LIVER ANATOMY---MNEMONICS

LIVER ANATOMY

Gross Anatomy
The liver is a roughly triangular organ that extends across the entire abdominal cavity just inferior to the diaphragm. Most of the liver’s mass is located on the right side of the body where it descends inferiorly toward the right kidney. The liver is made of very soft, pinkish-brown tissues encapsulated by a connective tissue capsule. This capsule is further covered and reinforced by the peritoneum of the abdominal cavity, which protects the liver and holds it in place within the abdomen.

Ligaments of the liver

The peritoneum connects the liver in 4 locations: the coronary ligament, the left and right triangular ligaments, and the falciform ligament. These connections are not true ligaments in the anatomical sense; rather, they are condensed regions of peritoneal membrane that support the liver.

• The wide coronary ligament connects the central superior portion of the liver to the diaphragm.
• Located on the lateral borders of the left and right lobes, respectively, the left andright triangular ligaments connect the superior ends of the liver to the diaphragm.
• The falciform ligament runs inferiorly from the diaphragm across the anterior edge of the liver to its inferior border. At the inferior end of the liver, the falciform ligament forms the round ligament (ligamentum teres) of the liver and connects the liver to the umbilicus. The round ligament is a remnant of the umbilical vein that carries blood into the body during fetal development.

The liver consists of 4 distinct lobes – the left, right, caudate, and quadrate lobes.

• The left and right lobes are the largest lobes and are separated by the falciform ligament. The right lobe is about 5 to 6 times larger than the tapered left lobe.
• The small caudate lobe extends from the posterior side of the right lobe and wraps around the inferior vena cava.
• The small quadrate lobe is inferior to the caudate lobe and extends from the posterior side of the right lobe and wraps around the gallbladder.

GENERAL ANATOMY AND LIVER LIGAMENTS

 

INFERIOR VIEW OF LIVER---NETTER'S ATLAS

  

LIVER- ANTERIOR AND POSTERIOR VIEW

Bile Ducts
The tubes that carry bile through the liver and gallbladder are known as bile ducts and form a branched structure known as the biliary tree. Bile produced by liver cells drains into microscopic canals known as bile canaliculi. The countless bile canaliculi join together into many larger bile ducts found throughout the liver.

These bile ducts next join to form the larger left and right hepatic ducts, which carry bile from the left and right lobes of the liver. Those two hepatic ducts join to form the common hepatic duct that drains all bile away from the liver. The common hepatic duct finally joins with the cystic duct from the gallbladder to form the common bile duct, carrying bile to the duodenum of the small intestine. Most of the bile produced by the liver is pushed back up the cystic duct by peristalsis to arrive in the gallbladder for storage, until it is needed for digestion.

Blood Vessels
The blood supply of the liver is unique among all organs of the body due to the hepatic portal vein system. Blood travelling to the spleen, stomach, pancreas, gallbladder, and intestines passes through capillaries in these organs and is collected into the hepatic portal vein. The hepatic portal vein then delivers this blood to the tissues of the liver where the contents of the blood are divided up into smaller vessels and processed before being passed on to the rest of the body. Blood leaving the tissues of the liver collects into the hepatic veins that lead to the vena cava and return to the heart. The liver also has its own system of arteries and arterioles that provide oxygenated blood to its tissues just like any other organ.

Lobules
The internal structure of the liver is made of around 100,000 small hexagonal functional units known as lobules. Each lobule consists of a central vein surrounded by 6 hepatic portal veins and 6 hepatic arteries. These blood vessels are connected by many capillary-like tubes called sinusoids, which extend from the portal veins and arteries to meet the central vein like spokes on a wheel.

Each sinusoid passes through liver tissue containing 2 main cell types: Kupffer cells and hepatocytes.

• Kupffer cells are a type of macrophage that capture and break down old, worn out red blood cells passing through the sinusoids.
• Hepatocytes are cuboidal epithelial cells that line the sinusoids and make up the majority of cells in the liver. Hepatocytes perform most of the liver’s functions – metabolism, storage, digestion, and bile production. Tiny bile collection vessels known as bile canaliculi run parallel to the sinusoids on the other side of the hepatocytes and drain into the bile ducts of the liver.
  

MNEMONICS

Liver: side with ligamentum venosum/ caudate lobe vs. side with quadrate lobe/ ligamentum teres "VC goes with VC":
The Venosum and Caudate is on same side as Vena Cava [posterior]. Therefore, quadrate and teres must be on anterior by default.
· See inferior-view diagram.

Liver inferior markings showing right/left lobe vs. vascular divisions There's a Hepatic "H" on inferior of liver. One vertical stick of the H is the dividing line for anatomical right/left lobe and the other vertical stick is the divider for vascular halves. Stick that divides the liver into vascular halves is the one with vena cava impression (since vena cava carries blood, it's fortunate that it's the divider for blood halves).

Liver lobes:  Gallbladder is associated with the quadrate lobe (think GQ magazine).   The blood supply and bile drainage is from the left hepatic a. and v. and left hepatic duct.  (LGBQ!)  The IVC is associated with the caudate lobe, and more generally with the left hepatic vessels, because there is an “i” in both “ivc” and “right”, and a “c” in both “ivc” and “caudate”.

ANATOMY HUMAN EYES

Anatomy of the Human Eye

Anatomy can be painful for some (personally, I don't like anatomy ) so I’m going to keep this simple. Let us start from the outside and work our way toward the back of the eye.

Eyelids

The eyelids protect and help lubricate the eyes. The eyelid skin itself is very thin, containing no subcutaneous fat, and is supported by a tarsal plate. This tarsal plate is a fibrous layer that gives the lids shape, strength, and a place for muscles to attach.

Underneath and within the tarsal plate lie meibomian glands. These glands secrete oil into the tear film that keeps the tears from evaporating too quickly. Meibomian glands may become inflamed and swell into a granulomatous chalazion that needs to be excised. Don’t confuse a chalazion with a stye. A stye is a pimple-like infection of a sebaceous gland or eyelash follicle, similar to a pimple, and is superficial to the tarsal plate. Styes are painful, while chalazions are not.

Eyelid Movement

Two muscles are responsible for eyelid movement. The orbicularis oculi closes the eyelids and is innervated by cranial nerve 7. Patients with a facial nerve paralyses, such as after Bell’s Palsy, can’t close their eye and the eye may need to be patched (or sutured closed) to protect the cornea. The levator palpebrae opens the eye and is innervated by CN3. Oculomotor nerve palsy is the major cause of ptosis (drooping of the eye). In fact, a common surgical treatment for ptosis involves shortening the levator tendon to open up the eye.

CN 3 opens the eye like a pillar
CN 7 closes like a fish-hook

Conjunctiva

The conjunctiva is a mucus membrane that covers the front of the eyeball. When you examine the “white part” of a patient’s eyes, you’re actually looking through the semi-transparent conjunctiva to the white sclera of the eyeball underneath. The conjunctiva starts at the edge of the cornea (this location is called the limbus). It then flows back behind the eye, loops forward, and forms the inside surface of the eyelids. The continuity of this conjunctiva is important, as it keeps objects like eyelashes and your contact lens from sliding back behind your eyeball. The conjunctiva is also lax enough to allow your eyes to freely move. When people get conjunctivitis, or “pink eye,” this is the tissue layer affected.

There is a thickened fold of conjunctiva called the semilunar fold that is located at the medial canthus – it is a homolog of the nictitating membrane seen on sharks.

Tear Production and Drainage

The majority of tears are produced by accessory tear glands located within the eyelid and conjunctiva. The lacrimal gland itself is really only responsible for reflexive tearing. Tears flow down the front of the eye and drain out small pores, called lacrimal punctum, which arise on the medial lids. These puncta are small, but can be seen with the naked eye.
After entering the puncta, tears flow down the lacrimal tubing and eventually drain into the nose at the inferior turbinate. This explains why you get a runny nose when you cry. In 2-5% of newborns, the drainage valve within the nose isn’t patent at birth, leading to excessive tearing. Fortunately, this often resolves on it’s own, but sometimes we need to force open the pathway with a metal probe.

Lid Lacerations

Most lacerations through the eyelid can be easily reaproximated and repaired. However, if a laceration occurs in the nasal quadrant of the lid you have to worry about compromising the canalicular tear-drainage pathway. Canalicular lacerations require cannulation with a silicone tube to maintain patency until the tissue has healed.

Warning: Drug absorption through the nasal mucosa can be profound as this is a direct route to the circulatory system and entirely skips liver metabolism. Eyedrops meant for local effect, such as beta-blockers, can have impressive systemic side effects when absorbed through the nose. Patients can decrease nasal drainage by squeezing the medial canthus after putting in eyedrops. They should also close their eyes for a few minutes afterwards because blinking acts as a tear pumping mechanism.

The Eyeball

The eyeball is an amazing structure. It is only one inch in diameter, roughly the size of a ping-pong ball, and is a direct extension of the brain. The optic nerve is the only nerve in the body that we can actually see (using our ophthalmoscope) in vivo.

The outer wall of the eye is called the sclera. The sclera is white, fibrous, composed of collagen, and is actually continuous with the clear cornea anteriorly. In fact, you can think of the cornea as an extension of the sclera as they look similar under the microscope. The cornea is clear, however, because it is relatively dehydrated. At the back of the eye, the sclera forms the optic sheath encircling the optic nerve.

The eyeball is divided into three chambers, not two as you might expect. The anterior chamber lies between the cornea and the iris, the posterior chamber between the iris and the lens, and the vitreous chamber extends from the lens back to the retina.

The eye is also filled with two different fluids. Vitreous humor fills the back vitreous chamber. It is a gel-suspension with a consistency similar to Jell-O. With age and certain degenerative conditions, areas of the vitreous can liquefy. When this occurs, the vitreous can fall in upon itself – usually a harmless event called a PVD (posterior vitreous detachment). However, this normally benign vitreous detachment can sometimes tug on the retina and create small retinal tears.

Aqueous humor fills the anterior and posterior chambers. This is a watery solution with a high nutrient component that supports the avascular cornea and lens. Aqueous is continuously produced in the posterior chamber, flowing forward through the pupil into the anterior chamber, where it drains back into the venous circulation via the Canal of Schlemm. 

The Cornea

The cornea is the clear front surface of the eye. The cornea-air interface actually provides the majority of the eye’s refractive power. The cornea is avascular and gets its nutrition from tears on the outside, aqueous fluid on the inside, and from blood vessels located at the periphery.

On cross section, the cornea contains five distinct layers. The outside surface layer is composed of epithelial cells that are easily abraded. Though epithelial injuries are painful, this layer heals quickly and typically does not scar. Under this lies Bowman’s layer and then the stroma. The corneal stroma makes up 90% of the corneal thickness, and if the stroma is damaged this can lead to scar formation. The next layer is Descemet’s membrane, which is really the basal lamina of the endothelium, the final inner layer.

The inner endothelium is only one cell layer thick and works as a pump to keep the cornea dehydrated. If the endothelium becomes damaged (during surgery or by degenerative diseases) aqueous fluid can flow unhindered into the stroma and cloud up the cornea with edema. Endothelial cell count is very important as these cells don’t regenerate when destroyed – the surviving endothelial cells just get bigger and spread out. If the cell count gets too low, the endothelial pump can’t keep up and the cornea swells with water, possibly necessitating a corneal transplant to regain vision.

Decemet’s membrane is “deep,” while Bowman’s layer is high up in the “belfry.” A belfry is a room, usually high up in a tower, where bells are hung.

The Anterior Chamber Angle

The angle formed by the inner cornea and the root of the iris is particularly important in ophthalmology. Here you find the trabecular meshwork with its underlying Schlemms Canal. This is where aqueous is drained, and blockage of this pathway/angle will become important as we discuss glaucoma.

The Uvea

The iris, ciliary body, and the choroid plexus are all continuous with each other and are collectively called the uvea. This is an important term, as many people can present with painful “uveitis” – spontaneously or in associated with rheumatologic diseases.

The iris is the colored part of the eye and its primary function is to control the amount of light hitting the retina. Sympathetic stimulation of the pupil leads to pupil dilation and parasympathetic stimulation leads to constriction. In other words, if you see a bear in the woods, your sympathetics kick in, and your eyes dilate so you can see as much as possible as you run away. I’ll be using this mnemonic/metaphore many times throughout this book to help you remember this concept.

The inner iris flows back and becomes the ciliary body. The ciliary body has two functions: it secretes aqueous fluid and it controls the shape of the lens. The ciliary body contains sphincter muscles that change the lens shape by relaxing the zonular fibers that tether to the lens capsule.

The choroid is a bed of blood vessels that lie right under the retina. The choroid supplies nutrition to the outer one-third of the retina which includes the rod and cone photoreceptors. Retinal detachments can separate the retina from the nutritious choroid, which is disastrous for the photoreceptors as they quickly die without this nourishment.

FUN FACT:
An ostrich’s eye is larger than its brain.

Lens:
The lens sits behind the iris. The lens is unique in that it doesn’t have any innervation or vascularization. It gets its nourishment entirely from nutrients floating in the aqueous fluid. The lens also has the highest protein concentration of any tissue in the body (65% water, 35% protein).

The lens has three layers in a configuration similar to a peanut M&M. The outer layer is called the capsule. The capsule is thin with a consistency of saran wrap and holds the rest of the lens in place. The middle layer is called the cortex, while the central layer is the hard nucleus. Cataracts are described by where they occur such as nuclear cataracts, cortical cataracts, and subcapsular cataracts. With cataract surgery the outer capsule is left behind and the artificial lens is placed inside this suporting bag.

The capsule is held in place by suspensory ligaments called zonules that insert around the periphery and connect to the muscular ciliary body. Contraction of the ciliary muscle causes the zonule ligaments to relax (think about that for a minute), allowing the lens to become rounder and increase its refracting power for close-up reading.

In children the lens is soft but with age the lens hardens and becomes less pliable. After age 40 the lens starts having difficulty “rounding out” and people have problems focusing on near objects. This process is called presbyopia. Almost everyone over 50 needs reading glasses because of this hardening of the lens.

The Retina

The retina is the sensory portion of the eye and contains layers of photoreceptors, nerves, and supporting cells. Histologically, many cell layers can be seen, but they are not worth memorizing at this point. The important ones include the photoreceptor layer, which is located further out (towards the periphery), and the ganglion nerve layer which lies most inward (toward the vitreous). For light to reach the photoreceptor it has to pass through many layers. After light reaches the photoreceptors the visual signal propagates back up to the ganglion nerves. These ganglion nerves, in turn, course along the surface of the retina toward the optic disk and form the optic nerve running to the brain.

The macula is the pigmented area of the retina that is responsible for central vision. Within the central macula lies the fovea, which is a small pit that is involved with extreme central vision. The fovea is very thin and derives its nutrition entirely from the underlying choroid, making it susceptible to injury during retinal detachments.

The optic disk is the entry and exit point of the eye. The central retinal artery and vein pass through here, along with the the ganglion nerves that form the optic nerve. A physiologic divot or “cup” can be found here that will become important when we talk about glaucoma.

The Orbital Walls

Seven different bones form the orbital walls: don’t be intimidated by this complexity, however, as these bones are not that confusing when you break them down. For example, the roof of the orbit is a continuation of the frontal bone, the zygomatic bone forms the strong lateral wall, while the maxillary bone creates the orbital floor. This makes sense, and you could probably guess these bones from the surrounding anatomy.

The medial wall is a little more complex, however, but is mainly formed by the lacrimal bone (the lacrimal sac drains tears through this bone into the nose) and the ethmoid bone. The thinnest area in the orbit is a part of the ethmoid bone called the lamina papyracea. Sinus infections can erode through this “paper-thin wall” into the orbital cavity and create a dangerous orbital cellulites.

Despite the fragility of the medial wall, it is well buttressed by surrounding bones, such that it’s the orbital floor that breaks most often during blunt trauma. The maxillary bone fractures downward and the orbital contents can herniate down into the underlying maxillary sinus. This is called a “blowout fracture” and can present with enopthalmia (a sunken-in eyeball) and problems with eye-movements from entrapment of the inferior rectus muscle. We’ll discuss blow-out fractures in more detail in the trauma chapter.

The back of the orbit is formed by the greater wing of the sphenoid bone, with the “lesser wing” surrounding the optic canal. There’s also a little palatine bone back there in the middle, but don’t worry about that one!

The Apex: Entrance into the Orbit

The orbital apex is the entry point for all the nerves and vessels supplying the orbit. The superior orbital fissure lies between the wings of the sphenoid bones, through which many vessels and nerves pass into the orbit.

The “Annulus of Zinn,” a muscular band that serves as the insertion point for most of the ocular muscles, rests on top of the superior orbital fissure. The four rectus muscles attach to the annulus and the optic nerve passes right through the middle.

Eye Muscles

Four rectus muscles control each eye. These muscles insert at the sclera, behind the limbus, and each pull the eye in the direction of their attachment.

The superior, medial, and inferior rectus muscles are all controlled by the oculomotor nerve (III). The lateral rectus, however, is controlled by the abducens (VI) nerve, which makes sense as the lateral rectus “abducts” the eye.

The remaining two eye muscles are the superior and inferior oblique muscles. The superior oblique also originates in the posterior orbit, but courses nasally until it reaches the trochlea (or “pulley”) before inserting onto the eye. The inferior oblique originates from the orbital floor and inserts behind the globe near the macula. Because of these posterior insertions, the oblique muscles are primarily responsible for intorsion and extorsion (rotation of the eye sideways), though they also contribute some vertical gaze action.

MNEMONICS FOR INNERVATION --- SO 4 LR 6 REST 3

Reference ---- www.ophthobook.com

Structures that pass through the diaphragm--- mnemonic

Structures that pass through the diaphragm--- Mnemonic

When we go to thorax or abdomen... It's hard to remember their relation... We created a mnemonic to make it easy for you.

What sort of relation? The relation of structures that pass through the diaphragm?

Ok I know one mnemonic for that:-

I ate (8) ten eggs AT twelve.

I: Inferior Vena Cava

aTe: T8!

Eggs: Esophagus (Vagus rhymes with it!)

Ten: T10

AT: Azygous vein(variable) , Aorta, Thoracic duct! Twelve: T12

So to summarize:-

IVC - T8

Esophagus, vagus - T10

Azygous,aorta, thoracic duct - T12

Hope this helps!

OPENINGS IN THE DIAPHRAGM---Reference GRANT'S ATLAS 

INFERIOR VIEW OF DIAPHRAGM

DIAPHRAGM WITH ITS MAJOR AND MINOR OPENINGS

BONE AND MUSCLE ANATOMY--- MNEMONICS (ANATOMY MADE EASY)

BONE AND MUSCLE ANATOMY--- MNEMONICS (ANATOMY MADE EASY)

Tarsal bones of ankle "Tiger Cubs Need MILC (MILK)":
Superior, then clockwise on right foot:
Talus
Calcaneus
Navicular
Medial cuneiform
Intermediate cuneiform
Lateral cuneiform
Cuboid.

BONES AT ANKLE JOINT AND FOOT

The feet are divided into three sections:

• The forefoot contains the five toes (phalanges) and the five longer bones (metatarsals).
• The midfoot is a pyramid-like collection of bones that form the arches of the feet. These include the three cuneiform bones, the cuboid bone, and the navicular bone.
• The hindfoot forms the heel and ankle. The talus bone supports the leg bones (tibia and fibula), forming the ankle. The calcaneus (heel bone) is the largest bone in the foot.

Muscles, tendons, and ligaments run along the surfaces of the feet, allowing the complex movements needed for motion and balance. The Achilles tendon connects the heel to the calf muscle and is essential for running, jumping, and standing on the toes.

Posterior ankle tendons (mnemonic)

Mnemonics that can be used to remember the anatomy of the ankle tendons from anterior to posterior as they pass posteriorly to the medial malleolus under the flexor retinaculum in the tarsal tunnel include:

• Tom, Dick and Harry
• Tom, Dick And Very Nervous Harry

Mnemonic

Tom, Dick and Harry

• T: tibialis posterior
• D: flexor digitorum longus
• H: flexor hallucis longus

Tom, Dick And Very Nervous Harry

An extension of the above mnemonic to include the positon of the neurovascular bundle.

• T: tibialis posterior
• D: flexor digitorum longus
• A: artery--- posterior tibial artery
• V: vein--- posterior tibial vein
• N: nerve---tibial nerve
• H: flexor hallucis longus.

TENDONS AT ANKLE JOINT

LIGAMENTS AT ANKLE JOINT

LATERAL AND POSTERIOR VIEWS

FOOT ANATOMY