بسم الله الرحمن الرحيم

Chest Wall

Objectives Identify the sternum and ribs with their

characteristic features.

Define intercostal space with its contents.

Describe intercostal muscles with their nerve

supply and actions.

Enlist the respiratory muscles with their

actions.

Explain the Bucket handle and pump handle

movements.

Thoracic cage

THORACIC CAGETHORACIC CAGETHORACIC CAGETHORACIC CAGEConical in shapeFormed of:

Sternum & costal cartilages: anteriorly

Twelve pairs of ribs: laterally Twelve thoracic vertebrae:

posteriorlyHas 2 apertures (openings):1. Superior (thoracic outlet):

narrow, open, continuous with neck

2. Inferior: wide, closed by diaphragm

ArticulationsArticulationsArticulationsArticulations

SternocostalSternocostal(synovial), mobile EXCEPT first, which is cartilagenous & fixed

CostochondralCostochondral(cartilagenous J.) no movements possible

CostovertebralCostovertebral (Synovial joint)

XiphisternalXiphisternal(fibrocartilagenous J.) no significant movements

ManubriosternalManubriosternal(fibrocartilagenous J.) Small angularMovement possible

Thoracic inlet

Boundaries:a. Anterior: Supra-sternal notch of the manubrium sterni.b. On each side: First rib.c. Posterior: First thoracic vertebra.

Thoracic outletBoundaries:a. Anterior: Xiphoid

process. b. On each side: Lower

six costal cartilages & Last two ribs.

c. Posterior: Last thoracic vertebra.

- It is closed by the diaphragm which separates it from the abdominal cavity.

RibsClassification according to their attachments to the sternum:

Total number of Ribs: 12 pairs

A: True ribs: Upper seven ribs (Directly attached to the sternum).

B: False ribs: Lower five ribs (Indirectly attached to the sternum).

The lower two ribs (11th & 12th) are called the Floating ribs because

they are free anteriorly.

 Classification of ribs according to their structure:

A: Typical: 3rd - 9th ribs.

B: Atypical:1st, 2nd, 10th, 11th, and 12th ribs. (first two and last 3) ribs.

Typical rib

Atypical ribsFirst rib (general features)

Shortest C- ShapedAnt end: cup shape.Post end: It has Head, neck and tubercle.Head: One facetSurfaces: Sup. & InferiorBorders: Outer (lateral) & Inner (medial).

Second rib-Twice the length of 1st - Head has 2 facets- Surfaces of shaft are in between that of 1st & typical

Tenth riba. Single articular facet on the head.

Eleventh riba. Single articular facet on the head.b. No tubercle.

Twelveth rib

a. Single articular facet on the head.b. No tubercle.c. No neck.d. No costal groove.e. Large head. f. Tapering anterior end.

Sternum

3 PARTS: Manubrium, Body * Xiphoid process.

Manubrium: Lies opposite T3,4.

Body: T5 toT8 Xiphoid T9

Sternum

Intercostal SpacesThere are 9 anterior and

11 posteriorEach space contains:1- Intercostal muscles:

(External, Internal and transversus thoracicus)

2- An Intercostal nerve.3- Intercostal vessels:a. Intercostal arteries (Anterior & Posterior)b. Intercostal veins (Anterior & Posterior).

Respiratory MovementsRespiratory MovementsA- Movements of DiaphragmA- Movements of DiaphragmRespiratory MovementsRespiratory MovementsA- Movements of DiaphragmA- Movements of Diaphragm

Contraction (descent) of diaphragm

Increase of vertical diameter vertical diameter of thoracic cavity

InspirationInspiration

ExpirationExpirationRelaxation (ascent)

of diaphragm)

Respiratory MovementsRespiratory MovementsB- Movements of RibsB- Movements of Ribs

Respiratory MovementsRespiratory MovementsB- Movements of RibsB- Movements of Ribs

PUMP HANDLE MOVEMENTPUMP HANDLE MOVEMENTElevation of ribsElevation of ribs

Increase in antero-posterior Increase in antero-posterior diameter of thoracic cavitydiameter of thoracic cavity

BUCKET HANDLE MOVEMENTBUCKET HANDLE MOVEMENTElevation of ribsElevation of ribs

Increase in lateral diameter of Increase in lateral diameter of thoracic cavitythoracic cavity

Inspiratory MusclesInspiratory MusclesInspiratory MusclesInspiratory Muscles

Diaphragm Diaphragm ((most important musclemost important muscle))External intercostal muscles External intercostal muscles Rib elevators:Rib elevators:Accessory muscles (Accessory muscles (only used during forced only used during forced

inspirationinspiration):):1.1. Scalene musclesScalene muscles2.2. Pectoralis majorPectoralis major3.3. SternomastoidSternomastoid

EXTERNAL INTERCOSTALEXTERNAL INTERCOSTALEXTERNAL INTERCOSTALEXTERNAL INTERCOSTAL

Attachments:Attachments: from from lower border of rib lower border of rib above to upper above to upper border of rib belowborder of rib below

Direction of fibers: Direction of fibers: downward & downward & mediallymedially

Nerve supply: Nerve supply: intercostal nervesintercostal nerves

Action: Action: rib elevators rib elevators (inspiratory)(inspiratory)

• Is partly traversed by the nerve & vessels, which splits each muscle into 2 parts:

• OuterOuter: Internal Intercostal (proper)

• InnerInner: Innermost Intercostal• (In the middle of the space)

• Transversus thoracicus• The most inner layer of

thoracic wall• It is formed of 3 muscles• 1- Innermost Intercostal.• 2- Sternocostalis.• 3- Subcostalis

Internal IntercostalInternal Intercostal

RIB DEPRESSORSRIB DEPRESSORSRIB DEPRESSORSRIB DEPRESSORS

1. Internal intercostal2. Innermost intercostalDirection: Direction: upward & medially

3. Subcostal4. Transversus thoracisNerve supply: Nerve supply: intercostal nerves

(ventral rami of T1-T11)

11 22

33

44

• 4 to 5 slips which arise from inner surface of lower part of body of sternum and costal cartilages

• Inserted into inner surface of costal cartilages from 2 to 6.

• Thin bands of muscle fibers.• Mainly in lower 6 spaces.• Only in post. part of spaces.• Origin: Inner surface & lower

border of rib above.• Insertion: Upper border of 2nd

or 3rd rib below.

SternocostalisSternocostalis

Subcostalis muscleSubcostalis muscle

Expiratory MusclesExpiratory MusclesExpiratory MusclesExpiratory MusclesAct only during forced expirationAct only during forced expiration• Rib depressors:Rib depressors:

Internal intercostalInternal intercostal Innermost intercostalInnermost intercostal SubcostalsSubcostals Transversus thoracis Transversus thoracis

• Anterior abdominal wall muscles:Anterior abdominal wall muscles: External obliqueExternal oblique Internal obliqueInternal oblique Transversus abdominisTransversus abdominis Rectus abdominisRectus abdominis

It contains:

1- Intercostal muscles.

2- Intercostal nerves.

3- Intercostal arteries.

4- Intercostal veins.

Intercostal musclesI. Outer layer: External intercostal muscle

II. Intermediate layer: Internal intercostal

muscle

III. Inner layer: Transversus thoracis group:

subdivided into:

a. Innermost inter-costalis

b. Sterno-costalis

c. Sub-costalis

Transversus thoracis group Arrangements and extension of the muscles

Intercostal Arteries

Intercostal Arteries:

 1- Anterior Intercostal Arteries.

2- Posterior Intercostal Arteries.

 •  •  •  •  •  •  •  •  •  •  •  •  •  •  •  •  •  •  •  •  

Anterior Intercostal Arteries Each anterior intercostal space contains two anterior intercostal arteries (except in the lower two inter-costal spaces).a.The upper 6 pairs arise from the internal thoracic artery.

b. The 7th, 8th, and 9th pairs arise from the musculo-phrenic artery.

Posterior Intercostal Arteries- Each posterior intercostal space contains one posterior

intercostal artery which runs in the costal groove .

*The upper two posterior intercostal

arteries superior intercostal artery (from the costo-cervical trunk) Subclavian artery.

* From 3 - 11 posterior intercostal

arteries and subcostal artery descending thoracic aorta.

Intercostal Nerves

- There are 11 intercostal nerves in the upper

11 intercostal spaces and a subcostal nerve

(12th ) below the last rib (on each side).

- Each intercostal nerve arises from the corresponding thoracic nerve.

Typical Intercostal Nerves

I. Anterior intercostal veins:

- They correspond to the

anterior intercostal arteries.

- They drain into the venae

comitantes of the

musculophrenic and internal

thoracic

arteries.

II. Posterior Intercostal VeinsRight side:

- 1st +2nd + 3rd post.

intercostal veins unite

to form the right

superior intercostal

vein azygos vein.

-4th - 11th post.

intercostal veins

azygos vein

-Subcostal vein Azygos

Vein

II. Posterior Intercostal VeinsLeft side:- 1stpost. intercostal vein

left innominate vein.- 2nd + 3rd post. intercostal

veins unite to form the superior intercostal vein

- 4th – 8th post. intercostal veins superior hemiazygos.

- 9th – 11th post. intercostal vein inferior hemiazygos vein.

- Subcostal vein inferior hemiazygos vein. 

Arrangement of intercostal nerve and vessels in the costal groove

Branches: White & grey rami (1)

communicans with sympathetic ganglion Collateral branch to

Intercostals (2) Lateral cutaenous

branch to skin (3) Anterior cutaenous (4) Muscular branchesPleural sensory

branches peritoneal branches (5) Articular branches.

Applied anatomy: Needles introduced into the intercostal spaces

(to remove collection in the pleura)

Site: They are done in the lateral part of the chest

wall.

Cause: To avoid injury of the posterio intercostal

nerve and vessels.

(It is also better to be introduced near the rib

below).

Thank you