerve?

Deltoid muscle

Which peripheral nerve from the brachial plexus has the most limited distribution?

Axillary nerve

The radial nerve arises from the ventral rami of what cervical and thoracic nerves and the corresponding cord?

C5-C8, T1 (medial cord)

1. The radial nerve serves the extensor muscles of what 2 body parts?

2. The radial nerve also serves what general feature of those 2 body parts along its course?

1. All the extensor muscles of...

• the arm
• forearm

2. The skin along its course

Give an example of a muscle served by the radial nerve.

Triceps brachii

The radial nerve is often injured in the axillary region by what 2 activities?

1. Using a crutch

2. Hanging an arm over the back of a chair

The median nerve arises from how many branches, and what are they?

2 branches: medial cord and lateral cord

The respective cords of the median nerve are composed of the ventral rami of which cervical and thoracic nerves?

Medial cord: C8, T1

Lateral cord: C5-C7

1. The median nerve supplies most of which groups of muscles in which 2 body parts and which general feature of the hand?

2. Give an example of one flexor muscle served.

1. Supplies flexor muscles in the forearm and several muscles in the hand and the skin of the hand

2. Flexor carpi radialis

The musculocutaneous nerve arises from the ventral rami of which cervical nerves and its corresponding cord?

C5-C7 (lateral cord)

The musculocutaenous nerve supplies which group of muscles (of which body part) and another general feature?

Supplies the flexor muscles of the forearm and the lateral skin of the forearm

Give an example of a muscle served by the musculocutaneous nerve.

Biceps brachii

The ulnar nerve arises from the ventral rami of which cervical and thoracic nerves and the corresponding cord?

C8, T1 (medial cord)

1. The ulnar nerve supplies which group of muscles of which body part, and give an example?

2. The ulnar nerve also supplies another group of intrinsic muscles in which body part?

1. Supplies the flexor muscles in the anterior forearm (i.e. flexor carpi radialis).

2. Supplies all intrinsic muscles of the hand not served by the median nerve

The ulnar nerve also serves which general feature of the hand?

Skin of the medial third of the hand, both anterior and posterior surfaces

When you hit the "funny bone," you have trauma in which nerve?

Ulnar nerve

Severe injuries to the brachial plexus cause what 2 conditions to the entire upper limb?

1. Weakness

2. Paralysis

Weakness and paralysis to the upper limb result from which 2 common injuries?

1. When the upper limb is pulled hard and the brachial plexus is stretched

2. Blows to the shoulder that force the humerus inferiorly

The lumbosacral plexus serves which 2 regions?

1. Pelvic region of the trunk

2. Pelvic region of the lower limbs

The lumbosacral plexus is a complex of which 2 plexuses?

1. Lumbar plexus

2. Sacral plexus

The lumbar plexus arises from the ventral rami of what lumbar nerves (and sometimes which thoracic nerve)?

L1-L4 and sometimes T12

The nerves of the lumbar plexus serves which region and which body part?

Serves the lower abdominopelvic region and the anterior thigh

What is the largest nerve of the lumbar plexus?

Femoral nerve

The femoral nerve arises from the ventral rami of what lumbar nerves?

L2-L4

The femoral nerve innervates which group of muscles? (Give an example)

Anterior thigh muscles

Ex. Sartorius muscle

The cutaneous branch of the femoral nerve also serves what general feature of which general body part?

Supply the skin of the anteromedial surface of the entire lower limb

The sacral plexus arises from the ventral rami of which lumbar and sacral nerves?

L4-S4

1. The nerves of the sacral plexus supply which 2 body parts?

2. The nerves of the sacral plexus also supply which 2 groups of fibers of which 2 body parts?

1. The sacral plexus nerves supply...

• buttock
• posterior surface of the thigh

2. The nerves of the sacral plexus also supply...

• sensory fibers of the leg and foot
• motor fibers of the leg and foot

What is the major peripheral nerve of the sacral plexus?

Sciatic nerve

The sciatic nerve arises from the ventral rami of what lumbar and sacral nerves?

L4-L5 and S1-S3

What is the largest nerve in the body?

Sciatic nerve

The sciatic nerve serves which group of muscles of which body part and also, which general feature of that body part?

Serves the flexor muscles of the posterior thigh and the skin of the posterior thigh

In the popliteal region, the sciatic nerve divides into which 2 nerves?

1. common fibular nerve

2. tibial nerve

The common fibular nerve and the tibial nerve supply the muscles of which body part, and what general feature of that body part?

Supply the leg muscles and the skin of the leg

1. Give an example of a muscle served by the common fibular nerve.

2. Give an example of a muscle served by the tibial nerve.

1. Extensor digitorum longus

2. Flexor digitorum longus

The common fibular nerve arises from the ventral rami of what lumbar and sacral nerves?

L4-S2

The tibial nerve arises from the ventral rami of what lumbar and sacral nerves?

L4-S3

What 2 common injuries that can damage the sciatic nerve?

1. a fall

2. herniated disc

Sciatica is characterized by what type of pain, and it radiates over the course of what nerve?

Characterized by stabbing pain that radiates over the sciatic nerve.

What happens to the legs when the sciatic nerve is completely severed?

The legs are rendered completely useless.

What medical condition arises from the severing of the sciatic nerve?

footdrop

Describe footdrop in 2 ways.

1. Legs cannot be flexed.

2. Foot drops into plantar flexion.

The spinal nerve is formed by the fusion of what 2 roots?

Dorsal and ventral roots.

White matter is composed of what?

Myelinated and nonmyelinated axons.

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