Anatomy- Thorax (BRS)

Question 1

Thoracic Inlet

Answer 1

is small and kidney shaped. The boundaries of the thoracic inlet are the manubrium anteriorly, rib 1 laterally, and thoracic vertebrae posteriorly.

Question 2

Thoracic outlet

Answer 2

is large and is separated from the abdomen by the diaphragm. The boundaries of the thoracic outlet are the xiphoid process anteriorly, costal cartilages 7–10 and rib 12 laterally, and T12 vertebra posteriorly.

Question 3

Diaphragm innervation

Answer 3

phrenic nerves (ventral primary rami of C3–5), which provide motor and sensory innervation.

Question 4

sensory innervation to the periphery of the diaphragm

Answer 4

Sensory innervation to the periphery of the diaphragm is provided by the intercostal nerves.

Question 5

Lesion of phrenic n.

Answer 5

paralysis and paradoxical movement of the diaphragm

Question 6

Typical Ribs Structures

Answer 6

■ Typical ribs are ribs 3 through 9, each of which has a head, neck, tubercle, and body (shaft). ■ The head articulates with the corresponding vertebral bodies and intervertebral disks and supraadjacent vertebral bodies. ■ The body (shaft) is thin and flat and turns sharply anteriorly at the angle and has a costal groove that follows the inferior and internal surface of a rib and lodges the intercostal vessels and nerves. ■ The tubercle articulates with the transverse processes of the corresponding vertebrae, with the exception of ribs 11 and 12.

Question 7

False Ribs

Answer 7

■ Are the lower five ribs (ribs 8–12); ribs 8 to 10 are connected to the costal cartilages immediately above, and thus, the 7th to 10th costal cartilages form the anterior costal arch or costal margin.

Question 8

True Ribs

Answer 8

Are the first seven ribs (ribs 1–7), which are attached to the sternum by their costal cartilages.

Question 9

Thoracic outlet syndrome

Answer 9

compression of neurovascular structures in the thoracic outlet (a space between the clavicle and the first rib), causing a combination of pain, numbness, tingling, or weakness and fatigue in the upper limb caused by pressure on the brachial plexus (lower trunk or C8 and T1 nerve roots) by a cervical rib (mesenchymal or cartilaginous elongation of the transverse process of the seventh cervicalvertebra). A cervical rib may also compress the subclavian artery in the thoracic outlet, resulting in ischemic muscle pain in the upper limb. Compression on the neurovascular bundle occurs as a result of cervical ribs or abnormal insertions of the anterior and middle scalene muscles.

Question 10

Rib fractures

Answer 10

Rib fractures: Fracture of the first rib may injure the brachial plexus and subclavian vessels. The middle ribs are most commonly fractured and usually result from direct blows or crushing injuries. The broken ends of ribs may cause pneumothorax and lung or spleen injury. Lower rib fractures may tear the diaphragm, resulting in a diaphragmatic hernia.

Question 11

First Rib

Answer 11

■ Is the broadest and shortest of the true ribs. ■ Has a single articular facet on its head, which articulates with the first thoracic vertebra. ■ Has a scalene tubercle for the insertion of the anterior scalene muscle and two grooves for the subclavian artery and vein.

Question 12

Second rib

Answer 12

■ Has two articular facets on its head, which articulate with the bodies of the first and second thoracic vertebrae. ■ Is about twice as long as the first rib.

Question 13

Sternocoastal Joints

Answer 13

Are the articulation of the sternum with the first seven cartilages. The sternum (manubrium) forms synchondrosis with the first costal cartilage, whereas the second to seventh costal cartilages form synovial plane joints with the sternum.

Question 14

Costochondral Joints- Type

Answer 14

■ Are synchondroses in which the ribs articulate with their respective costal cartilages.

Question 15

Subcostal n

Answer 15

The anterior primary ramus of the 12th thoracic spinal nerve is the subcostal nerve, which runs beneath the 12th rib.

Question 16

Intercostal nerves

Answer 16

■ Are the anterior primary rami of the first 11 thoracic spinal nerves. The anterior primary ramus of the 12th thoracic spinal nerve is the subcostal nerve, which runs beneath the 12th rib. ■ Run between the internal and innermost layers of muscles, with the intercostal veins and arteries above (veins, arteries, nerves [VAN]). ■ Are lodged in the costal grooves on the inferior surface of the ribs. ■ Give rise to lateral and anterior cutaneous branches and muscular branches.

Question 17

Intercostal nerves run between these two layer

Answer 17

■ Run between the internal and innermost layers of muscles, with the intercostal veins and arteries above (veins, arteries, nerves [VAN]). ■ Are lodged in the costal grooves on the inferior surface of the ribs. ■ Give rise to lateral and anterior cutaneous branches and muscular branches.

Question 18

Intercostal nerves give rise to

Answer 18

Give rise to lateral and anterior cutaneous branches and muscular branches.

Question 19

Intercostal n

Answer 19

Usually arises from the first part of the subclavian artery and descends directly behind the first six costal cartilages, just lateral to the sternum. ■ Gives rise to two anterior intercostal arteries in each of the upper six intercostal spaces and terminates at the sixth intercostal space by dividing into the musculophrenic and superior epigastric arteries.

Question 20

Pericardiophrenic a

Answer 20

Pericardiophrenic Artery ■ Accompanies the phrenic nerve between the pleura and the pericardium to the diaphragm. ■ Supplies the pleura, pericardium, and diaphragm (upper surface).

Question 21

Anterior Intercostal Arteries

Answer 21

Anterior Intercostal Arteries ■ Are 12 small arteries, 2 in each of the upper 6 intercostal spaces that run laterally, one each at the upper and lower borders of each space. The upper artery in each intercostal space anastomoses with the posterior intercostal artery, and the lower one joins the collateral branch of the posterior intercostal artery. ■ Provide muscular branches to the intercostal, serratus anterior, and pectoral muscles.

Question 22

Anterior perforating branches

Answer 22

Anterior Perforating Branches ■ Perforate the internal intercostal muscles in the upper six intercostal spaces, course with the anterior cutaneous branches of the intercostal nerves, and supply the pectoralis major muscle and the skin and subcutaneous tissue over it. ■ Provide the medial mammary branches (second, third, and fourth branches).

Question 23

Intercostal muscles

Answer 23

INTERCOSTAL MUSCLES 1. The intercostal muscles are thin multiple layers of muscle that occupy the intercostal spaces (1–11) and keep the intercostal space rigid during inspiration or expiration. 2. The external intercostal muscles elevate the ribs and play a role in inspiration during exercise or lung disease. 3. The internal intercostal muscles play a role in expiration during exercise or lung disease. 4. The innermost intercostal muscles are presumed to act with the internal intercostal muscles. 5. The intercostal vein, artery, and nerve run between the internal intercostal muscles and innermost intercostal muscles.

Question 24

Musculophrenic Artery

Answer 24

Musculophrenic Artery ■ Follows the costal arch on the inner surface of the costal cartilages. ■ Gives rise to two anterior arteries in the seventh, eighth, and ninth spaces; perforates the diaphragm; and ends in the 10th intercostal space, where it anastomoses with the deep circumflex iliac artery. ■ Supplies the pericardium, diaphragm, and muscles of the abdominal wall.

Question 25

Superior Epigastric Artery

Answer 25

Superior Epigastric Artery ■ Descends on the deep surface of the rectus abdominis muscle within the rectus sheath; supplies this muscle and anastomoses with the inferior epigastric artery. ■ Supplies the diaphragm, peritoneum, and anterior abdominal wall.

Question 26

Clavipectoral Fascia

Answer 26

Clavipectoral Fascia ■ Extends between the coracoid process, clavicle, and the thoracic wall and envelops the subclavius and pectoralis minor muscles. Its components are (1) the costocoracoid ligament, which is a thickening of the fascia between the coracoid process and the first rib; (2) the costocoracoid membrane, which lies between the subclavius and pectoralis minor muscles and is pierced by the cephalic vein, the thoracoacromial artery, and the lateral pectoral nerve; and (3) the suspensory ligament of the axilla, which is the inferior extension of the fascia and is attached to the axillary fascia, maintaining the hollow of the armpit.

Question 27

Axillary Fascia

Answer 27

Axillary Fascia ■ Is contiguous anteriorly with the pectoral and clavipectoral fasciae (suspensory ligament of the axilla), laterally with the brachial fascia, and posteromedially with the fascia over the latissimus dorsi. ■ Forms the floor of the axilla and is attached to the suspensory ligament of the axilla that forms the hollow of the armpit by traction when the arm is abducted.

Question 28

Axillary Sheath

Answer 28

Is a tubular fascial prolongation of the prevertebral layer of the deep cervical fascia into the axilla, enclosing the axillary vessels and the brachial plexus.

Question 29

Lymphatic drainage of the thorax

Answer 29

Sternal or parasternal nodes (internal thoracic) intercoastal nodes Phrenic nodes

Question 30

Mediastinum

Answer 30

■ Is an interpleural space (area between the pleural cavities) in the thorax and is bounded laterally by the pleural cavities, anteriorly by the sternum and the transversus thoracis muscles, and posteriorly by the vertebral column (does not contain the lungs). ■ Consists of the superior mediastinum above the pericardium and the three lower divisions: anterior, middle, and posterior.

Question 31

Superior mediastinum boundaries

Answer 31

Superior Mediastinum ■ Is bounded superiorly by the oblique plane of the first rib and inferiorly by the imaginary line running from the sternal angle to the intervertebral disk between the fourth and fifth thoracic vertebrae.

Question 32

Superior mediastinum contains

Answer 32

■ Contains the superior vena cava (SVC), brachiocephalic veins, arch of the aorta, thoracic duct, trachea, esophagus, vagus nerve, left recurrent laryngeal nerve, and phrenic nerve. ■ Also contains the thymus, which is a lymphoid organ; is the site at which immature lymphocytes develop into T lymphocytes; and secretes thymic hormones, which cause T lymphocytes to gain immunocompetence. It begins involution after puberty.

Question 33

Thymus

Answer 33

■ Arises from the third pharyngeal pouches, is supplied by the inferior thyroid and internal thoracic artery, and produces a hormone, thymosin, which promotes T-lymphocyte differentiation and maturation. ■ Is a bilobed structure, lying in the neck anterior to the trachea and the anterior part of the superior mediastinum, attains its greatest relative size in the neonate, playing a key role in the development of the immune system in early life but continues to grow until puberty, and then undergoes a gradual involution, in which the thymic tissue is replaced by fat.

Question 34

Anterior mediastinum

Answer 34

Anterior Mediastinum ■ Lies anterior to the pericardium and posterior to the sternum and the transverse thoracic muscles. ■ Contains the remnants of the thymus gland, lymph nodes, fat, and connective tissue.

Question 35

Middle mediastinum

Answer 35

Middle Mediastinum ■ Lies between the right and left pleural cavities. ■ Contains the heart, pericardium, phrenic nerves, roots of the great vessels (aorta, pulmonary arteries and veins, and vena cavae), arch of the azygos vein, and main bronchi.

Question 36

Posterior mediastinum

Answer 36

Posterior Mediastinum (See Structures in the Posterior Mediastinum) ■ Lies posterior to the pericardium between the mediastinal pleurae. ■ Contains the esophagus, thoracic aorta, azygos and hemiazygos veins, thoracic duct, vagus nerves, sympathetic trunk, and splanchnic nerves.

Question 37

Trachea

Answer 37

■ Begins at the inferior border of the cricoid cartilage (C6) as a continuation of the larynx and ends by bifurcating into the right and left main stem bronchi at the level of the sternal angle (disk between T4 and T5). ■ Is approximately 12 cm in length and has 16 to 20 incomplete hyaline cartilaginous rings that open posteriorly toward the esophagus and prevent the trachea from collapsing. ■ May be compressed by an aortic arch aneurysm, a goiter, or thyroid tumors, causing dyspnea. ■ Has the carina, a downward and backward projection of the last tracheal cartilage, which lies at the level of the sternal angle and forms a keel-like ridge separating the openings of the right and left main bronchi. ■ Carina may be distorted, widened posteriorly, and immobile in the presence of a bronchogenic carcinoma. The mucous membrane over the carina is one of the most sensitive areas of the tracheobronchial tree and is associated with the cough reflex.

Question 38

Right main bronchus

Answer 38

Right Main (Primary) Bronchus ■ Is shorter, wider, and more vertical than the left main bronchus; therefore, more foreign bodies that enter through the trachea are lodged in this bronchus or inferior lobar bronchus. ■ Runs under the arch of the azygos vein and divides into 3 lobar or secondary (superior, middle, and inferior) bronchi and finally into 10 segmental bronchi. The right superior lobar (secondary) bronchus is known as the eparterial (above the artery) bronchus because it passes above the level of the pulmonary artery. All others are the hyparterial bronchi.

Question 39

Left main bronchus

Answer 39

■ Runs inferolaterally inferior to the arch of the aorta, crosses anterior to the esophagus and thoracic aorta, and divides into 2 lobar or secondary bronchi, the upper and lower, and finally into 8 to 10 segmental bronchi. ■ Is also crossed superiorly by the arch of the aorta over its proximal part and by the left pulmonary artery over its distal part. ■ Dilates its lumen by sympathetic nerves and constricts by parasympathetic stimulation.

Question 40

Parietal Pleura

Answer 40

■ Lines the inner surface of the thoracic wall and the mediastinum and has costal, diaphragmatic, mediastinal, and cervical parts. The **cervical pleura (cupula)** is the dome of the pleura, projecting into the neck above the neck of the first rib. It is reinforced by **Sibson fascia** (suprapleural membrane), which is a thickened portion of the **endothoracic fascia**, and is attached to the first rib and the transverse process of the seventh cervical vertebra.

Question 41

Muscles of expiration

Answer 41

Muscles of expiration include anterior abdominal, internal intercostal (costal part), and serratus posterior inferior muscles. Quiet inspiration results from contraction of the diaphragm, whereas **quiet expiration** is a _passive_ process caused by the elastic recoil of the lungs.

Question 42

Muscles of inspiration

Answer 42

■ Muscles of inspiration include the diaphragm, external, internal (interchondral part), and innermost intercostal muscles, sternocleidomastoid, levator costarum, serratus anterior, serratus posterior superior, scalenus, and pectoral muscles.

Question 43

Most abscesses occur in ------ lung.

Answer 43

Most abscesses occur in the right lung, because the right main bronchus is wider, shorter, and more vertical than the left, and thus aspirated infective agents gain easier access to the right lung

Question 44

Pain from an infection of the pericardium (pericarditis) is carried by this nerve

Answer 44

Phrenic n.

Question 45

Phrenic n lesion and its effect on diagphragm

Answer 45

Phrenic nerve lesion _may not_ produce complete paralysis of the corresponding half of the diaphragm because the accessory phrenic nerve usually joins the phrenic nerve in the root of the neck.

Question 46

The innervaiton of the central and peripheral part of the diaphragm

Answer 46

■ Phrenic nerve supplies ***somatic _motor_ fibers*** to the diaphragm. ## Footnote The **central part** of diaphragm receives _***sensory** fibers*_ from the **phrenic nerve**, whereas the **peripheral part** receives *_**sensory** fibers_* from the **intercostal nerves.**

Question 47

Trachea ## Footnote What prevents trachea from collapsing

Answer 47

Trachea ■ **Begins** at the inferior border of the **cricoid cartilage** (C6) as a continuation of the larynx and **ends** by bifurcating into the right and left main stem bronchi at the level of the **sternal angle (disk between T4 and T5).** ■ Is approximately 12 cm in length and has **16 to 20 incomplete hyaline cartilaginous rings** that open posteriorly toward the esophagus and prevent the trachea from collapsing.

Question 48

Trachea compression

Answer 48

Trachea may be compressed by: * an aortic arch aneurism * a goiter or thyroid tumors casing **dyspnea**.

Question 49

Dyspnea (trachea compression)

Answer 49

Trachea may be **compressed** by _an aortic arch aneurism_ , a _goiter_ or _thyroid tumors_ casing dyspnea.

Question 50

A downward and backward progection of last tracheal cartilage

Answer 50

Carina

Question 51

Carina and cough reflex

Answer 51

■ Carina may be distorted, widened posteriorly, and immobile in the presence of a bronchogenic carcinoma. The **mucous membrane over the carina** is one of the most sensitive areas of the tracheobronchial tree and is associated with the cough reflex.

Question 52

Carina

Answer 52

■ Has the carina, a downward and backward projection of the last tracheal cartilage, which lies at the level of the sternal angle and forms a keel-like ridge separating the openings of the right and left main bronchi. ■ Carina may be distorted, widened posteriorly, and immobile in the presence of a bronchogenic carcinoma. The mucous membrane over the carina is one of the most sensitive areas of the tracheobronchial tree and is associated with the cough reflex.

Question 53

R. main Bronchus (primary)

Answer 53

``` Right Main (Primary) Bronchus ■ Is **shorter, wider, and more vertical** than the left main bronchus; therefore, more foreign bodies that enter through the trachea are lodged in this bronchus or inferior lobar bronchus. ``` ■ Runs under the **arch of the azygos vein** and divides into 3 lobar or secondary (**superior, middle,and inferior**) bronchi and finally into 10 segmental bronchi.

Question 54

More foreign bodie sthat enter through the trachea are lodged in this bronchus or inferior lobar bronchus.

Answer 54

**Right main** bronchus or **inferior lobar** bronchus ## Footnote bc it's shorter, wider and more cervical than the left main bronchus

Question 55

(R) Epiarterial bronchus

Answer 55

The **right superior lobar** (secondary) bronchus is known as the **eparterial** (***above the artery***) bronchus because it passes above the level of the pulmonary artery.

Question 56

Hyparterial bronchi

Answer 56

out of 3 lobar (secondary) bronchi of the right main bronchus, **middle** and **inferior** are **hyperarterial bronchi**. The **right superior lobar (secondary) bronchus** is known as the **eparterial** (above the artery) bronchus because it passes above the level of the pulmonary artery.

Question 57

Left main (primary) bronchus uder ANS

Answer 57

Sympathetic nn. ⇒ dialate lumen Parasympathetic nn. ⇒ constrict lumen

Question 58

Left main (primary) bronchus Position with respect to the artch of the aorta and L. Pulm a.

Answer 58

Left Main (Primary) Bronchus ■ Runs inferolaterally **inferior to the arch of the aorta**, crosses anterior to the esophagus and thoracic aorta, and divides into **2 lobar or secondary bronchi,** the upper and lower, and finally into 8 to 10 segmental bronchi. ■ Is also crossed **superiorly by the arch of the aorta** over its proximal part and by the **left pulmonary artery** over its distal part.

Question 59

Pleura

Answer 59

■ Is a thin serous membrane that consists of a parietal pleura and a visceral pleura.

Question 60

Parietal Pleura Innervation

Answer 60

■ Is innervated by the **intercostal nerves** (costal pleura and the peripheral portion of the diaphragmatic pleura) and the **phrenic nerves** (central portion of the diaphragmaticpleura and the mediastinal pleura). The parietal pleura is very **sensitive to pain.**

Question 61

Pulmonary Ligament

Answer 61

■ Parieal pleura forms the pulmonary ligament, **a two-layered vertical fold of mediastinal pleura**, which extends along the mediastinal surface of each lung from the **hilus** to the **base** (diaphragmatic surface) and ends in a free falciform border. It supports the lungs in the **pleural sac** by retaining the lower parts of the lungs in position.

Question 62

Parietal Pleura

Answer 62

Parietal Pleura ■ Lines the inner surface of the thoracic wall and the mediastinum and has costal, diaphragmatic, mediastinal, and cervical parts. The cervical pleura (cupula) is the dome of the pleura, projecting into the neck above the neck of the first rib. It is reinforced by **Sibson fascia** (suprapleural membrane), which is a **thickened portion of the endothoracic fascia**, and is attached to the first rib and the transverse process of the seventh cervical vertebra. ■ Is separated from the thoracic wall by endothoracic fascia.

Question 63

Endothoracic fascia

Answer 63

extrapleural dascial sheet lining the thoracic cavity. + Seperates the parietal pleura from the thoracic wall

Question 64

Parietal and visceral pleura bld supply

Answer 64

■ Is supplied by branches of the 1. internal thoracic 2. superior phrenic 3. posterior intercostal 4. superior intercostal arteries However, the visceral pleura is supplied by the bronchial arteries. The veins from the parietal pleura joins systemic veins.

Question 65

Visceral pleura (pulmonary pleura)

Answer 65

Visceral Pleura (Pulmonary Pleura) ■ Intimately invests the lungs and dips into all of the fissures. ■ Is supplied by bronchial arteries, but its venous blood is drained by pulmonary veins. ■ Is insensitive to pain but is sensitive to stretch and contains vasomotor fibers and sensory endings of vagal origin, which may be involved in respiratory reflexes.

Question 66

Pleural cavity

Answer 66

Pleural Cavity ■ Is a potential space between the parietal and visceral pleurae. ■ Represents a closed sac with no communication between right and left parts. ■ Contains a film of fluid that lubricates the surface of the pleurae and facilitates the movement of the lungs.

Question 67

Costodiaphragmatic Recesses

Answer 67

■ Are the pleural recesses formed by the reflection of the costal and diaphragmatic pleurae. ■ Can accumulate fluid when in the erect position. ■ Allow the lungs to be pulled down and expanded during inspiration.

Question 68

Costomediastinal Recesses

Answer 68

■ Are part of the pleural cavity where the costal and mediastinal pleurae meet.

Question 69

Lungs

Answer 69

■ Are the essential organs of respiration and are attached to the heart and trachea by their roots and the pulmonary ligaments. ■ Contain nonrespiratory tissues, which are nourished by the bronchial arteries and drained by the bronchial veins for the larger subdivisions of the bronchi and by the pulmonary veins for the smaller subdivisions of the bronchial tree. ■ Have bases that rest on the convex surface of the diaphragm, descend during inspiration, and ascend during expiration. ■ Receive parasympathetic fibers that innervate the smooth muscle and glands of the bronchial tree and probably are excitatory to these structures (bronchoconstrictor and secretomotor). ■ Receive sympathetic fibers that innervate blood vessels, smooth muscle, and glands of the bronchial tree and probably are inhibitory to these structures (bronchodilator and vasoconstrictor). ■ Have some sensory endings of vagal origin, which are stimulated by the stretching of the lung during inspiration and are concerned in the reflex control of respiration.

Question 70

R Lung

Answer 70

Right Lung ■ Has an apex that projects into the neck and a concave base that sits on the diaphragm. ■ Is larger and heavier than the left lung, but is shorter and wider because of the higher right dome of the diaphragm and the inclination of the heart to the left. ■ Is divided into upper, middle, and lower lobes by the oblique and horizontal (accessory) fissures, but usually receives a single bronchial artery. The oblique fissure usually begins at the head of the fifth rib and follows roughly the line of the sixth rib. The horizontal fissure runs from the oblique fissure in the midaxillary line at the sixth rib level and extends forward to the fourth costal cartilage level. ■ Has 3 lobar (secondary) bronchi and 10 segmental (tertiary) bronchi. ■ Has grooves for various structures (e.g., SVC, arch of azygos vein, esophagus).

Question 71

Left Lung

Answer 71

Left Lung ■ Is divided into upper and lower lobes by an oblique fissure that follows the line of the sixth rib, is usually more vertical in the left lung than in the right lung, and usually receives two bronchial arteries. ■ Contains the lingula, a tongue-shaped portion of the upper lobe that corresponds to the middle lobe of the right lung. ■ Contains a cardiac impression, a cardiac notch (a deep indentation of the anterior border of the superior lobe of the left lung), and grooves for various structures (e.g., aortic arch, descending aorta, left subclavian artery). ■ Has 2 lobar (secondary) bronchi and 8 to 10 segmental bronchi.

Question 72

Bronchopulmonary segment

Answer 72

Bronchopulmonary Segment ■ Is the anatomic, functional, and surgical unit (subdivision) of the lungs. ■ Consists of a segmental (tertiary or lobular) bronchus, a segmental branch of the pulmonary artery, and a segment of the lung tissue, surrounded by a delicate connective tissue septum (intersegmental septum). It is drained by the intersegmental part of the pulmonary vein. ■ Refers to the portion of the lung supplied by each segmental bronchus and segmental artery. The pulmonary veins are said to be intersegmental. ■ Is clinically important because the intersegmental pulmonary veins form surgical landmarks; thus, a surgeon can remove a bronchopulmonary segment without seriously disrupting the surrounding lung tissue and major blood vessels.