Peripheral Nerves and Arteries. Information IN Sensory or “afferent” neurons carry information...
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Transcript of Peripheral Nerves and Arteries. Information IN Sensory or “afferent” neurons carry information...
Information IN
Sensory or “afferent” neurons carry information into the CNS from receptors
located throughout the body.
Information OUT
Motor or “efferent neurons” carry electrical impulses away from the CNS
to innervate “effector organs,” like muscles and glands.
Sensory Receptors in Skin
•They detect sensory input and convert them into electrical impulses that will travel up neurons along the spinal cord.
•Sensory input about touch, pain, heat, cold, pressure.
Proprioceptors•Sensory receptors that report on internal events in your muscles and joints.
•They report on muscle stretch and joint position.
•They generate electrical impulses that will travel up neurons to the CNS.
Upper and Lower Motor Neurons
Of course, the signal to initiate motor movement does not begin at the neuron cell body in the spinal cord; it begins in the brain.
The motor neuron whose cell body is in the brain is called an upper motor neuron.
It relays the signal to the motor neuron whose cell body is in the spinal cord, called the lower motor neuron.
The lower motor neuron synapses on a muscle, causing contraction.
Motor Neurons “Innervate” Muscle Cells
Neuron “innervates” muscle and triggers it to contract by the release of a chemical neurotransmitter.
Order of Nerves Firing
To pick up an object, you wrap your hand around the object. This gives you a sensory input as you feel the object.
The sensory neuron sends the impulse to the spinal cord where it synapses on an interneuron.
The interneuron synapses on a motor neuron The motor neuron tells your muscles to
contract so you can pick up the object.
Upper and Lower Motor Neuron Diseases Some diseases only effect the UMN, and
some only effect the LMN. Lower motor neuron disorders:
Multiple Sclerosis Polio
Upper motor neuron disorder: Cerebral palsy
Autonomic Neuropathy
Autonomic neuropathy is damage to autonomic nerves.
The autonomic nerves are those that supply involuntary body functions, including heart rate, blood pressure, perspiration and digestion.
A common symptom in autonomic neuropathy is dizziness. Muscle twitches and lack of sensation are NOT symptoms, since they are not supplied by autonomic nerves.
Spinal Nerve Plexi
A network of ventral rami
Interlacing network Each branch carries
fibers from several spinal nerves
Gives redundancy in case of nerve damage
C1-C4- Cervical plexus
C5-T1- Brachial plexus
L1-L4- Lumbar Plexus
L4-S4- Sacral Plexus
Cervical Plexus
Nerves innervate skin of neck, back of head and upper shoulder.
Phrenic nerve (important for breathing!) from C3, C4, C5. Carries afferent and efferent fibers to the respiratory diaphragm.
Brachial Plexus
Damage to Brachial Plexus Klumpke’s paralysis (brachial plexus damaged
during birth) Acquired Brachial Plexus injuries
Crutch paralysis (total upper extremity paralysis) Claw Hand / Ape hand Hand of benediction Wrist Drop (Waiter’s Hand)
Median Nerve
Supplies no muscles of the arm Supplies anterior forearm (except flexor carpi
ulnaris) Carpal Tunnel Syndrome Hand of benediction
Radial Nerve
Supplies muscles on the posterior arm and forearm Triceps brachii Extensor carpi radialis Extensor digitorum communis
Damage can cause wrist drop
Sciatic Nerve
Supplies back of thigh Biceps femoris Semimembranosis Semitendonosis
Supplies leg and foot
Common Peroneal Nerve
Superficial branch Lateral side of leg Supplies peroneal muscles
Deep branch Supplies anterior leg muscles Injury causes “Foot Drop”
Dermatomes
The area of skin innervated by a cutaneous branch of a spinal nerve at a particular level.
Arteries of the Upper Extremity
Subclavian (becomes axillary artery in armpit) Axillary (becomes brachial artery in arm)
Supplies triceps brachii Brachial (divides into radial and ulnar arteries
when it reaches the elbow) Supplies arm muscles except triceps brachii
Radial Ulnar
Arteries of the Lower Extremity
External iliac (becomes femoral artery) Femoral (becomes popliteal artery at knee)
Femoral artery supplies muscles of thigh (including adductor muscles)
Popliteal (becomes tibial artery in leg) Tibal
Leg muscles
Peripheral Vascular Disease (PVD)
Refers to the obstruction of large arteries, frequently in the lower extremity. Usually caused from atherosclerosis (fatty plaques).
Symptoms Claudication: pain, weakness, numbness, or cramping
in muscles due to decreased blood flow Sores, wounds, or ulcers that heal slowly or not at all Change in color (blueness or paleness) or temperature
(coolness) when compared to the other limb Diminished hair and nail growth on affected limb and
digits (shiny, hairless skin)