Lecture 9 - Spinal cord Flashcards
End-point of the spinal cord
Conus medullaris
Within the spinal cord are 2 enlargements
Cervical and lumbar enlargement
Cervical enlargement
From which the brachial plexus is formed
Innervates the upper extremities (C5-T1)
Lumbar enlargement
From which the lumbar plexus is formed
Innervates the lower extremities (L1-S4)
The spinal cord is practically divided into R/L halves by depressions called the:
Anterior (ventral) median fissure
Posterior (dorsal) median sulcus
Center of grey matter
Central canal
Central canal (3 things)
Continuous the length of the spinal cord
Continuous with the 4th ventricle of the brain
Filled with CSF
surrounding the H-form on all sides are areas of ___ matter
White
Equivalent of schwann cells of the PNS in the CNS
Oligodendrocytes
Tracts (2)
Ascending tracts
Descending tracts
Ascending tracts
Sensory facts/afferent
Relay impulses from the periphery or spinal levels to the brain
Descending tracts
Motor tracts/efferent
Relay impulses from the brain to different spinal levels and the periphery
the grey commissure (H) has a pair of horns, name them
2 anterior (ventral) horns 2 posterior (dorsal) horns
Only found in T-spine and upper L-spine
Lateral horns
The group of nerve fibers which enter the Dorsal Horn are called + content
Dorsal roots Sensory information (no disregard from location)
The group of nerve fibers which enter the Ventral horn are called + content
Ventral roots
Motor information
Contains sensory neurons
Their cell bodies lie outside the s.c. in the intervertebral foramen and are called ?
Dorsal roots
? = dorsal root ganglia or spinal ganglia
Contains axons of motor neurons
Cell bodies are contained within the anterior and lateral horns
Ventral roots
The dorsal and ventral roots come together to form what?
The spinal nerve
Spinal nerve exits where?
Through the intervertebral foramen
The spinal nerve divides into
Dorsal and ventral rami
Supplies the deep vertebral muscles and skin of the back
Dorsal rami
Supplies all the ventral and lateral musculature
Ventral rami
Spinal nerves are mixed, only sensory, or only motor
Mixed
There are __ pairs of nerves + elaborate
31
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
Role of meninges
- Protect the brain and spinal cord
- Form the supporting framework for arteries, veins and venous sinuses
- Encloses the subarachnoid space for the circulation of CSF
3 layers of meninges
Pia mater
Arachnoid
Dura mater
Dura mater
Diaphragm Sellae
Arachnoid
Subarachnoid space contains CSF
Pia mater
Denticulate ligaments
All three layers cover the spinal nerves until they exit through the _____ _____
Intervertebral foramina
Specialized nerve endings
Free nerve endings (bare dendrites)
Encapsulated sensory endings (enclosed dendrites)
- They branch between epithelial cells, connective cells, muscle cells, etc.
- Are thought to act primarily as pain receptors of the body
- Also act as tickle, itch and thermal, and touch receptors
Free nerve endings
- They are surrounded by connective tissue capsules
- There are 6 in total
Encapsulated sensory endings
Types of encapsulated sensory endings
Meissner corpuscles Pacinian corpuscles End bulbs of Krause Ruffini corpuscles Muscle spindles Golgi tendon organs
Surrounds spinal ending of a dendrite
Sensitive to light touch, pressure, and slow vibrations
Rapidly adapting
Found in the skin, mucous membrane of the tongue, and other sensitive regions of the body
Meissner corpuscles - very superficially located
Located in the dermis and subcutaneous tissue, submucosa, joints, periosteum, and some viscera
Adapt rapidly
Stimulated by heavy pressure, fast vibrations, tickling
Pacinian corpuscles (located deeper)
Located in the mucous of the lips, tongue, conjunctiva, external genitalia
Common throughout the body (dermis of skin)
Serve as cold receptors
End-bulbs of Krause
Located in subcutaneous tissue, ligaments, tendons
Slow adapting
Respond to stretching of the skin (joint positioning, balance, posture, equilibrium, proprioception)
Ruffini corpuscles
Location of muscle spindles
Skeletal muscle
React to change in length
Muscle spindles
Response to stretching of the muscles by the muscles spindles
Stimulation of the efferent (motor) neurons to the same muscle that contracts it (stretch is reflexively resisted)/
Composition of golgi tendon organs
Dendrites that have many branches on the muscle tendon junction
React to muscle tension
Golgi tendon organs
Response of the golgi tendon orgnas
Stimulus will go back to the s.c. where the motor neurons to the same muscles are inhibited, thus relaxing the muscle
All spinal nerves are CUTANEOUS except ___ (innervate the skin)
C1
Dermatomes (3 things)
Important diagnostic technique
Each spinal nerve innervates a segmental field of skin
Generally there is a specific area for each of dermatomes (but considerable overlap)
Reflexes (3)
Cranial reflexes
Somatic reflexes
Autonomic reflexes
Reflex arc
Sensory receptor Sensory neuron Integrating center Motor neuron Effector
