ANATOMY- THORAX & ANTERIOR ABDOMINAL WALL

10- Thoracic Wall & Lung

1. Thoracic a. Superior thoracic aperture (Inlet): site of entrance of viscera and vessels from head,

neck, upper limbs into the thorax; Bounded by 1st rib, vertebral column, manubriumb. Inferior thoracic aperture (Outlet): closed by diaphragm, pierced by inferior

vena cava (T8), aorta (T12), esophagus (T10); innervated by phrenic n. (C3, 4, 5) 2. Sternum :

a. Manubrium : articulates at sternoclavicular joint, rib 1, & half rib 2i. Jugular (suprasternal) notch

b. Body : articulates with half of rib 2 head & heads of ribs 3-7; pec major attachc. Sternal angle (angle of Louis): 2nd rib attachment (T4/5 level)

i. Junction of manubrium with bodyii. Where trachea divides into right & left main stem bronchi

iii. 2nd intercostal space: listening to aortic (R) and pulmonary (L) valvesd. Xiphoid process : level of 6th thoracic dermatome

3. Ribs: a. Costochondral junction : between cartilages & ribsb. Head (crest) : articulates with sides of 2 vertebrae’s bodies at

the same superior (superior facet) & inferior (inferior facet) levels (except for rib 1, 11, 12); attached to IV disc by intraarticular ligament

c. Costovertebral ligaments : stability & flexibility of the jointsi. Costovertebral articulation: joint of head + joint of rib tubercle

d. Sternocostal ligaments : attach costal cartilages to the sternume. Body : f. Angle of the rib : frequent place of rib fractureg. Articulating Tubercle : attached to vertebra transverse process at same level

(rib 6 is attached to T6) via costotransverse jointh. Costal groove : i. Pectus excavatum : sunken-in chest; costal cartilages lengthen, pushing

sternum in crowding out mediastinum structuresj. Pectus carinatum : overly prominent, pigeon chestk. Kyphoscoliosis : hump & lateral spine bending; adds to thoracic wall stiffness

4. 12 pairs of ribs: a. 1-7 : vertebro sternal (true ribs): costal cartilages articulate directly with sternumb. 8-10 : vertebro chondral (false ribs): cartilage articulates with cartilage above itc. 11 & 12 : vertebral (floating): don't have costal cartilages, necks, or tubercles;

ends in musculature of posterior abdominal walld. Cervical rib : extra rib which usually arises from C7 (0.2% of people)

i. Can become entrapped between cervical rib and scalenus muscle Thoracic Outlet Syndrome due to compression of the:

1. Brachial plexus lower trunk hand muscle weakness, pain/numbness in medial side of forearm & hand

2. Subclavian artery loss of pulse when arm is abducted

1

e. Flail chest : multiple rib fracturesi. In spiration : intrapleural pressure becomes more

negative, flail segment & underlying lung tissue sucked in ward , collapsing lung on affected side, shifting mediastinum toward UN affected side

ii. Expiration : as intrapleural pressure becomes less negative, flail segment & tissue pushed outward, mediastinum shifts to affected side

5. Thoracic Wall Intercostal muscles: (phrenic nerve C3, 4, 5)a. External intercostal : inspiration; project inferiorly in a posterior to anterior

direction; replaced in front by external intercostal membranei. Inspiration : external I.M. contract to raise

ribs diaphragm flattens as it contracts increases thoracic cavity height & circumference; decreases intrathoracic pressure & pulls air into lungs

1. Bucket handle: thoracic cavity increased by 7-10th ribs moving laterally

2. Pump handle: sternum pushed forward by true ribs (1-6) increasing anteroposterior dimension

ii. Accessory muscles : pectoralis major & minor, sternocleidomastoid, scalenes (1st & 2nd rib)

b. Internal intercostal : expiration; project superiorly in a posterior to anterior direction (perpendicular to external intercostals); replaced in the back by internal intercostal membrane

i. Expiration : quiet expiration chiefly passive1. Inspiratory muscles relax; Rib cage drops under force of gravity;

Relaxing diaphragm moves superiorly; Elastic fibers in lung recoil2. Volume of thorax and lungs decrease simultaneously,

increases intrathoracic pressure air forced out c. Innermost (incomplete) intercostal :

i. Transversus thoracis : from back of sternum and xiphoid process, onto costochondral junctions ribs 3-6; travels superior & laterally to 2nd – 6th ribs

ii. Subcostalis : can bridge more than one intercostal space6. Vessels and nerve of thoracic wall:

a. Axillary : i. Supreme thoracic : supplies first two intercostal spaces from inside

ii. Lateral thoracic : supplies first few intercostal spaces from outsideb. Subclavian :

i. Internal thoracic artery : deep to intercostal cartilages to anterior abdominal wall to give rise to anterior epigastric arteries

1. Musculophrenic : 2. Superior epigastric : 3. Anterior intercostal artery : supply sternum skin; anastomose

with posterior vessels in intercostal spaces around midclavicular line

2

c. Thoracic Aorta : i. Posterior intercostal artery: travel with intercostal nerves, giving

branches to intercostal musclesd. Aortic coarctation : lower BP in lower limb than in arm; intercostal arteries

can be used to supply blood past the constriction below the diaphragmi. In an infant, post-ductal coarctation is better adapted to than pre-ductal

ii. Rib notching : due to intercostal a. carrying more blood than normal (from coarctation)

e. Anterior intercostal veins drain into internal thoracic vein drains into brachiocephalic vein

f. Posterior intercostal veins drain into right azygos & left hemiazygos vein drains into superior vena cava

g. Intercostal nerves (Ventral primary rami of thoracic T1-12 spinal nerves): mixed nerves containing both motor & sensory fibers

i. Damage to spinal cord between C8 & T1 would affect all intercostal nerves – affects muscles of respiration

1. Diaphragm unaffected (still functions)ii. Anterior (ventral) rami : innervate intercostal muscles

(run between innermost & internal intercostals), rib periostum, & skin of the thorax (dermatome)

iii. Herpes zoster (shingles): painful rash of blisters in a dermatonal pattern (limited area on one side of body); virus affects dorsal root ganglia and travels down nerve axons to cause viral infection of the skin in the region of the nerve

iv. Posterior (dorsal) rami : innervate back muscles between angle of the ribs & vertebrae spinous processes; cutaneous branches innervate overlying skin

v. T7, 8, 9, 10, 11 : innervate abdominal wallvi. T12 (subcostal nerve) & L1: innervate region above pubis

vii. Neurovascular bundle : intercostal vein (below rib above), artery, nerve (above rib below)

(VAN) travel between innermost & internal intercostal muscles

1. Main NV bundle travels just below the rib above the intercostal space

2. Collateral nerve & vessels travel just above rib below

3. Important for thoracocentesis – don't want to insert needle just below the rib above so as to avoid the main NV bundle – want to insert in the middle

7. Two pulmonary cavitiesa. Pleurae : fluid allowing lung to expand & contract during respiration

(lubricant); provides for surface adhesion between parietal & visceral pleuraei. Visceral pleura : on lung tissue; sensitive to visceral pain (stretching,

inflammation, noxious stimuli) - Generally insensitive to pain1. Blood supply from bronchial arteries

3

ii. Parietal pleura : not in direct contact with lung

tissue; sensitive to somatic pain (temperature, tough, pressure)

1. Costal pleura : deep to ribs; innervated by intercostal nerve

2. Innervated by phrenic nerve (C3,

4, 5) – referred pain to shoulder; blood supply from intercostal, musculophrenic arteries

a. Diaphragmatic pleura : above diaphragmb. Mediastinal pleurae : lateral to mediastinum

3. Cervical pleurae : extends above 1st rib

iii. Pleurisy : inflammation of visceral & parietal pleura rub against each other causing sharp pain during breathing; coughing, sneezing, rough, scratchy sound

1. Infections (pneumonia, TB), pneumothorax, pulmonary embolism, lung cancer2. May cause Pleural effusion: build-up of fluid in pleural space,

particularly in the costodiaphragmatic recessiv. Four types of fluids can accumulate in the pleural space

1. Serous fluid (hydrothorax); Blood (hemothorax)2. Lymph (chylothorax); Pus (pyothorax or empyema)3. Air (Pneumothorax – collapsed lung) air in pleural space

causes loss of adhesion & surface tension between visceral & parietal pleuras; pressure in pleural cavity slightly below atmospheric pressure (negative-pressure)

a. Pulmonary blebs: cause of spontaneous pneumothoraxb. Tension pneumothorax : wound allows air into pleural

space, but tissue flap does not allow air during expiration (‘one-way valve’); pressure continues to build causing mediastinal shift to UNaffected side

b. Costodiaphragmatic recesses : wedge space where costal pleura meets diaphragmatic pleura

i. Potential space where 1. Lung can move into during full inspirations2. Excess pleural fluid can accumulate (pleural effusion)

c. Bare area of pericardium : lateral to left edge of sternum; area where needle can be inserted during Pericardiocentesis without piercing the parietal pleura

d. Lung root : sheath of parietal pleura that conjoins the pericardium and encloses pulmonary arteries, veins, main bronchus, lymph nodes, and autonomic nerves

e. Pulmonary ligament : inferior to lung root; segment of reflected pleura forming a sleeve8. Lungs:

a. Cupola Hilus (root): point of entry of vessels, nerves, bronchii. Secondary bronchi : Most posterior structure in hillus (Bronchus Behind)

ii. Pulmonary arteries : bring deoxygenated blood for alveoli oxygenation1. Uppermost structure in the hillus (Artery Above)

4

2. Pulmonary Embolism : blockage of p.a. or branches that has traveled from elsewhere in the body through the bloodstream

a. Difficulty breathing, chest pain upon inspirationb. Low blood O2 levels, cyanosis, rapid breathing & HRc. Tx: anticoagulants & thrombolytics

iii. Pulmonary veins : oxygenated blood to left atrium from alveoliiv. Bronchial arteries : branches of descending aorta or intercostal

branch; carry oxygenated blood to airways & lung tissuev. Lymph nodes :

1. Pulmonary bronchopulmonary (hilar) inferior (carinal) & superior tracheobronchial nodes

2. Right lung drains into venous angle3. Left lung drains into thoracic duct

a. Left lower lobe may cross over to right side and effect the right lung if there is a tumor in the left lower lobe

b. Bronchopulmonary plexus : i. Parasympathetic : Vagus nerve (CN X)

1. Bronchoconstrictora. Asthma : dyspnea with wheezing due to spasmodic

contraction & airway narrowing; possibly by vagal stimulation

i. Tx: inhalation of sympathomimetics (mimic sympathetic effects relaxes muscle; prevents mucous)

2. Promotes secretion of mucous glands3. R-e-l-a-x-e-s blood vessels

ii. Sympathetic : postganglionic fibers & vasomotor to arterial system1. Bronchodilator; Inhibits mucous secretion; Constricts vessels

9. Right Lung: 3 lobes; shorter (diaphragm dome higher on right side)a. Superior , middle and inferior lobes: b. Oblique fissure : creates superior & inferior lobesc. Horizontal fissures : creates middle lobed. Azygous impression : from azygous vein e. 10 bronchopulmonary segments:

i. Right main stem bronchus wider, shorter, & more vertically oriented than left *more likely to be obstructed when standing

10. Left Lung: 2 lobesa. Superior and inferior lobes: divided by oblique

fissureb. Lingual : anterior projection of the superior lobe

overlying anterior aspect of the heartc. Cardiac notch : indentation formed by the heartd. Aortic impression : e. 10 bronchopulmonary segments:

5

11- Heart and Pericardium

1. Fibrous pericardium : outermost tough fibrous single layer2. Pericardial effusion : hemopericardium (blood in pericardial sac); water-bottle silhouette

a. If acute: Cardiac tamponade: pressure causes reduced cardiac outputb. Beck’s triad :

i. Muffled heart sounds – due to blood insulation, weakened beatii. JVD (Jugular venous distension) – due to reduced venous return

iii. Low arterial pressure – due to decreased stroke volumec. Tx: Pericardiocentesis: pericardial tap Larrey’s pt (left xiphosternal angle) or 5th/6th intercostal space

3. Serous pericardium (epicardium) : thin double wall inner layer4. Transverse pericardial sinus : posterior to aorta & pulmonary trunk

a. Permits expansion of great vessels during systole5. Oblique pericardial sinus : inferior, surrounded by veins & pul. arteries

a. Permits expansion of left atrium during exhalation6. Sulci : reduce friction against pericardial sac; facilitate coronary artery perfusion

a. Anterior Interventricular sulcus : i. Anterior: separates the R & L ventricles

ii. Posterior: separates RV from LVb. Coronary sulcus :

i. Anterior: separates RA from RVii. Posterior: separates L & R atria from L & R ventricles

7. Right, left auricles : (ear-like) small structures of the atria that are truly anteriorCoronary = arterial vessels; Cardiac = venous vessels

8. Coronary arteries: from corresponding L & R coronary sinuses of aortic valve; flow during diastolea. Right coronary artery : supplies RV wall, posterior LV wall, SA &

AV nodes; runs in the coronary sulcus between the RA & RV

i. SA nodal (atrial) branch : posterior aspect of RA ii. Right marginal branch : supplies the RV

iii. AV nodal branch : dominance depends on supply 1. Right dominant heat: formed by posterior IV artery2. Left dominant heart: formed by left circumflex artery

iv. Posterior (descending) interventricular artery : posterior IV sulcus; supplies posterior R & L ventricles and posterior ½ of IV septum

b. Left coronary artery : supplies LV, anterior 2/3 of septum (bundle branches)

i. Anterior interventricular (LAD): ant R&L V & anterior ½ IV septum

ii. Left Circumflex branch : between LA&LV; anastomoses w/ posterior IV sulcus a.

1. Left marginal branch : supplies lateral margin of the LV

c. Coronary artery bypass graft (CABG): hook new vessel upstream & connect to vessels distal to the damage, bypassing diseased tissue

i. CA occlusion: LAD: 50%; RCA: 40%; Circumflex branch: 20%; Graft options: 1. Great saphenous vein: (medial leg) *must reverse direction due to valves

2. Internal thoracic (mammary) a.: quick fix (location & high collateral flow)

3. Radial artery: greater longevity (patency) than vein grafts

6

9. Coronary sinus (thebesian valve) : derived from sinus venosus; drains cardiac veins drains into RA via opening to the left of IVC entrance

a. Great cardiac vein : forms in anterior IV sulcus; travels with anterior IV (left anterior descending) artery; joins coronary sinus near L heart margin

b. Middle cardiac vein : occupies posterior IV sulcus; travels with posterior IV artery; enters coronary sinus near RA

c. Small cardiac vein : follows RCA marginal branch; joins coronary sinus near middle cardiac vein junction

10. Atrioventricular valves : prevents blood rushing back into atria upon contraction; a. Free edges protrude into ventricles; big & floppy, requiring firm attachment to

ventricular wall through chordae tendinear & papillary muscles11. Semilunar valves : smaller valves in arterial outflow vessels prevent arterial blood

from rushing back into the ventricles when they relaxa. Small; forced close against each other by blood filling the sinuses

12. Right atrium : larger than left atrium, but thinner walla. Crista terminalis : ventricle muscular ridge running anteriorly along RA wall

from SVC opening to IVC openingi. Juncture of sinus venarum (smooth part of RA composed of former veins) &

more muscular atrium proper (pectinate muscles)b. Musculi pectinati : prominent ridges of atrial myocardium in auricles and RAc. Fossa ovalis : site of former communication between atria

i. Can be open in some congenital heart defects, allowing mixing of oxygenated & unoxygenated blood in atria

ii. Limbus fossa ovalis : closes at birth; opening in inter-atrial wall between RA & LA, allowing blood to cross right into LA

d. Opening for coronary sinus: draining of cardiac veinse. Tricuspid valve : right AV valve with 3 cusps and 3 corresponding papillary muscles

13. Right ventricle : works against low pulmonary circulation systolic pressure (25 mmHg); 1/3 as thick as LV; located right under sternum, most likely to be injured by blunt trauma

a. Trabeculae carnae : small muscular ridges of myocardiumb. Papillary muscles (anterior, posterior, septal): attaches tricuspid v. to chordae tendinaec. Moderator band (septomarginal trabecula): tissue band from septum to

anterior papillary musclei. Contains purkinje fibers: allows papillary muscles to fire slightly

before rest of myocardiumd. Chordae tendinae : attach to papillary muscles; taught to allow proper valve functione. Infundibulum : f. Pulmonic semilunar valve : right SL valve; 3 cuspsg. Anterior cardiac veins : drain anterior surface of RV; open directly into RA

7

14. Left Atrium : smaller than RA with thicker walls; most posterior of the 4 chambersa. Openings for pulmonary veins: oxygenated blood into LAb. Mitral valve : left AV valve with two cusps (anterior, posterior)

i. Stenosis : valve narrowing due to scarring & adhesion of diseases at the commissures pressure in chamber from which blood is being pumped

1. Mitral valve stenosis : pressure & dilation in LA & pul. veinsii. Incomplete valves : lead to regurgitation- increases pressure & dilation

in chamber from which blood was originally pumped1. Tricuspid valve regurgitation : blood in RA, SVC, IVC

15. Left Ventricle : works against systemic circulation high systolic pressure (120mmHg)

a. Chorda tendinae & 2 papillary muscles: prevents blood reflux from ventricle to atria

b. Aortic semilunar valve : left SL valve; three cusps

16. Systole : ventricular contraction AV valves open systemic flow out aorta & pul. trunk

a. Myocardial arteries are compressed during systoleb. S1 (“lub”: AV valves close)

i. Mitral : L 5th intercostal space in midclavicular lineii. Tricuspid : L 5th intercostal space over sternal xiphoid process

17. Diastole : Aorta elastic recoil blood backflow AV valves close myocardium relaxed, coronary artery filling & perfusion

a. S2 (“dub”: semilunar valves close) i. Pulmonary semilunar : L 2nd intercostal space

ii. Aortic semilunar : R 2nd intercostal space18. Conduction System of the Heart:

a. Sino-atrial node (100 bpm): junction of SVC & RA; spontaneous & rhythmical depolarizations (60-80/min) spread & cause atrial contraction

b. Atrioventricular node (50 bpm): in interarterial septum by coronary sinus; delays SA impulse

i. Sympathetic stimulation: conduction speed (stress; exercise)ii. Parasympathetic: conduction (Normal heart control predominately PNS)

c. Atrioventricular bundle (Bundle of His): sole electrical A-to-V connectioni. Left and right bundle branches: descend along septum surfaces to V

d. Purkinje fibers : widespread reticulum delivers impulses to V causing contractioni. Coronary artery disease : inner

(endocardial) surface dies first, including purkinje fibers (last perfused, first to die)

8

19. Heart beat: ~72/min (60)(24) = 103,680/day [~3 billion in 80 year lifespan] a. Sympathetic : fibers from T2-T4, to cardiac plexus, SA node, then cardiac muscle

i. @ SA node: HRii. @ Muscle: ventricular pressure rise, stroke volume

b. Parasympathetic : Vagus nerve (CN X)i. @ SA node: decrease HR

ii. @ AV node: excitability slower transmission possible AV block

iii. ✖ vagal innervation immediate acceleration of heart c. R Vagal & R sympathetic branches end in SA node; L Vagal & L sympathetic in AV node (RAS LAV)

20. Lymphatic drainagea. Right side drains to left, joins thoracic duct joins venous sys at left venous angleb. Left side drains to the right right lymphatic duct

12- Mediastinum

Superior mediastinum: above the T4/5 level to the superior thoracic aperature1. Brachiocephalic veins : union of subclavian & internal jugular (@ L & R venous angles

where thoracic & R lymphatic ducts also drain); joint to form SVCa. Right BCV : (shorter) No valves - assess Jugular Venous Pressure (CVP, RA pressure)

b. Left BCV : (longer; posterior to manubrium) drains upper 2-3 intercostal spaces on left; joined by:i. Left superior intercostal v. (crosses anterior

aortic arch); goes between the two nerves – superficial to vagus, deep to phrenic

ii. Highest posterior intercostal v. (1st intercostal)

c. Inferior thyroid v.s. at union of L & R brachiocephalic v.s. 2. Superior vena cava : formed by L & R brachiocephalic v.; enters RA

a. Superior Vena Cava Syndrome : blockage of SVC by tumor (lung cancer) causing collateral vein dilation

3. Aorta : from LV @ T4-T5 junction; situated left of vertebral column; approaches median line as it descends

a. Ascending : gives rise to R & L coronary arteries arising within the Sinus of Valsalva

b. Passes superiorly to the right, forming aortic arch

9

c. Arch : passes posteriorly and to left, descending along left side of esophagus

i. Right Brachiocephalic trunk : forms right subclavian (to superior extremity) & right common carotid (to head/neck)

ii. Left common carotid artery : to head/neckiii. Left subclavian artery : to superior extremity

1. Aortic Coarctation : if occurs proximal to left subclavian artery origin, adequate collateral circulation does not develop; results in enlarged vessels (internal thoracic, intercostal, epigastric, scapular)

a. Radial artery – elevated BPb. Femoral artery – decreased BP, occurring after radial pulse

iv. Aortic Arch Aneurysm : sac formed by arch dilation; compresses left recurrent laryngeal nerve cough, hoarsness, ipsilateral vocal cord paralysis, dysphagia, dyspnea, downward tug on trachea during systole

v. Variations:1. Left common carotid arising from brachiocephalic trunk (27%)2. L vertebral a. arising from aortic arch (5%)3. Anomalous (retroesophageal) R subclavian artery (difficulty swallowing)

d. Descending (thoracic) aorta : left side of body @T5, descends left to vertebral column posterior to L lung root, midline @T8, passes through aortic hiatus @T11/12, joins greater splenic nerve as it enters abdomen

i. Firmly anchored to posterior body wall by posterior intercostal arteriesii. Parietal (thoracic) branches: Posterior intercostal arteries join

posterior intercostal veins & nerves = neurovascular bundle iii. Bronchial branches enter lung rootiv. Esophageal branches to pericardium & diaphragmv. Pericardial arteries

4. Pulmonary trunk : starts at RV basea. Left & Right pulmonary arteries : deoxygenated blood from RV to lungb. Carina landmark for: Transverse thoracic plane (sternal angle T4/5), L&R pul. artery bifurcation

5. Ligamentum arteriosum : vestige of fetal ductus arteriosus (connect pul. trunk & aortic arch)

where blood was shunted into arterial system when lungs were not functionala. Located at origin of LP artery & aortic arch; point of weakness in traumab. Aorta is relatively fixed in place; heart & lungs are more mobile

i. In trauma, aorta & visceral organs tend to go separate ways - aortic ruptureii. Aortic dissection : inner blood vessel lining torn arterial pressure

into vessel wall aortic lumen; commonly at ligamentum arteriosum6. Thoracic duct : on posterior thoracic wall between azygous vein & aorta

a. Begins in abdomen as cisterna chili [L1-L3]b. Enters thorax posterior to descending aortac. Stays on right of vertebral column; posterior to esophagus @T8d. Ascends to T4, crossing to left aortic side just anterior to anterior longitudinal

ligament, entering the neck to empty into union point of L subclavian v. & L internal jugular v. (L venous angle) forms brachiocephalic v.

10

e. Drains all of body’s lymph except upper right quadrant (right thorax, right upper limb, right side of head/neck) and often left lower lung lobe drain into R lymphatic duct joins R internal jugular & R subclavian veins

7. Mediastinal Lymph Nodes enlarged in Hodgkin’s lymphoma: Virchow’s (sentinel); Paratracheal; Superior/inferior tracheobronchial; Posterior mediastinal; Superior phrenic

INFERIOR mediastinum : below T4/5 level

8. ANTERIOR Mediastinum : Thymus; internal thoracic vessels; sternopericardial ligaments; fat, lymph nodes

9. MIDDLE Mediastinum : a. Phrenic nerves : descend from cervical plexuses, lateral to jugular vein & pericardium

i. innervate diaphragm muscles (motor); sensory to diaphragmatic & mediastinal pleurae (C3,4,5 keeps the diaphragm alive)

10. POSTERIOR Mediastinum :a. ESOPHAGUS : posterior pharynx C6 level to stomach; pierce diaphragm at rib 7/T10 level

i. Constricted in 4 regions, where obstructions may occur:1. C6 (cricopharyngeus (upper esophageal sphincter) – voluntary)

a. Inferior esophageal cardiac sphincter – under control of: Vagal (opens); sympathetic fibers (closes)

2. T2/3 (crossing of aortic arch)3. T4/5 (crossing of L primary bronchus)4. T10 (diaphragm)

ii. Anterior to vertebra C7-T8, thoracic duct, R posterior IC a., azygous & hemiazygous

iii. Posterior to the trachea (C7-T4) & heart base (LA)iv. Transesophageal EKG : pass through esophagus to get clear heart pictures

b. Azygous system of veins : drains thoracic wall from 3rd intercostal space to the subcostal veins; found behind & alongside thoracic duct; begins in abdomen as ascending lumbar veins

i. Provides venous shunts in SVC/IVC pathology (malignancy; DVT)

ii. Azygous vein : (right side; larger) begins at junction of ascending lumbar vein & subcostal vein, passes deep to diaphragm, along right side of thoracic vertebrae, receiving posterior intercostal veins along the way

1. At T8 forms arch over R lung root, enters posterior SVC @ rib 3, draining L superior intercostal vein and 2nd/3rd posterior intercostal spaces into SVC

2. Right superior intercostal vein drains 2nd, 3rd, 4th

right intercostal spaces & then joins azygous

iii. Hemiazygous vein : (left side) really tributaries draining into azygous v.; pass upward, superior & inferior, drain upper & lower intercostal spaces, then join to form one hemiazygous passing behind thoracic duct to empty into azygous vein

11

1. Posterior intercostal veins drain into hemiazygous; join azygous mid-thorax by passing anterior to vertebral column

iv. Accessory hemiazygous vein : passing downward on the leftc. Nerves of Cardiac plexus: cervical cardiac branches from Vagus (CN X; PNS),

Cardiopulmonary (SNS) & Thoracic sympatheticd. Vagal nerves : (PNS) descend from skull lateral to carotid arteries, posterior to heart; innervate

thorax & abdomen viscera esophageal peristalsis; motor to mucous glandsi. Right vagus nerve: posterior to esophagus

ii. Left vagus nerve: anterior to esophagus (LARP – L Ant, R Post)iii. Branches form A&P Esophageal Plexuses: single nerve pierce diaphragm at hiatus

iv. Recurrent laryngeal nerves : not symmetrical; both sensory & motor; damaged from thyroid surgery, mediastinal pathology (aortic aneurisms, enlarged lymph nodes) presenting with increasingly hoarse voice

1. Left recurrent laryngeal n. :posterior to lig. arteriosum & around A. arch;

between trachea & esophagus; innervate larynx muscles for phonation2. Right recurrent laryngeal n. : around R subclavian up to larynx

v. Below diaphragm: renamed A & P gastric nerves

11. 31 segments of the spinal cord with 31 pairs of spinal nerves: 12. 14 White rami communicantes: arise from spinal cord T1 - L2; preganglionic axons13. 31 Gray rami communicantes: exit from paravertebral chain ganglia interconnected by sympathetic trunk

a. Sympathetic trunks : (T1-L3) begin in intermediolateral cell columni. Pre -ganglionic: myelinated; sits in CNS, motor route out to synapse ganglion

ii. Post -ganglionic: unmyelinatedb. Greater splanchnic nerves : from sympathetic chains & thoracic ganglion T5-T10;

postganglionic fibers form plexuses on blood vessels, pass to gut organs (L. entrails); branches:

i. Cardiopulmonary : (T1-4) originate at upper thoracic levels1. Synapse at thoracic ganglia, postganglionic fibers travel

a. To the heart, trachea, esophagus, or,b. Upwards: synapse at cervical ganglia, travel back down as superior,

middle & inferior cardiac nerves to innervate the heart, trachea, esophagus

2. Speed up HRii. Thoracic : first neuron in intermediolateral cell column (T5-T12)

1. Preganglionic (long) passes through sympathetic chain2. Synapses at prevertebral (preaortic) ganglia3. 3 Thoracic splanchnic: Greater (T5-9); Lesser (T10-11); Least (T12)

iii. Also: Lumbar, Sacral, & Pelvic (PNS) Splanchnic nerves

12

13- Anterior Abdominal Wall

1. Abdominal cavity Roof: diaphragm; Floor: none (continuous with pelvic cavity); Surface: surrounded by multilayered abdominal wall

2. Camper’s Fascia : outer fatty layer; continues from abdomen onto thigh’s fatty layera. Passes into scrotum (loosing fat, gaining smooth muscle) becomes Tunica Dartos: wrinkling

3. Scarpa’s Fascia : inner membranous layer; attach to iliac crest; fascia lata inferior to inguinal ligament, allowing free passage into the uppermost thigh deep to SF

a. Fibers to fundiform ligament; Passes into scrotum to become Colle’s Fascia4. Transversalis Fascia : lines cavity deep to abd muscles; forms Internal Spermatic Fascia5. Linea Alba : midline tendinous band formed by aponeurosis of 3 flat abd muscles6. Three flat muscles:

a. External Oblique : most anterior; forms external spermatic fascia; origin from ribs 5-12, interdigitate with

i. Serratus anterior (upper fibers) - terminate on aponeurosis in linea albaii. Latissimus dorsi (lower fibers) - terminate on anterior iliac crest

b. Internal Oblique : origin from lateral half of inguinal ligament & anterior iliac crest, inserts ribs 9-12; contributes to rectus sheath

i. Conjoint tendon (Falx inguinalis): formed by medial fibers of internal oblique and underlying fibers of transversus abdominis aponeurosis

ii. Cremaster muscle : formed by lower internal oblique border at inguinal canal1. Cremaster reflex : contraction pulls up on the side stroked2. Afferent (sensory): ilioinguinal nerve (L1)3. Efferent (motor): genitofemoral nerve (L1/L2)4. NB cremaster muscles has some smooth muscle fibers which

contract under sympathetic stimulation to coldc. Transversus Abdominus : origin from lateral inguinal lig., anterior iliac crest, thoraco-lumbar

fascia, & ribs 5-12; terminates on an aponeurosis which fuses with internal oblique aponeurosisi. Arcuate Line : formed by splitting of the aponeurosis of transversus

d. Contraction action of the 3 flat muscles: Expiration, micturition (urination), defecation, emesis (vomiting), parturition, abdominal content support

i. Contraction of the diaphragm (inspiration) opposes actions of these muscles 7. Two vertical muscles:

a. Rectus Abdominus : origin from pubic crest via two tendons; separated along middle by linea alba; inserts

in cartilages of ribs 5-7 & side of xiphoid process; flexes vertebral column & tenses abdomen; innervated by intercostal nerves 7-12

i. Tendinous intersections : fibrous bands transversing rectus muscle; firmly attached to anterior rectus sheath, but dorsal rectus sheath free of attachments

ii. Linea Semilunaris : lateral border of rectus abdominisiii. Rectus sheath : covering for rectus abdominis from the 3 aponeurosis forming 2 layers

@ Linea Semilunaris; deficient inferior to Arcuate Line on posterior aspect 1. Anterior (ventral) RS : fusion of ant. internal oblique & external

oblique with transversus muscle (below arcuate line)

13

2. Posterior (dorsal) RS: formed by posterior aponeurosis & internal oblique fusion with transversus muscle (above arcuate line)

b. Pyramidalis : small muscle keeps tension on linea alba; innervated by a nerve from T128. Inguinal Region/Peritoneum:

a. Inguinal (poupart’s) ligament : anterior superior iliac spine to pubic tubercle; formed by inferior border of aponeurotic external oblique fibers rolling under lower aponeurosis border; medially forms inguinal canal floor

i. Gives rise to Lacunar (gimbernat’s) & Pectineal (cooper’s) ligamentsb. Inguinal canal : tunnel deep to abd. aponeurosis from the deep to the superficial inguinal ring

i. Transmits spermatic cord (male) & round ligament (female)1. (transversus abdominis muscle does not contribute to cord & testis layers)

ii. Anterior wall: external oblique aponeurosisiii. Posterior wall: transversalis fascia, conjoint tendoniv. Roof: internal oblique transverse abdominal mm.v. Floor: in-curving external oblique apponeurosis

c. External ( SUPERFICIAL ) inguinal ring : formed by termination of (opening in) external oblique at pubic tubercle; bordered by superior & inferior crus of ext. oblique aponeurosis

d. Internal ( DEEP ) inguinal ring : opening in transv. fascia; lateral to inferior epigastic vessels

e. Umbilical folds (5) : abd wall ridges within the transversalis fascia i. Median : urachus (old allantoic duct) connected bladder to umbilical cord

ii. Medial (2) : remnants of umbilical arteriesiii. Lateral (2) : inferior epigastric vessels; anastomose within rectus sheath

with superior epigastric vessels from internal thoracic/subclavian vessels

14

9. Hernia : abd straining forces contents to perforate abd wall (where there is no skeletal muscle); can damage spermatic cord (compression), or contents can be infarcted (strangulation) resulting in gangrene

a. Direct & indirect pass through superficial IR - superior & medial to pubic tubercleb. Indirect inguinal hernia : (congenital) pass through

deep inguinal ring, inguinal canal, and out superficial inguinal ring (same as testes & spermatic cord)

i. Lies above IL & lateral to deep inferior epigastric vessels

c. Direct inguinal hernia : (acquired) asymptomatici. Lies medial to deep epigastric vessels &

above IL in Hesselbach’s triangle1. Ignores deep inguinal ring

ii. Hesselbach’s triangle : rectus abdominus, inguinal lig., deep inferior epigastric a.

d. Femoral hernia : through femoral ring into

femoral canal, BELOW IL; protrusion on thigh anterior to saphenous opening, inferior & lateral to pubic tubercle

e. Lumbar hernia : through lumbar (petit’s) triangle superior to middle iliac crestf. Spiegelian hernias : umbilicus, linea alba, and/or linea semilunaris; mid-clavicular lineg. Also: ventral hernia; incisional hernia

10. Blood supply:a. Superficial vessels : run between Camper’s & Scarpa’s fascia

i. Superficial inferior epigastric ; circumflex iliac; external pudendal vesselsii. Superficial arteries : from femoral artery close to inguinal ligament

iii. Superficial veins : pass through saphenous opening to empty into femoral v.b. Deep vessels :

i. Epigastric: 1. Superior (from internal thoracic a.)2. Inferior (from external iliac, empties into femoral vein)

a. Deep inferior epigastric artery : hernia landmark

15

ii. Deep iliac circumflex vessels : from external iliac arteryiii. Testicular vessels : from anterior aorta

11. Lymphatic drainage:a. Above the umbilicus: Axillary nodesb. Inferior to umbilicus: Superficial Inguinal lymph nodesc. Testis: para-aortic nodes cysterna chili (beginning of thoracic duct)

12. Innervationa. Ilio-hypogastric nerve : (branch of lumbar plexus L1 level) pierces transversus

& internal oblique (antero-laterally); lies posterior to external obliqueb. Ilio-inguinal nerve : (branch of lumbar plexus L1 level) same course as IHG n.

but exits through the superficial inguinal ring and proceeds into scrotumc. Genito-femoral nerve : (branch of lumbar plexus) motor + sensory fibers; enters

anterior abd wall through deep inguinal ring to supply cremaster muscles

14- Back

1. Causes of Low Back Paina. Lumbar strain or sprain (70%); Degenerative changes (10%); Herniated disk

(4%); Osteoporosis compression fractures (4%); Spinal stenosis (3%)b. Spondylolisthesis (2%): anterior slippage of vertebrae or column; may cause nerve damage

i. Pain (back, thigh, buttocks), tightness (hamstrings); stiffness; tendernessii. Causes: congenital; isthmic (fracture); degenerative (arthritic); trauma;

pathological (osteoporosis, infection, tumor); post-surgical1. Spondylolysis : fracture or malformation of pars interarticularis

(region between inferior & superior articular processes)2. Ankylosing Spondylitis : chronic inflame. arthritis; eventual spine fusion – stiff & inflexible3. Pott’s Disease : from hematogenous TB spread to spine; may lead to psoas abscess4. Scoliosis : Four general causes

i. Congenital: malformation of vertebrae or fused ribs during developmentii. Functional: spine normal, abnormal curve develops because of problem elsewhere

iii. Neuromuscular: by poor muscle control/weakness, or paralysis due to diseasesiv. Idipoathic: unknown cause, appears in a previously straight spine

b. Kyphoscoliosis : combination lateral bending & excessive thoracic curvature

5. Range of vertebral column motion limited by: a. Thickness, elasticity, & compression of IV disksb. Shape of facet joints between adjacent vertebraec. Resistance of back muscles & ligamentsd. Bulk of surrounding tissue

6. Vertebral column : a. Kyphosis : anteriorly concave curvature of thoracic & sacral regions (KATS)b. Lordosis : posteriorly concave curvature of cervical & lumbar regions (LPLC)c. Cervical (7): Atlas (C1): no vertebral body - space for dens of Axis (C2)d. Thoracic (12): have 4 costal facets for rib articulation

16

i. Articulate with same number (T6 superior facet articulates with head of rib 6)ii. Thoracic aorta depression on anterior left surface of each vertebrae

e. Lumbar (5): thicker bodies & laminae; two extra sets of processes (mammillary & accessory)

f. Sacral (5, fused): transmits body weight from spine to pelvic girdle

i. Sacral hiatus (S5): lacks laminae; exit of sacral canal; bounded by cornuaii. Sacral groove: between median & lateral crests; contains posterior sacral

foraminaiii. Female sacrum is shorter, wider, and less curved than in males

g. Coccygeal (4, fused): only vertebral bodies, no processes; gluteus max attachment7. Spina bifida : (split spine) incomplete embryonic neural tube closing; some vertebrae not fully formed,

unfused & open allowing spinal cord protrude (occulta), with meninge-filled cyst (mningocele)8. Vertebral body : anterior weight-bearing; separated from other bodies by disks9. Vertebral arch : posterior, encircles & protects spinal cord/meninges

a. 2 Pedicles (lateral): each has superior & inferior vertebral notchb. 2 Laminae (postero-lateral): flat surfacec. 7 bony processes (spinous, transverse, articular): deep back

muscle attachment10. Spinal process : Base of the neck (C7); Scapular spine (T4); Inferior

angle of the scapular spine (T7); Level of the iliac crests (L4); Sacral triangle apex (S3)

11. Intervertebral notch : adjacent notches form intervertebral foramen for spinal nerves & vertebral arteries

a. Spinal Canal : enclosed within intervertebral foramen; protected by ligamentum flavum posteriorly & posterior longitudinal ligament anteriorly

12. Spinal Cord : extends from foramen magnum to second lumbar vertebraa. Gray matter : (cell bodies, dendrites, axons) posterior (dorsal), anterior (ventral), lateral horns

i. Dorsal roots : receives sensory info (afferent: to spinal cord); bipolar;1. Dorsal root ganglia : cell bodies outside cord

ii. Ventral roots : sends motor signals (efferent: away from spinal cord)1. Cell bodies lie in clusters (ganglia) within ventral gray horn2. Unipolar: singular axon leaving cord as part of a ventral rootlet

b. White matter : myelinated; 3 columns (funiculli) divided into sensory or motor tractsc. Spinal nerve : (31 pairs) mix of motor & sensory between rootlets & d/v branches

i. Exits each level through intervertebral foramen (cervical – above respective vertebrae; rest of spine –below), splitting into:

ii. Dorsal primary rami : motor to back, sensation to posterior trunk1. Also send sensory branches to IV joints

iii. Ventral primary rami : motor & sensation to abd & limb muscles

d. Cauda medullaris : spinal cord distal to L2 tapers to a fibrous strandi. Filum terminale : fibrous extension anchors cord limiting movement in canal

ii. L3-Co1 nerve rootlets travel down parallel to filum terminalee. Cauda equina : bundle of nerve rootlets below conus medularisf. Lumbar cistern : subarachnoid space between L2 & S2 (dural sac termination)

13. Meninges :

17

a. Epidural space : contains venous plexuses, fat, and loose connective tissuei. Caudal Epidural nerve block : anesthesia injected into epidural space

diffuses though arachnoid granulations into CSFb. Dura : outermost membranous CT layer; helps anchor spinal cordc. Subdural space : separates dura from arachnoid

d. Arachnoid : intermediate membranous layer of CT; covers cauda equinai. Arachnoid granulaitons pump CSF out of subarachnoid space, to venous

ii. Denticulate ligaments : arachnoid extensions that connect to dura (stability)e. Subarachnoid space : filled with arachnoid trabeculae (CT strands) & CSF

i. Lumbar puncture site : between L3/L4; contains CSF, cauda equina, & filum terminale; located at upper edge of iliac crest

f. Pia : innermost membranous CT layer, adheres to cord; coats each nerve; anchors the cord, preventing lateral deflection; continues as filum terminale

14. Anterior (1) & Posterior (2) spinal arteries: (branches of vertebral a.) run longitudinally on pia matter (pierce arachnoid & dura), and supply spinal cord

a. Anterior & posterior radicular a. : collateral circulation between spinal a. & intercostal a.15. Internal (epidural) venous plexus: extends from pelvis to brain; potential route for

prostate cancer metastasis to spine & skull/brain16. Joints of the back:

a. Intervertebral disk : largest in lumbar region, thickest in cervical & lumbari. Annulus fibrosus : outer, washer-like, fibrous CT & fibro-cartilage

ii. Nucleus pulposus : fills AF hole; highly cartilaginous & elastic, high water content; avascular, receives nourishment via diffusion from AF

1. Progressively dehydrates with age reduction in stature iii. Stenotic lumbar vertebrae: with age, ligaments (flavum) & bones thicken

narrowing spinal canal squeezes nerves pain, numbness in back & legs

b. Anterior longitudinal ligament : flat vertically oriented fibers; prevents hyperextensionc. Posterior longitudinal ligament : narrow; against anterior surface of vertebral canal covering posterior

of all vertebral bodies (except C1) & disks; prevents hyperflexion & disk herniation into canal

d. Ligamentum flava : between adjacent laminae in posterior canal (anterior surface of superior lamina to posterior surface of inferior lamina)

i. Preserves natural shape & curvatures, assists in maintaining upright posture after flexion

ii. Hypertrophy of ligamentum flava : causes spinal canal stenosis (narrowing) severe back & lower limb pain

e. Interspinous ligament : between adjacent spinous processes, from ligamentum flavum anteriorly to supraspinous ligament posteriorly

f. Supraspinous ligament : tough, vertical cord running along spinous processes tips; prevents hyperflexion

g. Sacroiliac ligaments : (anterior & posterior) stability between spine & ilium

18

17. Muscles of the back:a. Superficial layer : move upper extremity; not true muscles of the back

i. Trapezius : moves scapula; innervated by CNXI (spinal accessory n.)ii. Latissimus dorsi : extends & adducts upper limb; Thoracodorsal n. (brachial plexus)

b. Intermediate layer : respiratory muscles (insert onto ribs)i. Innervated by dorsal scapular nerve (brachial plexus)

1. Levator scapulae : elevate & adduct scapula2. Rhomboid major/minor : move scapula medially

ii. Innervated by intercostal nerves (T1, T2, T10/11)1. Serratus posterior superior : raises ribs in inspiration2. Serratus posterior inferior : lowers ribs in expiration

c. Deep layer : all act to extend trunk (straighten back) when acting bilaterally; true back muscles: innervated by dorsal primary rami

i. Splenius : thin, flat, ‘bandage-like’ muscleii. Erector spinae : fibers parallel to vertebrae column covered by

thoracolumbar fascia; when acting unilaterally laterally flexes column 1. Form two longitudinal bulges on column sides & extend into neck2. Iliocostalis lumborum : most lateral3. Longissimus thoracis : intermediate4. Spinalis thoracis : most medial (closest to spinous processes)

iii. Transversospinalis : deep to erector spinae; fibers angled up and toward spines; parts differ in how many vertebrae they cross:

1. Semispinalis : 5 or 62. Multifidius : 3 or 4; laterally flexes & rotates column

(unilaterally); stabilize column as other muscles contractiv. Rotatores : (long & short): stabilize & assist with local extension & rotationv. Levator Costarum : elevate ribs; vertebral column lateral flexion

19