G5_Spinal_Cord_Somatic_NS_EXAM1 Flashcards
(42 cards)
Neuronal cell bodies organized into nuclei or columns
Gray matter
Axons organized into tracts
White Matter
What are the 3 types of GANGLIA in the PNS?
- Cranial nerve ganglia (afferent)
- Posterior root ganglia (afferent)
- Autonomic ganglia (efferent)
What are the 2 Types of Peripheral Nerves?
Cranial Nerves (12 Pair) Spinal Nerves (31 Pair)
What are the two somatic sensory receptors of the nervous system?
- Exteroceptors (mechano,thermo,noci)
2. Propioceptors (muscle spindles, golgi tendon organs)
Sensory Receptors of NS:
What two Categories? what types in each?
- Somatic (Exteroceptors & Propioceptors)
- Exteroceptors-Mechano, Thermo, Nociceptors
- Proprioceptors- muscle spindles, golgi tendon organs - Visceral (Interoceptors)
- Chemo, Baro, Mechano, Nociceptors
Somatic Pain vs Visceral Pain
Somatic pain- Very acute/Well known/
Visceral pain- broad/not well identified/generalized internal
What is a MOTOR UNIT?
BOTH: LMN + MUSCLE
- LMN (neuron directly innervates skeletal muscle)
- Muscle fiber it innervates
Effector Organs
Somatic- Skeletal muscle
Visceral- Cardiac/Smooth/Glandular epithelium
Where does the spinal cord start and end? What is that called?
Where does it end in Fetus? Neonate?
STARTS: Foramen Magnum (medulla)
ENDS: L1/L2 IVD in ADULTS at CONUS MEDULLARIS
Fetus: Sacrum
Neonate: L3/L4
What 2 places do the spinal cord change size? why? What called?
Enlarges due to extremities:
- Cervical enlargement (brachial plexus)
- Lumbosacral enlargement (lumbar/sacral plexus)
What is the anterior/posterior parts of the spinal cord called?
Anterior median fissure (Wider groove)
Posterior median sulcus (thin crack)
anterior vs posterior Rootlets/roots
Anterior rootlets/roots: MOTOR ONLY
Posterior rootlets/roots: SENSORY ONLY
Describe the formation of Spinal Nerves. Describe the Anterior ramus vs Posterior ramus.
- Anterior roots merge with posterior roots to form a mixed spinal nerve (short/motor & sensory)
- MSN branches to Anterior & Posterior Ramus
Ant Ramus- LARGE- (Efferent hypaxial- afferent: skin)
Post Ramus- SMALL- (Efferent Epaxial- afferent: skin)
What innervates Efferent Hypaxial muscles of the body wall and limb? What is Afferent function?
What innervates Efferent Epaxial deep back muscles?
What is its Afferent innervation?
Anterior Ramus- Hypaxial- wall/limbs- Large
- Motor Efferent- muscles wall/limb - Sensory Afferent- skin over limbs/wall
Posterior Ramus- Epaxial- Deep back muscles
- motor- deep back muscles - sensory- skin over middle of back
What happens to the relative locations of spinal nerves and the corresponding roots on the spinal cord where the spinal nerves are derived from?
Spinal cord segment and spinal nerve location gets further away from each other as you move inferiorly because the spinal cord ends at L1/L2 IVD, but spinal nerves continue down to the sacral level
How many CERVICAL spinal nerves are there? Why? What is significant about C1 spinal nerve?
8 cervical spinal nerves b/c of the space between the skull and C1.
C1 spinal nerve lacks Afferent component and its posterior roots are absent in 50% of individuals.
How many THORACIC spinal nerves? What do thoracic spinal nerves form?
What special about the last thoracic spinal nerve?
T1 to T12 (start between rib 1 and 2)
-Anterior rami of thoracic spinal nerves form intercostal nerves
T12- “Subcostal nerve” - Under last 12th rib
How many spinal nerves in lumbar, sacral, and coccyx?
Which pass through the sacral hiatus?
Lumbar L1-L5
Sacral S1-S5
Coccygeal Co1
S5 and Co1 pass through SACRAL HIATUS
What does the Cauda equina consist of?
Anterior and posterior roots arising from conus medullaris and coursing within the lumbar cistern (filled w/ CSF)
Dermatome Vs Myotome
Dermatome: Area of skin innervated by all the sensory nerve fibers of a single spinal nerve
Myotome- Muscles innervated by all the motor nerve fibers of a single spinal nerve
What dermatome located at the Nipple and Umbilicus?
Caution: What is the generalization?
T4 Dermatome at the Nipples
T10 Dermatome at the Umbilicus
Dermatome maps are idealized b/c of OVERLAP of adjacent dermatomes
What offers reliable locations to test sensory abnormalities of spinal nerve/root lesions?
“Autonomous Sensory Zones”
What do most spinal nerves do/go? What spinal nerves are the exception? what are these types of spinal nerves called?
Most spinal nerves merge with adjacent spinal nerves to form a PLEXUS
- Except for thoracic (intercostal) spinal nerves