anatomy presentation ho10(thorax 1)

The Thorax The thorax (chest) is the superior

part of the trunk between the neck and abdomen.

The thoracic cavity, surrounded by the thoracic wall ,contains the heart, lungs, thymus, distal part of the trachea, and most of the esophagus.

To perform a physical examination of the thorax, a working knowledge of its structure and vital organs is required.

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Thoracic Wall

The thoracic wall consists of skin, fascia, nerves, vessels, muscles,

and bones. The functions of the thoracic wall

include protecting of the thoracic and abdominal

internal organs; resisting the negative internal pressures

generated by the elastic recoil of the lungs and inspiratory movements;

providing attachment for and supporting the weight of the upper limbs;

and providing attachment for many of the muscles of the upper limbs, neck, abdomen and back, and the muscles of respiration.

The mammary glands of the breasts are in the subcutaneous tissue overlying the pectoral muscles covering the anterolateral thoracic wall.

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Skin of the Thorax

The thoracic skin is relatively thin and contains a variable amount of hair, which depends on age, sex and race; i.e. its amount is genetically determined.

Thoracic hair is abundant in males than in females.

It is found in a higher density at the median plane and extends to the anterior abdominal wall for a variable distance.

In male the amount of hair on the chest and on the head are inversely related.

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Blood Vessels of the Skin of the Thorax Arteries - cutaneous branches of lateral

thoracic and intercostal arteries Veins - drain into lateral thoracic,

thoracoepigastric and intercostal veins Innervation of the Skin of the Thorax

The thoracic wall is innervated by the cutaneous branches of the segmental ventral rami spinal nerves and by supraclavicular nerves

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Fascia of the Thorax

The fascia of the thorax can be divided into two:

The outer thoracic fascia on the outside of the thoracic wall having its

own two layers Superficial layer

a part of the superficial fascia of the body containing the breast, which is fibrous and tough

Deep layer a thin layer inseparable from the epimysium of the

underlying muscles, except dorsally where it forms the thick thoracolumbar fascia

The inner endothoracic fascia found on the inner surface of the thoracic wall

covering the thoracic surface of the ribs, muscles and diaphragm.

Internally it is related to the parietal pleura. Its part covering the cervical pleura (cupola) is

known as suprapleural membrane (Sibson's fascia) and the part related to the diaphragmatic pleura is called phrenicopleural fascia.

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Skeleton of Thoracic Wall

The thoracic skeleton forms the osteocartilaginous thoracic cage

The thoracic skeleton (bony thorax) includes 12 pairs of ribs and costal

cartilages, 12 thoracic vertebrae and

intervertebral (IV) discs, and the sternum.

Costal cartilages form the anterior continuation of the ribs, providing a flexible attachment at their articulation with the sternum

Ribs and their cartilages are separated by intercostal spaces, which are occupied by intercostal muscles, vessels, and nerves.

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Skeleton of Thoracic Wall

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The Bony Thorax

Sternum Manubrium, Body

(Gladiolus), Xiphoid Process

Ribs 7 True Ribs 5 False Ribs

Clavicle Scapula Vertebrae

Cervical,Thoracic, Lumbar, Sacral (Sacrum), Coccygeal (Coccyx)

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Projections and Depressions

Site of muscle and ligament attachments Spine Process

Help form joints Head Facet

Allow BV, nerves, and muscles to pass Notch Fossa

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Thoracic Cage Borders:

Thoracic vertebrae posteriorly

Ribs laterally Sternum and

costal cartilages anteriorly

Forms protective cage around heart, lungs, and other organs

Composed of: Sternum Ribs Vertebrae

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The Sternum (Composed of fused sternebrae)

Manubrium Jugular (sternal) notch Articulation with rib #1 &

2 Clavicular Articular facets Sternal Angle – 2nd rib

Body (Gladiolus) Articulates w/ribs 2-7 Xiphosternal joint

Xiphoid process Cartilage-calcifies thru

time Partial attachment of

many muscles

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The Ribs Usually, 12 pairs

7 True ribs-direct attachment to sternum

5 False ribs-indirect or no attachment to sternum

Floating ribs-make up 2 of 5 False ribs, no ventral attachment

Typical Ribs Ribs # 2-9

Atypical Ribs Ribs #1, 10, 11, 12

Reinforce thoracic cage

Typical rib. The features (A) and midbody cross section (B) of a typical rib are demonstrated

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Rib Anatomy

Typical Ribs Head Neck Tubercle Angle Shaft Subcostal

Groove

Typical rib. The features (A) and midbody cross section (B) of a typical rib are demonstrated

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Rib Anatomy

Atypical Ribs #1-short, flat (S-I),

wide, Supports Subclavian vessels

#1, 10-12 articulate with only = # vertebra

#11, 12 don’t articulate with transverse processes, or anteriorly at all Atypical ribs. The 1st (A) and 12th (B) ribs are

shown.

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Joints of Thoracic Wall

Although movements of the joints of the thoracic wall are frequent e.g., during respiration, the range of movement at the individual joints is small.

Any disturbance that reduces the mobility of these joints interferes with respiration.

Joints of the thoracic wall occur between the: Vertebrae (intervertebral joints). Ribs and vertebrae (costovertebral joints: joints of

the heads of ribs and the costotransverse joints). Sternum and costal cartilages (sternocostal joints). Sternum and clavicle (sternoclavicular joints). Ribs and costal cartilages (costochondral joints). Costal cartilages (interchondral joints). Parts of the sternum (manubriosternal and

xiphisternal joints) in young people; usually the manubriosternal joint and sometimes the xiphisternal joint are fused in the elderly.

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Typical Rib Articulation Dorsal (P) Attachment Thoracic

Vertebrae Head of Rib 2 costal facets

Superior costal facet Inferior costal facet of vertebra

above it Intervertebral disc

Tubercle of Rib Transverse Costal Facet

e.g. Rib #4 articulates with Superior Costal Facet and Transverse Costal Facet of T4 & Inferior Costal Facet of T3

Ventral (A) Attachment to Sternum Via costal cartilage

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Typical Rib Articulation

Costovertebral joints. The elements of the joint of the headof the rib and the costotransverse joint are identified.

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Muscles of the Thoracic Wall Except a small area posteriorly, the thorax is entirely

covered by muscle. These muscles can be grouped into two groups. Muscles on the Outside of the Thorax,

most of which are inserted to the upper limb and include: Pectoralis major Serratus anterior Pectoralis minor Trapezius Rectus abdominis Latissimus dorsi External oblique Rhomboids Internal oblique Serrati posterior

Muscles of the Thoracic Wall Proper – that are attached to the vertebrae (muscles of the back), the

ribs and the sternum (intercostal muscles).

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The Intercostal Muscles

The intercostal muscles fill the intercostal spaces together with the intercostal vessels, nerves and membranes.

Their fibers attach the ribs above and below each space and assist in respiration.

They appear in the following three layers. External layer - formed by the external

intercostal muscle Middle layer - formed by the internal

intercostal muscle Internal layer - formed by intercostalis

intimi (inner most intercostal),subcostalis and transverse thoracis muscles.

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Intercostal Muscles

External Intercostals O: Inferior border of rib above I: Superior border of rib below Fibers run OBLIQUE (down and forward) Aid in Inspiration (lift ribcage, increase dimensions)

Internal Intercostals O: Superior border of rib below I: Inferior border of rib above Fibers run at RIGHT ANGLES to external intercostals Aid in forced expiration (depress ribcage, decrease

dimensions) Innermost Intercostals, Subcostals, Transversus

thoracis Attachments similar to Internal Intercostals, Attach ribs Small, variable, function unclear

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Intercostal Muscles

All the intercostal muscles are innervated by the ventral rami of the spinal nerves that form the intercostal nerves.

The intercostal spaces near the sternum and the vertebrae are not completely filled by muscles, vessels or nerves.

The filling of the spaces near the sternum is completed by external (anterior) intercostal membrane, while the internal (posterior) intercostal membrane completes that of those near the vertebrae

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Intercostal Muscles22

DiaphragmDiaphragm Origin:

1. Sternal head: from xiphoid process.2. Costal head: lower six ribs and costal

cartilage.3. Vertebral head: right and left crura from

the first, second and third lumbar vertebrae and arcuate ligaments.

Insertion:Central tendon of the diaphragm.

Nerve Supply:Motor: phrenic nerve.Sensory: phrenic and Intercostal nerves.

Action:Increase the vertebral diameter of the

thoracic cavity (muscle of inspiration).

Origin:1. Sternal head: from xiphoid process.2. Costal head: lower six ribs and costal

cartilage.3. Vertebral head: right and left crura from

the first, second and third lumbar vertebrae and arcuate ligaments.

Insertion:Central tendon of the diaphragm.

Nerve Supply:Motor: phrenic nerve.Sensory: phrenic and Intercostal nerves.

Action:Increase the vertebral diameter of the

thoracic cavity (muscle of inspiration).

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Muscles of ThoraxMuscle Origin Insertion Action Innervation

Pectoralis major

Sternum, Ribs 2-6

Greater tubercle of humerus

Adduct, Flex, Med Rotate Arm

M & L pectorals

Pectoralis minor

Ribs 3-5 Coracoid process of scapula

Depress, Rotate scapula

M & L pectorals

Serratus anterior (ventralis)

Ribs 1-9 Scapula Protract, Rotate scapula

Long Thoracic

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Muscle Origin Insertion Action Innervation

Trapezius Ligamentum nuchae, C7-T12

Clavicle, Spine of scapula

Elevate, Adduct, Rotate, Depress

Accessory

Levator Scapulae

C1-C4 Medial border of scapula

Elevate scapula

D. Scapular

Rhomboids C7-T5 Medial border of scapula

Adduct, Elevate, Rotate

D. Scapular

Muscles of Thorax26

Muscles of Thorax


Deltoids Clavicle, Scapula

Deltoid tuberosity of humerus

Flex, Abduct, Extend, Lat & med. rotate arm

Axillary

Latissimus dorsi

Iliac crest,

T7-12, Lumbar fascia

Inter-tubercular groove of humerus

Extend, Adduct, Med. rotate arm

Thoraco-dorsal

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Rotator Cuff Muscles


Supraspinatus

Supraspinous fossa of scapula


Abduction of arm

Suprascapular

Infraspinatus Infraspinous fossa of scapula


Lat rotation of arm

Suprascapular

Teres Minor Lateral border of scapula


Lat rotation of arm

Axillary

Subscapularis Subscapular fossa of scapula

Lesser tubercle of humerus

Med rotation of arm

Subscapular

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Nerves and Vessels (Neurovascular bundle) of the thoracic wall

The main nerve and vascular supplies to the thoracic wall run in the intercostal spaces in bundles that form the neurovascular bundle of the thoracic wall.

Each bundle consists of vein, artery and nerve, which are related to the lower borders of the ribs, where they lie In the costal grooves and protected by their sharp lower edges.

The components of the bundle are arranqed from cranial to caudal in the order of VAN, i.e. Vein, Artery, and Nerve.

To avoid the injury of this neurovascular bundle during thoracic tap (thoracentesis), needle must be inserted near the upper border of a rib (not near the lower border).

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Neurovascular bundle of the thoracic wall

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The Intercostal Nerves

There are 12 pairs of intercostal nerves. Each intercostal nerve is divided into

anterior (ventral) and posterior (dorsal) branches or rami.

The posterior branches supply the muscles, bones, joints and skin of the

back. The anterior branches

run segmentally in the intercostal spaces as intercostal nerves.

At the level of the midaxillary line, they give lateral cutaneous branches to the skin of the lateral thoracic wall.

Near the edge of the sternum, anterior cutaneous branches are given off to the anterior thoracic wall

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The intercostal nerves innervate all the muscles along their

way. carry sensory fibers not only from

the skin of thorax but also from the abdominal wall, breast, parietal pleura and parietal peritoneum.

They also carry postganglionic sympathetic fibers to blood vessels, sweat glands, arrectores pillorum muscle.

The anterior branch of the 12th spinal nerve runs below the costal margin, and hence called subcostal nerve.

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Dermatomes and myotomes of the trunk. Note the relationship between the area of skin (dermatome) and skeletal muscle (myotome) innervated by a spinal nerve or segment of the spinal cord.The dermatomes of the thorax (T1 to12) are shown at the right.

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Intercostal Arteries

There are two sets of intercostal arteries: anterior and posterior intercostal arteries.

the posterior intercostal arteries Allarise from the thoracic aorta, except the first two, the first two arise from the intercostalis suprema

(supreme intercostal) artery, a branch of branch of costocervical trunk originating from the subclavian artery.

anterior intercostal arteries The upper six are branches of the internal thoracic, while the lower five are branches of the

musculophrenic artery, a branch of the internal thoracic artery running along the lower border of the thorax.

The thoracic wall gets additional arterial supply by some branches of the axillary artery.

In addition to the thorax, the intercostal arteries supply the spinal cord, the breast and abdominal wall

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Intercostal Arteries35

Intercostal Veins & Lymphatic Drainage

Intercostal Veins Similar to the arteries there are posterior and

anterior intercostal veins. The posterior intercostal veins drain into the

brachiocephalic, azygos (right side), hemiazygos and accessory hemiazygos (left side) that ultimately drain into the superior vena cava.

The anterior intercostal veins drain into musculophrenic and internal thoracic veins that finally end in the brachiocephalic vein.

Lymphatic Drainage of the Thoracic Wall Superficial and deep lymphatic vessels drain the

lymph from the thoracic wall. Anterior thoracic wall

Superficial vessels - drain into anterior axillary lymph nodes

Deep vessels - drain into internal thoracic (parasternal) lymph nodes

Posterior thoracic wall Superficial vessels - drain into the posterior

axillary lymph nodes Deep vessels - drain into the intercostal lymph

nodes

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Intercostal Veins37

Thoracic Apertures

The thoracic cavity communicates with the neck and upper limb through the superior thoracic aperture, the anatomical

thoracic inlet Structures entering and leaving the thoracic

cavity through this aperture include the trachea, esophagus, vessels, and nerves.

The adult superior thoracic aperture measures approximately 6.5 cm anteroposteriorly and 11 cm transversely.

Because of the obliquity of the 1st pair of ribs, the superior thoracic aperture slopes anteroinferiorly.

The superior thoracic aperture is bounded: Posteriorly by the T1 vertebra. Laterally by the 1st pair of ribs and their costal

cartilages. Anteriorly by the superior border of manubrium.

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Thoracic Apertures

The thoracic cavity communicates with the abdomen through the inferior thoracic aperture, the

anatomical thoracic outlet In closing the inferior thoracic aperture, the

diaphragm separates the thoracic and abdominal cavities almost completely.

The inferior thoracic aperture is more spacious than the superior thoracic aperture.

Structures passing to or from the thorax to the abdomen pass through openings in the diaphragm (e.g., the inferior vena cava and esophagus) or posterior to it (e.g., aorta).

The inferior thoracic aperture is bounded: Posteriorly, by the T12 vertebra. Posterolaterally, by the 11th and 12th pairs of

ribs. Anterolaterally, by the joined costal cartilages of

ribs 7 to10, forming the costal margin. Anteriorly, by the xiphisternal joint.

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The Breast

Location: (female breast) Superior border: 2nd rib Inferior border: 6th rib Medial border: Sternum Lateral border: Midaxillary line

Location: (male nipple) Fourth Intercostal Space, Midclavicular line

Underlying muscle Pectoralis major and minor Part of serratus anterior, external obliques

Lateral Thoracic Artery, branches of Internal Thoracic A., Post. Intercostals

Intercostal, Internal Thoracic, Axillary Veins Branches of Intercostal Nerve

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Mammary Glands

Lactiferous (modified sweat) Glands Breast made of 15-25 lobes (each a compound alveolar

gland) Lobes made of lobules (= clusters of acini/alveoli) Acini/Alveoli lined w/milk-secreting simple epithelial cells Lactiferous Ducts of lobes open at nipple Areola-ring of pigmented skin around nipple

Sebaceous gland produce sebum during nursing Lobes separated by adipose tissue and suspended by

connective tissue = Suspensory Ligaments of the Breasts

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Surface Anatomy

Use the next 3 slides and follow the book to

palpate (feel) the features listed

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Anterior Surface of Thorax

Palpate the following Sternum (3 parts) Jugular notch Sternal Angle (= 2nd

rib) Clavicle Costal margin Xiphosternal joint

Midclavicular Line Midaxillary Line

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Anterior Surface of Thorax45

Anterior Surface of Thorax46

Posterior Surface of Thorax

Palpate the following Spinous Process of C7 Scapula (ribs 2-7)

Scapular spine Acromion Process Inferior Angle of Spine Inferior Border

Read about breast & diaphragm

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Locating Internal Structures

Pleural Cavities Inferior margin = adjacent to

T12 in Posterior Midline To Rib 10 at Midaxillary line To Rib 8 at Midclavicular line To Xiphosternal joint medially Lungs posterior border is 2 ribs

superior to pleural cavity (rib 8) Heart

Deep to xiphisternal angle

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Vertebral Column

Humans’ made of 26 bones Cervical 7 Thoracic 12 Lumbar 5 Sacrum (5 fused sacral vertebrae) Coccyx (4 fused coccygeal

vertebrae) Extends from skull to pelvis Supports body, muscle

attachment Vertebral Canal

Created by vertebral foramen Contains + protects spinal cord

Intervertebral foraminaPg 45, 18

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Cervical Vertebrae (7)

**Transverse Foramen ** Superior Articular Facets face superoposteriorly Inferior Articular Facets face inferoanteriorly Allows wide range of motion Spinous process fairly short, bifid (except for

C7) Vertebral Foramen is Triangular Body is wider laterally than in A-P direction

Page 31

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Atypical Cervical Vertebrae

C1 – Atlas No body No Spinous Process Superior Articular

facets are kidney shaped

C2 – Axis Odontoid Process =

Dens Other features typical

Page 32

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Thoracic Vertebrae (12) **Transverse Costal

Facets ** *S/I Costal facets on

vertebral body* Spinous Processes long,

point inferiorly Superior Articular Facets

face Dorsally/Posteriorly Inferior Articular Facets

face Ventrally/Anteriorly Vertebral Foramen is

Circular Body is Heart-shaped

Pg 119

52

Lumbar Vertebrae (5)

Spinous process is short, rectangular, projects dorsally

Superior Articular Facets face Medially Inferior Articular Facets face Laterally Vertebral Foramen is Triangular Body is large and Kidney-shaped

Page 30

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Sacrum & Coccyx

5 fused Sacral Vertebrae Articulates with

5th Lumbar vertebra Coccyx Ilia of coxal bones

Functions in weight transfer

Has a body, sacral canal, sacral foramina

Remnants of other typical vertebrae features visible Lateral & median sacral

crest

3-4 fused Coccygeal vertebrae Articulations

#1 articulates with 5th Sacral Vertebra

Some muscle + ligament attachment

Slightly different orientation in males vs. females

No canal

Sacrum Coccyx

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Intervertebral Discs Absent between

C1 and C2 Sacrum and coccyx

Annulus Fibrosus Outer collar of concentric rings Outer rings = ligaments Inner rings = fibrocartilage Supportive/Structural

Nucleus Pulposus Inner disc, cushiony pad Remnants of notocord Shock Absorber

Pg 41

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Vertebral Column

Lateral Curvature (Following Dorsal Side) Cervical Region = Concave curve Thoracic Region = Convex curve Lumbar Region = Concave curve Sacrum = Convex curve

IN

IN

OUT

OUTPage 45

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Abnormal Curves

Scoliosis-abnormal lateral curve of more than 10° “twisted disease”

Kyphosis-exaggerated thoracic curve “humped disease”

Lordosis-accentuated lumbar curve “bent-backward disease”

www.nlm.nih.gov

www.nlm.nih.gov

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Ligaments of Vertebral Column

Anterior Longitudinal Ligaments (neck – sacrum) Run vertically on anterior surface of vertebral bodies +

intervertebral discs Wide,strong Prevents hyperextension

Posterior Longitudinal Ligaments (neck – sacrum) Run vertically on posterior surface of intervertebral discs only Narrow, weak Prevents hyperflexion

Ligamentum Flavum (contains elastic connective tissue) Attaches lamina of vertebrae (one on right, one on left) Very strong Page 44

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anatomy presentation ho10(thorax 1)

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