ANATOMY OF THE THORAX

THORACIC CAGE, THORACIC WALL &

SURFACE ANATOMY
DR. A.O.AJELETI
 OUTLINE
• THORACIC CAGE
• SKELETAL ARTICULATION
• THE THORACIC VERTEBRAE
• THE STERNUM
• THE RIBS
• MUSCELES OF THORACIC WALLS
• THE THORACIC WALL VESSELS
 Learning objective
• By the end of this lecture, students should be
able to:
• Know the types and apertures of thoracic skeleton
• Know the thoracic skeletal arrangement and
articulation
• Have the knowledge of manubrium and clinical
importance
• Know the types of ribs and coastal joints.
• Understand the thoracic wall muscles and vessels
• Describe the clinical correlates.
 THORACIC CAGE
• Thoracic skeleton consists of consists of 12
thoracic vertebrae, 12 pairs of ribs and coastal
cartilages and the sternum
• Upper Aperture is formed by the body of the 1st
thoracic vertebrae, 1st rib, 1st cartilage and the
upper sternum margin.
• The lower aperture is formed by the lower 6
coastal cartilages and the 12th ribs, the xiphoid
process in front and the body of the 12th thoracic
vertebra behind.
• The 11th rib is longer than the 12th rib even close
to the iliac crest.
THORACIC WALL & CAVITY
• Thoracic cavity is kidney shaped on T/S
because the ribs are carried backward beyond
the vertebral bodies.
• Diaphragm dome rises to 5th or 6th rib level so
bony thorax protects the heart and lungs also
the upper abdominal viscera: liver, stomach
and spleen.
TYPICAL THORAX
 SKELETAL ARTICULATION
• The costovertebral articulations include the joints of the head of the
rib with two adjacent vertebral bodies and the tubercle of the rib
with the transverse process of a vertebra.
• There are two articular facets on the head of the rib: a larger,
inferior costal facet for articulation with the vertebral body of its
own number, and a smaller, superior costal facet for articulation
with the vertebral body of the vertebra superior to the rib.
• The crest of the head of the rib separates the superior and inferior
costal facets.
• The smooth articular part of the tubercle of the rib, the transverse
costal facet, articulates with the transverse process of the same
numbered vertebra at the costotransverse joint.
 THORACIC VERTEBRAE – TYPICAL FEATURES
THE BODY
• The body has an upper and lower demifacet
on each side for articulation with the head of
ribs.(some bodies has only one).
• Middle thoracic bodies are heart-shaped
making thoracic portion of the vertebral
column concave forward.
 TRANSVERSE PROCESSES

• Act as buttress.
• They are stout and conform with the
backward sweep of the ribs, having on their
tips facets for the tubercles of the ribs.
• The transverse process become progressively
shorter from 1st to the 12th.
 SPINOUS PROCESS (SPINES)
• Intermediate four (5,6,7and 8) are long and
vertical.
• Those above and below are progressively
more horizontal.
 ARTICULAR PROCESSES

• They are set almost vertically on the arc of a

circle.
• They cause rotary movement between
adjacent thoracic vertebrae.
• Superior articular facets faces posterolaterally
and inferior is anteromedially.
 VERTEBRAL FORAMEN

• Small and circular.

 INFERIOR VERTEBRL NOTCHES

• They are large.

• The superior ones are absent.
 TRANSITION

• Thoracic vertebrae from the middle up and

down assume characteristics of cervical and
lumbar vertebrae.
• Th. 1 is very much like C7 and Th. 12 is like L.
1.
 STERNUM

• A breast bone, likened to a broad sword.

• It is composed of 3 parts:
• Manubrium
• Corpus sterni or body
• Xiphoid process.
STERNUM
 MANUBRIUM

• Very thick concave border called jugular notch.

• Much deepened by the proximal sternal ends of
the clavicles.
• Below the clavicle is the 1st costal cartilage joining
the manubrium to the rib by synochondrosis.
• Manubrium is 5cm long.
• Upper border lies at the level of Th.2 lower
border.
• Its lower border articulates with the body at
sternal angle.
 MANUBRIUM

• Very thick concave border called jugular notch,

readily palpated at the root of the neck.
• Has a clavicular notch on each side for articulation
with the clavicle.
• Manubrium is 5cm long.
• Also articulates with the cartilage of the first rib,
the upper half of the second rib, and the body of
the sternum at the manubriosternal joint, or
sternal angle.
 Sternal Angle (Angle of Louis)
• This is the junction between the manubrium and the
body of the sternum.
• It’s located at the level where:
• The second ribs articulate with the sternum.
• The aortic arch begins and ends.
• The trachea bifurcates into the right and left bronchi
at the carina.
• The inferior border of the superior mediastinum is
demarcated.
• A transverse plane can pass through the intervertebral
disk between T4 and T5.
 BODY OF THE STERNUM
• It is composed of 4 fused pieces or sternebrae.
• It is slightly more than twice the length of the
manubrium.
• Articulates with the second to seventh costal
cartilages.
• The 2nd rib cartilage articulates in a notch on the side
of the sternal angle.
• The 7th cartilage articulate with the angle between
the body and the front of the xiphoid.
• The symphysis joint type of the manubriosternal joint
affords hinge-like movements of the body of the
sternum forward and backward.
• Xiphisternal joint is at level with the ninth thoracic
vertebra.
 THE XIPHOID PROCESS.
• Is a flat, cartilaginous process at birth that ossifies
slowly from the central core and unites with the
body of the sternum after middle age.
• Lies at the level of T10 vertebra, and the xiphisternal
joint lies at the level of the T9 vertebral body, which
marks the lower limit of the thoracic cavity in front,
the upper surface of the liver, diaphragm, and lower
border of the heart.
• It descends a variable distance downward to the
posterior wall of the sheath of the rectus abdominis.
• Its half as thick the body of the sternum and
posteriorly flush with the posterior surface of the
body.
STERNUM –CLINICAL CORRELATES
• Bone marrow biopsy
• Sternotomy.
 USEFUL LANDMARKS
• Vertebral level of:
• Jugular notch – 2nd thoracic
• Sternal angle – 4th thoracic
• Xiphisternal joint – 8th+ thoracic
POSTERIOR MUSCLES ATTACHMENT &
RELATIONS
• MANUBRIUM: Sternothyroid
Sternohyoid - Neck muscles
• BODY: Transversus Thoracis
• XIPHOID PROCESS: Diaphragm

POSTERIOR RELATIONS:
• Pleura and lungs, heart and great vessels,
thymus.
ANOMALY
 THE RIBS
• A rib bone and its cartilages constitute a costa.
• There are 12 pairs of costae.
• Every rib articulates posteriorly with the vertebral column.
• They are in 3 classes:
• True or Vertebrosternal ribs: The cartilages of the upper 7 pairs
of ribs articulate directly with the sternum.
• Vertebrochondral ribs: the cartilages of 8th, 9thand 10th
articulate each with the costal cartilage above it.
• Floating or Vertebral ribs: The cartilaginous end of the last pairs-
11th & 12th are free.
• Classes 2 & 3 are also called false ribs.
• Ribs are flattened ,a very thin outer compact layer and highly
resilient.
• The 1st rib is the highest , strongest, flattest and most curved
ribs.
 RIBS
TYPICAL COMPARING TYPICAL WITH ATYPICAL
CHEST WALL SKELETAL STRUCTURE
WOMAN MAN
 THE RIBS (CONTD)
• Typical rib consists of:
• BODY: Internal and external surfaces, superior or
inferior borders; an angle and a costal groove.
• The body posterior ¼ is cylindrical and anterior ¾
is compressed.
• VERTEBRAL END: Head, neck and tubercle.
• STERNAL END: Pit for costal cartilage.
 COSTAL JOINTS –

HEAD OF A RIB
• The head of a rib articulates with the sides of
the bodies of the 2 vertebrae.
• The tubercle of a rib articulates with tip of a
transverse process.
• The costal cartilage articulate with the sides of
2 sternebrae.
 ANOMALIES
• BIFID • BICIPITAL
 COSTAL JOINTS-
Costovertebral articulation:
• Joint of the head of the rib.
• Joint of the tubercle of a rib.
• The head of each typical rib (2nd – 10th) articulates
with the demifacet of 2 adjacent vertebrae and
with the intervertebral disc between them.
• Attachment to the intervertebral disc is by the
intra-articular ligament.
• Ribs 1, (10), 11 and 12 heads are confined to
single vertebrae, are rounded and have no intra-
articular ligament.
• Sternocostal articulation: Each joint cavity is
divided into 2 by intra-articular ligarment, it is
closed ventrally by a ligament that radiates
from the perichondrium to the sternum.
• Interchondral articulation: Except for the 12th
cartilage, the lower cartilages form joint –
synovial or fibrous, or complete union with
each other.
 TUBERCLE OF A RIB
• The tubercle of a rib articulates with the facet at the
tip of the transverse process of its own vertebra
(except 11 and 12) to form a synovial joint called a
costotransverse joint.
• The ligamentous fibers are divided into medial and
lateral group.
• Medial costotransverse ligament for ligament of the
neck and lateral costotransverse ligament for the
ligament of the tubercle.
• Another band of superior costotransverse descend
from a transverse process to the upper border of the
of the rib next below, producing a sharp crest of the
neck.
 ANGLE OF THE RIB

• Vertical insertion of the iliocostalis are at most

backwardly projecting part of the outer surface
of the ribs.
• Anterior to this, the ribs are twisted downward,
forward, and medially.
 MUSCLES OF THORACIC WALL

ABDOMINAL THORACIC
• External Oblique External Intercostal
• Internal Oblique Internal Intercostal
Nerves and Vessels in the Interval
Innermost Intercostal
• Transversus abdominis Subcostals
Transversus thoracics
 Intercostal Nerves
• Anterior primary rami of the first 11 thoracic spinal nerves.
• Subcostal nerve: This is the anterior primary ramus of the
12th thoracic spinal 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]).
• Give rise to lateral and anterior cutaneous branches and
muscular branches.
• Lateral cutaneous branch is the largest of the branches is
the which pierces the lateral thoracic wall and divides into
an anterior branch and a posterior branch that innervate
the overlying skin.
THORACIC WALL ARTERIES .
 THE INTERNAL THORACIC ARTERY
(INTERNAL MAMMARY A.)
• It is a branch of the Subclavian artery, descend from the sternum
behind the upper 6 costal cartilages.
• Gives rise to two anterior intercostal arteries in each of the upper six
intercostal spaces
• It divides into 2 terminal branches at the coastal margin: Superior
Epigastric & Musclophrenic arteries.
• Musclophrenic artery gives off 2 Ant. Intercoastal Arteries at 7th, 8th
and 9th intercoastal spaces. It passes backward to anastomose with
the posterior vessels.
• The superior epigastric artery descends behind 7th costal cartilage to
anastomose with the inferior epigastric branch of the external iliac A.
Branches:
• Pericardiophrenic artery that run with Phrenic N.
• Perforating or cutaneous
 THORACIC WALL VEINS
Intercostal Vein
• Each intercostal space has 1 posterior and 2 anterior
intercostal veins of the accompanying artery.
• Anterior veins Musculophrenic & Int. thoracic V.
• Posterior veins are not regular Brachiocephalic vein.
Internal Thoracic Vein
• Formed by the confluence of the Sup. Epigastric &
Musculophrenic veins, ascends on the medial side of the
artery, receives the upper six Ant. Intercostal &
Pericardiacophrenic Veins Brachiocephalic vein.
Thoracoepigastric Vein
• Venous connection between the lateral thoracic vein and the
superficial epigastric vein.
THORACIC WALL VEINS
 LYMPHATICS OF THORACIC WALL
PARASTERNAL NODES
• Associated with the internal thoracic arteries
• Receive lymph from the medial portion of the breast, intercostal
spaces, diaphragm, and supraumbilical region of the abdominal
wall.
• Drain into the junction of the internal jugular and subclavian veins.
INTERCOSTAL NODES
• Associated with the heads and necks of ribs
• Receive lymph from the intercostal spaces and the pleura.
• Drain into the cisterna chyli or the thoracic duct
DIAPHRAGMATIC NODES
• Associated with the diaphragm
• Receive lymph from the pericardium, diaphragm, and liver.
• Drain into the sternal and posterior mediastinal nodes.
LYMPHATICS OF THORACIC WALL
Text & Image Sources: Acknowledgement
• Drake, Vagi & Mitchell. 2015. Gray’s Anatomy for Students
3rd Ed; Churchill Livingstone Elsevier Inc. Philadelphia
• Agur & Dalley II. 2013. Grant’s Atlas of Anatomy, 13th Ed;
Lippincott Williams & Wilkins. Philadelphia.
• Sinnatamby C.S. 2011. Last’s Anatomy Regional & Applied
Anatomy, 12th Ed; Churchill Livingstone Elsevier Inc.
Philadelphia
• Moore, Dally II & Agur. 2014. Lippincott Williams & Wilkins.
Philadelphia.
• Chung & Chung. 2012. BRS Gross Anatomy, 7th Ed;
Lippincott Williams & Wilkins. Philadelphia.
• Basmajian J.V. Grant’s Method of Anatomy. Williams &
Wilkins
 THANK GOD YOUR
THORAX
IS COMPLYING TO LIVING