Chapter 24 - Thoracic Wall

form protective cavity for the heart and lungs and for the organs of the superior aspect of the abdomen

function of the thoracic wall

sternum

breast bone

sternum

the flat bone located at the anterior aspect of the thorax in the midline

3

number of parts the sternum is divided into

manubrium

superior part of the sternum

sword

the shape/resemblance of the sternum

handle

the shape/resemblance of the manubrium

jugular notch

found on the superior border of the manubrium

clavicle, first 2 pairs of costal cartilage

articulations of the manubrium

hyaline

type of cartilage making up the intercostal cartilage

body

middle portion of the sternum

body

part of the sternum that is long, narrow, and thinner than the manubrium

costal cartilage of ribs 2-5

what the body of the sternum articulations

sternal angle

the junction of the manubrium and body

sternal angle

important, plapable landmark for counting ribs

xiphoid process

smallest, most variable, inferior part of the sternum

epigastric fossa

pit of the stomach

epigastric fossa

depression on the anterior aspect of the xiphoid process - palbable and often visible

xiphisternal joint

found between the xiphoid process and the body at the superior aspect of the epigastric fossa

ribs

12 pairs of flat bones that form most of the thoracic wall

12

number of ribs

anterior and inferior

direction that the ribs course from the thoracic vertebrae

head

portion of each rib that articulates with the bodies of the thoracic vertebrae

neck

constricted portion of the rib lateral to the head

tubercle

posterior projection lateral to the neck that articulates with the transverse process of the thoracic vertebrae

body

shaft part of the rib

angle

point where the curve (or angle) of the rib is the sharpest

anterior end

portion of the rib that articulates with the costal cartilage

costal groove

ridge that lies on the inferior surface of the shaft of the rib

costal groove

groove where the intercoastal vein, artery, and nerve pass through (superior to inferior)

increase

change of length from the 1st-7th ribs

decreases

change of length from the 7th rib to the 12th rib

true ribs

1st 7 ribs

true ribs

ribs directly connected to the sternum via costal cartilages

false ribs

lower 5 ribs

8-10

costal cartilage of these false ribs that join its suprajacent cartilage

11-12

costal cartilages of these ribs end blindly in muscle with no anterior articulations

floating ribs

ribs 11-12

coastal margin

formed by the costal cartilages of ribs 8, 9, and 10, which course medially and superiorly

infrasternal angle

formed by the intersection of the coastal margins at the xiphoid porcess

superior thoracic aperture

bounded by the upper border of the sternum and by the ribs

superior thoracic aperture

opening through which the great vessels and visceral tubes ascend and descend between the neck and the thorax

inferior thoracic aperture

opening in the thoracic cavity that is normally closed by the diaphragm

diaphragm

normally “closes” the inferior thoracic aperture, contains 3 openings for the inferior vena cavity, esophagus, and aorta

inferior vena cava, esophagus, aorta

3 vessels that pass through openings of the diaphragm

external, internal, innermost

3 layers of the intercoastal muscles

external intercostal muscles

external layer of the intercoastal muscles

internal intercostal muscles

middle layer of the intercoastal muscles

innermost intercoastal muscles

internal layer of the intercoastal muscles

lower margin of the rib above

origin of the external intercostal muscles

upper margin of the rib below

insertion of the external intercostal muscles

elevation of the ribs during inspiration

action of the external intercostal muscles

intercostal nerves T1-T6

thoracoabdominal nerves T7-T11

innervation of the external intercostal muscles

11

number of PAIRS of external intercostal muscles

medial and inferior

direction coursed by the external intercostal muscles from their point of origin to their point of insertion

tubercle of the rib

posterior extension of the external intercostal muscles

costochondral junction

anterior extension of the external intercostal muscles

external intercostal membrane

name of the external intercostal muscles where they thin out and become membraneous

costochondral junction

region where the external intercostal muscles thin out and become the external intercostal membrane

upper margin of the rib below and its costal cartilage

origin of the internal intercostal muscles

lower margin of the rib above and its costal cartilage

insertion of the internal intercostal muscles

depression of the ribs during expiration

action of the internal intercostal muscles

intercostal nerves of T1-T6

thoracoabdominal nerves T7-T11

innervation of the internal intercostal muscles

11

number of PAIRS of internal intercostal muscles

medial and superior

direction the internal intercostal muscles course from their point of origin to their point of insertion

internal intercostal membrane

in the intercostal spaces, where the muscles extend from the sternum anteriorly to the angles of the ribs posteriorly where they thin out

11

number of pairs of innermost intercoastal muscles

intercostal vessels and nerve

structures that separate the innermost intercostal muscles from the internal intercoastal muscles

neurovascular plane

region between the innermost intercostal muscles and the internal intercoastal muscles

12

number of PAIRS of thoracic spinal nerves

dorsal and ventral ramus

what all the 12 thoracic spinal nerves divide into

dorsal rami

course posteriorly and divide into medial and lateral branches

ventral rami

the larger branches of the spinal nerves that course forward into the intercostal spaces

T1-T6

intercostal nerves (proper) [ventral rami]

T7-T11

thoracoabdominal nerves [ventral rami]

below the rib

where the intercostal nerve passes its corresponding rib

between the internal and innermost intercostal muscles

where the intercostal nerve crosses the intercostal muscles

costal groove

part of the rib that the intercostal nerve passes through

inferior

where the intercostal nerve passes relative to the intercostal vein and artery

lateral cutaneous branch

part of the intercostal nerve that pierces the internal intercostal, external intercostal, and serratus anterior and posterior branches that supply the skin of the chest wall

skin of the chest wall

supplied by the lateral cutaneous branch

anterior end

part of the intercostal space where the intercostal nerve turns forward though the internal intercostal muscle, external intercostal membrane, and the pectoralis major

anterior cutaneous branch

branch of the intercostal nerve that supplies the skin of the front of the chest

breasts

sweat glands modified to produce milk

lactation

major function of the mammary gland

lactation

tosecrete milk for the nourishment of the child

15-20 lobes of the glandular tissue

main constituent of the mammary gland

lobes

contain alveoli or milk secreting mammary epithelial cells

grape-like clusters

arrangement of the lobes of the breast

alveoli

glandular tissue of the breast

6-8

number of breast lobes that assume the entire functional load while the remaining lobes are small and poor developed

fat

surrounds and overlies the glandular tissue of the breast and makes up a majority of the organ

lactiferous duct

drains each lobe of the breast and dilates near its termination

nipple

where the lactiferous duct empty

lactiferous sinus

dialation of the lactiferous duct near its termination ar the nipple

axillary tail

extends into the axilla

heavy ligamentous bands

connective tissue that firmly attaches the breast tissue to the skin

heavy ligamentous bands

firmly attach the breast tissue to the skin

retinacula cutis

well developed region where traverse and subdivide the fat and anchor the glandular tissue to the skin

suspensory ligaments

cooper’s ligament