Ribs - Chapter 9 - Merrils Atlas

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Purpose of the Bony thorax?

The bony thorax supports the walls of the pleural cavity and the diaphragm used in respiration

What is the bony thorax formed by?

The bony thorax is formed by the sternum, 12 pairs of ribs, and 12 thoracic vertebrae

Position of the Sternum?

The sternum, or breastbone is directed anteriorly and inferiorly and is centered over the midline of the anterior thorax.

Describe the sternum...

a narrow flat bone about 6 inches in length, the sternum consist of 3 parts: manubrium, body and xiphoid process.

What does the sternum support?

supports the clavicles at the superior manubrial angles and provides attachment to the costal cartilages of the first seven pairs of ribs at the lateral borders.

Describe the manubrium...

The manubrium, the superior portion of the sternum, is quadrilateral in shape and is the widest portion of the sternum.

Jugular Notch

at the center superior border of manubrium is the jugular notch (easily palpable)

Clavicular Notch

posterior on each side of the jugular notch is an oval articular facet that articulates with the sternal extremity of the clavicle

Body of the sternum

is the longest part of the sternum (4 inches) and is joined to the manubrium at the sternal angle

Xiphoid process

is the distal and smallest part of the sternum it is cartilaginous in early life and partially or completely ossifies, particularly the superior portion in later life

How are the ribs numbered?

12 pairs of ribs are numbered consecutively from superiorly to inferiorly

Costal cartilages attachement

1-7 directly attached, 8-10 attached to 7th rib

How are the ribs situated?

on an oblique plane so that their anterior ends lie 3-5 inches below the level of their vertebral ends

True Ribs?

1-7 because they attach directly to the sternum

False Ribs?

8-12 because they do not attach directly to the sternum

Floating Ribs?

Last 2 (11-12) because they attach only to the vertebrae

Cervical Ribs?

articulate with the C7 vertebrae but rarely attach to the sternum, they may be free or fuse with the first rib

Parts of the ribs

head, a flattened neck, a tubercle, and a body, the ribs have facets on their heads for articulation with the vertebrae

What are the two ribs ends called?

Vertebral end and the sternal end

Describe the sternoclavicular (SC) joints...

are the only points of articulation between the upper limbs and the trunk

Joint Classification- sternoclavicular (SC)

Synovial, Gliding, Freely Moveable

Joint Classification - Costovertebral (1-12 ribs)

synovial, gliding, freely moveable

Joint Classification - Costotransverse (1-10 ribs)

Synovial, Gliding, Freely Moveable

Describe the Costovertebral Joint

posteriorly the head of the rib is closely bound to the demifacets of two adjacent vertebral bodies to form a synovial gliding articulation

Describe the Costotransverse joint & Costovertebral joint

the tubercle of a rib articulates with the anterior surface of the transverse process of the lower vertebra at the costotransverse joint, and the head of the rib articulates at the costovertebral joint

Describe the Costochondral articulations

The Costochondral articulations are found between the anterior extremities of the ribs and the costal cartilage, these articulations are cartilaginous sychondrosis and allow no movement

Describe the Sternocostal Joints

The articulation between the costal cartilages of the true ribs and the sternum

Respiratory Movement - quiet respirations

The normal oblique orientation of the ribs changes little during the quiet respiration movements; however the degree of obliquity decreases with deep inspirations and increases with deep expirations

Respiratory Movement - deep inspiration and expiration

On deep inspiration the anterior ends of the ribs are carried anteriorly, superiorly, and laterally while the necks are rotated inferiorly. On deep expiration the anterior ends are carried inferiorly, posteriorly, and medially while the necks are rotated superiorly

How are ribs above the diaphragm best examined

through the air filled lungs

How are the ribs below the diaphragm best examined

through the upper abdomen

body habitus and position of the diaphragm

higher level in hyperstenic patients, and lower in hypostentic patients

how much does respiration move the diaphragm?

averages 1.5 inches between deep inspiration and deep expiration. Movement is less in hyperstenic patients, and more in hypostentic patients.

Why the second respiration?

because there is deeper inspiration and expiration and therefore greater depression or elevation of the diaphragm.

Why not do ribs supine?

the anterior ends of the ribs are less sharply visualized when the patient is in the supine position.

How do you determine if the patient should be radiographed supine or upright?

unless the change can be done with a tilting table, patients with recent rib injury should be examined how they arrive in the radiology department

Ambulatory patients supine or upright?

the ambulatory patient can be positioned for the recumbent images with minimal discomfort by bringing the tilt table to the vertical position for each positioning change, The patient stands on the footboard is comfortably adjusted, and is then lowered to the horizontal position.

Fracture

disruption of the continuity of the bone

Metastases

Transfer of a cancerous lesion from one area to another

Paget's Disease

Thick soft bone marked by bowing and fractures

Tumor

New tissue growth where cell proliferation is uncontrolled

Problems radiographing the sternum...

The sternum is located directly anterior to the thoracic spine, so an AP or PA projection provides little useful diagnostic information. To separate the vertebrae and the sternum it is necessary to angle the CR about 15 degrees (deep chests less angle, shallow chests more angle).

Thorax thickness and central ray angulation

thorax thickness = 15cm, then CR angle = 22
thorax thickness = 30cm, then CR angle = 12

Sternum- PA Oblique RAO

SID = 30, 15-20 degree rotation, place top of IR about 1.5 inches above jugular notch, shallow breaths during exposure, unless short exposure time then suspend on expiration, CR enter elevated side at T7 and 1 inch lateral to msp

Sternum- PA Oblique (Moore's Method) Modified Prone

SID = 30, for ambulatory patients that is more comfortable, bend at waist and put sternum in center of table while standing, CR angled 25 degrees (less for large patients, and more for thin) respiration-slow shallow breathing or a low ma with 1-3 seconds use end of expiration

Sternum- Lateral (Upright)

SID = 72 to reduce magnification, have patient rotate shoulders posteriorly and lock hands behind back, adjust to true lateral, IR 1.5 inches above jugular notch, suspend on inspiration (sharper contrast), CR perpendicular to IR

Sternoclavicular Articulations - PA (Prone)

Center at 3rd Vertebrae or Jugular Notch, arms by side, palms upward, for bilateral pt head goes on chin so msp is vertical, for single head toward affected side, suspend on expiration, CR perpendicular to T3

Sternoclavicular Articulations - PA Oblique Projection (Body Rotation Method) RAO or LAO

keep affected side down with an oblique angle to project the vertebrae well behind the SC joint closest to the IR (10-15 degrees), suspend on expiration, CR enters T2-T3 (3 inches distal to vertebral prominence, 1-2 inches lateral to MSP), if CR enters right then left SC joint is shown

Evaluating Criteria of Sternoclavicular Articulation PA Obliques

SC joint in center, Open SC joint space, SC joint of interest immediately adjacent to vertebral column with minimal obliquely

Size of IR for ribs?

35x43 cm IR should be used to identify the ribs involvement and determine the extent of trauma or pathological condition.

How is the patient positioned for the anterior ribs?

PA projection, facing the IR

How is the patient positioned for the posterior ribs?

AP projections, facing the xray tube

When is the left ribs clear from the heart?

LAO or RPO, these 2 positions place the right-sided ribs parallel with the plane of the IR and are reversed to obtain comparable projections of the left-sided ribs.

Technicals factors for Ribs?

Technical factors that result in a short scale radiograph are often used (above 70 kvp)

Respiration for Ribs?

usually with respiration suspended on full inspiration or full expiration, sometimes shallow breathing may be used to obliterated lung markings.

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