155 pns -revised on 26-11-2013
TRANSCRIPT
DR. T.C. MATHEW, Kuwait University
PERIPHERAL PERIPHERAL NERVOUS SYSTEM NERVOUS SYSTEM
AND THEAND THESPECIAL SENSES
DR. T.C. MATHEW, Kuwait University
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
Anatomy of the Spinal CordAnatomy of the Spinal Cord
DR. T.C. MATHEW, Kuwait University
The Spinal CordThe 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
Gray Matter of the Spinal Cord and Gray Matter of the Spinal Cord and Spinal RootsSpinal 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
Spinal Nerves Posterior ViewSpinal 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 (C1-C8)
12 pairs of thoracic nerves (T1-T12)
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
Spinal NervesSpinal NervesThe 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
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 plexusBrachial plexusLumbar plexusSacral plexus Coccygeal plexus
DR. T.C. MATHEW, Kuwait University
The Cervical PlexusThe Cervical Plexus
Formed by ventral rami of first four cervical nervesMost are cutaneous nervesSome innervate muscles of the anterior neckPhrenic nerve – the most important nerve of the cervical plexus
DR. T.C. MATHEW, Kuwait University
The Brachial Plexus and Innervation of the Upper LimbThe 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
The Lumbar Plexus and Innervation of The Lumbar Plexus and Innervation of the Lower Limbthe Lower Limb
Lumbar plexus Arises from L1-L4
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
DR. T.C. MATHEW, Kuwait University
The Sacral PlexusThe Sacral Plexus Arises from
spinal nerves L4-S4
Caudal to the lumbar plexus
Often considered with the lumbar plexus Lumbosacral
plexus
DR. T.C. MATHEW, Kuwait University
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
Innervation of the Lower LimbInnervation of the Lower Limb
DR. T.C. MATHEW, Kuwait University
The Sacral PlexusThe Sacral Plexus
DR. T.C. MATHEW, Kuwait University
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
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
The Special SensesThe Special Senses
Taste – gustation Smell – olfaction Receptors – classified as chemoreceptors Respond to chemicals
Taste, smell, sight, hearing, and balance
Touch – actually a large group of general senses
DR. T.C. MATHEW, Kuwait University
THANK YOU