Exam III: Thorax I Flashcards
Thorax: General Information
Shape: abnormal cylinder; two openings-superior and inferior; superior is small and narrow superior thoracic aperture and it has a large domed bottom part via the diaphragm; Bony cage + exterior components/pectoral regions
Contents: thorax is divided into two pleural (R and L) with central pericardial cavity between them containing the heart (perfusion of blood) and lungs (gas exchange)
Functions; conduit: allows structures of head and neck to travel through it, bony structure providing protection around the soft viscera, solely responsible for gas exchange/ respiration; central pump of the body is located
Boundaries: looking down you see the trachea and the major vessels; see rib1, vertebral body 1, clavicle, and manubrium
Superior Boundary of the Thorax
Superior thoracic aperture, 1st ribs, 1st vertebra, trachea, clavicle, coracoid process, subclavian arteries and veins (R and L), esophagus, brachial plexus, scapula, and axillary inlet
BRACCESSS VT
Inferior Boundary of the Thorax
The diaphragm attaches to ribs 11 and 12
Body of vertebra XII posteriorly
Distal cartilaginous ends of ribs VII to X, which unite to form the costal margin anteriolaterally
Anteriorly: xiphoid process of the sternum
Thoracic cavity is a slanted structure
Everything superior to the diaphragm is thoracic cavity
Line of Reference
- Midclavicular: halfway down the clavicle and straight down the ribs (MCL), one of the coordinates when describing the topography of the body
- Midaxillary line: look at patient laterally ask them to raise arm, draw line down the ribcage
These are important for medical interventions in the thorax that are life threatening
Pectoral Region Compartments
- Superficial: mammillary glands
2. Deep: musculature over the cage
The Breast
Modified sweat gland with series of suspensory ligaments for support and structure continuous with the dermis
When looking at breast, most is on the front, but also has an axillary tail in the axillary space; when preforming breast exam, need to also check the axillary process where tumors can hide
Breast Vasculature and Lymphatics
Vasculature: lateral thoracic, internal thoracic, and subclavian arteries
Feeders = pectoral branch of acromial artery and lateral thoracic artery both coming off axillary artery, but more medially are the mammillary branches coming off the internal thoracic artery
Venous drainage will parallel venous supply
Lymph node involvement= metastases
Surface anatomy of the breast around the nipple is divided into three sections:
- Lateral Breast= lymph flow to axillary nodes for metastasis
- Medial Breast: lymph flow to parasternal nodes
- Deep/inferior lymph flows down (gravity)
Breast Cancer
Supported in dermis in body wall by ligaments of Cooper
Mass in adipose= supply tension on ligaments, which causes pitting or dimpling of skin, called the Peau D’Orange
The mass will grow and put tension on suspensory ligaments causing puckering= highly suggestive of mass present; 9/10 means tumor or other mass
Men are also susceptible to breast cancer
Pectoral Musculature
Deep to breast musculature
Pectoralis major, minor, and subclavis
Pectoralis Major: large sheet muscle from sternum to proximal humerus
Pectoralis Minor: underneath pectoralis major and passes from the anterior surfaces of ribs 3-5 to the coracoid process of the scapula
Subclavis: underneath pectoralis major; small and passes laterally from the anterior and medial part of rib I to the inferior surface of the clavicle
Pectoralis Major
Origin: Medial half of clavicle and anterior surface of sternum, first seven costal cartilages, aponeurosis of external oblique
Insertion: Lateral lip of intertubercular sulcus of humerus
Innervation: Medial and lateral pectoral nerves
Function: Adduction, medial rotation, and flexion of the humerus at the shoulder joint
Subclavius
Origin: Rib I at junction between rib and costal cartilage
Insertion: Groove on inferior surface of middle third of clavicle
Innervation: Nerve to subclavius
Function: Pulls clavicle medially to stabilize
sternoclavicular joint
Pectoralis Minor
Origin: Anterior surfaces of the third, fourth and fifth ribs, and deep fascia overlying the related intercostal spaces
Insertion: Coracoid process of scapula
Innervation: Medial pectoral nerves
Function: Depresses tip of shoulder; protracts scapula
Skeletal Structure of Thorax
Osteology of the thoracic cage: posterior surface has spinal column, anterior is sternum, and ribs are lateral
Never have a direct bone to bone connection
Costal condral junction: cartilage to ribs= NEED TO BREATH because if bone to bone we wouldn’t be able to breath
Structure of the Sternum
Manubrium: articulation with clavicle, rib 1, and rib 2 (body shares connection to rib 2)
3,4,5,6,7 ribs= cartilaginous connection with sternum
True Ribs: 1-7
8,9,10 are specially connected to the sternum; don’t have direct cartilaginous connection to sternum, but articulate with costal cartilages of the ribs above
False Ribs: 8-12
Floating Ribs: 11 and 12 don’t have a connection to anything
Vertebral Structure
Vertebral body: weight bearing
Pedicle: connect arch to body (arch made of lamina)
T1-9 have demifacets because half of the articulation; rib 1 will articulate with T1, and so on… superior and inferior demifacet… T2 and T3 will articulate with a rib inferior and superior
Superior articular process allowing for articulation with superior vertebra, and two inferior for the inferior vertebra
T1 will have small vertebral body and as we move down they get bigger
Rib 10 with vertebrae 10
Rib 1 T1, Rib 10 T10,…. Everything else will share articulations ex. T2 and 3 articulate with Rib 2
No articulation point on transverse process
Rib Structure
Breast bone to spinal column
Head of rib to connect to demifacets
Articular facet on tubercle for connection to transverse process
All ribs have angles, where it starts to bend
External and internal surface of rib
Internal: look at posterior and see costal groove for location of artery, vein, and nerve
Special Features of Ribs I, XI, and XII
Rib1 is flatter, and unique because see circular pits on the external surface for large vessels like the subclavian artery and vein; bump in between the vessels is the scalene tubercle
Rib 12 looks like bony finger with not much of a curvature same with Rib11
The rest of the ribs are curved
Different and unique: Ribs 1, 11, 12
Take all the ribs and generally size up the ribs, where 7 is the largest
Vertebral Joints
Reinforced with ligaments
No place in the body has bone to bone connections, but has synovial joints that don’t provide much give
Synovial Joint: series of ligaments with joint capsule
Costotransverse Joints: synovial joints between tubercle of a rib and the transverse process of the related vertebra
Costotransverse Ligaments: medial to the joint and attaches the neck of the rib on the medial and lateral sides of the joint
Lateral Costotransverse Ligament: is lateral to the joint and attaches the tip of the transverse process to the nonarticular tubercle of the rib
These ribs are held by at least 3 ligamentous connections allowing some space for movement, but not too much
Interchondral, Sternocostal, and Fibrocartilaginous Joints
Interchondral Joints: cartilage to cartilage connections have synovial joints between ribs 6/7, 7/8, 8/9, and 9/10
Sternocostal Joints: between upper seven costal cartilages and the sternum
Rib 1 = fibrocartilaginous joint and very anchored
Thoracic Wall Musculature
Intercostal muscles: in between ribs with internal, external, and innermost layers
External are oriented in one plane and the internal in another plane; why are they in different directions? To have higher strength and resistance
External “hands in your pocket” are the way the fibers go
Innermost is the same as internal in direction (opposite of external)
Subcostal muscles: span a rib or two and go from rib to rib
Transversus thoracis muscles: originate on sternum and radiate outwards to connect with ribs
External Intercostal
Superior attachment: Inferior margin of rib above
Inferior attachment: Superior margin of rib below
Innervation: Intercostal nerves; T1-T11
Function: Most active during inspiration; supports intercostal space; moves ribs superiorly
Internal Intercostal
Superior Attachment: Lateral edge of costal groove of rib above
Inferior Attachment: Superior margin of rib below deep to the attachment of the related external intercostal
Innervation: Intercostal nerves; T1-T11
Function: Most active during expiration; supports intercostal space; moves ribs inferiorly