Week 7 - Chapter 13: The Spinal Cord
The spinal cord is protected by the:
Vertebral column, the meninges, cerebrospinal fluid, and denticulate ligaments.
The three meninges are coverings that run continuously around the spinal cord and brain:
Dura mater, arachnoid mater, and pia mater.
The spinal cord contains ______ and ______ enlargements that serve as points of origin for nerves to the limbs.
Cervical, lumbosacral
The tapered inferior portion of the spinal cord is the:
Conus medullaris
Spinal nerves connect to each segment of the spinal cord by ____ roots.
2
The posterior root contains ____ axons
Sensory
The anterior root contains _____ neuron axons.
Motor
The anterior median fissure and the posterior median sulcus partially divide the spinal cord into:
Right and left sides.
In the center of the spinal cord is the ______, which runs the length of the spinal cord.
Central canal
The spinal cord functions:
Conveys sensory and motor information
How many pairs of spinal nerves are there:
31
There are _____ pairs of cervical spinal nerves
8
There are ____ pairs of thoracic pairs of spinal nerves
12
There are _____ pairs of lumbar spinal nerves
5
There are ____ pairs of sacral spinal nerves
5
There is ____ pair of coccygeal spinal nerves
1
Three connective tissue coverings associated with spinal nerves are the:
Endoneurium, perineurium, and epineurium.
The posterior ramus, anterior ramus, meningeal branch, and communicating rami are:
Branches of a spinal nerve
The anterior rami of spinal nerves, except for T2–T12, form networks of nerves called ______.
Plexuses
Anterior rami of nerves T2–T12 do not form plexuses and are called _______ nerves.
Intercostal
Sensory neurons within spinal nerves serve specific, constant segments of the skin called ________.
Dermatomes
Nerves of the cervical plexus functions:
Supply the skin and muscles of the head, neck, and upper part of the shoulders
Connect with some cranial nerves and innervate the diaphragm.
Nerves of the brachial plexus function:
Supply the upper limbs and several neck and shoulder muscles
Nerves of the lumbar plexus function:
Supply the anterolateral abdominal wall, external genitals, and part of the lower limbs
Nerves of the sacral plexus function:
Supply the buttocks, perineum, and part of the lower limbs
Nerves of the coccygeal plexus function:
Supply the skin of the coccygeal region
What are the main functions of the white matter tracts in the spinal cord?
Act as highways for nerve impulses, carrying sensory information to the brain and motor commands from the brain to muscles.
What is a key role of the spinal cord besides transmitting signals?
It serves as an integrating center for spinal reflexes, which occur in the gray matter
A reflex is a:
Quick, automatic response to changes in the environment, like muscle contractions or gland actions.
What are the components of a reflex arc?
A reflex arc includes a sensory receptor, sensory neuron, integrating center, motor neuron, and effector
Examples include the stretch reflex, tendon reflex, flexor reflex, and crossed extensor reflex, all of which involve reciprocal innervation.
Examples of Somatic Spinal Reflexes
What is a monosynaptic reflex arc?
A reflex arc that consists of one sensory neuron and one motor neuron, like the patellar (knee-jerk) reflex
What is the function of the stretch reflex?
The stretch reflex is important for maintaining muscle tone and occurs on the same side of the body (ipsilateral)
This reflex arc includes sensory neurons, interneurons, and motor neurons, with examples like the tendon reflex and flexor reflex
A polysynaptic reflex arc
How do specific reflexes respond to harmful stimuli?
The tendon reflex prevents muscle damage, the flexor reflex withdraws a limb from pain, and the crossed extensor reflex shifts body weight
Which somatic reflexes are used for diagnosing disorders?
Important reflexes for diagnosis include the patellar reflex, Achilles reflex, Babinski sign, and abdominal reflex
The central canal circulates:
CSF
White matter is divided into:
Funiculi
Grey matter is divided into:
Horns
All spinal nerves contain ____ and ____ axons. They are mixed nerves.
Motor, sensory
A second major function of the spinal cord is to serve as an _________ for spinal reflexes. This integration occurs in the gray matter.
integrating center
Sensory input travels along two main routes in the white matter of the spinal cord:
the posterior funiculi and the spinothalamic tract.