Exercise 19: Spinal Cord, Spinal Nerves, and the ANS Flashcards
The spinal cord is located within the vertebral canal of the spinal column and held in place by ____ ____, which are part of the ____ ____.
- Denticulate ligaments
2. Pia mater
The cylindrical continuation of the brain stem that provides neural pathways throughout the body
Spinal cord
The spinal cord ranges from the ____ ____ to its terminal end, the ____ ____.
- Foramen magnum
2. Conus medullaris
CSF-filled meninges go beyond the ____ ____, allowing a good placement for a lumbar tap, typically around ____-____.
- Conus medullaris
2. L3-L5
Anesthesia for childbirth is normally injected between ____ and ____.
- L3
2. L5
____ ____ of spinal nerves arise from the ____ ____ and pass through ____ ____ to serve the body at different regions.
- 31 pairs
- Spinal cord
- Intervertebral foramina
Since the spinal cord doesn’t fully extend through the vertebral column, the spinal nerves emerging from the interior end of the cord (____ ____) must travel through the vertebral canal for some distance before exiting at the appropriate ____.
- Cauda equina
2. Foramina
Looks like an H or butterfly on spinal cord cross section
Gray matter
Two dorsal projections
Dorsal (posterior) horns
The dorsal horns contain ____ and ____ ____ that enter the cord from the body via the ____ ____.
- Interneurons
- Sensory fibers
- Dorsal root
An enlarged area of the dorsal root that contains the cell bodies of the sensory neurons
Dorsal root ganglion
Overall, the posterior side of the spinal cord would be considered the ____ side of the spinal cord.
Sensory
Two ventral projections
Ventral (anterior) horns
The tips of the ventral horns are ____ and ____-____ than the dorsal horns.
- Broader
2. Less-tapered
The ventral horns contain cell bodies of ____ ____ of the ____ nervous system (voluntary system) which send their axons out via the ____ ____.
- Motor neurons
- Somatic
- Ventral root
Overall, the anterior side of the spinal cord would be considered the ____ side of the spinal cord
Motor
Formed by the fusion of he dorsal and ventral roots; mixed nerves containing both sensory and motor fibers
Spinal nerves
Lateral outpocketings of gray matter
Lateral horns
The lateral horns contain nerve cell bodies of ____ ____ of the ____ nervous system (____ division)
- Motor neurons
- Autonomic
- Sympathetic
The axons of the lateral horns leave the cord by ____ ____ along with those of the motor neurons of the ____ ____.
- Ventral roots
2. Ventral horns
Central area of gray matter connecting the two vertical regions
Gray commissure
The gray commissure surrounds the ____ ____ of the spinal cord which contains CSF.
Central canal
Composed of myelinated fibers
White matter
The white matter of the spinal cord is nearly bisected by ____.
Fissures
In white matter, the more open ventral fissure
Ventral median fissure
In white matter, the dorsal shallow fissure
Dorsal median sulcus
3 primary regions (or white columns) of white matter
- Dorsal (posterior) funiculi
- Lateral funiculi
- Ventral (anterior) funiculi
Each funiculus contains a number of ____ ____ composed of axons with the same ____, ____, and ____.
- Fiber tracts
- Origin
- Terminus
- Function
Tracts that conduct sensory impulses to the brain
Sensory (ascending) tracts
Tracts that carry impulses from the brain to skeletal muscles
Motor (descending) tracts
____ pairs of human spinal nerves arise from fusion of ventral and dorsal roots of the spinal cord
31
There are ____ pairs of cervical nerves (____ to ____)
8
C1 to C8
There are ____ pairs of thoracic nerves (____ to ____)
12
T1 to T12
There are ____ pairs of lumbar nerves (____ to ____)
5
L1 to L5
There are ____ pairs of sacral nerves (____ to ____)
5
S1 to S5
There is ____ pair of coccygeal nerves (____)
1
Co1
The first pair of spinal nerves leaves the vertebral canal between the base of the ____ and the ____, but all the rest exit by the ____ ____.
- Occiput
- Atlas
- Intervertebral foramina
The first through seventh pairs of cervical nerves emerge ____ the vertebra for which they are named.
Above
C8 emerges between the ____ and ____ vertebrae.
- C7
2. T1
Spinal nerves T1 and lower emerge from the spinal cord ____ the same-numbered vertebra.
Below
Each spinal nerve divides into the ____ and ____ ____.
- Dorsal
2. Ventral rami
Rami contain both ____ and ____ fibers.
- Sensory
2. Motor
Rami that serve the skin and muscles of the posterior body trunk
Dorsal rami
Rami that pass anteriorly as the intercostal nerves to supply intercostal muscles and skin and muscles of anterior and lateral trunk
Ventral rami of spinal nerves T2 and T12
Form complex networks of nerves called nerve plexuses
Ventral rami of all spinal nerves other than T2 and T12
Complex network of nerves
Nerve plexus
The ventral rami of all spinal nerves besides T2 and T12 serve the ____ and ____ needs of the muscles of the anterior and lateral trunk; they primarily serve the ____ and ____ of the limbs.
- Motor
- Sensory
- Muscles
- Skin
The 4 major nerve plexuses
- Cervical plexus
- Brachial plexus
- Lumbar plexus
- Sacral plexus
C1 to C5
Cervical plexus
The major motor branch of the cervical plexus
Phrenic nerve
The phrenic nerve innervates the ____; one of it’s jobs is to facilitate ____.
- Diaphragm
2. Breathing
C5 to T1
Brachial plexus
The nerves of the brachial plexus involve ____ ____ and ____skin.
- Arm muscles
2. Skin
5 major peripheral nerves of the brachial plexus
- Axillary nerve
- Radial nerve
- Musculocutaneous nerve
- Median nerve
- Ulnar nerve
2 innervations of the axillary nerve
- Deltoid muscle
2. Teres minor
2 innervations of the radial nerve
- Triceps brachii
2. Forearm extensor muscles
2 innervations of the musculocutaneous nerve
- Biceps brachii
2. Anterior upper arm flexor muscles
2 innervations of the median nerve
- Anterior forearm flexor muscles
2. Lateral palm and fingers
2 innervations of the ulnar nerve
- Anterior forearm flexor muscles
2. Intrinsic muscles of hand
2 major nerves of the lumbar plexus
- Femoral nerve
2. Obturator nerve
5 innervations of the femoral nerve
- Hip flexors
- Quadriceps femoris
- Sartorius
- Pectineus
- Skin
Innervation of the obturator nerve
Femur adductor muscles
L4 to S4
Sacral plexus
3 parts of the body that the nerves of the sacral plexus supply
- Buttocks
- Posterior surface of the thigh
- Nearly all sensory/motor fibers of the leg and foot
Major peripheral nerve of the sacral plexus
Sciatic nerve
Leaves the pelvis and travels down the posterior thigh, serving its flexor muscles and skin
Sciatic nerve
In the popliteal region, the sciatic nerve divides into the ____ ____ ____ and the ____ ____, serving leg muscles and skin.
- Common fibular nerve
2. Tibial nerve
2 branches of the sciatic nerve
- Common fibular nerve
2. Tibial nerve
Innervation of the tibial nerve
The hamstrings group
3 innervations of the common fibular nerve
- Biceps femoris
- Tibialis anterior
- Extensor muscles of the toes
Regulates the body activities that are involuntary
Autonomic nervous system
The autonomic nervous system is a subdivision of the ____ nervous system
Peripheral
3 parts of the body that are served by the ANS
- Heart
- Smooth muscle found in organs and blood vessels
- Internal glands
The ANS consists of chains of 2 motor neurons on the ____ pathway.
Efferent
2 motor neurons of the ANS
- Preganglionic neuron
2. Ganglionic/postganglionic neuron
The first motor neuron that resides in the spinal cord (CNS); its axon leaves the CNS to synapse with the second motor neuron
Preganglionic neuron
The second motor neuron; its axon goes to the target organ
Ganglionic/postganglionic neuron
A ganglion refers to a cell body located ____ the CNS.
Outside
What happens to the axon of the preganglionic neuron?
It leaves the CNS to synapse with the second motor neuron
What happens to the axon of the ganglionic/postganglionic neuron?
It goes to the target organ
2 major functional subdivisions of the ANS
- Sympathetic NS
2. Parasympathetic NS
“Fight or flight”
Sympathetic nervous system
“Rest and digest”
Parasympathetic nervous system
