1) Superior Rectus: moves eyeball up

2) Inferior Rectus: moves eyeball down

3) Lateral Rectus: moves eyeball lateral

4) Medial Rectus: moves eyeball medial

5) Superior oblique: Body of the muscle is located on the medial wall; attachment is through a "U" shaped fibrous connective tissue and loops around to fasten behind the superior rectus

6)Inferior Oblique: attachment point with the eye is on the lateral portion, inferiorly

7) Levator Palpabrae Superioris: sits on top of the superior rectus; moves eye up

Refers to skeletal muscle

3 Cranial Nerves

1)CN III: Oculomotor: provides innervation to almost all eye muscles (all but the lateral rectus); largest of the three that exit the orbital fissure

2) CN IV: Trochlear: exits fissure @ back; winds around to provide innervation to the superior oblique

3) CN VI: Abducens: innervates the lateral rectus. "abduction"

CN V (5)

V-1

Opthalmic Nerve of the Trigeminal Nerve

-has a number of branches

1st large nerve/branch: Frontal Nerve: has 3 divisions:

1) Lacrimal Nerve: control secretion from lacrimal gland

2) Supraorbital Nerve: sensory from the forehead to the coronal suture

3) Supratrochlear Nerve: provides sensory innervation to bridge of the nose and middle of forehead

2nd branch: Infratrochlear nerve (more inferior than #2 above)

provides sensory info to areas of skull a little inferior to where supratrochlear nerve innervates (to the middle of the nose, just under the bridge)

Trigeminal Nerve

Very large; has 3 divisions

V-1: Opthalmic; provides sensory to top of head

V-2: Maxillary; provides sensory to majority of face

V-3 Mandibular; provides sensory to the mandible

Controls 2 muscles of mastication: temporalis and both parts of Masseter (deep and superficial)

one of the muscles of mastication

fastened to sygomatic bone (superficial part of muscle) and temporal bone (deep part of muscle)

-fastened to the parts of these bones that make up the zygomatic arch!

CN V  (5)

V-2

Maxillary: goes through the Rotundum Foramen in sphenoid bone (internally)

-Exits the skull @ infraorbital foramen

Infraorbital branch/nerve: provides sensory for deeper parts of the nasal cavity & mouth

CN V  (5)

V-3

Mandibular

Inferior alveolar nerve: 2 branches

-Lingual nerve: smaller of branches; provides innervation to inside of the mouth

-Mental nerve: more inferior of branches; exits through the mental foramen; provides innervation to mandable (superficial structures) such as skin and sensory for lower teeth.

*lingual nerve provides sensation to anterior 2/3 of the tongue. *Not taste, but somatosensory (pain, pressure)

(CN VII: Facial Nerve)

Superior salivatory nucleus and facial nucleus

-cell bodies within the pons, where CN originates

Facial Nerve: plays a role in glandular secretion, mostly with submandibular & sublingual gland

-both mucus secreting glands

-submandibular ganglion: where glandular nerves split off (cell bodies that is important point of conrtol for secretion from these 2 nerves)

-Responsible for taste in anterior 2/3 of tongue

-connection with glands on inside of nose*

-Plays supportive role of lacrimal gland (secondary innervation)*

*via sympathetic fibers*

-Originate on inferior end of Pons

Vestibulocochlear Nerve

2 Branches

1) Vestibular root/nerve: balance, body orientation

2) Cochlear root/nerve: hearing, sense vibration of eardrum (tympanic membrane)- attached to smallest bones i the body: incus, stapes, and malleus

Sagittal plane: detect rotation if doing a somersault

Coronoal: detect rotation if doing cartwheels

aka eardrum

-Tensor tympani muscle: inside the eardrum, puts tension on the tympanic membrane and reinforces the eardrum in anticipation of hearing a loud sound. This decreases the likelihood of the tympanic membrane breaking.

-Pharyngo-tympanic tube: connects ear to the back/superior portion of the throat

Pharyngo-tympanic tube/ auditory tube/ Eustachian tube

-people who have narros tubes can have frequent ear infections d/t problems with drainage from the ear. Swelling from this canal is one of the things that cause ear infections. If you have a sinus infection, swelling from this can cause the Eustachian canal to close off, causing pressure and pain, as well as distort structures within the inner ear (leads to balance disturbances)

-can put in tubes for chronic problems

-when you "pop" your ears, you're equalizing pressure between the ear and the back of the throat

2 fluid filled compartments in the cochlea that sense vibrations and transmit these through fluid that is carried in different directions via tiny hairs. These hairs are mechanoreceptors that change their activity depending on how much/which direction they are bending.

-The loss of little hairs is what causes a loss of hearing as one ages.

Glossopharyngeal Nerve: (Fairily large)

~has secretory innervation of the parotid glands (on the outside of your cheek bone and runs down the side of our face; very large and very vascular).

~innervates important ANS sensors that are connected to the Carotid bifurcation (Carotid Body Chemoreceptors) as well as Baroreceptors

~Responsible for taste and sensory for the posterior 1/3 of the tongue (provides sensory for back of the throat up to the top of the epiglottis

Carotid Body Chemoreceptors

and

Baroreceptor actions

Carotid Body Chemoreceptors:

sensors that detect changes in O₂ and CO₂ at the carotid body

Baroreceptos: two crucual sensors (each branch of carotid) of the CP system that get feedback about what peripheral blood gases and peripheral BPs are

Internal Carotid: supplies blood to the brain

External Carotid: provides blood to the other, more superficial places in the head (side of the face, nose, etc.)

CN X 

(10)

Vagus Nerve: innervates the vast majority of the epiglottis and some of pharynx (which is more heavily innervated by CN IX)

-primary output for the PSNS; does a number of important things like ↓HR, bronchoconstriction (when we are at rest, our airways are slightly constricted to protect us from germs floating in the air)

*in the 50's, a radical treatment for asthma was to cut/resect the vagus nerve*

In your femoral triangle, you have a fibrous sheath that encases/protects your femoral arter and nerve.

In the upper body, the Vagus nerve, Carotid arteries, and jugular veins tend to run together

CN XI

(11)

Accessory Nerve:

Innervates and provides motor function for the trapezius muscle and the sternocleidomastoid to help you hold your head up.

CN  XII

(12)

(there was once thought to be only 11 CNs)

Hypoglossal Nerve:

(has limited function)

Innervates the styloglossus, geniolossus, and hyoglossus

-3 muscles located on the floor of the mouth under the tongue; used during speech and chewing

Difference between blood vessel locations in the spinal cord vs. the brain

In the spinal cord, almost all the blood vessels are sandwiched in between the pia and the arachnoid mater.

In the brain, a significantly higher proportion of blood vessels sit in between the dura and arachnoid mater as well as on top of the dura mater, just under the skull

Arachnoid Trabeculae:

act as reinforcement between the Pia and Arachnoid maters

underneath the Arachnoid layer; Arachnoid Granulations are points at which CSF can be absorbed into the sinuses to exit the circulatory center.

-Eventually all CSF has to go through these to get into the sinuses of the cranium

CSF has:

~less glucose and amino acids (both of these travel accross the BBB via facilitated diffusion, so this is how they get into the brain, because it's concentration gradient is less
~lower K+ level (not abnormal to see a K+ of 2.9-3; plasma 4-4.4) *most noticible difference
~higher Mg++ level
~lower pH than that of blood (approx. 7.31)

*not usually a difference in Na+ levels, but if there is, then CSF has a slightly lower concentration of Na+*

 Mg⁺⁺ is very similar to Ca⁺⁺ (both large divalent ions) but Mg⁺⁺ is smaller. This allows Mg⁺⁺ to occupy places that Ca⁺⁺ would normally bind to (causing an excitatory effect)

~So because Mg⁺⁺ blocks the excitatory effects of Ca⁺⁺, it is said to be inhibitory

~throughout the body, there is about 3x more Mg⁺⁺ intracellularly than extracellularly

150 cc in an adult

30 cc is in the ventricles

120 cc is outside the ventricles (to bathe the brain and spinal cord)

In a healthy adult, 500 cc/day of new CSF is replaced daily

*if you could "flush" the system, getting rid of old CSF and replace it will all new CSF, this flush would happen 3 times a day*

Epithelial cells (Ependymal cells) in the ventricles produce CSF--> Choroid Plexus is the specific tissue

Lateral ventricles (next to Corpus Colosum) produce the vast majority

3rd and 4th ventricles produce a small amount

~Lateral ventricles drain into the 3rd ventricle via the Intraventricular foramen of Monroe/Intraventricular foramen (each lateral ventricle has a foramen)

~the 3rd ventricle drains into the 4th via the Cerebral Aquaduct/Aquaduct of Slyvios

~and then CSF exits the circulatory via 4 routes/points into the sinuses

•  Median Apperature (Apperature/Forament of Magendi): opening that is midline, inferior, and posterior, that empties CSF into just underneath the cerebellum, into the Cisterna Magna/Cerebromedullary Cistern
• The Lateral Apperature/Foramen of Lusca (you have two of these): project laterally from the 4th ventricle
• The Central Canal: smack dab in the middle of the anterior medial fissure (in a cross section of the spinal cord), inferiorly, that allows for CSF to flow in all directions in the spinal cord. *The superior portions of the spinal canal will get the freshest CSF while inferior parts will get more stagnant CSF supply

pass out

vomiting

panic attack

palpitations

ETOH

Anesthetic agents

Both of these cause nausea d/t changes in the canals (tells the brain you're moving, eyes tell the brain the opposite, body acts in response ("melt down"))

In an adult with 5-6L of blood,

15% of that goes to the brain

for every 100gms of brain = 50cc/min of blood flow;

average brain weighs approx. 1300 gms

Of cerebral blood flow,

80% goes to Gray matter (where all the thinking action is

20% goes to White matter

Energy consumption in brain r/t ion transport

About 60% of all energy in brain is used for transporting ions.

This % is proportionate to metabolic demands:

Increased demand = increased flow

Controllers of blood flow in the brain

(locally, you have Histamine and ACh)

Locally or globally, and more important, you have

↑ CO₂/↑ H+ (most important):

Causes increase in cerebral blood flow

↓ PO_{2 (hypoxia):}

Causes increase in cerebral blood flow

Pentobarb coma (decrease metabolic demand/metabolic rates)

Hyperventilate (blow off CO2 in the brain, decrease blood flow)

Lower Limit of Autoregulation;

Body is able to maintain a cerebral blood flow at a fairly constant level until this point (limit).

In a normal patient (with no pharmacological intervention), this LLA is around 50-70mmHg.

If BP continues to drop after this, cerebral blood flow will also decrease.

Upper Limit of Autoregulation;

Highest point at which cerebral blood flow will remain unchanged. Anything above this point will result in an increase in cerebral blood flow

ULA in adult (with no pharmacological intervention) is 150mmHg

Blood pressure in the carotid and vertebral arteries.

This pressure/force to push blood into the closed system is dependent on many things.

Primarily, the squeeze of the vessels. the MAP is referring the the pressure that is the driving force for blod flow into the brain.

Dilation vs. Constriction of blood vessels:

What happens to blood flow?

Dilation: blood flow increases to the area

Constriction: blood flow decreases to the area

(*5-HT is the only endogenous NT that will cause cerebral vasoconstriction)

This happens because resistance in the vessel has increased;the pressure is essentially being used up.

Since it's harder to get through the vessel, energy is being lost throughout the travel

Myogenic constriction

This is a reglex constriction to an increase in BP as to blunt the increase in flow that would otherwise occur (and could be dangerous the brain/tissues). This happens so that pressure will be decreased, preventing any possible damage.

Blood vessels in the brain dilate, increasing flow to the cerebral vessel.

(This happens independently of a NT)

Because the brian does not store energy very well (needs a constant supply of Oxygen and glucose), you have about 8 seconds worth of energy before the brain is affected (passing out, LOC).

 Cerebral vessel response to giving vasopressors or vasodilators

Cerebral vessels do not response to vasopressors directly. When BP and MAP increase, the brain reacts with myogenic constriction in response to increasing MAP.

*the ONLY NT that will directly vasoconstrict cerebral vessels...?*

However, vasodilators will directly cause vasodilation not only in systemic vessels but cerebral vessels (also causing indirect dilation in response to decreased MAP) as well.

hemorrhagic stroke

rupture of aneurysms

elevated ICP

rupture trauma

These two values shift up in a person who is hypertensive. If they're set-point is usually around a MAP of 150,

the ULA will be approx. 50mmHg higher,

the LLA will be approx. 50mmHg lower.

*this patient will not tolerate MAP of 55 for a long period of time like a normotensive person would without suffering injury (ischemia)*

This flow is driven by BP in the glomelular capillary. This pressure pushes blood into the primary tubule;

60mmHg (highest BP in any capillary). This is so high because there isn't a lot of resistance between this and the large renal arteries

Normal systemic capillaries have a BP of 17mmHg

Two capillaries in kidneys (discussed in class initially)

Pressure will drop distal to the constriction. If you constrict blood flow to the glomerular capsule (which normally has a GFR of 120mL/min), you will decrease flow, therefore decreasing GFR→less force driving fluid to the tubule from the capillaries.

Because you are filtering less fluid, you are going to excrete less fluid→fluid retention!→increased BP

Reabsorption in the peritubular capillaries is driven by low pressure. If you constrict the efferent arterioles, you will lower pressure more than it already is (because the peritubular capillaries are distal to the efferent arteriole), reabsorption will be increased

*High pressure drives filtration, low pressure facilitates reabsorption*

Cerebral Perfusion Pressure

8-12mmHg in a normal, healthy person.

MAP-ICP = CPP

This is the additional "squeeze" left over to drive blood flow to the brain after you take into account the outside squeeze that the CV system has to overcome to get blood to the system.

Carotid arteries.

They start off as one on each side, called the Common Carotid Arteries, then they birfurcate into two section on each side:

Internal: goes through the carotid foramen and supplies the vast majority of the brain with oxygenated blood

External: provide blood to the more superficial portions of the head/skull

Vertebral arteries.

Go through the vertebral foramen of C1-C6 and up through the Foramen Magnun

2 carotid arteries and

2 vertebral arteries are the source of blood to the upper portion of hte head and neck!

Move superior and anterior to a point where they come together and form a singular Basilar Artery (sits underneath the Pons)

The three feed vessels for the Basilar artery are the 2 vertebral arteries (main suppliers) and the Anterior Spinal artery

Carries blood superior and anterior until it bifurcates into the Posterior Cerebral Arteries. These supply a decent amount of blood to the posterior portions of the cerebral cortex.

Posterior Cerebral Arteries have 2 branches:

Precommunicating portion

Postcommunicating portion

Precommunicating part: proximal to bifurcation of the Basilar Artery

Postcommunicating part: distal to the birfurcation

 The Posterior Communicating Artery is what differenciates pre- from postcommunicating parts of the PCA;

separates the Posterior Cerebral Artery from the Internal carotid

Connection of arteries in center of brain

(just anterior to Midbrain)

Circle of Willis:

combination of the blood vessels that connect with each other to provide limited anastomosis to supply the entire cerebral cortex with blood. Basically one continuous structre that is interconnected by a number of large and small arteries.

this portion of the blood vessel is called the Middle Cerebral Artery; continues out laterally and supplies the vast majority of the blood to the cerebral cortex

*If you have an occlusion of the MCA, the brain damage is catastrophic*

**Largest of the three arteries that supply the cerebrum (Anterior, Middle, and Posterior)**

Anterior Cerebral Artery

Moves anteriorly to feed the anterior/medial portions of the cortex with oxygenated blood.

Tends to branch superiorly, right along the Longitudinal Fissure

These arteries have 2 branches:

Precommunicating part

Postcommunicating part

Precommunicating part: more proximal to MCA

Postcommunicating part: more distal to MCA

These two are separated by the Anterior Communicating Artery

Carry oxygenated blood to cerebellum:

1. Superior Cerebellar Artery: most superior of the 3 branches; will provide blood to the more superior portion of the Cerebellar corticies
2. Anteroinferior Cerebellar Artery: inferior to Superior CA, but anterior to the 3rd branch (which is how it gets its name)
3. Posteriorinferior Cerebellar Artery: most posterior and inferior of the 3

Branches of the MCA

(from a lateral view)

1. Artery of the Central Sulcus: sits in the Central Sulcus
2. Artery of the Precentral Sulcus: sits in the sulcus just anterior to the Precentral Gyrus
3. Artery of the Postcentral Sulcus: sits in the sulcus just posterior to the Postcentral Gyrus
4. Temporal branches: Anterior, middle, and posterior arteries in temporal lobe

Jugular vein, which has 2 divisions (like the Carotid)

Internal branch will pass through the Jugular Foramen into the cranium to provide drainage middle and front parts of brain

-IJ has a branch off it: Anterior jugular vein provides drainage to the superficial areas of the anterior of the head and face

External branch will branch towards the posterior portion of the skull to provide venous drainage for the posterior portions of the head

Superior Sagittal Sinus; sits along the Longitudinal Fissure.

this is where you will find the vast majority of the Arachnoid Villi/Arachnoid Granulations-> allows CSF to pass into the venous drainage system coming from the cranium (these granulations act as one-way pressure activated valves that aloow the CSF to leave the CSF system into the Sagittal Sinus, once enough pressure has built up within the CSF system.

Cingulate/Cingular Gyrus

(sits on top of the Corpus Colosum and just inferior to the Inferior Sagittal Sinus (which turns into the Straight SInus before it drains into the Confluence of the Sinuses))

thought to be part of the Limbic System

Two important sinuses that align the lesser wing of the Sphenoid bone and the other that is on the body of the Sphenoid bone

(from a superior view)

Cavernous sinus sits on the body of the Sphenoid bone; fairly large, has a lot of sinuses draining into it

Sphenoparietal Sinus runs parallel to the Sphenoid bone, just along the posterior part of the lesser wing-> drains into the Cavernous Sinus. Will provide drainage from regions of the brain around the Parietal Cortex

Falx Cerebri: runs in between the left and right cerebral hemispheres

Tentorium Cerebelli: a fairly rigid piece of fibrous tissue that sits in between the cerebral cortex and the cerebellar cortexes. It separates the lower portion of the cerebral cortex from the cerebellar corticies

Basilar vein goes around the upper portion of the brain stem (the midbrain) instead of starting more inferiorly.

Basilar vein is circular in nature, and is the venous version of the Circle of Willis. This is one of the most anterior large veins that we need to be aware of.

Any "problem" in this area (of Circle of Willis), whether it be arterial or venous, is extremely difficult to fix d/t its location. It is close to many important structures, ie. brain stem, hypothalamus, pituitary gland.

Epidural: above the dural layer, normally arterial bleeds, associated mostly with trauma (skull fractures)

Subdural: below the dural layer, above the arachnoid, normally venous bleeds, associated with rupture in the Superior Sagittal Sinus

There is a greater likelihood that blood can penetrate the Pia matter with a subarachnoid bleed-> it is almost impossble to separate the blood from the underlying neurons

Also, at the very top of the brain, you have the Arachnoid Granulations that sit next to the Superior Sagittal sinus and they are designed to be a pressure valve that open to drain CSF into the sinus.If you have a SAH near these granulations, you can have blood clog up the valves and have a build up of CSF--> hydrocephalus!

increase in CSF and pressure inside the cranium.

2 categories:

Communicating: seen when ICP increases outside the ventricular system. CSF has exited the system through 1 of the 4 ways mentioned and there is pressure build up outside the ventricles (ie. Arachnoid Granulations)

Non-communicating: obstruction of CSF flow through any or all of the ventricular system and CSF builds up within the ventricles

How CSF is made

C1-C4, where there is a joining of several layers of spinal nerves

Cervical Plexus; located a little more anterior to the spinal cord and lateral to the transverse processes, hidden behind the sternocleidomastoid muscle.

Consists of:

Lesser Occipital Nerve

Greater Auricular Nerve

Transverse Cervical Nerve

Supraclavicular Nerves

Phrenic Nerve

Lesser Occipital Nerve: small near on top, coming off "U" shaped nerve in between C2 & C3 (usually most neurons for this nerve are from spinal nerve (SN) 2). Provides sensory innervation to the lateral portions of the back of the head.

Greater Auricular Nerve: Just inferior to the Lesser Occipital Nerve, branches off C2 & C3. Innervates around the ear (name suggests this)

Transverse Cervical Nerve: Coming down just after previous nerve, branches off C2 & C3. Transverse in nature, wraps around to the front to provide sensory to the more anterior portion of the throat, the Platysma muscle (thin muscle that extends from base of jaw bone all the way down to the clavicle)

Supraclavicular Nerves: Multiple nerves arise from between C3 & C4. Provide sensory to the region above the clavicle where transverse no longer covers (just superior to the clavicle)

Phrenic Nerve: C3,4,5!!! Innervates diaphragm!!!!!

Originate from posterior rami, or small branch points, coming off spinal nerves C3/C4  and extend all the way down to the L spine.

Provides sensor innervation for the middle of posterior neck and back.

Scalene Muscles (mainly Anterior Scalene); Phrenic nerve rides just anterior to this muscle (which is is right next to the Jugular Vein and the Vagus Nerve).

Located slightly lateral to the Vagus Nerve, but still very close to it.

Brachial Plexus

C5-T1

Upper Trunk: combination of C5 & C6

Middle Trunk: continuation of C7

Lower Trunk: combination of C8 & T1

These 3 trunks separate into 2 divisions: Anterior division (of C5-C7) and Posterior division (of C5-T1)

Which then divide into Cords:

Lateral Cord: combination of anterior divisions of upper and middle trunk

Posterior Cord: combination of all 3 posterior divisions

Medial Cord: anterior division of the lower trunk continue but change names

5 terminal branches:

Musculocutaneous nerve:arises from the lateral cord (C5-7)

Axillary Nerve: arises from Posterior Cord (C5-6). Smallest of the terminal branches

Radial Nerve: Large nerve just posterior to the Axillary artery, arises from all spinal nerves in plexus (C5-T1

Median Nerve: combo of portions of the Lateral and Medial Cord (C6-T1)

Ulnar Nerve: portion of the medial cord (C8-T1(some books will say C7 as well))

 (combo of portions of the Lateral and Medial Cord (C6-T1));

provides sensory innervation to the thumb, first 2 fingers and a small slice of the ring finger, on posterior side of hand, it covers the tip of your index and middle finger and a small slice of the medial ring finger. In anatomical position, provides sensory innervation to the anterior portion of the lateral hand

(Palmer Branch innervates the vast majority of the palm)

Rexed's Laminae:

numbering system used to describe the location of synaptic connections and pathways that run within the gray matter of the cord.

1-10 (in Roman Numberals: I-X)

Posterior to anterior (higher #'s)

Lamina 1

(Rexed's Laminae)

Laminae Marginalis:

most important feature for this is that it's the location of synaptic connections for fast pain transmission.

The delta fibers will synapse on the 2nd order neurons located in laminae one.

The first order neuron is a pain receptor that will meet up with the 2nd order neuron in the path

Laminae II & III

(Rexed's Laminae)

Substantia Gelatinosa:

part of the dorsal spinal cord that comes into contact with nociceptors carrying slow pain signals- C fibers.

The first order slow pain sensors synapse on the 2nd order neurons in Laminae II & III (just anterior to fast pain)

Laminae IV-VI

(Rexed's Laminae)

-Involved with reflex pathways; interneurons in the gray matter that are involved in reflexes (some are ipsilateral, others are contralateral).

-Lots of general sensory info runs through/has connections in the middle portions.

-ie: Aβ mechanoreceptors (muscle spindle fibers) send info back to the cerebellum about muscle function via 2 tracks

Dorsal Spinocerebellar

Ventral Spinocerebellar

Laminae VII

(Rexed's Laminae)

Intermediolateral Nucleus:

the lateral gray horn/intermediate horn

(in areas of the spinal cord that have a lateral horn)

Laminae VIII & IX

(Rexed's Laminae)

almost all composed of motor neurons.

(sits anterior to all other laminae)

Laminae X

(Rexed's Laminae)

Tract of Lissauer:

chunk of white matter that a decent amount of sensory inflow into the spinal cord can pass through. Pain receptors being one to keep in mind.

Lays just dorsal to the dorsal horn

Anterior White Commissure (AWC):

Important because the vast majority of crossover that happens in the spinal cord will happen in the AWC or Laminae X. 

Spinocerebellar tracts

Dorsal column medial lemniscal

Spinothalamic tracts

Corticospinal tracts ("Pyramidal Tracts")

Extrapyramidal tracts

Spinocerebellar tracts:

Dorsal and Ventral:

2 main types of info that go to the cerebellum that provides feedback about body movement and muscle contractions:

-Muscle spindle: usually associated with the dorsal tract. Look at stretch of muscle fibers

-Golgi tendon stretch receptors: tells the brain when it's pulling so hard on a tendon that it may come out of its insertion site. Usually associated with ventral tract

***note: sensory input from both of these mechanoreceptors are found in both tracts, but more than likely to be concentrated in the "usually associated" one***

-Info through ventral tract crosses over at level of entry, and ends up in the superior cerebellum

-info through dorsal tract does not cross over!!!!! (it stays ipsilateral)and ends up in the inferior cerebellar peduncle (the inferior portion of the cerebellum)

lots of higly discriminatory info sent fast; Aα neurons make up the bulk of the this column, sense the pressure portion of a skin prick on the finger

infor coming into the spinal cord at the dorsal rootlets where it moves over into of of the 2 dorsal roots, crosses over into the dorsal column and moves up towards the brain, crosses over at the Lemniscal Decussation in the Medulla, heads to the thalamus (Ventrobasal complex), and then the info will be relayed out to portions of the parietal cortex for processing so your brain can figure out what's going on (pressure?)

*Spinal cord->medulla->thalamus->parietal cortex*

 Fasciculus Gracilis: carries sensory signals from the lower portion of the body, more medial in dorsal column

(just remember, the Gracilis muscle in in the leg. Leg->Lower body!)

Fasciculus Cuneatus: carries sensory signlas from the upper parts of the body, more lateral in dorsal column

**in a cross section of the spinal cord in the lower portion of the spine, you would not expect to see any Cuneatus, as it only supplies signals from the upper body**

4 divisions that correspond to 4 regions of the body:

Cervical, Thoracic, Lumbar, Sacral

*the more medial your signals travel in the brain (the Postcentral Gyrus) the lower the portion of the body that sensory info is coming from in the path*

(ie: most medial = sensory from sacral, more lateral  = lumbar, more lateral = thoracic, most lateral = cervical)

Homunculus: shows which portions of the parietal cortex process sensory information from which portions of the body.

Medial --> lateral

Lower extremities --> upper extremities

The larger the area that corresponds with the parts of the body, the more sensory receptors you have coming from that particular tissue. *Lips and hands have a lot! From nipple line to pelvis does not!

Anterior Lateral Tract

 aka "spinothalamic tract" (sometimes the name changes when it's regerred to as an anterolateral tract)

Responsible for pain transmission signals: Cross over happens at the level of entry!

2 portions:

Anterior portion of the ST tract: carries slow pain signals; go to brain stem mostly (don't make it all the way to brain), also carry info for temperature and other nociceptors (tickle and itch); signal comes in and synapses with 2nd order neuron in the Substantia Gelatinosa; cross over occurs in the AWC!

Lateral portion of the ST tract: carries fast pain signals; cross over happens in Laminae X!

Substance P and Glutamate:

Substance P is slower (slower response, slower metabolization)

-body has poor localization of slow pain signals because these signals terminate in the brain stem at the Reticular Nuclei that is in the medulla (as well as the pons and midbrain (whereas fast pain goes all the way through the parietal cortex)

Glutamate is also released in fast pain (the only NT in fast pain)

Neospinothalamic tract: fast pain

(the newer of the two)

Paleospinothalamic tract: slow pain

Laminae 1, 2, and 3 (dorsal horns).

Laminae 5 is also thought to have termination of nociceptors in it.

 Primary Corticospinal Tract:

primary descending motor pathway.

Carries 90-95% of the motor signal coming from the brain. Cross over occurs at the Medulla pyramids.

The remaining portion of the efferent motor output is carried by the Anterior Corticospinal tract (more anterior to the lateral tract and isn't as big because it doesn't have as big of a role). Cross over occurs at the level of the spinal cord where the motor neuron will exit toward the target.

(he said it won't be on the test, but you know how that is...)

Vestibulospinal: control of eye and muscle orientation especially when the body is detecting acceleration.

Involve connections in the gray matter of the cord. Some are ipsilateral, some are contralateral. many use inhibitory neurons (with GABA or Glycine(<--ALWAYS inhibitory!))

Stretch Reflex

Tendon Reflex

Flexor Reflex

Crossed Extensor Reflex

Doesn't use interneurons; simple reflex.

Stretch of a muscle causes it to contract to return it to a normal length.

ie: if you are being pushed backward, some of the muscles in the legs will be stretched (quads). when this happens, signals travel through the dorsal horn and synapse with motor neurons on the ventral horn, and cause your muscle to contract to bring you back up to a vertical stance.

**Stretch receptor = Muscle spindle fiber!**

Don't want to pull too hard on our muscles or the tendons may be pulled out of their insertion site.

ie: if you are lifting a very heavy barbell, your bicep muscle will want to relax, while your tricep contracts to increase the speed of lowering the barbell.

Involves 2 connections:

inhibition of bicep (with inhibitory neurons)

excitatory connection between the golgi tendon stretch receptor on the motor neuron innervating the tricep muscle.

works similarly to the tendon reflex but associated with pain. This involves contracting the flexor muscle and relaxing the contractor muscle on the side of the body where the pain is occurring.

ie: this would occur if you're in a standing position and hit your toe against a bed post.

You have a large amount of info carried within the reflex arc that will move upward to recruit more superior neurons and info is also carried inferiorly to recruit motor neurons at a point in the cord that's lower than where the pain signal is coming from. **only example of where sensory information travels down the cord!!**(just outside the Tract of Lisseuer)

Cross Extensor Reflex

Occurs when you have withdraw of an injured limb while having contraction on the opposite side to support the injured side

ie: while walking and stubbing toe on a bedpost

This would involve contraction of the extensor muscles (quad) in the non-injured limb and contraction of the flexor muscles in injured limb to pull limb away from pain source. Because you're also involving muscles on the opposite side of the body, it's called a crossed reflex (the reflex arc crossing from one side to the other). (with a cross over neuron)

Most superior is Femur

Just inferior to this is the Tibia (medial leg->ankle) and Fibula (lateral leg->ankle)

Calcaneal bone is the heel

Maleoli are the ankle bones (Malleus is singular)

 Subcostal Nerve:

Provides innervation for the areas below th costal portions of the thorax (right under your bottom ribs)

T12-L4. Branches include:

1. Iliohypogastric: T12-14
2. Ilioinguinal: T12-L1
3. Genitofemoral: L1-2
4. Lateral Femoral Cutaneous: L2-3
5. Obturator: L2-4
6. Femoral: L2-4

Iliohypogastric: T12-14. Runs below the gastric contents (including the intestines)

Has 2 branches:

• Anterior Branch: more superior to the inguinal ligament, anterior and medial of the two branches. Innervates the superficial anterior region of the genitalia
• Lateral Cutaneous Branch: wraps around the lateral hip right on top of the anterior pelvis. Innervates the anterior, lateral, superficial hip.

Ilioinguinal: T12-L1.

Slightly inferior to the Hypogastric branch, runs along the inguinal ligament. Provides sensory for the very top portion of the medial thigh.

Part of Lumbar Plexus. L1-2

2 branches:

• Genital Branch: provides innervation for the genitals! (in a man it would be the scrotom)
• Femoral Branch: the more lateral branch. *note that the iliolinguinal provides the extremely medial upper part of the groin and this branch innervates a spot on the thigh that is slightly lateral to that.

Obturator Nerve: L2-4

Part of the Lumbar Plexus:

Supplies innervation to a very small portion of the medial knee.

**Even though it's small, when doing regional blocks for the knee, you have to make sure this is covered/blocked!**

Femoral Nerve: L2-4

2 branches:

• Anterior Cutaneous Branch: innervates the anterior portion of the thigh at the superficial level. Fills in the anterior portion fo the thigh that the other nerves don't cover
• Saphenous branch: runs along the lower portion of the leg. Will provide innervation to the medial portion of the lower leg (knee to the medial ankle)

L4-S3/4 (some books say S3, some say S4)

Branches include:

1. Lumbosacral Trunk: L4-5
2. Superior gluteal: L4-S1
3. Inferior Gluteal: L5-S2
4. Sciatic N.: L4-S3
5. Posterior Femoral Cutaneous: S1-3
6. Pudendal: S2-4

Superior Gluteal: L4-S1

Sensory innervation for the superior part of the gluteal maximus. Will be slightly superior and superifical to the

Inferior Gluteal: L5-S2

Sensory innervation for the inferior gluteus maximus.

Sciatic N: L4-S3

 As it travels parallel to the Femus, it holds the term Sciatic N, but once it gets to just above the posterior knee it splits into

Tibial Branch (L4-S3): medial

Fibular Branch (L4-S2): lateral

S1-3. Part of the Sacral Plexus.

Provides sensory innervation for the posterior portion of the upper leg (hamstring).

Most of the structures in the upper leg have "femor" in them because they are around the area of the femur.

Pudendal: S2-4

Provides sensory innervation for the significant chunk of the genitals and rectum. This is the functionally important innervation for the genitals that comes from around the pelvis

2 Branches:

• Rectal: slightly more posterior. Supplies rectal area
• Reproductive: (in a male) would be the Posterior Scrotal N. Important in reproductive health and in women, in childbirth.

AKA Common Fibular N
(innervates the lateral portion of the lower leg, both anterior and posterior)

First branch is the Lateral Sural Cutaneous N/Lateral Fibular N

Inferior to this point, the Femoral Nerve is sometimes called the Deep Fibular Nerve (not a branch, just a name change!). Off this, branches the Superficial Fibular Nerve (with the Deep N. continuing on to a point of termination).

The Deep Fibular N runs deep after the Superificial Fibular branch, down the length of the shin under the muscles and doesn't emerge until the foot, where it terminates between the first and second toes.

AKA Sural Nerve

Branching of a superior portion of this is the Medial Sural Cutaneous Nerve (innervates a portion of the lower leg that is medial to twhat the Lateral Sural Cutaneous N innervates)-> splits into the Medial and Lateral Plantar Nerves (providing innervation to the lateral and medial areas of the bottom of the foot)

Femoral Triangle: Point from which you can gain access to the Femoral vein, artery, and nerve (*from medial to lateral)       (NAV VAD)

To do an anterior approach femoral block: find pulse, 2cm lateral from the pulse will be the nerve. Your point of access will be 2 cm inferior to the inguinal ligament (not as much branching in this area; if you block superior to this, you will block all of the nerves inferior to that)

*you can access this from the posterior using posterior landmarks such as the hips or the greater trochanter (lower than the pelvis, top bulge on the femur)

Connective tissue coverings of nerve bundles:

Epineurium: surrounds all branches (outermost cover)

Fascicle: one bundle of neurons. Covered by the Perineurium.

The individual neurons inside the Fascicle is covered by the Endoneurium.

Larger vessels on the more superior surface of a nerve have more permeability than those deeper in the bundle. Although the deeper vessels are not as permeable as the BBB, it is still more permeable than the larger, more external vessels on the nerve bundle.

*remember, these bundles/nerves/neurons have a rich blood supply because they cannot store energy very well!

A-delta fibers: synapse happens in the Laminae Marginalis.

C-fibers synapse more anteriorly in the Substantia gelatinose

(sometimes these synapses can happen in Laminae 5, but most of these terminations are modulated by some interneuron, not the actual nociceptor)

Descending Inhibitory Complex: second descending inhibitory pain pathway.

This is a portion ofhte brain that has descending projections that tell the cord to slow pain transduction.

Located at the top of the brainstem in a region that borders the 3rd ventricle.

Specific places:

Periventricular Nuclei (close the the 3rd ventricle)

Periaquaductual Gray Area (near the Cerebral Aquaduct)

Neurons origniating in these two areas have projections that reach down into the Pons, to the Nucleus Raphe Magnus/Raphe Magnus Nucleus (these are 1st order neurons)

The binding of Enkephalin has an inhibitory effect via an ion channel, specifically a promoting the efflux of K+ channels (which hyperpolarizes the cell membrane)(this how Opiates work in the spinal cord)

Enkephalin receptors also decrease the ability of the membrane to become permeable to Ca++ (which would be excitatory)

Third NT of pain pathways (can be in both fast and slow, but moreso associated with slow pain pathway)

CGRP: Calcitonin Gene Related Protein

Made of amino acids. Resembles Calcitonin (signaling compound that is r/t homeostasis of Calcium)

Anterior part: Adenohypophysis

Posterior part: neurohypophysis

Responsible for release of ADH, Oxytocin (reproductive neuro-endocrine signaling molecule. Most that is released is coming from the Paraventricular nucleus)

Osmoreceptors: monitor osmolality

Infections sensors

body temperature sensors

 Osmoreceptors are connected with cells that arise from the Paraventricular nuclei (control 1/6 of ADH that is released) and Supraorbital nuclei (control 5/6 of the ADH that is released) have projections that run down the posterior Pituitary gland where ADH is released.

60% of body weight (kg) is water. (42L)

of the 42L: 2/3 is ICF (28L),1/3 ECF (14L)

ECF: Plama-in CV system (3L or 1/5 of vol.)

Interstitial fluid-outside CV (11L or 4/5 of vol.)

Water and gases move freely

Proteins are usually stuck in the three individual compartments

(once a protein is in the intracellular compartment, it stays there; those that are in the interstitial compartment consist of glycoproteins that are attached to the connective tissue, proteoglycan filaments, and lots of large molecules that are stuck in the interstitial fluid compartment; proteins in the CV compartment are not going to move freely across the capillary membrane)

Ions have a harder time moving across the cell membrane compared to water.

Adding isotonic saline is going to add fluid volume exclusively to the ECF compartment.

Even though water is able to move freely across any of those barriers, there is no motivation for water to move either in or out of the ICF compartment.

Overall volume increases, but the it is increasing solely in the ECF compartment

You add both water and salt into the CV system, and both of them can leave the CV system and move into the interstitial fluid compartment.

If you are making the ECF more salty than normal, in will increase the osmolarity of the ECF, causing fluid to shift from inside the cell to outside of the cell in order to make the system iso-osmotic (having equal osmolarity throughout).

This will cause expansion in the ECF compartment and a decrease in ICF compartment.

You are making the ECF less salty than usually, decreasing the osmolarity of the ECF. This will cause water to move into the cells because now the cells are more salty than the ECF.

Expansion will happen in both ICF and ECF compartments.

Because water and Na+ can move about the compartments freely, fluid will shift where it normally lies in the body, meaning that

1/5 of it will settle in CV system/plasma

4/5 will settle in the interstitial comp.

*can possibly have problems if you infuse too much fluid volume: pressure will build in the brain from volume expansion, and in the lungs there is a small lining of fluid that sits outside of the vessels where gas exchange occurs. If this fluid volume becomes too much, it can cause oxygenation issues.

if you infuse large molecules or proteins that are going to be confined to the CVS, they can

1) hold fluid in the CVS or

2) pull fluid into the CVS from the interstitium (if you add enough)

Use radioactive water (tritiated water) which is a heavy water than can be infused IV, it distributes throughout all of the body fluid compartments.

When you know the concentration of the water, and you let it distribute thoughout the patient's body, you can then draw a sample from the patient at a later time and you can estimate the size of the compartment by using a simple indicator dilution method.

VOLUME B = VOLUME A x CONCENTRATION A

CONCENTRATION B

 How do you determine ECF fluid volume (in a non-"normal" patient)?

Infuse some stable bu radioactive substance that is going to be relatively confined to the ECF compartment.

Radioactive Na+ works well here because IV bolus of heavy Na+ will mostly equilibrate between the capillary and interstitial fluid compartment.

(it is almost imporssible to use a marker to get it inside of all the ICF compartment and back out, so use the equation

TBW - ECF = ICF

~28 mmHg

Pulls fluid into the capillary (or keeps it there). This is the pressure within the CV system that pulls/keep fluid from moving out of the capillary/CV system

~30 mmHg

Pushes fluid out of the capillary (BP within the capillary). This happens because the pressure is higher inside the capillary than outside of the capillary.

~8 mmHg

Pulls fluid out of the capillary. There are a smaller amount of proteins outside of the CV system that pulls fluid out of the CV system.

-3 mmHg

Pulls fluid out of the capillary. This is a negative pressure because of the physiology of the lymphatic system (acts like a big vacuum).

The artery just before a capillary. This is where all of your regulation of flow through a capillary occurs.

After a capillary

Conduit by which blood flowing through the capillary is going to exit the capillary

BP usually decreases as you move down the capillary, so by time you get to the venule, the BP is 10 mmHg

Lymphatic system

Fluid that sneaks out of the capillaries gets put back into the CV system by the Lymphatic system, which functions by 

emptying fluid into large veins close to the heart.

17.3 mmHg

Total forces moving fluid outward: 28.3 mmHg

Moving in: 28

Net outward force: 0.3

Second circulatory system!

Normal flow: 2 L/day

*Maximum flow: up to 50-150 L/day!

reabsorb all the fluid that is filtered by the capillaries

Albumin (travels throughout the body; used as a nonspecifictransport protein within the CV system to help deliver things such as lipid soluble agents)

Globulins (immunoglobulins, or portions of the immune system)

Fibrinogen (important clotting factor)

Heart failure

Cancer

Burns

Hepatic failure

Trauma/Infection

Septic shock

Anaphylactic shock

Steroids: decreases permeability of the capillary

Colloid transfusion: replaces lost colloids from the CV system

Pressors: counteract some of the relaxation of the arterioles that is present in shock

Relies entirely on some outside forces squeezing lymphatic vessels to push fluid through the lymphatic system (through the one-way valves)

(this schematic is also applicable to some veins that drain the CV system)

Outside forces: skeletal muscles, large arteries (pulsating between heart beats)

supportive/structural proteins:

pyloronic acid, proteoglycan filaments, collogen, titan

"organ pain"

• Internal organs contain diffuse pain R's (small intestine, liver, bladder (hollow organs that usually only have R's around the lining), lungs, brain (brain itself has minimal pain-R's but the dural layer has a lot! as you can tell with CSF leaks and brain loses it's bouyancy)
  
• Need widespread damage to elicit visceral pain
• Usually referred to "surface locations" located to associated dermatomes
• Almost always a slow, dull, achy pain associated with C fiber!

Nociceptors for this pain connect to sympathetic fibers and then ascend 2-3 levels in the spine, and then enter the dorsal horn of the cord.

Enters dorsal root with other sensory info from that region of the body.

ie: appendix pain travels up a couple of spinal levels, enters the spine at about T10 and travels to the brain with other sensory from the T10 dermatome (just below the umbilicus)-> "referred pain" - has to do with embryonic development and where things originate in the embryo

*remember that some slow pain can travel all the way up to the brain!*

"lining pain"

• associated with the inner or outer lining of something.   ie: lungs have a lot of pain receptors on the lining of the lungs, parietal pericardium, inside of the lung and/or abdominal cavity (or any cavity)
• will have both slow and fast pain signals (C and A-beta fibers)
  
• percieved to be in the tissue close the to actual damage

When you have both Visceral and Parietal pain

Example is Appendix pain: you have both dull pain at the umbilicus (referred; varietal) and sharp pain in the RLQ (actual site; parietal)-->decompression pain (if you apply pressure it feels better, remove pressure and it hurts worse (this is also an example of lateral inhibition where A-beta fibers stop pain signals!)

• Dura Mater
• Pericardium
• blood vessels (arteries)-> especially coronary vessels (sensitive to acidosis and hypoxia)
• Joints and bones
• periostium of bone (covering of connective tissue that covers bone)