Unit 4: Skeleton of the Thorax Breast

Body

*Inferior to sternal angle *Forms joints laterally w/costal cartilages: ribs 2-7 *Forms joint inferiorly w/Xiphoid process

Xiphoid process

*Most inferior section of sternum -Clinical marker for: *Superior liver surface *Apex (tip) of heart *Central tendon of diaphragm

Anterior Rib Joints:

*Ribs 1-10 hv costal cartilages (hyaline cartilage) *Costal cartilages of vertebrosternal ribs (1-7) attach rib ends to sternum. *Costal cartilages of vertebrochondral ribs (8-10) attach rib ends to rib 7 costal cartilage

Respiratory Diaphragm

-Dome shaped muscle separating thoracic & abdominal cavities. -Function: primary muscle of respiration -Composed of a wide, heart shaped sheet of skeletal muscle -Muscle fibers converge upon crescent shaped central tendon

3 types of ribs

1. Vertebrosternal (vertebrocostal): Ribs 1-7 *Also called "true ribs" *Each directly attaches to the sternum via its own costal (rib) cartilage 2. Vertebrochondral: ribs 8-10 *All attached to rib 7 by an elongated cartilage (chondros=cartilage) *NO direct connection to the sternum 3. Vertebral (floating ribs): ribs 11 & 12 *no sternal attachment; end muscles of lower lumbar area *Ribs 8-12 are also called "False Ribs"

Posterior Rib Joints

ALL ribs form joints w/their respective vertebral bodies. *Articular facet-(flattened surface) on head of rib forms a facet joint w/COSTAL FACET of vertebral body. -Rib 1 & ribs 10-12 hv only one costal facet on their heads -Ribs 2-9 hv both superior & inferior articular facets. -Thoacic vertebral bodies 1-9 also hv superior/inferior costal facets. -Ribs 1-10 hv tuberacle on rib; Tuberacles form joints laterally w/transverse costal facets.

Human Breasts: Blood & Lymphatic Supply

Blood supply: -Internal thoracic artery -lateral thoracic artery Lymphatic drainage: -Axillary lymph nodes (to clavicular & cervical) -Parasternal lymph nodes

Thoracic skeleton is OSTEOCARTILAGINOUS:

Composed of bone: *12 thoracic vertebrae *12 pairs of ribs *Sternum And cartilage: *10 pairs of Costal cartilages (ribs): last 2 rib pairs do not have costal cartilages. *Composed of Hyaline cartilage Cartilage joints mean that the thoracic skeleton is FLEXIBLE & slightly moveable as a person breathes.

Human Breast

Found on the fascia covering the pectoralis major muscle. *Modified apocrine sweat gland: -Similar to sweat glands found in the axilla & genital areas in both genders. -Milk secreting cells are found in lobules: small oval structures lined w/secretory cells. -Drained by a lactiferous duct, which empties into a lactiferous sinus, just deep to the nipple. -Usually 15-20 lobules in each breasts; organized into lobes.

Respiratory Diaphragm cont'd

Insertion of fibers: *Anterior: Xiphoid process of sternum *Anteriolateral: Costal cartilages of ribs 6-10 *Posteriolateral:Portion of rib 12 *Posterior: Bodies of L1-L3 lumbar vertebrae -The epimysium of the respiratory diaphragm blends w/the epimysium of 2 posterior back muscles: *quadrants lumborum *psoas major

Breast Cancer cont'd

Lymphatic drainage of breast is primarily to nodes at end of axillary tail; cancer cells can spread by breaking free of the tumor & traveling here -Cancer cells may also spread to parasternal nodes & cross to opposite breast -Cancer cell spread is called metastasis *Sentinal lymph node=1st node in chain of lymph nodes draining breast *If surgically removed & free of cancer, patient may hv metastasis *More conservative surgery reduces lymphedema: swelling of limb distal to where the nodes were removed.

Sternum is divided into 3 sections:

Manubrium: Superior joint w/clavicles *Lateral joint w/costal cartilages of Rib 1 *Inferior joint w/body of sternum & part of 2nd costal cartilages.

Atypical Ribs:

Rib 1: Flattened; shortest rib *Grooves for subclavian vessels on its superior surface *Forms joints w/T1 vertebral body & T1 transverse costal facet *Lies directly inferior & posterior 2 the clavicle Ribs 11 & 12: Single facets on their heads *No tuberacles *Each has a SINGLE joint: w/their respective vertebral bodies ONLY

Structure of a typical rib

Ribs 3-9 are typical ribs w/these features: *Head:forms joints w/thoracic vertebral bodies; has flattened articular facets *Neck:between head;tuberacle *Tuberacle: (on ribs 1-10):forms joint w/transverse processes of vertebrae *Costal groove: location of the costal Vein-artery-nerve (VAN) *Angle: rib travels lateral, then anterior

Manubrium cont'd

Superior feature: sternal (jugular) notch *Blood pushing thru the aorta-body's largest artery-can be seen above the notch: *If exercising very heavily *If its valve doesn't function properly *If its diameter is 2 small Inferior feature: sternal angle *Where manubrium and body meet *Clinical marker for the 2nd rib *2nd intercostal space=location of 2 major heart valves

Human Breasts cont'd

Support Structure: *Surrounded by adipose; supported from skin & fascia by suspensory ligaments Areola=Darkly pigmented ring of skin surrounding nipple;contains numerous areolar glands tht lubricate nipple during lactation. Breast is arranged into 4 quadrants: *upper outer & inner quadrants *lower outer & inner quadrants Axillary Tail: extension into the axilla

Breast Cancer

Usually begins in cells of lobules or lactiferous sinuses -Signs & symptoms: *Painless lump or thickening in breasts; found by self examination or screening mammography *Painful lump *Swelling, puckering, or redness of skin *Bloody discharge from nipple *Changes to size, shape or skin appearance *Inverted nipple