Thoracic Wall

Note : I put the sheet's info within the slides to easily understand this lecture

Done by : Zaid Al-Ghnaneem

Lecture Objectives• Describe the shape and outline of the thoracic cage including inlet 

and outlet.• Describe the anatomical landmarks of the anterior chest wall.• List various structures making the thoracic wall.• Make a list of muscles of the thoracic wall including their nerve and 

blood supply and their actions.• List various parts of the thoracic vertebrae and name its 

characteristic features.• Describe the sternum with its joints.• Classify ribs, name their various parts and compare them with each 

other.• Define intercostal spaces and discuss their various components 

including intercostal muscles.• Describe the diaphragm, its origin, insertion, function, nerve and 

blood supply.  Study openings in the diaphragm and structures that pass through.

Thoracic Cage

Bony cage flattenedfrom front to back

• Sternum (breastbone)• Ribs

– 1‐7 are true ribs(vertebrosternal)

– 8‐10 are false ribs(vertebrochondral)

– 11‐12 are floating• Costal cartilages• Bodies of the thoracicvertebrae

Anteriorly

laterally

anteriorly

posteriorly

Directly attachedto sternum

Indirectly attachedto sternum

No connectionwith sternum

Skeleton of Thoracic Wall

Thoracic Cage: Functions

• Enclose and protect the organs in the thoracicand abdominal cavities

• Provide support for the bones of the upperlimbs

• Play a role in breathing

Also attachment for muscles

Sternum• Manubrium

– 1st & 2nd ribs– Clavicular notch(sternoclavicular joint)

– Sternal angle– T3‐T4

• Body– Costal cartilages of 2‐7 ribs

• Xiphoid– Ossifies by 40– CPR position– Abdominal mm.– T9

sternum parts will ossifies to become one bone

join manubrium with body , second costal cartilagejoin sternum at this level

site of attachment for abdominal muscles

Sternum

Ribs

• Increase in length fromribs 1‐7, thereafter decreasing

• Head and tuberclearticulate with facets

• Body with costalgroove containing nerve & blood vessels

• Intercostal spacescontain intercostalmuscles

these facets on body and transverse processof vertberae , we will disscus them

Ribs• Typical ribs

– Long & twisted– Rounded superior edge– Grooved inferior edge (costal groove)– Head (2 facets 2‐9, 1 facet 1, 10‐12), neck, tubercle,shaft & angle

2-10th ribs Head for ribs from 2-9 has 2 facets because it will articulate with 2sucessive vertebrae

Ribs

• Atypical ribs– 1st rib

• Widest, shortest, mostcurved true rib

• Articulate with T1• Surface marking …

– 11th and 12th• No neck• No tubercle• floating

have one facet on head so articulate only withbody of vertebrae

Thoracic Wall: JointsCartilaginous Joints • Joints of sternum

– Manubriosternal joint (2°)– Xiphisternal joint

• Costochondral joints• 1st sternocostal joint

Synovial Joints (plane joints)• Joints between ribs and

thoracic vertebrae• 2nd ‐7th sternocostal joints• 6th – 10th interchondral joints

Head with body of vertebrae

Tubercle with transverse processImmovable (fibrous) joint

costal cartilage itself between them(costal cartilage and the next one) has cavity that allow movement and it is synovial joint

Joints of the Heads of Ribs• 2‐9 ribs

– 2 synovial joints– With thecorresponding vertebra and one above

– Intra‐articularligament• Between head and IVD

• 1, 10‐12 ribs– 1 synovial joint withthe corresponding vertebra

intervertebral disk

so we willhave 2 cavities

so only one cavity

Costotransverse Joint• Joints of the tubercles (1‐10 ribs)

–With the transverse process of thecorresponding vertebra

remember 11th and 12thrib don't have tubercle

Thoracic Wall: Joints

Thoracic Apertures

There is debate about inlets and outlets , some books consider the upper opening is inlet and the lower isoutlet , other books the opposite ,, so we will call them : Superior and inferior thoracic apertures

Boundaries

anteriorly by suprasternal notch

posteriorly by first thoracic vertebrae

laterally by medial border of 1st rib

Orientation is anterior inferior or forward downward

Boundaries

Posteriorly by body of 12ththoracic vertebrae

Laterally by inferior margins of ribs and costalcartilages

Anteriorly by xiphesternaljoint

Superior Thoracic Aperture• Between thoracic cavity

and the root of the neck• Boundaries ..• Orientation ..• Content

– Trachea– Esophagus– Nerves & BVs– Lungs & pleurae

• Suprapleural membrane– Close the sides of the

opening above the parietal pleurae

this membrane attached laterally with 1st rib , posteriorly , with transverse process of vertebrae , medially with deep fasica of the viscera

Previous slide

Superior Thoracic Aperture

Inferior Thoracic Aperture

this is liver not lung because the section is at level of T12 and because of the dome within the center ofthoracic cavity

NOTE : periphery of thoracic cavity is more longer than center of thoracic cavity because of domes

Intercostal Spaces

• Between successive ribs• Contain the intercostal

mm.– External , internal, and

innermost intercostal mm.

• Neurovascular bundle runsuperficial to the innermost intercostal m.– Arranged from superior to

inferior as vein, artery , and nerve

between internal andinnermost

Intercostal Muscles Nerve supply: intercostal nerves• Three layers

– External intercostal• Orientation• Anterior (external) intercostal 

membrane• Helps in inspiration

– Internal intercostal• Orientation• Posterior (internal) intercostal 

membrane• Helps in expiration

– Innermost intercostal• Cross more than one intercostal spaces• Attached to the endothoracic fascia 

internally– Attached to parietal pleura

• Divided into three parts• Works with the internal intercostal

Accessory Muscles of Respiration

• Transversus thoracis– Help in expiration

• Pectoralis major, pectoralis minor, serratus anterior, scalene mm.– May help in inspiration

Accessory Muscles of Respiration• Levator costarum

– Between the transverse processes and the ribs 

– Nerve supply: posterior rami of thoracic spinal nerves

– Help in inspiration• Serratus posterior superior m.

– Deep to rhomboids– Nerve supply: 1‐4 intercostal

nerves– Help in inspiration

• Serratus posterior inferior m.– Deep to latissmus dorsi– Nerve supply: last 4 intercostal

nerves– Help in expiration

Diaphragm• Physical barrier between

thoracic and abdominal cavities

• Functions– Inspiration– Abdominal pressure– Abdominothoracic pump

• Dome like shape– Peripheral muscular

• Reach up to the 5th rib– Central tendon

• At level of xiphisternaljoint

to push the blood within the veins becuase as we know the pressurewithin the vein is low

Origin of the diaphragm

• Sternal‐ posterior surfaceof xiphoid process

• Costal‐ the lower six ribsand their costal cartilages

• Vertebral‐– Right crus‐ bodies of L1‐L3– Left crus‐ bodies of L1‐L2

• Arcuate ligaments– Medial‐ L2 (body) to L1(transverse process)

– Lateral‐ L1 (transverseprocess) to 12th rib

– Median‐ connects cruraanterior to aorta

these are thicking of theaponeurosis of the muscles

Openings in the Diaphragm • Aortic opening‐ T12

– Between crura– Content

• Aorta, thoracic duct, &azygos vein

• Esophageal opening‐ T10– In right crus– Content

• Esophagus, vagi, BVs &lymphatic vessels

• Caval opening‐ T8– Content

• IVC, branches of rightphrenic nerve

most inferior

most superior

Openings in the Diaphragm 

• Other structures passthe diaphragm– Splanchnic nerves –through crura

– Sympathetic trunk –medial arcuate lig.

– Subcostal nerve –lateral arcuate lig.

– Superior epigastricvessels – between sternal & costal origins remember .. part of rectus sheath

Diaphragm: Innervation

• Motor– Phrenic nerves (C3‐C5)

• Sensory– Centrally – phrenicnerves

– Peripherally –intercostal nerves (T7‐T12)

Diaphragm is skeletal muscle so it needs somatic nerves

sensory for diaphragm and other structers linked directly with diaphragm from superior and inferior , such as parietal layer of serous membrane

these nerves are responsible for referred pain

Diaphragm: Blood SupplySUPERIOR INFERIOR

Arteries of Thoracic Wall• Posterior intercostal aa.

– 1‐2 ← superior intercostal← costocervical trunk ← 2nd part of supclavian

– 3‐12 ←descendingthoracic aorta

• Anterior intercostal aa.– 1‐6 ← internal thoracic←1st part of subclavian

– 7‐12 ← musculophrenic← internal thoracic

اغلبھم من Thoracic aorta ما عدا االول والثاني النھ thoracic aorta ما بصلھم

Internal thoracic artery major branches at end of sternum to : superior epigastric and musculophrenic

Veins of Thoracic Wall• Posterior intercostal veins

– Drain into azygos and hemiazygos veins

• Anterior intercostal veins– Follow the corresponding aa. (internal intercostal and musculophrenic vv.)

Nerves of Thoracic Wall

• Anterior rami of thoracicspinal nerves– 1‐11 intercostal nerves

• 1‐6 end within theintercostal spaces

• 7‐9 pass anterior deep tothe costal cartilage to reach the abdominal wall

• 10‐11 continue anteriorly tothe abdominal wall

– 12 subcostal nerve• In the abdominal wall

these nerves are exceptions ,, the nerves in all the body once they exit the intervertebral foramen theydivide to dorsal and ventral , most of nerves are ventral , they make plexuses except in thoracic region

remember..exit the diaphragm thoughlateral arcuate ligament

Branches of the Intercostal Nerves• Rami communicants• Collateral branch• Lateral cutaneous branch

– 1st ‐ part of the brachial plexus

– Intercostobrachial nerve (2nd)• Referral pain in coronary 

artery disease

• Anterior cutaneous branch• Muscular branches• Pleural sensory branches• Peritoneal sensory branches 

(6‐11)

Surface Anatomyat the level of T2-23

at level of T4-T5