Download Chapter 13 | DENT - Oral Anatomy & Physiology and more Quizzes Dental Anatomy in PDF only on Docsity!
Functions of the Spinal Cord Conduction (1 of
1. Conduction: It contains bundkes of nerve fibers that
conduct information up and down the cord, connecting diff
levels of the trunk w/ each other and within the brain
enabling sensory information to reach the brain, motor
commands to reach the effectors, and input received at one
level of the cord to affect output from another level
TERM 2
Neural Integration (2 of 4)
DEFINITION 2
2. Pools of spinal neurons receive input from multiple
sources, integrate the information, and execute an
appropriate output. i.e. the spinal cord can integrate the
stretch sensation from a full bladder with cerebral input
concerning the appropriate time and place to urinate and
execute control of the bladder accordingly
TERM 3
Locomotion (3 or 4)
DEFINITION 3
Simple repetitive muscle contraction such as putting one foot
in front of the other to walk are coordinated by groups of
neurons called central pattern generators in the cord.
TERM 4
Reflexes (4 of 4)
DEFINITION 4
They are involuntary stereotyped responses to stimuli, such
as the with drawl of a hand from pain. They involve the brain,
spinal cord, and peripheral nerves.
TERM 5
Spinal Cord
DEFINITION 5 Arises from the brainstem at the foramen magnum of the skull, passes through the vertebral canal as far as the inferior margin of the first lumbar vertebra (L1) or slightly beyond. It is about 45cm and 1.8 cm thick (little finger).-31 pairs of spinal nerves-Spinal cord exhibits longitudinal grooves on its anterior and posterior sides- anterior median fissure and posterior median sulcus
Spinal Cord Divisions
The regions are named for the level of the vertebral cloumn from which the spinal nerves emerge, not for the vetebrae that contain the cord itself.1. Cervical: Cervical enlargement due to appendages coming off the body. Gives rise to nerves of the upper limbs2. Thoracic:3. Lumbar: Enlargement that issues nerves to the pelvic region and lower limbs.4. Sacral: TERM 7
Meninges
DEFINITION 7
The three fibrous connective tissues that enclose the spinal
cord and brain. They separate the soft tissue of the central
nervous system from the bones of the vertebrae and skull.
From superficial to deep they are the dura mater, arachnoid
mater, and pia mater.
TERM 8
Conus Medullaris and Cauda Equina
DEFINITION 8
1.Located inferior to the lumbar enlargement, the cord tapers
to *this point.2. Arises from the lumbar enlargement and
medullary cone. It is a bundle of nerve roots that occupy the
vertebral canal from L2 to S5. Resembles a horse's tail.
Innervates the pelvic organs and lower limbs
TERM 9
Dura Mater
DEFINITION 9
"tough mother"-Forms a dural sheath (loose-fitting sleeve)
around the spinal cord. It's a tough collagenous membrane.
The space between the sheath and vertebral bones is called
the epidural space. It is occupied by blood vessels, adipose
tissue, and loose connective tissue. Usually where
anasthetics are introduced during childbirth. 1\
TERM 10
Arachnoid Mater
DEFINITION 10 Looks like a spider. consists of a squamous epithilium, the arachnoid membrane, adhering to the inside of the dura, and a loose mesh of collagenous and elastic fibers spanning the gap between the archnoid membrane and the pia mater. This gap is called the subarachnoid space, which is filled with cerebrospinal fluid.Inferioir to the medullary cone, the space is called the lumbar cistern and contains cauda equina and CSF.
ALS (Amyotrophic Lateral Sclerosis or Lou
Gehrig)
Denegeration of motor neurons AND scarring within the
spinal cord-Muscle weakness-Paralysis-Difficulty in speaking
and swallowing-Lack of reabsorbtion in synaptic cleft-Gets
progressively worse-Patients are still capable of hearing,
thinking, seeing, smelling, other motor sensors are blocked.-
There is too much glutamate in the synaptic cleft
TERM 17
Spina
Bifida
DEFINITION 17 One or more vertebraes fail to fuse together for the enclosure of the spinal cord.-Oculta: Least severe, 1 or 2 vertebrae not attatched. Some people may not even be aware of it.-Meningocele: 2-3 vertebrae fail to fuse together and meninges pops out with cerebral spinal fluid-Meningomyelocele: (Cystal) most severe form. Pertrution of not only meningocele but also spinal cord. Urgent surgery is required in 72hr. (within 72hrs) LACK OF FOLIC ACID during the first 4 weeks. (Vit B) TERM 18
Nerves
DEFINITION 18
It is a cordlike orgaan composed of numerous nerve fibers
(axons) bound together by connective tissue (Don't confuse
with nerve fiber which is just one single strand)-Ganglion: A
cluster of neurosomas outside the CNS, enveloped in
epinerium-Endoneirum:A thin sleeve of connective tissue that
TERM 19
Nerve fibers of the PNS are covered
with....
DEFINITION 19 Schawnn cells, which form a neurilemma and often a myelin sheath around the axon.-Endonerium: A thin sleeve of connective tissue external to the neurilemma that surrounds each fiber- Perinerium: Sheath that wraps each fascicle (fibers gathered in bundles) It is composed of squamous, epithelium-like cells.- Epineurium: Surrounds groups of fascicles. Outermost layer or the spinal nerve. TERM 20
Spinal Nerves
DEFINITION 20
-8 Cervical-12 Thoracic-5 Lumbar- 5 Sacral- 1 coccygeal
Spinal Nerves Emerge...
-The first cervical nerve emerges between the skull and atlas, and the others emerge through intevertebral foramina.-C1-C-7 emerge superior to the correspondingly numbered vertebrae (i.e. C5 above vertebrae C5)-C-8 emerges inferior to vertebra C7 and below this, all the remaining nerves emerge inferior to the correspondingly numbered vetebrae (i.e. nerve L3 inferior to vertebra L3) TERM 22 DEFINITION 22
Review slide #16 on powerpoint
TERM 23
Nerve Plexuses
DEFINITION 23
Networks of nerve branches that include 5 total:-Cervical:
Small, located in the neck-Brachial: Near the shoulder, most
well studied-Lumbar: Located in the lower back-Sacral:
Immediately inferior to the sacral-Coccygeal: tiny in size.
Adjacent to the lower sacrum and coccyx.
TERM 24
Order of Roots to branches
DEFINITION 24
Roots -> Trunks -> Divisions -> Cords -> Branches
TERM 25
Dermatomes
DEFINITION 25 An area of skin in which sensory nerves derive from a single spinal nerve root-Each spinal nerve except C1 receives sensory inputThere are 30 pairs of dermatomes that can each be traced back to a single nerve root.Although maps may show areas where dermatomes are, they actually overlap.-You need to sever or anesthetize 3 successive spinal nerves to produce a total loss of sensation from one dermatome-Spinal nerve damage can be testes with pinpricks
Reflex Arc
Employed by the somatic reflex, in which the signals travel along the following pathway:-Somatic receptors: in the skin, muscles, tendons-Afferent nerve fibers: carry info from these receptors to the posterioir horn of the spinal cord or the brainstem-Integrating center: a point of synaptic contact b.t. neurons in the gray matter of the cord or brainstem-efferent nerve fibers: carry motor ipulses to muscles and...-effectors: the muscles that carry out the response TERM 32
Flexor & Crossed Extension
Reflexes
DEFINITION 32 A pain stimulus triggers a withdrawl reflex, which results in contraction of flexor muscles of the injured limb. At the same time, a crossed extension reflex results in contraction of extensor muscles of the opposite limb. The latter reflex aids in balance when the injured limb is raised. Note that while the agonist contracts, the alpha motor neuron to its antagonist is inhibited. TERM 33
Steps of flexor and crossed extension
DEFINITION 33
- Stepping on glass stimulates pain receptors in right foot.2. Sensory neuron activates multiple interneurons (3. Ipsilateral motor neurons to flexor excited4. Ipsilateral motor neurons to flexor excited5. Contralateral motor neurons to extensor excited6. Contralateral extensor contracts(1-4 show withdrawl of right leg, flexor reflex)(5-6 show extension of left leg, crossed extension reflex) TERM 34
Afferent and Efferent Fibers
DEFINITION 34
A: Carry sensory signals from receptors to the CNSE: Carry
motor signals from the CNS to effectors
