Pathophysiology Exam #3 Flashcards
How many total vertebra are in the spinal column?
33
How many vertebra in the cervical region of the spinal column?
7
How many vertebra in the thoracic region of the spinal column?
12
How many vertebra in the lumbar region of the spinal column?
5
How many vertebra in the sacral region of the spinal column?
5
How many vertebra in the coccygeal region of the spinal column?
4
Is the word vertebrae plural or singular?
plural, vertebra is singular
How many curvatures of the spine is seen normally and describe each curvature.
There are 4 curvatures(from an anterior perspective)
- cervical convexity-curved towards the ANTERIOR part of the body
- thoracic concavity-curved towards the POSTERIOR part of the body
- lumbar convexity-curved towards the ANTERIOR part of the body
- sacral concavity-curved towards the POSTERIOR part of the body
What is the purpose of the body of the vertebra?
BODY: weight bearing and protection of spinal cord
o Largest and the thickest part of the SCol
o In between sits the intervertebral disk
§ separates and cushions
§ integrity is important for the disk,
§ keeps the intervertebral foramen the same size
What makes up the vertebral arch of the vertebra, and where does it attach in relation to the other structures of the spinal column?
(1) Two pedicles, attached to body
(2) Two laminae, joins lamina from opposite half of
arch
§ lamina from one side and the lamina from the
other, form the SPINOUS PROCESS
Describe the traverse process of the spinal column.
o Extends laterally from each side of arch between
lamina and pedicle
o Attachment for skeletal muscles
Describe the spinous process of the spinal column.
o Junction between TWO lamina o Attachment for skeletal muscles o Sometimes curved down, sometimes they’re horizontal o What you are palpating down the spine
What is the purpose of the vertebral foramen?
foramina of all vertebrae;It forms the vertebral canal for the entire spinal cord
• This is where the SCord sits
• The vertebral foramen size is different, in
different segments of the vertebral columns
because the SCord is not the same diameter all the
way down
Describe the intervertebral foramina(notch).
o Exit for spinal nerves and blood vessels
o Formed by superior and inferior intervertebral
notches in pedicles of adjacent vertebrae
o INFERIOR and SUPERIOR INTERVERTEBRAL NOTCH
§ WHERE THE SPINAL NERVE ROOTS EXIT
o DO NOT CONFUSE VERTEBRAL FORAMEN WITH INTERVERTEBRAL FORAMEN
What is the pedicle of the spinal column?
Foot of the arch with one on each side; forms the lateral wall of the vertebral foramen
What is the lamina of the spinal column?
Posterior part of the vertebral arch; forms the posterior wall of the vertebral foramen
What is the function of the articular processes of the spinal column?
Superior and inferior projections containing articular facets where vertebrae articulate with each other; strengthen the vertebral column and allow for movement.
What is different about C1(atlas) from the rest of the cervical region of the spinal column?
§ ATLAS (C1): - no body -no spinous process -large superior articular facets for base of skull (occipital condyles) to sit -large vertebral foramen v supports the skull v facet is where the DENS sits v allows the head and neck to move up and down (to nod)
What is different about C2(axis) from the rest of the cervical region of the spinal column?
§ AXIS (C2): dens that fits into vertebral foramen of atlas
v DENS (projection upwards) aka the ODONTOID PROCESS
Ø allows for the rotation of the neck
§ Superior articular facet on C2 sits into the inferior articular facet of C1
What is a bifid spinous process of the spinal vertebra?
o Bifid spinous processes
§ bifid: split at the end of the spinous processes
§ muscles of the neck connect here
§ most cervical vertebrae are bifid, for muscle attachment
What are the characteristics of the cervical region of the spinal column?
• CERVICAL(7 vertebrae)
o Small bodies
o Bifid spinous processes
o Horizontal spinous processes
o Transverse foramina (located in the transverse processes) for vertebral arteries(except C7)
§ very important: the cervical transverse foramina have
vertebral arteries that pass through the foramen magnum
that supply the base of the brain
o Relatively large vertebral foramina for cervical
enlargement of spinal cord
What is special about C7?
C7 (VERTEBRA PROMINENS); usually (but not always) has no transverse foramina
*sometimes associated with an extra “cervical rib”
What are the characteristics of the thoracic region of the spinal column?
• THORACIC VERTEBRAE(12 vertebrae)
o Long, thin spinous processes, which become more vertical from above downward
o Vertebral foramina smaller than in cervical vertebrae
o Bodies larger than cervical vertebrae and increase in size from above downward
§ more weight bearing
o Only the first 10 (thoracic vertebrae) have costal facets on transverse processes and bodies for articulations with rib heads and tubercles
§ Superior articular facet for rib head
§ Inferior articular facet for rib head
§ Articular facet for tubercle of rib
o Does not have any transverse foramina in the transverse processes (not arteries)
o Spinous processes are no longer bifid and are fairly
vertical
o Vertebral foramen smaller
o Superior articular facet articulates with the inferior
articular facet above that
o Inferior intervertebral notch: where nerve roots exit
What are the characteristics of the relationship between the thoracic column and the rib articulations?
• THORACIC VERTEBRAE AND RIB ARTICULATIONS
o 12 ribs in man and woman
o 1st seven ribs are called TRUE
RIBS
§ posteriorly they articulate with the vertebral column
§ continue out posteriorly then laterally
§ then curve anteriorly
§ joined with cartilage SEPARATELY, that then joins
to the body of the sternum
o Rib #1 articulates with the manubrium
o Rib #2 joins at the sternal angle
o Ribs #3-7 articulate with the sternum
o Ribs 8-12 are called the FALSE RIBS
§ each rib does not directly join to cartilage that attaches to sternum
§ cartilage to cartilage
o Ribs 11-12 do not join at all and are called the FLOATING RIBS
What is the significance of the “sternal angle”?
o Sternal angle (significance): to properly find the proper correct anatomical landmarks for assessing heart
sounds(T2)
What are the characteristics of the lumbar region of the spinal column?
• LUMBAR VERTEBRAE(5 vertebrae)
o large, thick vertebral bodies
o heavy transverse and spinous processes for HEAVY WEIGHT BEARING and limited rotation;
o no transverse foramina and no costal facets;
o almost horizontal spinous processes
What are the characteristics of the sacral region of the spinal column?
• SACRAL VERTEBRAE
o 5 vertebrae fused to form sacrum
§ no disk between the vertebral bodies
o Intervertebral foramina: Dorsal and ventral foramina
(where nerve roots exit)
o Anterior edge of body of first sacral vertebra bulges to
form sacral promontory
o 1st sacral vertebra is called the SACRAL PROMONTORY
( that was used to measure the diameter of the birth canal -unknown if this is stilled used)
o SACRAL HIATUS (posterior): used for caudal blocks
What are the characteristics of the coccyx region of the spinal column?
• COCCYX à
o 3-5 (average 4) fused bones; no vertebral foramina or transverse processes
o the opening or junction between the sacrum and coccyx is where the coccygeal spinal nerve exits
What is the purpose of the intervertebral disks of the spinal column?
Provides cushion
Adds length to SC in the adult
• Fibrocartilaginous structures between adjacent vertebral bodies from AXIS TO SACRUM; prevent vertebrae from rubbing against each other
• There is not a disk between the skull and C1; or
between C1 and C2; no disk in the sacral either
• 25% of length of adult vertebral column; thickest in
lumbar region
What are the two parts of the intervertebral disk and their function?
o ANULUS FIBROSUS (can be spelled with one or
two N’s): outer concentric fibrous tissue
o NUCLEUS PULPOSUS: central, springy, pulpy
zone(§ provides cushioning between vertebral bodies
and adds a significant percentage to the length of the vertebral column
WITH AGE THE DISC LOOSE WATER AND COLLAGEN CAUSING SHRINKAGE AND DECREASE IN ABILITY OF MOVEMENT(or painful movements)
Why is it important that the disk remain a consistent size?
• Its important that the intervertebral disks remain at a
consistent size because of the intervertebral foramen; so
the opening will remain the same size
o if the intervertebral disk loses volume/ water, becomes dehydrated, that area will be narrowed,
o placing pressure on the sensory nerves that enter
and motor nerves that exit.
o Which can cause problems in the periphery, in terms
of sensations; loss of sensations/ painful sensations
o Can also cause alterations in motor movement
What are herniated disc?
o Many people have herniated disks
o As I mentioned the outer part is the annulus fibrosis.
o The center is the nucleus pulposus; a pulpy area
§ Sometimes the integrity of the annulus fibrosus is lost, allowing the nucleus pulposus to herniate.
§ It usually herniates POSTERIORLY
§ It compresses the intervertebral foramen, compressing that nerve root that exits there
§ Loss of sensations, loss of muscle activity, painful sensations, etc.; to the various parts of the body that is innervated
o Repair:
§ old approach: laminectomy
§ modern approach: use of a cushioned disk to supplement that area
Where does the Anterior Longitudinal Ligament extend from, towards what and what does it connect?
• ANTERIOR LONGITUDINAL
LIGAMENT:
o extends from ANTERIORLY tubercle of ATLAS TO SACRUM;
o increases in width from above downward;
o CONNECTS THE ANTERIOR VERTEBRAL BODIES AND
INTERVERTEBRAL DISKS
Where does the Posterior Longitudinal Ligament extend from, towards what and what does it connect?
o extends from AXIS TO SACRUM
o CONNECTS THE POSTERIOR VERTEBRAL BODIES AND INTERVERTEBRAL DISKS
o broader above than below;
o lies within vertebral canal behind vertebral bodies
What is the function of the Ligamenta Flava
• LIGAMENTA FLAVA: o JOIN ADJACENT LAMINAE; o small gap in midline between right and left ligamentum flavum for passage (exit) of (small) veins o LIGAMENTUM FLAVUM = SINGULAR (talking about either the one on the L or the R); LIGAMENTA FLAVA = PLURAL (talking about both) SPELLING IS IMPORTANT!!!
Where does the Supraspinal Ligaments extend from and to, and what are their function?
• SUPRASPINAL LIGAMENTS: o INTERCONNECT TIPS OF SPINOUS PROCESSES FROM 7TH CERVICAL VERTEBRA TO SACRUM; o continuous with ligamentum nuchae above and interspinal ligaments in front; o increase in thickness from above down
Where does the Interspinal Ligaments extend from and to, and where are they best developed?
• INTERSPINAL LIGAMENTS:
o EXTEND BETWEEN ROOTS AND APEXES OF
SPINOUS PROCESSES;
o best developed in lumbar region
What do the Inter-transverse Ligaments adjoin, and where do they extend from and to?
• INTERTRANSVERSE LIGAMENTS:
o ADJOIN ADJACENT TRANSVERSE PROCESSES
o Run the length of the Spinal Column
What separates the inferior medulla oblongata from the superior SC?
foramen magnum
How long is the spinal cord? Where does the spinal cord terminate?
SPINAL CORD
• Continuation of medulla oblongata; foramen magnum divides spinal cord from medulla oblongata
• About 46 cm long
• Extends from foramen magnum/atlas to where it terminates at the conus medullaris at vertebrae
L1 – L2
What are the two enlargements of the spinal cord?
cervical enlargement
lumbosacral enlargement
- The diameter of the SCord is not the same all the way down
- There is an ENLARGEMENT IN THE CERVICAL AREA because that is the ORIGIN OF THE NERVES THAT INNERVATE THE ARMS, HANDS AND FINGERS
- There is also an ENLARGEMENT OF the SCord in the LUMBAR SEGMENT because that is the ORIGIN OF NERVES THAT INNERVATE THE HIPS, LEGS, FEET, AND TOES
At what structure does the SC terminate(L1,L2)?
conus medullaris
Whats the name of the ligament that anchors the spinal cord to the coccyx?
From conus medullaris, there’s a ligament called the FILUM TERMINALE that extends to coccyx and anchors spinal cord to coccyx
What nerves supply the upper limbs?
C4-T2
What nerves supply the lower limbs?
L3-S3
How many total pairs of nerves are there?
31
How many cervical nerves?
8
How many thoracic nerves?
12
How many lumbar nerves?
5
How many sacral nerves?
5
How many coccygeal nerves?
1
How are the nerve rootlets named?
- The various segments of the SCord are named according to the vertebrae beside which they originated during fetal development.
- In adulthood, those SCord segments no longer lie adjacent to those vertebrae, but they still carry the same names as they always did.
spinal cord segments move up in relation to the spinal column
What is the name of the group of rootlets that extend below the level of the SC and terminating at the Filum terminale called?
Cauda equina(horses tail)
Where does the first cervical nerve exit the spinal column?
above C1 and below the skull
What nerves make up the Brachial plexus?
v BRACHIAL PLEXUS: from ventral rami of C5,
C6, C7, C8, T1 (with contributions from C4 and T2)
What does the gray matter of the spinal cord consist of(2) and what happens there?
- nerve cell bodies
- and their dendrites
axons synapse with those dendrites
The gray matter is divided into what two sections?
- Dorsal(posterior) horn
2. Ventral(anterior) horn
Only those segments of the SC associated with the autonomic nervous system have _____ _____ in the gray matter of the SC.
lateral horns(primarily T1-L2 and the sacral segments of the SC) sympathetic and parasympathetic
What is located in the central canal of the SC?
CSF
What is the area within the gray matter called where it crosses from one side of the SC to the other?
gray commissure
The central canal communicates with what structure at its most superior point?
the 4th ventricle
What does the white matter consist of(2)?
Bundles of axons and their myelin sheaths or we could say consist of tracts that ascend and descend
What separates the right and left sides of the SC on the posterior side?
posterior median sulcus
What separates the right and left sides of the SC on the anterior side?
anterior median fissure
Whats the difference between a sulcus and a fissure
fissure is a fairly wide and deep separation, whereas a sulcus is not as wide or deep although it still separates
Is there a posterior white commissure?
No just an anterior white commissure
What structure runs the length of the anterior median fissure?
The anterior spinal artery
What types of information is transferred via the dorsal root(column) of the spinal cord?
sensory
What types of information is transferred via the ventral root(column) of the spinal cord?
motor
What types of infuriation is transferred via the lateral root(column) of the spinal cord?
autonomic
The dorsal, ventral and lateral roots or columns of the spinal cord is a part of the _____ _____.
white matter
The sensory information is transported from the _____ to the _____ _____ via the _____ _____.
peripheral, spinal cord, dorsal root
What makes up the dorsal root ganglion?
contain a cluster of nerve cell bodies (and their associated dendrites) of these afferent sensory
neurons
What type of neurons make up the dorsal root ganglion?
unipolar or pseudo-unipolar neurons
Where do sensory impulses terminate?
§ AFFERENT SENSORY PATHWAYS:
v Sensations are conducted from the periphery toward the SCord, first through a sensory spinal
nerve
v then they follow the DORSAL ROOT
v then the dorsal root divides into the DORSAL ROOTLETS
v THEN THEY TERMINATE IN THE POSTERIOR HORN OF THE GRAY MATTER IN THE SCORD
The cross section of the spinal cord is both _____ and _____.
bilateral and symmetrical
What is the function of the ventral rootlets?
Ventral (anterior)
§ VENTRAL ROOTLETS exit the spinal cord near anterior (ventral) horns, and transmit efferent nerve impulses (action potentials) away from the cord;
§ Ventral rootlets then converge into the VENTRAL ROOT (NO VENTRAL ROOT GANGLION)
v these nerve impulses consist of somatic motor impulses to skeletal muscles and
v autonomic (sympathetic and parasympathetic) impulses to smooth muscles, thoracic and abdominal organs, glands, etc.
What is the Efferent somatic motor pathway?
EFFERENT SOMATIC MOTOR PATHWAYS:
- impulse comes from the brain down the SP
- Nerve cell body will be somewhere in the anterior horn
- the axon exits through the ventral rootlets to the ventral root
- joins to with the dorsal root ganglion to form the common spinal nerve
- terminates on skeletal muscle fibers
What is the Efferent autonomic pathways?
EFFERENT AUTONOMIC PATHWAYS:
v Nerve cell bodies are located in the lateral horn
v Autonomic nerve cell bodies will exit the same as Efferent somatic motor pathways
v Axon continues from that nerve cell body and then terminates on organs and tissues that have autonomic innervation
Dorsal (posterior) and ventral (anterior) root unite to form ?
The common spinal nerve
What is the difference between Afferent and Efferent nerves?
Afferent is sensory while Efferent is motor or autonomic
How many Laminae of Rexed are located in gray matter?
10
Laminae Rexed 1-6 are located where? What impulse information do they transmit?
- Dorsal horns of the gray matter;
- Laminae 1 =fast pain/acute pain(A-alpha)
- Laminae II and III (together are often referred to as the substantia gelatinosa): associated with Type C neurons and slow pain transmission
- Laminae III, IV, V, VI: primary neurons that are transmitting other sensations will terminate in one of these laminae of Rexed
Laminae Rexed 7-9 are located where? What impulses do they transmit?
Laminae VII – IX of ventral (anterior) horn contain cell bodies of efferent somatic motor neurons to skeletal muscles
- Lamina of Rexed VII is located in the LATERAL horn: AUTONOMIC PATHWAY
- the ventral horn is where nerve cell bodies for LOWER MOTOR NEURONS that exit the SCord and
transmit efferent somatic motor pathways to skeletal muscle fibers
Where is Laminae Rexed 10 located, and what is it associated with?
v Neurons that are going to cross from one side of the SCord to the other are going to cross here at the lamina of Rexed X. A point of crossover(gray comminsure).
v Notice that the lamina of Rexed X is right around the central canal of the SCord
What is another name for Laminae Rexed 1?
(aka, lamina marginalis)
Laminae 2 and 3 together are called?
the substantia gelatinosa
Small tract of white matter just off the dorsal horn is called the?
tract of Lissauer-specifically related to pain pathways
the meninges surrounding the spinal cord is continuous with?
the meninges surrounding brain
Characteristics of the Dura mater?
o around the SCord, the dura mater is only one
single layer that DOES NOT ADHERE TO VERTEBRAE
o unlike the brain, the SCord dura mater has a
space between the DURA MATER and the
VERTEBRAL SPACE that is called the EPIDURAL SPACE
Under the Dura mater is the?
Underneath the dura mater is the subdural space: more of a potential space (than a real space) with thin film of fluid
What space lies under the subdural space of the meninges of the SC?
Arachnoid mater;
o Has extensions of the arachnoid
o has lots and lots and lots of small, fragile vessels and CSF in the subarachnoid space
how does CSF enter the Subarachnoid mater?
§ from the 3 foramina, from the 4th ventricle;
§ moves into the subarachnoid space around
the brain;
§ and the subarachnoid space around the brain
is continuous with the subarachnoid space around the SCord.
o Subarachnoid space: continuous with cranial
subarachnoid space; filled with cerebrospinal
fluid and weblike extensions of arachnoid
o Ends at level of S2 vertebra along with dura
mater
Below the Subarachnoid mater lies the?
Pia mater
What are the characteristics of the Pia mater?
o Firmly attached to the SCord
o Thin vascular, connective tissue covering spinal
cord and nerve roots
o Below conus medullaris, pia mater continuous
with filum terminale, pierces dura mater and
arachnoid, and blends with connective tissue
behind coccyx
o On each side, pia mater attached to dura mater
by 22 denticulate (means tooth-like) ligaments, which anchor the cord
§ The denticulate ligaments: is where the pia mater extends outward and attaches to the dura mater
§ Extension of the pia mater, out through the arachnoid mater, that attaches to the dura mater.
§ That’s sort of a way of attaching the SCord, holding it in place, giving it a foundation
Cervical nerves 1-8 lie approximately at what level of the spinal column in the adult?
Nerve/vertebrae C: 1 - C : 1 C: 2 - C: 2 C: 3 - C: 2-3 C: 4 - C: 3-4 C: 5 - C: 4-5 C: 6 - C: 5 C: 7 - C: 6 C: 8 - C: 6-7
Thoracic nerves 1-12 lie approximately at what level of the spinal column in the adult?
Nerve/vertebrae T: 1 - C: 7 – T: 1 T: 2 - T: 1-2 T: 3 - T: 2 T: 4 - T: 3 T: 5 - T: 3-4 T: 6 - T: 5 T: 7 - T: 6 T: 8 - T: 7 T: 9 - T: 8 T: 10 - T: 9 T: 11 - T: 10 T: 12 - T: 10-11
Lumbar nerves 1-5 lie approximately at what level of the spinal column in the adult?
Nerve/vertebrae L: 1 - T: 11-12 L: 2 - T: 11-12 L: 3 - T: 12 L: 4 - T: 12 – L: 1 L: 5 - T: 12 – L: 1
Sacral nerves 1-5 lie approximately at what level of the spinal column in the adult?
Nerve/vertebrae S: 1 - L: 1 S: 2 - L: 1 S: 3 - L: 1 S: 4 - L: 1-2 S: 5 - L: 1-2 *(THESE 5 VERTEBRAE ARE FUSED IN ADULTS, BUT THE FORAMINA ALLOW PASSAGE OF THE NERVES.)*
The coccyx nerve lies where in proximity to the spinal column in the adult?
Coc: 1 - L: 1-2
In regards to the sensory dermatomes, the cervical nerves are responsible for?
Head, neck, shoulders, upper chest(arm pits up), and the upper extremities(arms, hands, fingers)
In regards to the sensory dermatomes, the thoracic nerves are responsible for?
trunk(armpits down) and the posterior arms/forearms
In regards to the sensory dermatomes, the lumbar nerves are responsible for?
anterior pelvis, anterior legs and tops of feet
In regards to the sensory dermatomes, the sacral nerves are responsible for?
genitals, posterior pelvis, legs, bottom of the feet
In regards to the sensory dermatomes, the coccygeal nerves are responsible for?
area right above the anus
Dorsal ramus transmits?
somatic sensory
Do Dorsal rami form plexus?
no
Ventral ramus transmits?
somatic motor
autonomic
Do ventral ramui form plexus?
yes
The brachial plexus originates from?
C5, C6, C7, C8 and T1(with contributions from C4 and T2)
How many trunks are in the brachial plexus and their names?
3
- superior
- middle
- inferior
How many divisions are in the brachial plexus?
6
- 3 ventral
- 3 dorsal
How many cords are in the brachial plexus and their names?
3
- lateral
- posterior
- medial
What are the 5 nerves that comes off the terminal branches of the brachial plexus? spelling counts
- musculocutaneous
- axillary
- radial
- median
- ulnar
What is the origin of the musculocutaneous nerve?
([C4], C5, C6, C7)**
What is the origin of the axillary nerve?
(C5, C6)**
What is the origin of the radial nerve?
(C5, C6, C7, C8, T1)**
What is the origin of the median nerve?
([C5], C6, C7, C8, T1)**
What is the origin of the ulnar nerve?
([C7], C8, T1)**
The axillary nerve origin is _____ and its cutaneous sensory innervation is?
O:POSTERIOR cord of brachial plexus(C5-C6)
INNERVATION: Inferior lateral shoulder(deltoid)
The radial nerve origin is _____ and its cutaneous sensory innervation is?
O:Posterior cord of brachial plexus(C5-T1)
INNERVATION: Posterior surface of arm and forearm, lateral 2/3 of dorsum of the hand(triceps)
The musculocutaneous nerve origin is _____ and its cutaneous sensory innervation is?
O:Lateral cord of brachial plexus(C5-C7[C4])
INNERVATION: Lateral surface of forearm(biceps)
The ulnar nerve origin is _____ and its cutaneous sensory innervation is?
O:Medial cord of brachial plexus(C8-T1[C7])
INNERVATION: Medial third of hand, little finger and medial half of ring finger
The median nerve origin is _____ and its cutaneous sensory innervation is?
O:Medial and lateral cords of brachial plexus(C5-T1)
INNERVATION: Lateral 2/3 of palm of hand, thumb, index and middle fingers, and the lateral 1/2 of ring finger and dorsal tips of the same fingers(PALMER AND DORSAL SURFACE)
What is the motor function of the cervical nerves?
- head movement
- diaphragm movement
- neck and shoulder movement
- some upper limb movement
What is the motor function of the thoracic nerves?
- some upper limb movement
- rib movement in breathing, vertebral column movement and tone in postural back muscles
- also some hip movement
What is the motor function of the lumbar nerves?
- hip movement
- some lower limb movement
What is the motor function of the sacral nerves?
-lower limb movement
MOST superiorly, what is the origin of both anterior and
posterior spinal arteries?
o THE RIGHT AND LEFT VERTEBRAL ARTERIES
o So if there is decreased blood flow through the
vertebral arteries, that’s going to affect blood flow
through both anterior and posterior spinal arteries.
What artery perfuses the anterior 2/3 of spinal cord?
ANTERIOR SPINAL ARTERY
Which artery Run length of spinal cord and originates from left and right vertebral arteries?
Left and Right posterior spinal arteries
In most people, what is the origin of the Adamkiewicz artery(a major radicular artery)?
Left intercostal artery
What artery supplies 1/3 left and 1/3 right of the posterior SC?
LEFT AND RIGHT POSTERIOR SPINAL ARTERIES
The outer zone of the SC is supplied by?
Outer zone: is supplied mainly by the penetrating pial plexuses
PENETRATING BRANCHES OF PIAL PLEXUS SUPPLY outer part of substance of spinal cord, including:
o Posterior horns (posterior gray matter)
o Anterior horns (anterior gray matter)
The middle zone of the SC is supplied by?
Middle zone: is supplied by both central and penetrating pial plexuses
The inner zone of the SC is supplied by?
Inner zone: is supplied mainly by the central pial plexuses
central canal
So, if I told you that a person has complete occlusion of their LEFT INTERCOSTAL ARTERY what would that mean?
no blood flow through the artery of ADAMKIEWICZ
The artery of Adamkiewicz perfuses SCord segments T9 all the way down through the conus medullaris; Occlusion of the anterior 2/3 of that part of the SCord, what S/S do you expect that person to have?
motor deficits
How many anterior and posterior spinal arteries are there?
1 anterior spinal artery
2 posterior spinal artery
Where do radicular arteries originate?
Radicular arteries have their origin somewhere outside the vertebral column
Pass through intervertebral foramina, along with nerve
roots, the arteries that reach the SC make contributions to the anterior spinal artery
What is the major radicular artery that makes a contribution to the anterior spinal artery?
Artery of Adamkiewicz
What is the origin of the Artery of Adamkiewicz?
Left Intercostal Artery
Is there ever communication in flow between the anterior and posterior spinal arteries?
yup; Anastomotic loop from both the anterior and posterior arteries.
What is the name of the arteries that rise off the anterior and posterior arteries that supply blood flow to the SC?
Arise from anterior and posterior spinal arteries and interconnect on surface of spinal cord to form pial
plexus
Name of the structures of the SC midline posterior to anterior.
- SKIN – POSTERIOR SURFACE OF BODY
- SUBCUTANEOUS TISSUE
- SUPRASPINAL LIGAMENT
- INTERSPINAL LIGAMENT
- GAP BETWEEN LEFT AND RIGHT
LIGAMENTA FLAVA - EPIDURAL SPACE
- DURA MATER
- SUBDURAL SPACE
- ARACHNOID MATER
- SUBARACHNOID SPACE/CEREBROSPINAL
FLUID - POSTERIOR (DORSAL) MEDIAN SULCUS
- PIA MATER
- POSTERIOR (DORSAL) COLUMN WHITE
MATTER - POSTERIOR GRAY COMMISSURE
- CENTRAL CANAL OF SPINAL CORD
- ANTERIOR GRAY COMMISSURE
- ANTERIOR WHITE COMMISSURE
- PIA MATER
- ANTERIOR (VENTRAL) MEDIAN FISSURE
- ANTERIOR SPINAL ARTERY
- SUBARACHNOID SPACE
- ARACHNOID MATER
- SUBDURAL SPACE
- DURA MATER
- EPIDURAL SPACE
- POSTERIOR LONGITUDINAL LIGAMENT
- ANULUS FIBROSUS
- NUCLEUS PULPOSUS
- ANULUS FIBROSUS
- ANTERIOR LONGITUDINAL LIGAMENT
What surrounds the central canal of the SC?
Gray commissure surrounds the central canal
o Located in the gray commissure = axons passing from on side of the SCord to the other side
Anterior White Commissure location and function?
Anterior white commissure: is also where axons pass from on side of the SCord to the other side
o There is no POSTERIOR white commissure; the posterior median sulcus comes all the way in to the
gray matter
Afferent Sensory Pathways?
Afferent sensory pathways
o come from the periphery and pass through the common spinal nerve
o the common spinal nerve divides
o and then travels through the dorsal root ganglia
§ dorsal root ganglion is the location of the nerve cell
bodies of those primary sensory neurons
o then the dorsal root
o then the dorsal rootlets
o into the dorsal horn of the gray matter of the SCord
Somatic Motor and Autonomic Pathways?
Somatic motor and autonomic pathways
o Somatic motor neurons exit from the ventral horn of the gray matter
o into the ventral rootlets
o then the ventral root
o then enters the common spinal nerve
o then terminates in the skeletal muscle fibers to bring about a response
What is the origin of pathways?
Pathways: is from the periphery all the way to the brain
o Starts in the periphery, goes to the SCord, up the SCord and terminates in the brain
What is the origin of tracts?
Tracts: is the part of the pathway that is in the white matter in the SCord
o The part of the pathway that is in the white matter of the SCord is TRACTS
Whats structures make up the Dorsal column of the ascending sensory tracts/pathways(2)?
- Fasciculus gracilis
2. Fasciculus cuneatus
What is the ascending tract or pathway located in the white matter of he anterior/lateral system that we are focusing on?
Spinothalamic-important role in the transmission of pain
How many neuron are in a sequence in Ascending sensory pathways? What are their names?
3; primary, secondary, tertiary
The primary neuron is a part of the _____ nervous system.
peripheral
The sensory receptors of the Spinothalamic tract are classified as?
free nerve endings
What types of sensations excite free nerve endings(6)?
pain, temperature, light touch, pressure, tickle and itch
What is the origin of the Anterolateral system of Ascending sensory pathways?
cutaneous receptors
Where is the termination point of the Anterolateral system of ascending sensory pathways?
Cerebral cortex-post central gyrus
The axon again ascends from the thalamus, to
the primary sensory cortex, the post central gyrus and it terminates according to the layout of the sensory homunculus
What is the primary cell body(primary neuron) of the Anterolateral system of ascending sensory pathways?
Dorsal root ganglion
What is the secondary cell body(secondary neuron) of the Anterolateral system of ascending sensory pathways?
It is located in the POSTERIOR horn of the
SCord
What is the tertiary cell body of the Anterolateral system of ascending sensory pathways?
• The nerve cell body of the TERTIARY neuron
is in the THALAMUS
-Up through the medulla, pons, and midbrain
and terminates in a specific nucleus of the
thalamus
• ALL SENSATIONS USUALLY END UP IN
THE THALAMUS before their transmitted to
other parts of the brain
What is the entrance and crossover points of the Anterolateral system of ascending sensory pathways?
enters at the posterior white commissure(Laminae 1 if fast pain) and crossover at anterior white/anterior gray commissure
If there in an interruption at the primary neuron where would be the affected side?
same side of the body(ipsilateral)
If there in an interruption in the spinothalamic tract after the crossover, where would be the affected side?
contralateral
What is the neuron is the dorsal root ganglion?
unipolar or pseudo-unipolar
What if it was fast pain that was being transmitted? What neurotransmitter is released at that synapse? What type of fiber?
Glutamate; type A delta
What if it was slow-pain; what neurotransmitter is released at that synapse?• If it is slow-pain than it will be?
- Initially glutamate followed by Substance P.A.
- Type C unmyelinated.
What are the characteristics of the secondary neuron as it crossover?
the axon of the secondary neuron immediately crosses over through the anterior white/ anterior gray commissure; opposite side of the SCord.
• The point of crossover is in the same segment of the SCord where the primary neuron entered
• Primary neuron enters in through a certain segment of the SCord
• Terminates/ synapses with the secondary neuron
Immediately the axon of the secondary neuron crosses over, through the anterior white or anterior gray commissure, to the opposite side of the SCord
• And enters into the SPINOTHALAMIC
TRACT
If there was interrupted transmission in the PRIMARY neuron; on which side of the body would there be loss of those sensations?
The same side where the interrupted transmissions is
If there is interrupted transmission in the spinothalamic tract, between a certain segment of the SCord and the thalamus; on which side of the body would there be loss of those sensations?
Contralateral or the opposite side
If there is interrupted transmission in the spinothalamic tract between the thalamus and the sensory cortex???
Contralateral
If there was interrupted transmission in the PRIMARY neuron; How much of the same side of the body would there be loss of those sensations?
Just the dermatomes that are innervated for that peripheral nerve
If there is interrupted transmission of the spinothalamic tract in the SCord up to the thalamus, how much of
the opposite side of the body would be affected?
Below the level where the interrupted transmission has occurred
o So if interrupted transmission is in the lumbar segment of the SCord, it would involve the hips, legs and feet of the opposite side.
o If interrupted transmission is in the thoracic segment of the SCord, then all the body below where the interrupted transmission will experience a loss of those sensations
What are the two tracts/pathways of the Dorsal column/medial Lemniscal system?
- Fasiciculus cuneatus
2. Fasciculus gracilis
What sensations is the Fasiciculus cuneatus transmitting?
From the neck, thorax, nipple line, arms, hands and fingers
What sensations is the Fasiciculus gracilis transmitting?
From the nipple line to lower part of the body
What types of sensations are transmitted by the Dorsal column/medial Lemniscal system(4)?
- Proprioception, PRIMARILY CONSCIOUS PROPRIOCEPTION
- Two point discrimination (fewer receptors on back as opposed to arms/ hands)
- Pressure (deep)
- Vibratory sensations
If you are looking at a cross section of the SC in the lumbar region which of the fasiciculus would be represented?
Fasiciculus gracilis
If you are looking at a cross section of the SC in the thoracic/cervical region which of the fasiciculus would be represented?
Both because the gracilis still has to travel up the SC to brain
What is the sensory neuron of the Dorsal column/medial lemniscal system?
PACINIAN CORPUSCLE
§ those are sensory receptors that are modified nerve endings to respond to the types of sensations are listed ABOVE
What is the primary neuron of the Dorsal column/medial lemniscal system?
Dorsal root ganglion
In the Dorsal column/medial lemniscal system what forms the ascending tract?
the primary neuron
In the Dorsal column/medial lemniscal system where does the impulse crossover in the SC?
A. IN THE MEDULLA
o Ascends on the same side of the SCord and terminates in either the nucleus cuneatas/ gracilis
o Synapses with the nerve cell body of the secondary neuron
o Now the axons crossover to the opposite side of the medulla
o Ascend in what is called the medial lemniscus, up to the thalamus
o Then tertiary neuron, then primary sensory cortex
Trace the pathway of the Dorsal column/medial lemniscal system.
Beginning of the primary neuron; notice that the sensory receptor is the PACINIAN CORPUSCLE
• Nerve cell body there in the dorsal root
ganglion
• The axon enters into the dorsal horn of the
gray matter of the SCord
• NOW watch carefully; as soon as the axon of
the primary neuron, enters into the dorsal horn
of the gray matter of the SCord
• It continues from the gray matter into the
dorsal column white matter
• Enters into the fasiciculus cuneatas (or
gracilis) [picture shows gracilis]
• Ascends up the SCord to the medulla where it
terminates to the NUCLEUS cuneatas or
gracilis
• Axons from the primary neuron, enter into the fasiciculus cuneatas or gracilis
• Axons of the primary neuron form the
ascending tract and IT HAS NOT YET CROSSED OVER
• Continues up the SCord on the same side it entered up to the medulla
• Once we get to the medulla, were the primary neuron terminates; the nucleus cuneatas/ gracilis synapses
with the nerve cell body of the secondary neuron
• The axon of the secondary neuron crosses over to the opposite side of the medulla
• Enters into the MEDIAL LEMNISCUS
• Ascends up through the pons, midbrain and terminates in a specific nucleus of the thalamus Synapses with the nerve cell body of the tertiary neuron and that axons continues from the thalamus to the
primary sensory cortex according to the layout of the sensory homunculus
In the Dorsal column/medial Lemniscal system, if there was interrupted transmission in the peripheral portion of the pathway (between the periphery and the
SCord); which side of the body will there be loss of those sensations? Ipsilateral or contralateral?
• How much of the same side would be involved?
- Ipsilateral
- The dermatomes that are innervated by that peripheral nerve
In the Dorsal column/medial Lemniscal system, If there’s interrupted transmission in either FC or FG in the SCord; which side of the body will there be loss of those sensations? And how much of the same side of the body
- Ipsilateral. The pathway has not yet crossed over.
- Below the SCord segment where the transmission is interrupted
If there is interrupted transmission in the medial lemniscus between the medulla and the thalamus; which side of the body is going to be involved? And how much of the opposite side of the body would be involved?
- contralateral
- All of it because it has input from FC and FG.
And IF given the opportunities, this is one thing that students OFTEN SCREW UP
I want to impress upon you, the importance of:
o what forms the ascending tract?
o which side of the SCord does the tract ascend on?
o and where is the point of crossover?
§ if interrupted transmission is BEFORE the crossover, the loss is on the SAME side of the body as interrupted transmission
§ if interrupted transmission is AFTER the crossover, the loss is on the OPPOSITE side of the body
What information is transmitted by the Spinocerebellar Posterior and Anterior system?
These are going to transmit primary proprioceptive information to the cerebellar hemispheres
o And this is for the most part UNconscious
proprioception (almost all)
What is the origin of the sensations of the posterior Spinocerebellar system?
joints, tendons
The beginning point of the primary neuron is
the GOLGI TENDON ORGANS
o Golgi tendon organs are part of the
skeletal muscles system
o Actually outside of the skeletal muscle
fiber
o As the tension on the skeletal muscle
changes, the tension on the golgi tendon
organ changes also
o This is detecting changes in muscle
tension; allowing it to transmit proprioceptive information
What is the primary neuron of the Spinocerebellar system?
The primary neuron, the nerve cell body is
located in the dorsal root ganglion
Trace the pathway of the posterior Spinocerebellar system after if enters the SC from the dorsal root ganglion
Enters into the dorsal horn of the gray matter
of the SCord where it terminates
• Synapses with the nerve cell body of the
SECONDARY neuron
• The axon of the secondary neuron immediately continues out into the posterior column white matter, on the same side
• Ascends in the posterior spinocerebellar tract
• Then terminates in the cerebellar hemisphere
• ALL OF THAT IS ON THE SAME SIDE
• NO CROSSOVER IN POSTERIOR
SPINOCEREBELLAR
Of the anterior/posterior Spinocerebellar system, which is most important?
So through posterior spinocerebellar,
proprioceptive information from the RIGHT
side of the body ends up in the RIGHT
cerebellar hemisphere and the LEFT to LEFT
• POSTERIOR SPINOCEREBELLAR IS GENERALLY
BELIEVED TO BE THE MORE IMPORTANT OF THE TWO
IN HUMANS
Trace the pathway of the anterior Spinocerebellar system.
• Little different than POSTERIOR
• It does transmit proprioceptive information
• Primary neurons begin with golgi tendon organs
• Enters into the dorsal horn of the gray matter of the SCord where it terminates
• Synapses with the nerve cell body of the secondary neuron
• THE AXON OF THE SECONDARY NEURON CROSSES OVER, ANTERIOR WHITE/ ANTERIOR GRAY COMMISSURE TO THE OPPOSITE
SIDE OF THE SCORD
• Enters into the ANTERIOR spinocerebellar tract where ascends to the medulla
• AND CROSSES OVER AGAIN AND ENDS UP IN THE CEREBELLAR HEMISPHERE OF THE SAME SIDE WHERE IT STARTED
So what is the major difference between the anterior and the posterior Spinocerebellar tracts?
- Posterior never crosses over
- Anterior crosses over and then crosses back over again ending up back on the same side where it started
The Corticospinal pathway is a part of what larger pathway?
Descending Somatic Motor also the Pyramidal Pathway
What makes it a part of the Pyramidal pathway?
The Corticospinal enter into the pyramids of the anterior/
inferior medulla
What is the Corticospinal pathway responsible for?
Responsible for MOST muscle movements
• Particularly muscle movement of our hands and fingers
• In the descending somatic motor pathways there are TWO neurons in sequence
• Designated an upper motor neuron and lower motor neuron
• Since they are descending somatic motor pathways, the point of origin will be in the primary motor cortex
• Descend downward and outward out of the SCord to skeletal muscle fibers
The Corticospinal Pathway:
• Start from the primary motor cortex
• Descend down to the cerebral hemisphere or internal capsule
• Down through the midbrain, pons, and medulla
• Enter into pyramids on the anterior/ inferior medulla
• Here on the most inferior part of the pyramids (referred to as the decussation of the pyramids); What happens?
about 75-80% of those axons DECUSSATE
• They cross over to the OPPOSITE SIDE of the SCord and
descend in the LATERAL corticospinal tract
What happens to the remaining 20-25% of the impulses that do not cross over at the decussation of the pyramids?
The other 20-25% that do not crossover at that point, remain on the SAME SIDE of the SCord and descend in the ANTERIOR corticospinal tract
So what’s the difference between the lateral and anterior Corticospinal Pathway ?
-The axon that are going to form the lateral corticospinal
tract and the decussation of the pyramids; the axons
crossover to the opposite side; enter into and descend in
the lateral corticospinal tract
-The 20-25% that do not decussate at that point continue descending on the same side of the spinal cord in the anterior corticospinal tract
In the Corticospinal Pathway, at some segment of the SCord, those upper motor neurons will _____ and _____ with nerve cell bodies of lower motor neurons
terminate, synapse
Where are the nerve cell bodies of the LOWER motor neurons located?
in the anterior (ventral) horns of the gray matter of the SCord
Those axon exits through ventral rootlets, then ventral roots
• Enter into a common spinal nerve
• Terminate at the neuromuscular junction; to bring about a response in a skeletal muscle fiber
For the anterior corticospinal tract:
For the ANTERIOR corticospinal tract; the upper motor neurons terminate and synapse with lower motor
neurons, then crossover in the SCord segment where they synapse with the lower motor neurons.
Of the anterior and the lateral corticospinal tract, which is most important in humans and why?
- In humans, the far more important is the lateral corticospinal tract
- Particularly the skeletal muscle movement of the arms, hand and fingers
If there is interrupted transmission between the primary motor cortex and the medulla;
Which side of the body is going to be affected?
• How much of the contralateral side of the body?
- Contralateral; The pathway has not yet crossed over
- Basically all of it
If there is interrupted transmission in the lateral corticospinal tract;
Which side of the body is going to be affected?
• And how much of the same side?
- Ipsilateral
- Below the level where the interrupted transmission occurs
If there is interrupted transmission in the lower motor neuron; which side of the body will be affected?
• How much will be affected?
- Ipsilateral
- Just the muscles innervated by that lower motor neuron.
If there was interrupted transmission in the anterior corticospinal tract; which side…?
• How much…?
- Contralateral: has not yet crossed over
- Below the level where the interrupted transmission occurs
Suppose there was interrupted transmission from where it starts to crossover and the lower motor neuron; which side…?
Ipsilateral; And just the muscles that are innervated by that lower motor neuron
What is the function of the Extrapyramidal pathways of the descending somatic motor tract?
Responsible for UNconscious coordination of skeletal muscle movement and maintaining posture and balance
Signs and symptoms of the people with alterations in the extrapyramidal pathways?
People who have extrapyramidal alterations in one or more pathways, usually have very poor posture; can’t stand up straight, tend to sway (because they do not know where their body parts are in time or space)
• They have unsteady and awkward gait
• Likely to fall on face if Romberg test is performed
• Uncontrollable muscle movements, such as: ticks of their face, head and other parts
• Lip smacking is very common with people who have
advanced extrapyramidal pathway alterations • Tongue rollin
What types of people historically had major alterations in
their extrapyramidal pathways?
People who had advanced mental disorders like
schizophrenia who were on high-dose antipsychotics
like Compazine, Thorazine, Phenergan, and others
like that.
o They were the first group of antipsychotics that were
available to pharmalogically control those severe
mental illnesses.
o And with very high doses, they had very severe
extrapyramidal side effects.
What somatic motor pathway is responsible for innervation of the skeletal muscles to control movements of face and head?
CORTICOBULBAR PATHWAYS
Of the Corticobulbar pathway, where do the upper motor neurons originate?
Upper motor neurons originate in cerebral motor cortex according to layout of motor homunculus
• The upper motor neurons of most, but not all, motor pathways originate in both left and right primary motor
cortices of the cerebral hemispheres. Thus these pathways contain crossed and uncrossed fibers.
o So, the motor pathways to the right side of the face and head originate in both the right and left cerebral
cortices and the motor pathways to the left side of the face and head originate in both the right and left
cerebral cortices.
Of the Corticobulbar pathway, where do the lower motor neurons originate?
Lower motor neurons are cranial nerves with a motor component
o CN: III, IV, V, VI, VII, IX, X, XI, XII
What is the pneumonic for the 12 cranial nerves?
On(Olfactory) Old(Optic) Olympus(Oculomotor) Tower(Trochlear) Tops(Trigeminal) A(Abducens) Fin(Facial) And(Auditory/Acoustic/Vestibulocochlear) German(Glossopharyngeal) Viewed(Vagus) Some(Spinal Accessory) Hops(Hypoglossal)
What is the pneumonic for the function of the 12 cranial nerves?
CN#1-Some(sensory) CN#2-Say(sensory) CN#3-Marry(motor) CN#4-Money(motor) CN#5-But(both) CN#6-My(motor) CN#7-Brother(both) CN#8-Says(sensory) CN#9-Big(both) CN#10-Brains(both) CN#11-Matter(motor) CN#12-Most(motor)
Which of the cranial nerves have proprioceptive sensory fibers?
Any CN that has motor fibers will also have proprioceptive sensory fibers
o So if there is motor innervation of the muscle, there has to be proprioceptive sensory feedback from the muscle group
o III, IV, V, VI, VII, IX, X, XI, XII
Which of the cranial nerves have parasympathetic fibers?
Some also have parasympathetic fibers
-III, XII, IX, X … 3,7,9,10 … 3,7,9,10 … 3,7,9,10 …
What is the primary parasympathetic nerve for the entire body?
CN X: IS THE PRIMARY PARASYMPATHETIC NERVE FOR THE ENTIRE BODY
o Descends down through the side of the neck
o down through the thorax
o pierces the diaphragm
o continues on down through the abdominal cavity and gives off collaterals to every major organ and
tissue all the way down
o DOES NOT innervate:
§ sigmoid colon
§ descending colon
§ anus
§ genitals
Where is the location of the nucleus for the cranial nerves?
• MEDULLA: CN IX, X, XI, XII
o CN IX, X:
§ sensory nucleus: nucleus solitarius (those who are too SENSitive may find themselves living in SOLITude)
§ motor nucleus: nucleus ambiguus (on SNL, the AMBIGUously gay duo were always riding around in an “oddly” shaped MOTOR vehicle)
• PONS: CN V, VI, VII, VIII
• MIDBRAIN: CN III, IV
• I cannot tell you where nerve cell bodies for CN I
& II are; they form very different pathways then
CN III – XII
CN PATHWAYS – GENERAL CONCEPTS?
Sensory pathways have 3 neurons in sequence similar to spinal sensory pathways:
o PRIMARY neuron with sensory receptors
§ The primary neuron is usually, but not always, the peripheral nerve (has not yet entered the brain)
component of the pathway
o SEONDARY neuron that usually, but not always, crosses (decussates) to opposite side of brain and
terminates in a thalamic nucleus
o TERTIARY neuron that terminates in sensory areas of the cerebral cortex for sensory perception/
interpretation and isolation to dermatomes
o CN I and II deviate from the general pattern of CN sensory pathways
Cranial nerve I-Olfactory:
• Sensory fibers only • function to smell • transmit olfactory sensations to many parts of the brain • that’s all I am going to say about that
Cranial nerves 3,4,6-Oculomotor, Trochlear, Abducens:
-You do need to remember that CN III is responsible
for MOST extra ocular movements (EOM)
-Most of the muscles that causes those movements are innervated by the CN III (oculomotor); however there are 2 other cranial nerves:
* CN IV – innervates one of those muscles
* CN VI – innervates one of those muscles
-Not only do those nerve pathways have to be intact
• the neuromuscular synapse has to be intact
• the muscles themselves have to be able to contract
CN #3 is primarily responsible in moving the eye which direction(3)?
- up and out
- up and in
- down and out
CN #4 is primarily responsible in moving the eye which direction(1)?
-down and in
CN #5 is primarily responsible in moving the eye which direction(1)?
-laterally
Cranial nerve 5-Trigeminal:
• I want you to primarily associate trigeminal with:
MOST of the sensations from the face and head
are transmitted through the trigeminal n.
• One branch of the trigeminal has SOME
motor function; primarily those muscles involved
with chewing
What are the 3 branches of the trigeminal nerve?
o V1: Ophthalamic: transmits sensations from the upper eyelid, most anterior part of the nose, and from the
cornea (reflex)
o V2: Maxillary: transmits sensations from the lateral side
of the head, lower eyelids, lateral side of the nose (not the sense of smell), and upper lip
o V3: Mandibular: transmits sensations from the lower lip, chin, and the mandibular branch has some motor fibers that innervate the muscles for chewing (mastication).
Cranial nerve #7-Facial:
• I want you to associate FACIAL: most facial
expressions, are caused my muscles innervated by the
facial CN
• It also has some sensory fibers
o for the most part taste
• And has some
parasympathetic function
• If both of the CNs are functioning; raise your
eyebrows, both should be raised at the same height
• If you were to frown or puff out your cheeks, it
should both be symmetrical.
o If there is asymmetry, there is weakness on the
affected side.
Cranial nerve #8-Acoustic/Auditory/Vestibulocochlear:
• Transmits hearing from the inner ear to the primary
auditory center located in the temporal lobe.
Cranial nerve #9-Glossopharyngeal:
• It has all 4 types of fibers
• The motor is primarily to some of the muscles of the
PHARYNX
• Proprioception sensation from those muscles
• Motor also has to do with; when you phonate
“ummm”, your uvula should rise in the midline
o If there is an abnormality to one side
or the other of the nerve, then the uvula will deviate from the midline; to the L or R
o Another test is the gag reflex (you have to actually touch the back of the throat)
• Sensory primarily has to do with taste
• Associated with the nucleus solitarius and ambiguus
Cranial nerve #10-Vagus:
• Has all 4 types of fibers
• It also associated with nucleus solitarius and
ambiguus
• Most of the motor is to pharynx (the muscles of
phonation)
• And of course proprioception
• Sensation: the pharynx and larynx
• Sensations for most abdominal organs are
transmitted through sensory fibers through the
vagus
o There is no area on the sensory homunculus for the internal organs
o So when sensations are transmitted to the vagus from those organs, when it gets to the SCord and then the brain; it perceives those sensations as if they originated from the surface of the body; this is called REFERRED PAIN
Cranial nerve #11-Spinal Accessory:
• Probably is not a CN at
all
• For many people the origin is in the upper part
of the SCord, not in the lower part of the medulla
• So if its origin is really part of the SCord, it
should be a spinal nerve, not a CN
• Motor and proprioception for the muscles of the shoulder; primarily the muscles for turning the head or shrugging the shoulders
Cranial nerve #12-Hypoglossal:
• Most of the muscle involved in the movement
of the tongue and some of the muscles in the throat
• Tongue should protrude in the midline
• If it deviates to one side or the other, that may
suggest an abnormality of CN XII; it points to the
side where the altered transmission is at
Now what are the optic radiations that I referred to? What are those axons radiating around?
A. The lateral ventricle of the brain
Notice the collaterals to the superior colliculi § Where are the superior colliculi?
corpora quadrigemina (located in the midbrain) v Associated with visual reflexes.
Do lateral or medial visual pathways cross and if so at what point?
Lateral don’t cross; medial cross in the optic chasm
