ANAT 5010 - unit 15

thoracic wall

external boundary of thoracic cavity

- ribs 1-12

- sternum

- costal cartilages

- vertebrae TV1-12

- intercostal muscles

- intercostal neurovasculature

what makes up the thoracic wall?

- TV1

- rib 1

- manubrium

what are the boundaries of the superior thoracic aperture?

- TV12

- rib 12

- anterior tips of ribs 1-12

- costal cartilages of ribs 11-12

- xiphoid process

what are the boundaries of the inferior thoracic aperture?

diaphragm

flat, skeletal muscle; floor of thoracic cavity; roof of abdominal cavity

manubrium

most superior bone of sternum; articulates with clavicles at clavicular notches; articulates with ribs 1-2; articulates with body of sternum at sternal angle

TV4-5

what vertebral level is the sternal angle at?

body of sternum

middle bone of sternum; articulates with ribs 2-7; articulates with xiphoid process at xiphisternal junction

TV9

what vertebral level is the xiphisternal junction at?

xiphoid bone

inferior bone of sternum; articulates with rib 7

head of rib

articulates with TV bodies

neck of rib

area between head and tubercle of rib

tubercle

rough patch with facet for transverse process of TV

angle of rib

curve; most posterior point of rib cage

shaft

body; central; lateral

costal groove

inferior; houses neurovasculature that passes through the ribs

scalene tubercle

divides grooves for subclavian vein and artery on the superior surface of rib 1; attachment point for anterior scalene muscle

costovertebral joint

between head of rib and bodies of two TV

costotransverse joint

between tubercle of rub and transverse process of same level TV

costal cartilages

attach to anterior ends of each rib via costochondral joints

costal arch

defined by margin of cartilages of ribs 7-10

joint 1

what rib joint is fibrocartilage, immobile, and articulates with the manubrium?

joint 2

what rib joint is synovial and articulates with the sternal angle?

joint 3-6

what rib joint is synovial and articulates with the body of the sternum?

joint 7

what rib joint is synovial and articulates with the xiphisternal junction?

true ribs (1-7)

cartilages attach directly to the sternum

false ribs (8-10)

cartilages attach indirectly to the sternum via other cartilages

floating ribs (11-12)

cartilages do not attach to sternum

origin: lower border of superior rib

insertion: upper border of inferior rib

action: elevate rib; assist in respiration

innervation: intercostal nerves

what is the o,i,a,in of the external intercostals?

origin: upper border of inferior rib

insertion: lower border of superior rib

action: depress ribs; assist in expiration

innervation: intercostal nerves

what is the o,i,a,in of the internal intercostals?

innermost intercostals

fibers of internal intercostals separated by the neurovascular bundle (V A N)

anterior intercostal membrane

fibrous continuation of external intercostal muscles

posterior intercostal membrane

fibrous continuation of internal intercostal muscles

origin: body of sternum, xiphoid process, costal cartilages

insertion: internal surfaces of costal cartilages of ribs 2-6

action: depress ribs; assist in expiration

innervation: intercostal nerves

what is the o,i,a,in of the transversus thoracis?

mixed

are the intercostal nerves mixed, motor, or sensory?

T1 VPR

atypical intercostal nerve that contributes to the brachial plexus

T2 VPR

atypical intercostal nerve; intercostobrachial nerve formed from lateral cutaneous branch of VPR; contributes to medial brachial cutaneous nerve

T12 VPR

atypical intercostal nerve; subcostal; abdominal

internal thoracic artery

branch of subclavian artery; travels in thoracic wall superficial to the transversus thoracis muscle; supplies anterior ICSs 1-6

- superior epigastric artery

- musculophrenic artery

what are the terminal branches of the internal thoracic artery?

superior epigastric artery

medial branch of the internal thoracic artery; courses inferiorly to the anterior abdominal wall

musculophrenic artery

lateral branch of the internal thoracic artery; courses along the costal margin

interal thoracic

what are the anterior ICS 1-6 arteries a branch of?

musculophrenic

what are the anterior ICS 7-11 arteries a branch of?

highest intercostal artery

what are the posterior ICS 1-2 arteries a branch of?

descending thoracic aorta

what are the posterior ICS 3-11 arteries a branch of?

anterior intercostal veins

drain into internal thoracic or musculophrenic veins

posterior intercostal veins

drains into azygos system of veins

mediastinum

midline space between lungs; divided into superior and inferior at sternal angle

- anterior mediastinum

- middle mediastinum

- posterior mediastinum

what are the divisions of the inferior mediastinum?

- thymus

- brachiocephalic veins and superior vena cava

- aortic arch and branches

- trachea

- esophagus

- thoracic duct

- phrenic nerves

- vagus nerves

what are the contents of the superior mediastinum?

thymus gland

primary lymphatic organ; begins involution into fatty tissue after 1 year old; bi lobed; anterior to major blood vessels

brachiocephalic veins

formed from subclavian vein and internal jugular vein

superior vena cava

where do the brachiocephalic veins drain into?

- brachiocephalic trunk

- left common carotid

- left subclavian

what are the branches of the aortic arch?

ligamentum artertiosum

connects inferior surface of aortic arch to pulmonary trunk; landmark for left recurrent laryngeal nerve

phrenic nerves

cross anterior to subclavian artery; cross anterior to root of lungs; run between mediastinal pleura (external) and pericardium (internal)

vagus nerves

cross anterior to subclavian artery; cross posterior to root of lungs; give off laryngeal branches

recurrent laryngeal nerves

branches of vagus nerves; mixed sensory and motor

right recurrent laryngeal nerve

loops under right subclavian artery

left recurrent laryngeal nerve

loops under aortic arch lateral/posterior to ligamentum arteriosum

- fat

- connective tissue

- inferior 1/2 of thymus

- lymph nodes

what are the contents of the anterior mediastinum?

- heart

- pericardium

- roots of great vessels

- primary bronchi

what are the contents of the middle mediastinum?

pericardium

membrane that surrounds the heart

serous membrane

double layered membrane with thin cavity of fluid between the layers

fibrous pericardium

external layer of serous membrane; dense CT

serous parietal pericardium

fuses to internal side of fibrous layer; external to serous fluid

serous visceral pericardium

adheres to heart surface; "epicardium"

phrenic nerve

what provides sensory innervation to the pericardium?

cardiac tamponade

compression of heart due to fluid accumulation in pericardium

- ascending aorta

- pulmonary trunk (pulmonary arteries)

- pulmonary veins

- superior vena cava

- inferior vena cava

what all makes up the roots of the great vessels?

descending thoracic aorta

inferior continuation of aortic arch at TV4; passes through diaphragm at TV12

abdominal aora

continuation of the descending thoracic aorta

- 3rd-11th posterior intercostal arteries

- subcostal artery

- left bronchial artery

- esophageal artery

- mediastinal artery

- pericardial artery

- superior phrenic artery

what are the branches of the descending thoracic aorta?

azygos system of veins

handles drainage of posterior thoracic wall

azygos vein

drains superiorly into superior vena cava; right of median plane

hemiazygos vein

drains into azygos vein; drains superiorly then crosses vertebral body at TV9

accessory hemiazygos vein

drains into azygos vein; drains inferiorly then crosses vertebral body at TV8

thoracic duct

largest lymphatic vessel in the body; extends superiorly from cisterna chyli at LV1-2; passes through superior mediastinum; empties into left venous angle

esophagus

flattened muscular tube; inferior continuation of pharynx at CV6; terminates at TV11; posterior to trachea and anterior to and right of the aorta

inferior thyroid artery

what is the origin of arterial branches to the upper portion of the esophagus?

- esophageal artery

- bronchial artery

- mediastinal artery

what is the origin of arterial branches to the middle portion of the esophagus?

esophageal branch of left gastric artery

what is the origin of arterial branches to the lower portion of the esophagus?

inferior thyroid vein to the SVC

what drains the upper portion of the esophagus?

azygos system to the SVC

what drains the middle portion of the esophagus?

esophageal branch of left gastric vein to the hepatic portal vein

what drains the lower portion of the esophagus?

esophageal plexus

supplies smooth muscle of esophagus; contains postganglionic sympathetic fibers from the cardiopulmonary splanchnic nerves; contains preganglionic parasympathetic fibers from the vagus nerve

anterior vagal trunk

continuation of the left vagus nerve

posterior vagal trunk

continuation of the right vagus nerve

thoracic sympathetic trunk

continuous with that of cervical and lumbar regions; lies near head and neck of ribs

lateral

where are white communicating rami located?

medial

where are gray communicating rami located?

thoracic splanchnic nerves

preganglionic sympathetic fibers; branch off thoracic ganglia medially without synapsing; innervate targets in abdomen

greater splanchnic nerve

branches from T5-T9 ganglia

lesser splanchnic nerve

branches from T10-T11 ganglia

least splanchnic nerve

branches from T12 ganglia