2b peripheral

Question 1

What is the function of the peripheral nervous system (PNS)?

Answer 1

It carries information to and from the central nervous system (CNS).

Question 2

What are afferent nerves?

Answer 2

Nerves that carry information to the CNS. (afferents arrive)

Afferents Arrive

Question 3

What are efferent nerves?

Answer 3

Nerves that carry information from the CNS. (efferents exit)

Efferents Exit

Question 4

What are the two main divisions of the PNS?

Answer 4

The autonomic nervous system and the somatic nervous system.

Question 5

How many neurons does the autonomic nervous system use to reach a target?

Answer 5

Two – a pre-ganglionic and a post-ganglionic neuron.

Question 6

Where do autonomic neurons synapse?

Answer 6

In ganglia located outside the spinal cord.

Question 7

What does the sympathetic nervous system do?

Answer 7

Initiates the ‘fight or flight’ response, preparing the body for stress or exertion.

Question 8

Where are sympathetic neuron cell bodies located?

Answer 8

In the thoracic and lumbar spinal cord segments.

Question 9

What is the sympathetic chain?

Answer 9

A chain of ganglia close to the spinal cord that sympathetic neurons connect to.

Question 10

Where do parasympathetic neurons arise from?

Answer 10

Cranial nerves and the lumbo-sacral spinal cord.

Question 11

Where are parasympathetic ganglia located?

Answer 11

Near or within the target organ.

Question 12

What is the somatic nervous system responsible for?

Answer 12

Conscious control of the body and feedback (e.g. pain, proprioception).

Question 13

What do somatic afferent nerves detect?

Answer 13

Pain, temperature, touch, and proprioception.

Question 14

What do somatic efferent nerves control?

Answer 14

Skeletal muscle movement.

Question 15

Do somatic neurons synapse before reaching their target?

Answer 15

No, they project directly via a single neuron.

Question 16

What are the two types of somatic nerves?

Answer 16

Cranial nerves (from the brain) and spinal nerves (from the spinal cord).

Question 17

Where do motor signals originate in the brain?

Answer 17

The precentral gyrus.

Question 18

What is the corticospinal tract?

Answer 18

The pathway from the brain to skeletal muscles.

Question 19

What is the neuromuscular junction?

Answer 19

The site where the axon communicates with a muscle to cause contraction.

Question 20

How many spinal nerve roots are there?

Answer 20

31, including one from the coccyx.

Question 21

How do spinal nerves exit the vertebrae?

Answer 21

Below each vertebra, except in the cervical region where they exit above (C8 has one above and one below C7).

Question 22

What do dorsal roots carry?

Answer 22

Afferent (sensory) information to the CNS.

Question 23

What do ventral roots carry?

Answer 23

Efferent (motor) information from the CNS.

Question 24

What forms a mixed spinal nerve?

Answer 24

The union of a dorsal and ventral root.

Question 25

What is a plexus?

Answer 25

A network of nerves blending from multiple spinal levels.

Question 26

What spinal nerves contribute to the lumbar plexus?

Answer 26

T12 to L5.

Question 27

What spinal nerves contribute to the femoral nerve?

Answer 27

L2, L3, and L4.

Question 28

What is a dermatome?

Answer 28

A skin area supplied by a single spinal nerve.

Question 29

What is a myotome?

Answer 29

A group of muscles innervated by a single spinal nerve.

Question 30

Why are dermatomes/myotomes clinically useful?

Answer 30

They help locate spinal damage by identifying sensory or motor loss.

Question 31

What muscles and skin does the sciatic nerve supply?

Answer 31

Posterior thigh muscles (hamstrings); lateral leg and foot skin.

Question 32

What muscles and skin does the femoral nerve supply?

Answer 32

Anterior thigh muscles (quadriceps); anterior thigh and medial leg skin.

Question 33

What do cranial nerves mainly innervate?

Answer 33

The head and neck (plus vagus beyond).

Question 34

Do cranial nerves follow dermatome/myotome rules?

Answer 34

No – they have individual specialised functions.

Question 35

What is CN I (Olfactory)?

Answer 35

Smell.

Question 36

What is CN II (Optic)?

Answer 36

Vision.

Question 37

What is CN III (Oculomotor)?

Answer 37

Eye movement, pupil constriction.

Question 38

What is CN IV (Trochlear)?

Answer 38

Eye movement (1 muscle).

Question 39

What is CN V (Trigeminal)?

Answer 39

Facial sensation & chewing.

Question 40

What is CN VI (Abducent)?

Answer 40

Eye movement (1 muscle).

Question 41

What is CN VII (Facial)?

Answer 41

Taste (anterior tongue), facial expression, saliva.

Question 42

What is CN VIII (Vestibulocochlear)?

Answer 42

Hearing & balance.

Question 43

What is CN IX (Glossopharyngeal)?

Answer 43

Taste (posterior tongue), swallowing, saliva.

Question 44

What is CN X (Vagus)?

Answer 44

Motor to pharynx/larynx, parasympathetic to organs.

Question 45

What is CN XI (Accessory)?

Answer 45

Motor to neck muscles.

Question 46

What is CN XII (Hypoglossal)?

Answer 46

Tongue movement.

Question 47

What is Bell’s Palsy?

Answer 47

Facial nerve (CN VII) paralysis causing facial drooping on one side.

Question 48

What causes Guillain-Barré Syndrome (GBS)?

Answer 48

Immune attack on the myelin of peripheral nerves, often after infection.

Question 49

What are early GBS symptoms?

Answer 49

Tingling and weakness in feet/hands (glove and stocking distribution).

Question 50

What serious complication can GBS cause?

Answer 50

Respiratory failure due to phrenic nerve involvement.