6. Gross Anatomy Flashcards
Central Nervous System • \_\_\_\_ • \_\_\_\_
Peripheral Nervous System • \_\_\_\_ pairs spinal nerves • \_\_\_\_ pairs cranial nerves • \_\_\_\_ nerves
brain
spinal cord
31
12
autonomic
Groups of anatomically or functionally related neuronal cell bodies in the PNS are found in ___ or ___ ganglia derived from ___ cells
sensory
autonomic
neural crest
Visceral ____ convey information from organs and bv (blood vessels) to the CNS = GVA
fibers
• On the \_\_\_\_ are somatomotor responsible for initiating the contraction of skeletal muscle (and visceral motor fibers which will be responsible, as we will see shortly, for the direct innervation of smooth muscle, cardiac muscle and glands)
afferents
efferent/motor
PNS > SOMATIC > BODY WALL AND EXTREMITIES:
MOTOR:
GSE - Somatic Efferent Fibers
Somatomotor fibers arising from ____ motor neurons: directly stimulate ____ and ____ contraction of ____ muscle
SENSORY:
GSA – Somatic Afferent Fibers
Somatosensory fibers transmit inputs to the CNS concerning the following modalities:
- ____, pain and temperature from the body wall
- Pain and ____ from the muscles, tendons and joints
lower
voluntary
reflex
skeletal
touch
proprioception
PNS > VISCERAL > VISCERA (internal organs):
MOTOR (GVE) components • Innervate \_\_\_\_ muscle • Regulate \_\_\_\_ • Innervate \_\_\_\_ muscle These components form the \_\_\_\_
SENSORY (GVA) components
•Convey information related to ____ reflexes
•Convey ____ sensations which are primarily affective in nature (e.g. hunger, satiety, nausea, anxiety, stress)
•Convey normally vague and poorly localized ____ pain
•Participate in pathways with GSA elements producing “____”
smooth
glands
cardiac
visceral
visceral
organic
referred organic pain
LIMBIC SYSTEM
HYPOTHALAMUS
While the ANS is generally defined as part of the PNS, it must be appreciated that the
____ NEURONS of the ANS
are under the control of higher CNS centers
visceral efferent
Peripheral nerves usually contain different combinations of ____ of motor neurons and ____ of sensory neurons.
____ nerves supply structures in the neck, trunk, and limbs as well as limited areas of the head.
ALL spinal nerves leaving the CNS contain both somatic ____ and somatic ____ fibers.
SOME spinal nerves leaving the CNS, but not all, convey ____ fibers as well.
Each spinal nerve divides just outside the spine into a
- a ____ ramus; and
- a ____ ramus.
- ____ branches of these rami supply specific dermatomes.
- ____ branches of these rami supply the derivatives of specific myotomes.
Cranial nerves and their branches may carry efferent fibers, afferent fibers of BOTH in different combinations. [???]
axons
processes
spinal
afferent
efferent
autonomic
ventral (anterior) primary
dorsal (posterior) primary
cutaneous
muscular
1 - ____ axis
- Caudal, dorsal, ventral, cranial/oral
2 - ____ axis
basal/ventral inferior, frontal/cranial/oral/rostral anterior, parietal/dorsal superior, occipital/caudal posterior
meynert’s
forel’s
The CNS is organized into regions of
gray matter and white matter
Gray matter contains ____ of neurons, their ____, and the proximal parts of their axons.
Groups of anatomically or functionally similar neuron cell bodies in gray may be found in a ____, lamina, or ____.
White matter contains ____ of neurons.
Groups of anatomically or functionally similar axons may be found in a ____, funiculus, ____, lemniscus, or ____.
cell bodies
dendrites
nucleus
layer
axons
peduncle
fasciculus
tract
Frontal
Parietal
Occipital
Temporal
Each cerebral hemisphere is divided into four lobes and is highly convoluted by ____ separated by ____
gyri
sulci
The ____ (primary motor cortex), immediately rostral to the central sulcus, contains ____ motor neurons that control skeletal muscles on the ____ side of the body
precentral gyrus
upper
contralateral
The precentral gyrus contains a motor homunculus, an orderly but distorted map of the ____ muscles in the ____ limbs and trunk controlled by ____ MOTOR NEURONS
- Upper motor neurons that control muscles innervated by cranial nerves are represented close to the ____. These-muscles, as well as muscles of the hand, are most heavily represented in the homunculus.
- Proceeding ____ on the lateral aspect of the hemisphere, upper motor neurons that vcontrol neck, upper limb, and trunk musculature are encountered.
- On the ____ aspect of the hemisphere are the upper motor neurons that control pelvic and lower limb muscles.
This primary motor cortex is known as ____.
These upper motor neurons encode for the
____, force, and ____ of each movement and control ____ muscles used in the execution of skilled movements
skeletal
contralateral
upper
lateral sulcus
dorsally
medial
MI
direction
velocity
individual
Though the descending pathways that convey the axons of M1 upper motor neurons to lower motor neurons in the brainstem and spinal cord will be discussed in a lecture in Mod 2, note already the significance of the
____
Corticonuclear (Corticobulbar) Tract
The ____ (primary somatosensory cortex), immediately posterior to the central sulcus, contains a ____ representation of the ____ side of thebody
postcentral gyrus
tactile
contralateral
The primary somatosensory cortex in the parietal lobe contains a ____ of the contralateral surface of the body that is distorted by the uneven cutaneous distribution of sensory receptors.
The ____, hands, and ____ are the most heavily represented areas of the homunculus in which the density of ____ is greater and the ____ are smaller than in other parts of the body.
The sensory homunculus has a ____ representation similar
to the homunculus in primary motor cortex.
- The head, neck, upper limb, and trunk are represented on the ____ aspect of the hemisphere.
- The pelvis and lower limb are represented in an extension of the postcentral gyrus onto the ____ aspect of the hemisphere.
sensory homunculus fingertips lips sensory receptors receptive fields
somatotopic
lateral
medial
Though a Mod 2 lecture will be devoted to the ascending somatosensory
and trigeminal pathways which convey inputs from ____ neurons located in peripheral ganglia just outside the CNS, note the role of the ____ in relaying afferent inputs to primary somatosensory cortex.
primary sensory
thalamus
The ____ system is involved in emotion, memory, feeding and mating behaviors
limbic
The ____ forms the ventral
portion of the
diencephalon
The Hypothalamus exerts its influence through the \_\_\_\_, autonomic and \_\_\_\_ systems to regulate: • \_\_\_\_ function • Body temperature • \_\_\_\_ balance • Food intake
hypothalamus limbic endocrine cardiovascular water
The SPINAL CORD
Descends from the caudal portion of the brain stem, the ____, through the ____
The cord descends through the ____ canal within a closed ____ sac which extends
to the ____ level
The cord presents ____ and ____ enlargements WHY?
medulla oblongata
foramen magnum
vertebral
dural (thecal)
S2
cervical
lumbo-sacral
The SPINAL CORD
Functionally distinct ____ and ____ roots of paired spinal nerves emerge segmentally from the cord…
The enlargements give rise to roots of the spinal nerves contributing to the ____ and ____ plexuses, innervating the upper and lower limbs respectively
The cord tapers caudally and terminates in the ____ at the ____ intervertebral level
dorsal
ventral
brachial
lumbosacral
conus medullaris
L1-L2
SPINAL CORD SEGMENTS
Each pair of spinal nerves is formed by the convergence of fibers arising from the dorsal and ventral aspects of a discrete segment of the cord
Arising from each segment are the somatic ____ & somatic ____ fibers
that supply, respectively:
A specific area of body wall, the ____
And a specific muscle mass, the ____
afferent
efferent
dermatome
myotome
Spinal gray
- Dorsal horn
- Ventral horn
Dorsal (posterior) Root comprised of somatic
____ Fibers carrying information from the ____ TO the ____
Ventral (anterior)
root comprised of somatic ____ Fibers carrying information FROM
the ____ to the ____
“Mixed” Spinal nerve in an ____
DORSAL (POSTERIOR)
RAMUS
VENTRAL
(ANTERIOR)
RAMUS
afferent
periphery
CNS
efferent
CNS
periphery
IV foramen
So upon exiting an intervertebral foramen, each mixed spinal nerve divides into…
A large ____ ramus Innervates anterolateral
body wall, ____ muscles
and the extremities
Like the spinal nerve, the rami contain both somatic ____ and ____
A smaller
____ ramus
Innervates skin of back and
posterior scalp, facet joints, posterior spinal ligaments and ____ muscles
ventral (anterior) primary
hypaxial
afferents
efferents
dorsal (posterior) primary
epaxial
In the
____ NERVOUS SYSTEM, there is only ONE neuron between the CNS and either:
Skeletal muscles innervated by ____ fibers; or
Sensory receptors innervated by ____ fibers
SOMATIC
GSE
GSA
The specific area of skin supplied by the somatic afferents in the pair of spinal nerves arising from each spinal cord segment is called a
____
Note that ____ innervation of face and anterior scalp
is mediated by ____- the ____ Nerve
dermatome
cutaneous
CN V
trigeminal
Dermatomes ____ - so that the loss of a single spinal nerve or dorsal root does not produce ____
____ dermatome
boundaries are much more
sharply defined with minimal overlap
overlap
anesthesia
CN V
CUTANEOUS NERVES
carry information from ____ (____
receptors) in the
skin to the CNS
Each is sensitive to a particular form of ____ which it transduces into an ACTION POTENTIAL
These “exteroceptors” include…
exteroceptors
cutaneous
physical energy
Exteroceptors:
- ____ - respond to deformation or displacement
- ____ - respond to changes in temperature
- ____ - respond to stimuli which damage tissue
All these receptors are continuous with peripheral processes of ____ NEURONS whose somata are located in ____ GANGLIA
mechanoreceptors
thermoreceptors
nociceptors
(pseudounipolar) sensory dorsal root (spinal)
Dorsal Root (Spinal) Ganglion
Each is a collection of ____ sensory neurons located on the dorsal root in an ____ foramen, just proximal to the mixed spinal nerve
No ____ occur here as the central processes of the neurons continue to the ____ horn of the ____ gray
pseudouniplar intervertebral synapses dorsal spinal
Exteroceptive inputs, along with inputs from ____ located in MUSCLES, ____ and JOINTS, enter the spinal cord via the central processes of the neurons in the
____ GANGLIA
proprioceptors
tendons
dorsal root
At the dorsal root entry zone, the central processes of neurons in the DRG enter in either a ____ or ____ division and are classified using two different criteria:
Dorsal root fibers of ____ nerves are classified according to ____ by Roman numerals.
Dorsal root fibers of ____ nerves are classified alphabetically according to their ____.
medial lateral muscular fiber diameter cutaneous conduction velocity
Muscle Spindles Ia
(muscle ____)
Golgi tendon organs Ib (muscle ____)
____, ____ fibers:
• Touch
• Vibration
• Pressure
____, ____ fibers
• Pain
• Temperature
Note how these somatic afferent inputs are segregated by ____
stretch
force
II, A-beta
A-delta, C
modality
Knowledge of the dermatomes of the body is a prerequisite for understanding patterns of both
____ PAIN and ____ PAIN
radicular
referred visceral
Contraction of skeletal muscle is a direct result of stimulus by ____ MOTOR NEURONS located in either the ____ or ____ cord
Most are ____ motor neurons innervating ____ muscle fibers responsible for skeletal muscle contraction
lower
brainstem
spinal
alpha
extrafusal
The ____ ROOTS convey axons of these LOWER MOTOR NEURONS, whose cell bodies are located in the ____ of the spinal gray, to the mixed spinal nerves
LOWER MOTOR NEURONS located in ____ give rise to axons found in ____ of the twelve pairs of cranial nerves
ventral
ventral horns
brainstem nuclei
nine
Damage to these
Lower Motor Neurons
produces ____ and ____ of skeletal muscle
flaccid paralysis
atrophy
