PNS - CNS with spinal cord anatomy and function and introduces students to the PNS and reflexes Flashcards
Identify the location of the spinal cord within the vertebral column
The spinal cord is encased within the vertebral foramen of each vertebrae.
What is the spinal cord protected by?
The spinal cord is protected by the vertebrae, meninges and CSF
At which level does the spinal cord terminate?
Between the first and second lumbar vertebrae in an adult
What does the structure of the PNS contain?
Nerves, ganglia, plexus and sensory receptors
Describe a nerve
A bundle of axons, which provides a structured pathway that supports the electrochemical nerve impulse transmitted along each of the axons
Describe a ganglia
A group of nuclei interconnected with the cerebral cortex, thalamus and brain stem
Describe a plexus
A network of capillaries and specialised ependymal cells which is found in the cerebral ventricles
Describe a sensory receptors
A structure that reacts to a physical stimulus in the environment, whether internal or external. It is a sensory nerve ending that receives info and conducts a process of generating nerve impulse to the transmitted to the brain for interpretation and perception.
What are the divisions of the PNS
Somatic and autonomic
What is the somatic system responsible for?
Voluntary control of skeletal muscles
What is the autonomic system responsible for?
Hypothalamus regulates homeostasis by involuntary control of smooth muscles, cardiac muscles and glands
Define a reflex
A fast, predictable ‘involuntary’ response to changes in the environment that helps maintain homeostasis
Locations of reflexes?
Spinal reflex and cranial reflex
What is the reason for testing reflexes?
To pick up on signs of nerve damage
Types of reflexes
Somatic refelex = effector skeletal muscles
Autonomic reflex = effector smooth muscles, glands and cardiac muscles
What is the function of the vagus nerve?
Forms part of the involuntary NS and commands unconscious body producers e.g keeping the heart rate constant and controlling food digestion
Name the four plexus
Cervical, branchial, lumbar and sacral
What is a plexus?
A network of converging and diverging nerve fibres
State the location and function of the phrenic nerve
(C3-C5) controls movement of the diaphragm
What is the difference between a somatic sensory tract and a somatic motor tract?
A somatic sensory tract ascends and the somatic motor tract descends
How many pairs of cranial nerves are there?
12 pairs (in roman numerals)
How many pairs of spinal nerves are there?
31 pairs
What is the function of the phrenic nerve?
Supplies motor and sensory nerves to the diaphragm. Controls 75% of breathing (C3-C5)
Explain the cervical plexus
Anterior and posterior branches of the spinal cord (C1-C2). Supplies parts of the head, neck, shoulders and chest
Explain the brachial plexus
Supplies anterior and posterior branches of the spinal nerves (C5-T1). It provides the entire nerve supply of the upper limbs. The major peripheral nerves include
- radial nerve
- medial nerve
- ulna nerve
Lumbosacral Plexus
Supplies anterior and posterior branches of spinal nerves (L1-L4 L4-L5 S1- S4). Supplies the external genital and anterior/medial thighn
Explain the femoral nerve
L2-4 supplies buttocks, perineum and part of the lower limb
Explain the sciatic nerve
L4-S3 supplies posterior thigh and rest of leg below the knee
What are dermatomes
An area of skin which sends most of it sensory input to the CNS from a. single pair of spinal nerves
The choroid plexuses are located in the?
ventricles of the brain
Inferior to the lumbar enlargement, the spinal cord tapers to a conical portion called the
conus medullaris
lists the parts of a reflex arc in the correct sequence?
receptor, sensory neuron, association neuron, motor neuron, effector
Cerebrospinal fluid is produced by what?
produced by the choroid plexuses
Cerebrospinal fluid is reabsorbed by arachnoid villi into the
superior sagittal sinus
The basilar artery is formed by the union of the _____ arteries
vertebral
