12 Questions
How are spinal nerves named and numbered?
By the region and level of the vertebral column where they arise
Why are all spinal nerves classified as mixed nerves?
Containing both sensory and motor neurons
How do the spinal nerves connect to the spinal cord?
By the interneurons
What regions of the body are supplied by plexuses, according to the text?
Branchial, lumbar, sacral, and cervical regions
What is the main function of a stretch reflex?
To instinctively contract a muscle as it is stretched
In relation to reflex arcs, what does 'ipsilateral' mean?
Relates to a response on the same side of the body
Where is the epidural space located in relation to the spinal meninges?
Between the bony wall of the vertebral canal and the outer surface of the dura mater
What is the location of the lumbar enlargement?
Extends from the ninth to the twelfth thoracic vertebra
What is the function of the filum terminale?
Fibrous band anchoring the spinal cord
At which level does the conus medullaris typically end in adults?
At the level of L1-L2
What characterizes the cauda equina?
It is a collection of nerves at the end of the spinal cord
What is a distinguishing feature of a spinal segment?
It exits from either side of the spinal cord
Study Notes
Spinal Cord Structure
- The spinal cord is partially divided into right and left sides by the anterior median fissure and posterior median sulcus.
- The spinal cord has cervical and lumbar enlargements, which are regions of the spinal cord that give rise to nerves that innervate the upper and lower limbs.
Spinal Nerves
- Spinal nerves are named and numbered by the region and level of the vertebral column where they arise.
- All spinal nerves are classified as mixed nerves because they contain both sensory and motor neurons.
- They transport motor impulses away from the central nervous system and sensory impulses towards it.
Connection to Spinal Cord
- Spinal nerves connect to the spinal cord at the intervertebral foramen.
- The posterior and anterior roots unite to form a spinal nerve at the intervertebral foramen.
Nerve Distribution
- Plexuses (branchial, lumbar, sacral, and cervical) supply nerves to specific regions of the body.
- Intercostal nerves supply nerves to the thorax region.
Reflexes
- Stretch reflex: a mechanism that enables skeletal muscle length control on an automated basis, contracting a muscle as it is stretched to avoid overstretching.
- Tendon reflex: a feedback system that regulates muscular tension by inducing muscle relaxation prior to the occurrence of high enough muscle force to potentially tear the tendons.
- Crossed extensor reflex: a mechanism that rapidly removes the injured limb from unpleasant stimuli while stabilizing the body to preserve balance and posture.
Reflex Arcs
- Monosynaptic: a reflex arc with a single synapse between the sensory neuron and motor neuron.
- Ipsilateral: occurring on the same side of the body.
Meninges and Spaces
- Spinal meninges: protective membranes that cover the spinal cord.
- Epidural space: located between the bony wall of the vertebral canal and the outer surface of the dura mater.
- Subarachnoid space: located deep within the arachnoid membrane, between it and the pia mater.
Spinal Cord Features
- Conus medullaris: the lower end of the spinal cord, ending at the level of the intervertebral disc between the first and second lumbar vertebrae (L1-L2) in adults.
- Filum terminale: a fibrous band that extends inferiorly and fuses with the arachnoid mater and dura mater, anchoring the spinal cord.
- Cauda equina: a collection of nerves and nerve roots that emerge from the spinal cord's distal end.
- Spinal segment: the dorsal roots and ventral roots exiting the cord, giving rise to nerves.
Test your knowledge on the locations of the spinal meninges, epidural space, subarachnoid space, as well as understanding the cervical and lumbar enlargements of the spinal cord.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
