Block 2: Back and Thorax

Back

Know the primary and secondary curvatures of the spine, as well as the number of vertebrae in each curvature. For the secondary curvatures, at what age do each develop?

• cervical curvature (concave): 7 vertebrae, C1- C7

  • secondary: form when we are in infants and start to move, start picking up their head

• thoracic curvature (convex): 12 vertebrate, T1-T12

  • primary: born with

• lumbar curvature (concave): 5 vertebrae. L1-L5

  • secondary: when babes stand up

• sacral curvature (convex): 5 fused vertebrate sacrum

  • primary: born with

• coccyx: 4 fused vertebrae

Know the Clinical significance of the following: scoliosis, kyphosis, and lordosis

• scoliosis:

  • abnormal curvature of the thoracic curvature,

  • spine is S or C shape

  • if caught during childhood can put on a brace

• kyphosis:

  • thoracic spine curves outward

  • apart of the aging process

  • loss in muscle tonicity and tissue and bone age

• lordosis:

  • “swoyvac“ lumbar spine curves inward

  • can be born with or do a lot of activities that manipulate the spine, like gymnasts

Know the common and unique characteristics for each type of vertebrae.

cervical vertebrate (smallest and lightest)

• Ccervical vertebrae (smallest and lightest)

• C3-C7

• rransverse foramen

• body is wider

• spinous process is short and is bifid

• vertebral foramen large and triangular

• transverse processes

• superior articular facets face superposteriosly

C1 (atlas)

• lacks a spinous process

• supports the skull

• superior articular facets receive the occipital condyles

• allows flexion and extension of neck (nodding yes)

• lateral masses

• anterior/posterior arch/tuberculate

C2 axis

• has body and spinous process

• dens (odontoid process)

• formed the fusion of the body of the atlas and axis '

• acts as a pivot for rotation of the atlas and skull

C3-C7

???

thoracic vertebrae

• all articulate with ribs

• heart shaped bodies from the superior view

• each side of the body of T1-T10 bears demifacets for articulation with ribs

• T1 has a full facet for the first rib

• T10-T12 have only a single facet

• spinous processes are long and point inferiorly

• vertebral foramen are circular

• transverse processes articulate with tubercles of ribs

• superior articular facets point posteriorly, outwards

• inferior articular facets point anteriorly, outwards

• allows rotation and prevents flexion and extension

• costo-vertebral joints:

  • the head of each rib articulates with 2 adjacent vertebrae and the disk between them

• costo-transverse joints:

  • between the tubercle of the rib and transverse process of its own vertebra

lumbar vertebrae

• bodies are thick and robust (weight of entire body)

• transverse process are thin and tapered (not receiving ribs)

• spinous processes are think and blunt and pointed posteriorly

• vertebral foramina are triangular

• superior and inferior articular facets directly medially

• allows flexion and extension - rotation prevented

sacrum

• shaped the posterior wall of pelvis

• formed 5 fused vertebrae

• superior surface articulates with L5

• interiorly articulates with coccyx

• sacral promontory

• where the first sacral vertebrae bulges into pelvic cavity

• center of gravity is 1cm posterior to sacral promontory

• ala:

  • develops from fused rib elements

• anterior sacral foramina:

  • spinal nerves passing through

coccyx

• tailbone

• formed from 3-5 fused vertebrae

• offers only slight support to pelvic organs

• Injury to coccygeal vertebrae

  • falling on buttocks, specially in females

  • painful delivery

• coccydynia:

  • pain in coccyx

What are the contents of the following: vertebral foramen, intervertebral foramen, and transverse foramen of the cervical vertebrae?

• vertebral foramen:

  • spinal cord

  • dorsal

  • ventral roots

  • meninges

  • CSF

  • fat

• intervertebral foramen

  • spinal nerves branching off spinal cards

• transverse foramen of cervical vertebrae

  • transverse foramina;

  • vertebral artery (pass through the 6 upper cervical vertebrae

  • enter skull through the foramen magnum (extra: converge and form the conbasler artery and participate in the formation of circle of willis and internal carotid artery)

What is the Clinical significance of the “Hangman Fracture?” Which specific vertebrae is effected?

• hangman fracture:

  • when someone is hanged, at the end of rope= arch of axis pushes the dens posteriorly and compresses the brain stem which causes death.

  • fracture of dens is a common fracture of C2 when we have traumatic injury of the neck.

What is the function of the intervertebral disc? What does it mean for a disc to herniate? What is the most common site of herniation?

/

• function:

  • acts as shock absorber

  • is compressible

  • permits slight degree of movement of the vertebrae over each other

  • makeup approx. 20% of the total length of the vertebral column (taller in the mornings)

• herniation:

  • injury to the back, abnormal displacement of tissue

  • mostly posterolaterally where annulus fibrosus is thinner

• four stages:

  • degeneration, prolapse, extrusion, sequestration

Know the location and function of the following muscles: trapezius, latissimus dorsi, and levator scapula.

trapezius:

• location: either side of upper back

  • elevation, retraction, and rotation of scapula

  • helps in adduction and slight elevation of arm'

    • innervation: spinal root of accessory nerve and c3-c4

  • descending: from external occipital protuberance, superior nuchal line, and ligamentum nuchae

    • insertion: lateral 3rd of clavicle

  • transverse: from C7-T3 spinous process

    • insertion: to clavicle and scapula

  • ascending: from T3-T12 spinous process

    • insertion: spine of scapula

latissimus dorsi (coughing muscle):

• location: on lower back, extending from below the shoulder balde down to teh pelvis

  • adduction and lowering the arm,

  • medial rotation and extension of the arm(humerus),

  • raises the body toward the arm when climbing

    • innervation: by thoracodorsal nerve C6,C7,C8

• vertebral part T7-T12 spinous process

• thoracolumbar part (from fascia)

• lliac part (from iliac crest)

• costal part: 10-12th rib

• inferior angle of scapula

  • insertion: crest of the lesser tubercle of humerus

levator scapula:

• location: runs from neck to the shoulder blade

  • elevates the scapula

    • innervation: innervated by dorsal scapular nerve C4-C5

  • the transverse process of C1-C4

    • insertion: superior angle of the scapula

Know the location, function, and innervation of the rhomboid major and minor.

• location: located in the upper back

• function: press the scapula to the thoracic wall, retraction of scapula medially

• innervation: dorsal scapular nerve (C4-C5)

  • minor: spinous process of C6-C7

    • insertion: medial margin scapula

  • major: spinous process of T1-t4

    • insertion: median margin of scapula

Which muscles are included in the erector spinae? What are their locations?

intermediate intrinsic back muscles

• lateral group muscles: iliocostalis lumborum, thoracis, cervicis; and longissimus thoracis, cervicis, capitas

• medial group muscles: spinalis thoracis and cervicis (capitas might be missing)

What are the boundaries and contents of the suboccipital triangle?

• boundaries: rectus capitis posterior major, obliques capitalist superior and inferior

• contents: suboccipital nerve (dorsal ramus of C1), III part of vertebral artery, and occipital venous plexus

At what level of the vertebral column does the spinal cord end? How is this information relevant when performing a lumbar puncture?

• spinal cords end at L1-L2= conus medullaris.

  • tapers off and spinal nerves come off of it called the cauda equina (horse hairs: course and thick)

  • spinal cord is anchored on the coccyx→ from a fine piece of pia mater.

• lumbar puncture: done at L3-L5 region.

  • the intercristal line (iliac crests) is at the level of L4 approximately (safe region).

  • here you collect the CSF (do not try to puncture spinal cords because it will severe axons) at this safe spot L4.

On the vertebral column, where is the site for epidural anesthesia? Why would this be given?

• caudal epidural: given at sacral hiatus point, and diffuse into S1-S2 region.

  • why: for labor and delivery, the nerve in the primnimeal area; pudendal nerve that innervates the muscles of the pelvic floor.

  • manage pain and block pudendal nerves.

  • given through knee scoping and awake

• epidural anesthesia: is given through the sacral hiatus to block pelvic nerves

  • also given through knee scoping and awake, pain management technique

What is the Clinical significance of spina bifida and spina bifida occulta?

• spina bifida occulta:

  • folic acid substitution in conception and during pregnancy decreases the risk of spina bifida.

  • closed asymptomatic NTD in which some of the vertebrae are not completely closed.

Thorax

What is the Clinical significance of fractures in the 1^st, middle, and lower rib cage?

• first rib:

  • superior surface and 2 grooves for subclavian artery + lower brachial plexus and subclavian vein

  • is atypical bc its flattened from the superior to inferior and is quite board bc its flattened from the superior to inferior and is quite broad

  • rarely fractured (danger to vessels) typically the clavicle would be fractured as well if the first rib was fractured

• middle rib:

  • most commonly fractured

• lower rib:

  • may damage the pleura and abdominal viscera(kidney,liver,spleen)

Know the parts of the sternum and rib. For the rib, know which structures articulate with the body and transverse process of the vertebrae.

• sternum:

  • top part: the manubrium, the line that cuts: sternal angle

  • middle part: body, then the bottom piece will be the xiphisternal joint attaching to the xiphoid process

• ribs:

  • 12 ribs in total 7 true 5 false ribs 11th & 12th are floating ribs

  • the tubercle of the rib articulates with the transverse costal facet or the transverse process of the same thoracic vertebra of the same number.

  • the head of the rib articulates with the superior costal facet that is on the body of the vertebra

Which muscles elevate the thoracic cage?

• scalene muscles (posterior, anterior, and middle)

• pectoralis major/minor

• sternocleidomastoid

In regards to the ribs, where is the location of the intercostal vessels and nerves? What is the Clinical significance of this information?

• location: intercoastal groove therefore each of the muscles has a nerve that innervates them. the intercostal vessels pass beneath the inferior border of the ribs

• clinical significance:

  • coarctation of aorta:

    • all theses arteries are dilated (eben braches off the subclavian artery)

    • IMA is associated with coarctation of the aorta because it is one of the 3 branching points that can become dilated

    • any structures that it would give blood to can be compromised due to the increase in the pressure

  • thoracentesis:

    • produce performed due to the increase of fluid in thoracic, involves using a needle to extract fluid

Know the internal structures of the breast, including the importance of the retromammary space and suspensory ligaments.

• internal structure:

  • situated in the superficial fascia and is separated from pectoral muscles by a deep (pectoral) fascia

  • composed of lobules of 15-20 glandular tissue (mammary gland); each lobule is drained by a lactiferous duct which opens into the nipple

  • lactiferous sinus

  • mammary gland is an apocrine gland (modified sweat gland)

  • during puberty, the lactiferous ducts undergo branching; an increase in fat deposition leads to breast enlargement

• retromammary space

  • between the breast and deep fascia, a tumor here may contract the pectoralis major

• suspensory ligaments

  • extend from the skin to deep fascia and support the breast; their invasion by tumor may cause dimpling of skin PROVIDES SUPPORT FOR BREAST

Which hormones are responsible for breast growth, and what specific structures are under the influence of each?

• estrogen:

  • growth of tubular system which is the lactiferous ducts

  • estrogen coming from ovaries helps develop the tubular system

• progesterone:

  • development of milk secreting lobules which is seen durong post ovulation and pregnant women

What is the Clinical significance of the following: Breast cancer, mastectomy, and gynecomastia?

• breast cancer:

  • cancer can be indicated by what is called orange peel: this is dimpling (invagination) thickening of the skin especially if the lymphatic system is blocked

  • blockage due to suspensory ligaments are being pulled on, invasive resulting in blockage of lymphatic drainage

• mastecomy:

  • is the removal of breast the long thoracic nerve (holds scapula in place) could be in danger which results in "winged scapula"

  • lumpectomy: most of the time if the cancer lump is removed via lumpectomy. specimen sent off to pathology in order to determine if margins are clear in order to make sure they got all of the cancer, whereas a biopsy (needle biopsy) is different.

• gynecomastia (Klinefelter syndrome):

  • XXY; most common congenital cause of infertility in males

What is the Clinical significance of a sucking and tension pneumothorax?

• sucking:

  • air enters and leaves the pleural cavity; mediastinal flutter \

  • mediastinal flutter (mediastinum shifted toward the normal side in inspiration and to the injured side in expiration)

• tension:

  • air enters the pleural cavity but not leaving it

  • mediastinal shift: the mediastinum is shifted toward the normal side, increased intrathoracic pressures

  • patient has dyspnea and/or cyanosis

  • hyper-resonant percussion tone, radiolucent area in lung, in radiography

Know the types of pleural effusion: hydrothorax, pyothorax, chylothorax, and hemothorax.

• pleural effusion: fluid in the pleural cavity

  • hydrothorax:

    • congestive heart failure

  • pyothorax:

    • infection pus

  • chylothorax:

    • injury to thoracic duct

  • hemothorax:

    • blood in pleural cavity

    • injury to right subclavian vein during catheterization

What is the Clinical significance of pleuritis and thoracocentesis?

• pleuritis (pleurisy): inflammation of the pleura

  • pain only if parietal pleura is involved, not the visceral layer

  • puncturing the intercostal space: always go superior to the inferior rib

• thoracocentesis (pleural tap): a procedure to drain pleural fluid in pathological conditions, performed posterior to the midaxillary line while patient is seated

  • first determine the fluid level by percussion and go 1-2 intercostal spaces below the fluid level but, not below the 9th intercostal space (danger to injure the liver on the right side)

Know the innervation of the lungs.

• sympathetic: from 5-6 upper thoracic

  segments; postsynaptic fibers end on SA and AV nodes

• action: increases heart rate and contraction force, coronary dilatation

• parasympathetic: vagus nerve terminates on many small ganglia on the heart

• action: decreases heart rate and force and vasoconstrictor coronary arteries

Know the tracheal divisions and bronchopulmonary segments within each lung, noting any unique features.

trachea: main bronchus and lobar bronchi

• is 12 cm long and 2 cm wide, from C6 to T4

  • trachea contains C-shaped cartilage rings, posteriorly, it has the muscle layer covered by the mucus membrane

• trachea divides to:

  • main bronchi (primary bronchus) at T4 (sternal angle), carina; right main i shooter (2.5 cm), wider and more vertical; left main is longer (5 cm), less steep

    • main bronchi divide into: lobar bronchi (secondary bronchus)

    • lobar bronchi divide into segmental bronchi (tertiary bronchus)

    • bronchopuolmonary segments (10 on each side)

• segmental bronchus

• branch of pulmonary artery

• branch of bronchial artery

• tributaries of the pulmonary vein are found in the periphery between the adjacent bronchopulmonary segments

• surgical landmarks

Understand the process of gas exchange within the lung in regards to the blood-air barrier

• little sacs called alveoli → oxygenated air fills the little alveoli and each sac has a branch of artery and a branch of vein interacting with it.

• fluid in sacs called surfactant secrets by an air cell, secretes the surfactant (because water is the universal solvent) so it makes easier gas exchange if dissolve gas in water to get across the blood air barrier.

• passive diffusion where gas exchange goes from higher concentration to lower concentration.

• oxygen is higher in the alveoli so it moves from the alveoli in higher concentration to the blood where it is in lower concentration.

• carbon dioxide goes from higher concentration to lower concentration

Know the pulmonary circulation pathway

• deoxygenated blood from the right ventricle of the heart goes into the pulmonary trunk and pulmonary arteries and to the right and left lungs; blood is oxygenated and comes back to the heart (the left atrium), usually by means of 2 pulmonary veins.

  

Know the layers of pericardium and heart wall

• pericardium- double wall of serous membrane covering the heart; 1-fibrous 2-serous

• serous membrane- two layers A-parietal, B-visceral

• pericardial cavity- space between the two layers of serous membrane, contains pericardial fluid

• visceral pericardium (epicardium)- closely attached to the heart

• 3 layers:

  • epicardium

  • myocardium (main mass)

  • endocardium

What is the Clinical significance of the following: pericarditis and cardiac tamponade?

• pericarditis: inflammation of the pericardium, usually from infection. swells and rubs against the heart that caused severe pain, friction rub

• cardiac tamponade: occurs when you have a heart attack and is quite severe bc it was built up, coming up for awhile bc there is blocked coronary arteries, death of cardiac cells, so when it happens the heart wall splits, so blood is coming from inside one of the chambers and out. Then blood fills the pericardial cavity sac and impedes the heart beating. Can remove the fluid with a pericardiocentesis: 5th or 6th left intercostal space near sternum

Know all the branches of the left and right coronary arteries.

• coronary arteries: functional end arteries

• right coronary artery: supplies right atrium

• right marginal artery: supplies both ventricles

• posterior interventricular artery: supplies both ventricles and posterior part of interventricular septum

• left coronary artery:

  • anterior interventricular artery: supplies both ventricles and interventricular septum

  • circumflex branch: supplies the left atrium, left surface of the heart, and let ventricle

  • left marginal artery: a branch of circumflex artery, supplies left ventricle

    • in 40% cases, the SA node and eve AV node and bundle of HIS are supplied by left coronary artery

Know the venous drainage of the heart.

• the main cardiac veins drain into coronary sinus:

  • great cardiac vein: lies in the anterior interventricular groove

  • middle cardiac vein: lies in the posterior interventricular groove

  • small cardiac vein: lies in right coronary groove (2 and 3 drain most of the right coronary artery blood)

  • posterior vein of the left ventricle: on inferior and posterior surface

• left marginal vein

• anterior cardiac veins: (several on the right ventricle) usually enter the right atrium

• smallest cardiac veins (thesbesian veins): begin in the myocardium and open directly into heart chambers, mainly atria; also carry blood to the myocardium

Know the blood flow pathway through the heart. Be able to identify each structure that blood would pass as it travels through the heart.

• superior/inferior vena cava or coronary sinus → right atrium → right ventricle through tricuspid valve → go through pulmonary valves into pulmonary trunk → pulmonary arteries that branch into the left and right lungs → red blood cells go to alveoli, release carbon dioxide and pick up oxygen → pulmonary veins bring blood back to heart from the lungs → coming into left atrium into bicuspid/mitral valve into left ventricle → goes into aortic semilunar valve → enters systemic circulation into aortic valve

What is the Clinical significance of rheumatic fever?

• acute inflammation as a result of complication of chronic tonsillitis or pharyngitis by streptococcus infection

• characterized by arthritis, chorea, skin involvement (erythema), subcutaneous nodules, and carditis

• nodules on the valve cause irregular blood flow, valvular incompetence (blood regurgitation causing murmur

• may cause stenosis (mitral stenosis)

Know the conduction system pathway of the heart.

• 1. intrinsic impulse- conducting system of the heart: heart contains a specialized muscle tissue (the impulse conducting system) which spontaneously generates rhythmic impulses

• 2. sinus (sinoatrial) node (keith flack node): pacemaker (impulse frequency:70)

• network of muscle cells

  • lies anterior margin of orifice of SVC, from which the impulse reaches the AV node

• 3. atrioventricular (aschoff tawara) node: situated in right atrium (interatrial septum) on the ventricular side of orifice of coronary sinus (impulse frequency: 50-60/min)

• 4. bundle of his (atrioventricular bundle): runs through the interventricular septum beneath the endocardium to the base of pupillary muscles (impulse frequency: 25-45/min)

• 5. purkinje fibers:terminal fibers of the bundle of His, merge with the cardiac muscles

What are the disorders of the conduction system

• arrythimas: variation from normal heart rhythm

  • ventricular fibrillataion: rapid, random firing of electrical impulses in the ventricles

  • atrial fibrillation: impluslses circle within atrial myocardium, stimulating AV node

What are the innervations of the heart?

• Sympathic: from 5-6 upper thoracic segments; postsynaptic fibers end on SA and AV nodes

• Action: increases heart rate and contraction force, coronary dilatation

• Parasympathic: Vagus nerve terminates on many small ganglia on the heart

• Action: decreases heart rate and force and vasoconstrictor coronary arteries

What structures would be found in the supracardiac mediastinum?

• mediastinum- the space between the right and left lungs

• 5 layers of structures:

  • thymus

  • great veins related to heart, the phrenic nerves, the thoracic duct and lymphatic trunks

  • arch of aorta including its branches and the vagus nerves,

  • sympathetic and parasympathetic nerves to the heart (cardiac plexus)

  • trachea and its bifurcation

  • esophagus, the recurrent laryngeal nerves

Know the Congenital Heart Defects

• Ventricular septal defect.:

  • The superior part of the interventricular septum fails to form; thus, blood mixes between the two ventricles. More blood is shunted from left to right because the left ventricle is stronger. 1/500

• Transposition of the great vessels;

  • Aorta comes from right ventricle; pulmonary trunk from left. Results when the bulbus cordis does not divide properly. Unoxygenated blood passes repeatedly around systemic circuit, while oxygenated blood recycles around the pulmonary circuit. 1/1000

• Coarctation of the aorta:

  • A part of the aorta is narrowed, increasing the workload of the left ventricle. 1/1500

• Tetralogy of Fallot.:

  • Multiple defects (tetra = four): (1) Pulmonary trunk too marrow and pulmonary valve stenosed, resulting in (2) hypertrophied right ventricle; (3) ventricular septal defect; (4) aorta opens from both ventricles. 1/2000