Efferent Somatic & Autonomic NS

Question 1

Pathway Damage

Answer 1

Unlike skeletal muscle, tissues innervated by the ANS often function
to some extent if their nerve supply is damaged or cut

Question 2

Spinal Nerves

Answer 2

• Cervical Nerves – 8 Pairs
• Thoracic Nerves – 12 Pairs
• Lumbar Nerves – 5 Pairs
• Sacral Nerves – 5 Pairs
• Coccygeal Nerves – 1 Pair

Question 3

Motor Cortex

Answer 3

For the cerebral cortex to perform its motor
functions, impulses must be conducted
from its motor areas to skeletal muscles by
relays of neurons referred to as
Somatic Motor Pathways

Question 4

Wilder Penfield

Answer 4

used electrical stimulation to map the cortices of

patients who were about to undergo neurosurgery

Question 5

Final Common Pathway (Sherrington)

Answer 5

Lower Motor Neurons
receive excitatory/inhibitory
synaptic inputs from
Upper Motor Neurons
of supraspinal origin either
directly or via interneurons

Question 6

Autonomic Nervous System: Anatomy

Answer 6

Both divisions of the ANS share the same general structure
Autonomic pathways always consist of two neurons in series
They synapse in an autonomic ganglion
The first neuron in the autonomic pathway is the pre-ganglionic neuron
• Cell body in CNS, myelinated and projects to the autonomic ganglion
While the second neuron is the post-ganglionic neuron
• Cell body in autonomic ganglion, unmyelinated and projects to the effector

Question 7

Sympathetic Division: Anatomy

Answer 7

Pre-ganglionic sympathetic fibres are short
Pre-ganglionic sympathetic fibres release acetylcholine (ACh) at ganglia
Post-ganglionic sympathetic fibres are long
Post-ganglionic sympathetic fibres release noradrenaline (NA) in most cases
and the effect can be stimulatory or inhibitory
Response of target organ is dependent upon the receptor type(s) expressed

Question 8

Adrenal Gland - The exception

Answer 8

• Pre-ganglionic fibers will pass
through sympathetic ganglia
without synapsing
• Pre-ganglionic fibers will
synapse on adrenal medulla

Question 9

CRANIAL OUTFLOW

Answer 9

III Oculomotor
VII Facial
IX Glossopharyngeal
X Vagus (major pre-ganglionic
supply to thorax and
abdomen)
- Synapse in ganglia within
wall of the target organ
-parasympathetic NS

Question 10

SACRAL OUTFLOW

Answer 10

- S2-S4 via pelvic splanchnic
nerves
- Gut, pelvic viscera and
external genitals
-parasympathetic NS

Question 11

Parasympathetic Division: Anatomy

Answer 11

Pre-ganglionic parasympathetic fibres are long
Pre-ganglionic parasympathetic fibres release acetylcholine (ACh) at ganglia
Post-ganglionic parasympathetic fibres are short
Post-ganglionic parasympathetic fibres release ACh and the effect can be
either stimulatory or inhibitory
Response of target organ is dependent upon the receptor type(s) expressed

Question 12

Antagonistic Control

Answer 12

Parasympathetic and Sympathetic stimulation have opposite impacts on effectors