Gross Dissection I

WI 2003 Midterm Lecture Notes
 Dr. Caine

Notes were taken and typed during lecture. Updates will not be made. Though the material is the same, the order may have changed.

Adult female breast

•	Mammary glands contained in breast tissue
•	Upper lateral portion with outer skin removed = Axillary Tail (aka Tail of Spence)
•	Superficially to deep, contains: Lactiferous (Mammary) ducts, sinus, ducts and glands
•	Susensory ligaments (aka ligaments of Cooper) seen throughout – aid in breast support
•	Blood supply/drainage
•	Arteral supply – originates from subclavian artery, 
•	Venuous drainage mainly to Axillary Vein. 
•	Branches are:
•	Medial breast = Internal Thoracic artery, vein 
•	Lateral breast = Lateral Thoracic artery, vein 
•	Lymphatic drainage – mainly in axillary area nodes
•	Clinical Note: Breast tissue has increased cell cycles resulting in higher cell production including abnormalities (cancer). Frequency of breast cancer to breast area: Nipple 25%, Upper lateral 45%, Upper medial 15%, Lower lateral 10%, Lower medial 5%

Anterior Wall

•	Pectoralis major and minor insert onto the coracoid process
•	Serratus Anterior functions to keep scapula against thoracic wall
•	Nerve supply to pectoralis major/minor = Medial & Laterial Pectoralis nerves. The medial pierces pec.minor to feed pec.major. Lateral does not pierce pec. minor
 
Thoracic Cage

•	12 pairs of ribs. 1-6 = true: attach directly to sternum, 7-12 = false: indirect sternum attachment. Ribs 11 & 12 are referred to as floating ribs as they do not attach to the sternum.
•	Costal Cartilage (hyaline cartilage) prolong the ribs anteriorly and contribute the the elasticity of the thoracic cage.
•	Aperatures:
•	Superior – bordered posteriorly by 1st thoracic vertebra, laterally by 1st pair of ribs, anteriorly by superior border of manubrium.
•	Inferior – bordered posteriorly by 12th thoracic vertebra, laterally by 11th & 12th pairs of ribs and anteriorly by Xiphisternal joint (T9 level).
•	Sternal Angle (manubrium/sternal body junction) (aka Angle of Louis) landmark = rib 2 or T4/T5 IVD level
•	Intercostal Muscles:
•	External \\\\\ – “hands in outside pockets” function during inspiration – pull ribs up.
•	Internal ///// -  function in expiration – pull ribs down
•	Innermost ///// - function in expiration (lecture) action unknown (text)
•	The innermost intercostals are further divided into:
•	Transverse thoracis (anterior – Depress ribs) I
•	Innermost proper (lateral – not mentioned in text) 
•	Subcostal (posterior – elevate ribs)
•	Ribs action 
•	A-P movement = pump handle
•	Transverse = bucket handle
•	Intercostal Nerve – passes between internal and innermost intercostals muscles within the intercostal spaces sheltered by the costal grooves. They function as both sensory and motor.
•	Aorta is located in the posterior ribcage. It is the origin for the Posterior Intercostal arteries, which pass posterior to anterior through the intercostals spaces.
•	Internal Thoracic Artery is located in the anterior ribcage. It is the origin for the Anterior Intercostal arteries which pass anterior to posterior through the intercostals spaces.
•	The Posterior Intercostal Artery and Anterior Intercostal Artery meet and form an Anastimoses  (meeting of vessels).
•	The Internal Thoracic Artery further branches into two terminal branches:
•	Superior Epigastric Artery
•	Musculophrenic Artery
•	The 12 pairs of thoracic nerves from the spinal column branch into both ventral and dorsal primary rami which then form the intercostals nerves running along the intercostals spaces. Within the intercostals spaces are:
•	“V” vein
•	“A” artery
•	“N” nerve
•	“VAN” is referred to as the Neurovascular Bundle (NB). The NB travels within the costal groove on the inferior part of each rib. 
•	Clinical Note: Thoracocentisis is the process of inserting a needle into the pleural cavity to withdraw fluid. To avoid damaging the NB the needle is inserted superiorly to the rib.
•	Inside layer of Thoracic Cage = Parietal Pleura – a serious fluid producing membrane. The pleura is held to the thoracic wall by Transversalis Fascia
•	The Parietal Pleura is further subdivided into:
•	Costal (rib cage)
•	Diaphragmatic (on diaphragm)
•	Cervical aka Cupola (around thoracic inlet)
•	Mediastinal (covers the mediastinum – heart chamber)

Diaphragm

•	General features: 
o	Striated muscle (skeletal) 
o	Central tendon (lobed leaf from top view)
o	Ability to change the shape of the thoracic cage, S-I direction resulting in a decrease in internal pressure (negative pressure).
o	Generally involuntary control (unique to this skeletal muscle)
o	Forms the inferior border of the Costodiaphragmatic Recess, a pleura-lined gutter. This recess is gravity dependant and important clinically as an area of fluid buildup.
•	Three major openings (aperatures) in the diaphragm 
o	Caval Opening (Inferior Vena Cava)
o	Esophageal Hiatus (espohagus)
o	Aortic Hiatus (aorta). The aortic hiatus in general is formed by the Right & Left Crus which are musculotendinous bundles arising from the A.L.L. (text 291).
•	Blood supply to the diaphragm:
o	Internal Thoracic Artery branches: Musculophrenic & Pericardiacophrenic 
o	Superior Phrenic Arteries, branche of the aorta (as stated in the text)
o	Inferior Phrenic Artery (branch of the aorta). The Inferior Phrenic Artery supplies the inferior side of the diaphragm.
•	Clinical Note: The most common hernia of the diaphragm is at the Esophageal Hiatus where portions of the stomach protrude through causing food entrapment. It is commonly referred to a “Hiatal Hernia” 
•	Types:
o	Gastroesophageal
o	Paraesophageal

Right/Left Pleurals & Mediastenium

Parietal Pleura – lines the pulmonary cavities with serous membrane called pleura. The parietal pleura is held to the thoracic wall by Transversalis Fascia. The parietal pleura can be removed from the wall in pieces. Parietal pleura is named according to the area it covers as stated earlier.
Visceral Pleura – surface of lungs including in the fissures
Pleural Space – a potential space between the parietal and visceral pleura. During inspiration the space is reduced and is a potential space for fluid buildup. Some fluid is always present.

Lungs 

•	Right Lung = rule of “3” which states that “generally” the right side of the body features are in threes.
o	Lobes = superior, middle, inferior
o	Fissures = horizontal and oblique
o	Apex, base, costal and mediastinal surfaces. The right lung has impressions (grooves) for major vessels (i.e. groove for SVC, IVC, azygos vein, cardiac impression, etc.)
•	Left Lung
o	Two lobes yielding only an oblique fissure.
o	The left lung also has impressions for major vessels. However, the left lung has a large cardiac impression.
o	Lingula = tongue-like extension that some consider a third lobe.

Trachea & Bronchi

•	Trachea bifurcates at the level of the sternal angle. From there each lung receives a Main (aka primary) Bronchus (right/left). The primary bronchi are further divided into Lobar Bronchi (aka Secondary Bronchi) feeding each lobe (3 right, 2 left). The lobar bronchi are further subdivided into Segmental Bronchi (aka Tertiary Bronchi) which feed the Bronchopulmonary Segments (subdivisions of each lobe). 
•	Clinical Note: The Bronchopulmonary Segments are each separated by connective tissue and therefore surgically accessible.
•	Clinical Note: Swallowed objects tend to fall into the right bronchus.
•	Segments have accompanying vessels (veins & arteries). 
•	Segments are supprted by Hyaline Cartlidge Plates up to the level of the Bronchioles.
•	Alveoli vessels:
o	Pulmonary Artery – carries unoxygenated blood (blue)
o	Pulmonary Vein – carries oxygenated blood (red)
o	Lymph Nodes are found around bronchi and lungs

Mediastinum

•	Encloses the heart and is the central compartment of the thoracic cavity. The mediastinum is a bi-fold layer of pleura resulting from surrounding pleural reflections.
•	Mediastinum is further divided into:
o	Superior Mediastinum – extends inferiorly from the superior thoracic aperture to the sternal angle.
o	Inferior Mediastinum – extends down from the sternal angle to the diaphragm. Further subdivided into: Anterior, middle and posterior parts. The heart and great vessels are located in the middle compartment.
•	Phrenic Nerve – major nerve innervating the diaphragm located in middle mediastinum
•	Thymus Gland – located over the heart – important from birth through 30’s for producing lymphocytes (“T”) which are an active role in immune responses.

Heart

•	Encased in fibrous pericardium (bag) – collagen fibers
•	Internal pericardium is fused to the fibrous pericardium and produces a serious fluid membrane which is reflected onto the heart at the great vessels (aorta, pul.trunk & veins and vena cave) – called the Visceral Layer of serous pericardium AKA Epicardium (visceral pleura). A pericardial cavity is present around areas other than the great vessels.
•	Clinical Note: A lack of serous fluid can cause layers to rub against each other – a condition known as “pericarditis”. This condition can cause great discomfort.
•	The heart of the embryo is developed in the 3rd week of pregnancy. 
•	Myocardium – next layer after epicardium
•	Endocardium – next layer after myocardium and is in direct contact with blood. The endocardium has a porous surface that filters particulate matter from the blood.
•	Inferior Vena Cava (IVC) & Superior Vena Cava (SVC) – receives deoxygenated blood 
•	Right Atrium
o	Rough inside surface = pectinate muscle – creates turbulance
o	Fossa Ovalis = position of Foramen Ovale – blood runs right to left prior to birth 
o	Sinus Venarum = posteriorly situated smooth wall area
o	Opening for Coronary Sinus – receives most of the cardiac veins
o	Right Atrioventricular Valve (AKA Tricuspid Valve)
o	Crista Terminalis = vertical ridge between pectinate and sinus venarum
o	Right Oricle = outside leaf-like feature not part of the right atrium
•	Right Ventricle
o	Trabeculae Carneae = rough ridges inside wall (myocardium)
o	Papillary Muscles = extensions of trabeculae carneae
o	Cordae Tendineae = extensions of papillary muscle (string-like)
o	Septomarginal Trabecula (aka Moderator Band) = bar of tissue from intertrabecular septum
o	Conus Arteriosus = smooth walled passage of deoxygenated blood to the pulmonary trunk. Blood enters the pulmonary trunk through the pulmonary semilunar valve. The pulmonary semilunar valve is a tricuspid valve.
•	Left Atrium
o	Mostly smooth surface wall
o	Blood passes through the left Atrioventricular Valve (aka Mitral Valve) into the left ventricle. The mitral valve is a bicuspid valve.
•	Left Ventricle
o	Has the thickest myocardium
o	Papillary muscles and cordae tendineae present
o	Blood leaves left ventricle through the Aortic Semilunar Valve – a tricuspid valve. Back pressure buildup in the ascending aorta closes the valve preventing backflow.
•	Heart myocardium & Epicardium are fed by coronary arteries connecting to the ascending aorta. The heart itself is fed during ventricular diastole (when the left ventricle is relaxed). 
•	External Surface of the Heart (Epicardium)
o	Atrioventricular Sulcus (aka Coronary Sulcus) contains the right coronary artery
o	Interventricular Sulcus – contains the left coronary artery (anterior interventricular branch).
o	Right and Left Coronary Arteries are branches of the ascending aorta that feed the myocardium
o	SA Node Artery = rises from right coronary artery and supplies the SA node.
o	Circumflex Branch arises from the left coronary artery and is continuous around to the posterior of the heart
o	Anterior Interventricular Artery (aka Anterior Descending) arises from the left coronary artery and is continuous with the Posterior Interventricular Artery.
o	Coronary artery network are arranged in a number of variations body to body.
o	Clinical Note: Most clots are formed at the circumflex/anterior interventricular junction of the left coronary artery.
•	System of cardiac veins run within the same sulci of the the coronary arteries.
o	Small Cardiac Vein
o	Great Cardiac Vein
o	Middle Cardiac Vein
o	Coronary Sinus = main drainage vessel of the heart – empties into the right atrium
o	Thebesian Veins = very small veins that dump into all chambers of the heart. They are not visible from outside of the heart
•	Deoxygenated blood exiting the heart via the pulmonary trunk enters the lungs at the Lung Hilus. At the hilus, vein orientation is always inferior to the artery. The primary bronchi are middle in position. Superior to inferior = Artery, Bronchi, Vein
•	Heart Surface Projections
o	Heart = rib 6 up
o	Valves Auscultation
•	Tricuspid – on the right side at the costal arch
•	Mitral – left side heart apex, 5th intercostals space (just medial to the nipple)
•	Aortic – right side, 2nd intercostals space
•	Pulmonary – left side, 2nd intercostals space
•	Valve auscultation can indicate incompetant valves causing a heart murmur (blood leaking through the valve. A woooooosh sound after closure of the valve
•	Heart Nerve Innervation
o	Heart is made of modified cardiac muscle – not neural tissue
o	SA Node (SVC area) and AV Node (between ventricles) are connected by internodal tracks within the cardiac muscle. The SA Node is known as the pacemaker of the heart.
o	Impulse conduction then travels to the AV Node giving rise to the AV Bundle (aka Bundle of His). The bundle then divides into right and left descending into the interventricular septum and terminating in the trabeculae carneae where they become Purkinje Fibers spreading into the ventricular walls.
o	Fine tuned by Sympathetic and Parasympathetic nervous system
o	Sympathetic Cardiac Nerve – superior, middle, interior to superfiscial enter the cardiac plexus
o	Right/Left Vagus Nerve (CN X) also enter the cardiac plexus via superior and inferior branches but continue after plexus. Only branches of the vagus enter the plexus
o	The Cardiac Plexus enters the right atrium.

•	Drainage System of the Thoracic Cage
o	Azygos Vein System drains both posterior and lateral thoracic walls including intercostals spaces having posterior intercostals veins
o	Azygos vein runs along the vertebral column
o	Accessory  Hemi-Azygos & Hemi-Azygos (Accessory is superior to Hemi)
o	The Accessory Hemi-Azygos drains the upper intercostals. 
o	The Hemi-Azygos drains the lower intercostals.
o	Both Accessory and Hemi cross over to the right side and dump into the azygos vein.
•	Thoracic Duct = lymphatic vessel travelling with the azygos system on the vertebral bodies & discs.
•	Edema = interstitial fluid buildup is caused by inadequate lymphatic function.
•	Right upper quadrant drains into the right lymphatic duct. All remaining body is drained by the left collecting duct
•	Thoracic Nerves
o	Thoracic dermatones are created by Lateral Cutanious and Anterior Cutanious branches of Dorsal/Ventral Rami.
o	Rami become Intercostal Nerves as they run in the intercostals spaces as part of the Intercostal Neurovascular Bundle.
o	Phrenic Nerve – seen in the thoracic cage and feeds the diaphragm.
o	Vagus Nerve (CN X) also seen running inferiorly through the thoracic cage.

Within the subcutaneous layer:
Lymphatic System – Axillary Nodes, Superfisial Inguinal Nodes

Abdomen

Regions of the Abdomen vs. Quadrant System

Right Hypochondriac		Epigastric Region		Left Hypchondriac

Right Lumbar Region		Umbilical Region		Left Lumbar Region

Right Inguinal Region		Hypogastric Region		Left Inguinal Region

OR

Right Upper Quadrant						Left Upper Quadrant
Right Lower Quadrant					Left Lower Quadrant

•	Lateral abdominal wall muscles: superficial to deep 
o	External Oblique
o	Internal Oblique
o	Transverse Abdominis
o	Transversalis Fascia
•	Rectus Sheath = an aponeurosis, tendons in sheet-like formation that are continuous with abdominal muscles - very strong and located extensively in groin area to hold insides in place.
•	Rectus Abdominis Muscles = muscle bellies with Tendinous Intersections between.
•	Anterior & Posterior Rectus Sheath sandwich the rectus Abdominis
•	Linea Alba = runs inferiorly between right/left rectus abdominis.
•	Superficial Inguinal Ring = opening at the inferior of the external oblique aponeurosis.
o	Clinical Note: In the inguinal region, all the fibers run in the same direction causing a structural weakness and a site for herniation. Inguinal herniation is caused by intraabdominal pressure. There are two types:
•	Indirect – a congenital herniation and most common
•	Direct – an aquired herniation and less common. The direct herniation does not penetrate the deep inguinal ring and therefore does not become scrotum material.
•	Transversalis Fascia contains the deep inguinal ring.
•	Both deep and superficial inguinal rings permit inside to outside access for the spermatic chord. A tendinous aponeurosis also wraps around the testes & spermatic chord.
•	Spermatic Chord layers:
o	External Spermatic Fascia – continuous with the external oblique
o	Cremaster Fascia – continuous with the internal oblique
o	Internal Spermatic Fascia – continuous with the transversalis fascia. 
•	Inguinal Ligament – external oblique aponeurosis folding onto itself.
•	Inguinal Triangle – site of direct (aquired) herniation.
•	Abdominal pelvic cavity = serious membrane, peritoneum (parietal, visceral pleura) which is stuck to the abdominal wall by Transversalis Fascia
•	Mesentary (aka Omentum) = continuations of peritoneum (double folds) – allows organs to be attached to the wall (suspension) yet remain moveable.
•	Mesentary is responsible for carrying neurovascular bundles, lymphatics and mobility.
•	Intraperitoneum organs and retroperitoneal organs are seen.
•	Greater Peritoneal Sac + Lesser Peritoneal Sac = Entire Peritoneal Cavity

Stomach

•	Esophageal Hiatus – stomach and esophagus meet. Location of a Cardiac Sphincter under ANS control (both sympathetic and parasympathetic).
•	Borders of the stomach
o	Fundus
o	Body (aka Corpus)
o	Angular Incisure (visible notch)
o	Pylorus – another sphincter called the Pyloric Sphincter controls discharge from the stomach to the duodenum
•	Liquid food = Chime
•	The stomach is the start of chemical breakdown. Mechanical breakdown occurs in the stomach.
•	Running in the Lesser Omentum = common bile duct, hepatic artery, portal vein

Small Intestine

•	Small Intestine consists of the duodenum, jejunum and ileum and extends from the pylorus to where the ileum joins the cecum.
•	Duodenum consists of: Superior, descending, horizontal and vertical portions
•	More folds are seen in the Jejunum vs. Ileum
•	Ileum contain isolated lymphatics called Peyers Patches.
•	Arterial Archades – many found in the Ileum and few in the jejunum.

Large Intestine

•	Large Intestine consists of the ascending colon, transverse colon, descending colon, sigmoid colon, rectum. Its primary responsibility is to remove water from the chime.
•	The LI contains bacteria
•	Chime is thickened and stored in the LI for discharge
•	Hepatic & Splenic Flexure
•	Appendices Epiploic = fat reserves
•	Teniae Coli = longitudinal muscle causing bunching of the LI (haustra) and promotes more internal surface area.
•	Cecum = blind end of the colon
•	Iliocecum Valve = sphincter for movement of substance
•	Appendix = blind tube and worm-like extension of the cecum
•	Goblet cells are present in the colon.

Liver & Gallbladder

•	Located just below the diaphragm in the upper right quadrant.
•	A very complex organ
•	Responsible for the production of  bile which breaks fat into smaller, more manageable units. The fat is NOT chemically broken down here.
•	The liver has extensive blood supply via the hepatic artery and portal vein (nutrient rich blood).
•	The liver consists of a right lobe, left lobe, quadrate lobe, caudate lobe
•	Organ impressions are visible on the outer liver walls
•	Falciform Ligament = a double folded peritoneum (peritoneal ligament) continuous with the Coronary Ligament which then ends as right/left triangular ligaments
•	Ligamentum Teres = leftover from umbilical vein (round ligament of liver)
•	The gallbladder is found on the posterior side of the liver between right and quadrate lobes. Its function is to store bile and remove water making it more concentrated.
•	Porta Hepitus (door to the liver) = hepatic artery, hepatic duct, portal vein, ANS and lympatics.
•	The Common Bile Duct empties into the duodenum
•	The Portal Vein brings oxygenated blood to the liver along with nutrients.
•	Common bile duct sphincter
•	Sphincter of Odi
•	Lesser Omentum connects the stomach and liver
•	Common Bile & Pancreatic ducts join at the Ampulla prior to duodenum

Pancreas & Spleen

•	Pancreas has dual function. Endocrine = hormones, insulin and glucagons and Exocrine = production of enzymes for digestive breakdown
•	The head of the pancreas folds into the duodenum (aka uncinate process)
•	Enzymes produced by the pancreas travel through the main pancreatic duct.
•	The spleen is covered by ribs 8,9,10. Its function is the site for lymphocyte production and contributes to the immune system.

Abdominal Blood Supply

•	Aorta splits into right/left common iliacs
•	Three major distributions:
•	Parietal supply
•	Genitourinary supply
•	Gastrointestinal supply
•	GI tract has 3 unpaired vessels that come from the aorta:
o	Celiac Trunk – artery to the foregut including: esophagus, stomach, 1st & 2nd parts of duodenum
o	Superior Mesentary Artery – artery to the midgut and branches including remaining duodenum, jejunim, complete ileum, cecum and appendix, ascending colon and ½ transverse colon
o	Inferior Mesentary Artery – artery to hindgut including the remainder of the transverse colon, sigmoid colon, descending colon and rectum
•	Celiac branches include: left gastric, splenic (associate to foregut) and common hepatic
•	Caval Venous System = Blood from extremeties, body wall, genitourinary system  which dumps into the right side of the heart.
•	Portal Venous System = additional venous return system responsible for gastrointestinal tract & associates (spleen, liver, pancreas)
•	There are small interconnections between Caval and Portal systems – an ineffeicient veinous system. Superior rectal of portal and middle/inferior rectal of caval.
•	Hepatic Portal system is rich in nutrients
•	Anatomy Note: Arteries have branches, Veins have Tibutaries.
•	The Portal Vein is made superiorly from the Superior Mesenteric Vein + Splenic Vein
•	Clinical Note: Portal Hypertension is caused due to portal backup from liver damage.

Nerve Supply

•	Mixed nerves exit the spinal IVF and branch into ventral and dorsal rami.
•	Dorsal Rami are responsible for:
o	overlaying skin on back
o	motor to paravertebral muscles
o	sweat glands in back
•	Ventral Rami are responsible for:
o	Motor to lateral & abdominal wall
o	Lateral cutaneous branch to skin and sweat glands
•	The are two sources of ANS in abdomen from T5-L1/2
•	T5-T9 = Greater Splanchnic Nerve synapse in Celiac Ganglion
•	T10/11 = Lesser Splanchnic Nerve synapse in Superior Mesentary Ganglion
•	T11/12 = Least Splanchnic Nerve synapse in Inferior Mesentary Ganglion
•	Pre/post ganglionic nerves
•	Parasympathetic = Craniosacral = smooth muscle, cardiac muscle and glands.

 Good luck on your midterm!!!