The document summarizes the anatomy and physiology of the peripheral nervous system and special senses. It describes the meninges that cover the brain and spinal cord, as well as the cerebrospinal fluid that circulates within. It details the structure of the spinal cord, spinal nerves, and plexuses like the brachial plexus. It also explains the roles and components of the autonomic nervous system, including the sympathetic and parasympathetic divisions. Finally, it provides a brief overview of the special senses like taste, smell, sight, hearing, and balance.

1. PERIPHERAL
NERVOUS SYSTEM
AND THE
SPECIAL SENSES
DR. T.C. MATHEW, Kuwait University

2. MENINGES OF THE BRAIN AND
SPINAL CORD
The brain and spinal cord is covered by three
layers of membranes called the meninges.
The outermost membrane is the dura mater.
Below the dura is the arachnoid mater.
The space that separates these two is called
the subdural space.
The innermost layer is the pia mater.
Between the arachnoid and pia is the
subarachnoid space, within which the
cerebrospinal fluid circulates.
Cerebrospinal fluid (CSF) provides a liquid
cushion for the brain and spinal cord.
CSF is formed by choroid plexuses in the
brain ventricles
DR. T.C. MATHEW, Kuwait University

3. Anatomy of the Spinal Cord
DR. T.C. MATHEW, Kuwait University

4. The Spinal Cord
It extends from the medulla oblongata
Extends from the foramen magnum to the level of
the vertebra L1 or L2
The spinal cord does not extend the entire length of
the vertebral column.
The spinal cord shows two enlargements.
They are the Cervical enlargement (from 4th
cervical to the first thoracic vertebra) and Lumbar
enlargement (from ninth to the 12th thoracic
vertebra)
The conical tapering of the spinal cord is called
conus medullaris.
Conus medullaris – the inferior end of the spinal cord
Filum terminale – long filament of connective tissue
Attaches to the coccyx inferiorly
Cervical and lumbar enlargements
Where nerves for upper and
lower limbs arise
Cauda equina – collection of nerve
roots
DR. T.C. MATHEW, Kuwait University

5. Gray Matter of the Spinal Cord and
Spinal Roots
Shaped like the letter H
Gray commissure – contains the central canal
Anterior horns – contain cell bodies of motor neurons
Posterior horns – consist of interneurons
DR. T.C. MATHEW, Kuwait University

6. Spinal Nerves Posterior View
31 pairs – contain thousands of
nerve fibers
Connect to the spinal cord
Named for point of issue from the
spinal cord
 8 pairs of cervical nerves (C -C )
1
8

12 pairs of thoracic nerves (T1T12)

5 pairs of lumbar nerves (L1-L5)

5 pairs of sacral nerves (S1-S5)

1 pair of coccygeal nerves (C0)
DR. T.C. MATHEW, Kuwait University

7. Spinal Nerves
The spinal nerve has two major branches.
The posterior (dorsal) ramus that innervate the deep muscles and skin of the
dorsal surface of the trunk and
anterior (ventral) ramus that innervate the muscles and structures of the
upper and lower limb and skin of the lateral and ventral surface of the trunk.
DR. T.C. MATHEW, Kuwait University

8. DISTRIBUTION OF SPINAL
NERVES AND PLEXUSES
Except for spinal nerves T1-T12, the anterior
rami do not go direcly to the body
structures.
Instead they form network by joining the
anterior rami of adjacent nerves.
A network of such axons is called a plexus.
They are:
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
Coccygeal plexus
DR. T.C. MATHEW, Kuwait University

9. The Cervical Plexus
Formed by ventral rami of first four cervical nerves
Most are cutaneous nerves
Some innervate muscles of the anterior neck
Phrenic nerve – the most important nerve of the cervical plexus
DR. T.C. MATHEW, Kuwait University

10. The Brachial Plexus and Innervation of the Upper Limb
Formed by ventral rami of C5-C8
Cords give rise to main nerves of the upper limb
DR. T.C. MATHEW, Kuwait University

11. The Lumbar Plexus and Innervation of
the Lower Limb
Lumbar plexus
Arises from L1-L4
DR. T.C. MATHEW, Kuwait University
Smaller branches
innervate the
posterior
abdominal wall and
psoas muscle
Main branches
innervate the
anterior thigh
Femoral nerve
– innervates
anterior thigh
muscles
Obturator
nerve –
innervates
adductor
muscles

12. The Sacral Plexus
Arises from
spinal nerves L4S4
Caudal to the
lumbar plexus
Often
considered with
the lumbar
plexus
Lumbosacral
plexus
DR. T.C. MATHEW, Kuwait University

13. Innervation of the Lower Limb
Sciatic nerve – the largest
nerve of the sacral plexus
Actually two nerves in
one sheath
Tibial nerve –
innervates most of
the posterior lower
limb
Common fibular
(peroneal) nerve –
innervates muscles
of the anterolateral
leg
DR. T.C. MATHEW, Kuwait University

14. The Sacral Plexus
DR. T.C. MATHEW, Kuwait University

15. AUTONOMIC NERVOUS SYSTEM (ANS)
The ANS is concerned with the innervation of viscera, glands, blood vessels
and the heart.
Their regulatory actions are considered to be automatic or autonomous.
The autonomic nervous system is divided into the sympathetic nervous
system (SNS) and the parasympathetic nervous system (PSNS).
DR. T.C. MATHEW, Kuwait University

16. The Sympathetic Nervous System



The SNS generally excites the nervous system.
It increases blood flow to the heart, muscles and brain but
decreases functions in the viscera that are not needed for fight
or flight.
The most common neurotransmitter used by the SNS is
norepinephrine.
The Parasympathetic Nervous System



The PSNS generally inhibits the nervous system.
It has a localized and narrow effect, slows the heart rate and
increased intestinal and digestive activities.
The most common neurotransmitter used by the PSNS is
acetylcholine (ACh).
DR. T.C. MATHEW, Kuwait University

17. The Special Senses
Taste, smell, sight, hearing, and balance
Touch – actually a large group of general senses
Taste – gustation
Smell – olfaction
Receptors – classified as chemoreceptors
Respond to chemicals
DR. T.C. MATHEW, Kuwait University

18. T
A
H
K
N
U
O
Y
DR. T.C. MATHEW, Kuwait University