Anterior Thoracic wall (EXAM 1- Anatomy)

Describe the Jugular notch

The visible dip at the superior border of the manubrium

Describe the sternal angle and its location

• Palpable horizontal ridge where the manubrium meets the body of the sternum

• Marks the level of various significance

  • 2nd costal cartilage (at level 2 rib)

  • corresponds to T4-T5

  • Bifurcation of the trachea

  • Beginning and end of the aortic arch

  • The superior border of the heart

  • Separation of superior and inferior mediastinum

Describe the costal margin and its location

• The curved lower boundary of the thoracic cage, formed by the cartilages of ribs 7 to 10.

Identify the location infrasternal angle

Identify the location midclavicular line

Identify the location Axillary lines

• Anterior axillary line

• Midaxillary line

• Posterior axillary line

what are the borders of the breast?

• Sternum to mid axillary line

  • axillary tail/ tail of spence

• Clavicle to 5th-6th intercostal space

what is the retromammary space?

• Fascia that separates the breast from the pectoralis major and serratus anterior muscle

Describe the mammary glands and what it contains?

• Functional unit of the breast responsible for milk production

• Each breast contains 15-20 lobes

• Each lobe is made up of mammary lobules

Describe the lactiferous ducts and what it contains?

• Milk from each lobule drains into the lactiferous ducts

• Ducts aim towards the nipple

• Near nipple, each duct enlarges → lactiferous sinus → small reservoir for milk

Describe the areola and what it contains?

• circular pigmented area of the skin surrounding the nipple

• light pink→ dark brown

• Sebaceous glands → lubricates/protect during breastfeeding

• Smooth muscle fibers → pucker areola and erect nipple

Describe the nipple and what it contains?

• Prominent, conical projection at center of areola

• Exit point for milk

• 15-20 openings from the lactiferous ducts

• No hair or sweat glands

• T4 dermatomal layer

Describe the suspensory ligaments (Ligaments of cooper) and what it contains?

• Fibrous connective tissue bands that extend from dermis →pectoral fascia

• Maintain breast shape and structural integrity

• age or disease→ ligaments stretched or pulled causing skin dimpling

Describe the primary lymphatic drainage of the breast

• Both breast drain into axillary lymph or parasternal lymph

  • 75-90% Axillary lymph nodes

  • 10-15% Parasternal lymph

Where does Metastasis most commonly occur?

Axillary nodes, with palpation they become hard and fixed

Describe the location of axillary lymph nodes and how Right/Left axillary nodes travel?

• Lateral breast tissue

• Right axillar nodes → right lymphatic duct →right internal jugular vein

• Left axillary nodes → thoracic duct → subclavian vein

Describe the location of the parasternal lymph

• Medial breast tissue

• Deep behind sternum

• harder to palpate which is why medial tumors=silent

What are the corresponding actions of the Pectoralis Major?

• Flexion

• Adduction and medial rotation of the arm

• Horizontal adduction of the arm

What is the innervation of the Pectoralis Major?

Medial pectoral (C8-T1) and Lateral pectoral nerves (C5-C7)

What are the corresponding actions of the Pectoralis Minor?

• Protraction of scapula

• Medial rotation of scapula

• Downward movement of scapula

What is the innervation of the Pectoralis Minor?

Medial pectoral nerve (branches will pierce pectoralis minor to innervate pectoralis major)

What are the corresponding actions of the serratus anterior muscles?

• Protraction of the scapula

• Upward rotation of the scapula

• Stabilization of scapula against the thoracic wall

What is the innervation of the serratus anterior muscles?

Long thoracic nerve

What are the corresponding actions of the subclavius?

Stabilizes and depresses the clavicle

What is the innervation of the subclavius?

subclavian nerve

What are the corresponding actions of the intercostals?

• Elevates ribs

• Prevents intercostal space blowing out or retracting in during respiration

What is the innervation of the intercostals?

intercostal nerves T1-T11

Describe the functions of the thoracic cage

• Protection of viscera

  • Thoracic: Heart, lung, great vessels

  • Abdominal organs due to dome shape of diaphragm: liver, spleen, stomach, kidneys

• Mechanics of respiration

  • changing the internal volume to create pressure changes

• Attachment point for musculature

  • Upper limb movement, postural support, abdominal wall, accessory muscles of respiration

what do the true ribs (1-7)/ Vertebrosternal ribs articulate with?

Both the vertebrae and the sternum

(connect directly via their own individual costal cartilages= sternocostal joint)

What do the false ribs (8-10)/ Vertebrochondral ribs articulate with?

vertebrae and the costal cartilage above it

What do the floating ribs (11-12) articulate with?

NO interchondral joints or costochondral joints

Describe the costal cartilage and what articulates with it

• Bones of hyaline cartilage that prolong the ribs forward and provide chest elasticity (acts as flexible bridge that attaches anterior end of rib to sternum)

• false ribs (8-10)/ Vertebrochondral ribs articulate

• true ribs (1-7)/ Vertebrosternal ribs articulate

Describe the costovertebral joint and what articulates with it

Hinge joint attaching the head of the rib to the thoracic vertebral bodies

• Typical ribs 3-9 articulate

  • Superior- attaches to vertebrae above

  • Inferior- attaches to its own vertebrae

• Rib 1, 10 (sometimes), 11 and 12 only articulate w/ inferior vertebrae

Describe the costotransverse joint and what articulates with it

• Articulation of the rib’s tubercle with the transverse process of the same numbered vertebrae

Describe the Costochondral joint and what articulates with it

• NO FUNCTIONAL MOVEMENT

• Cartilaginous joint allows thoracic cage to expand and recoil during breathing

The sternum contains what structures?

• Manubrium

• Sternal angle

• Sternal body

• XIphoid process

Describe the Manubrium

Superior portion containing jugular notch

• JN: Internal jugular vein runs deep)

Describe the sternum body

Middle portion of the sternum

Describe the xiphoid process

Lowest portion of sternum, used as a surgical landmark but can break during CPR

Describe the sternocostal joint and articulations

• Articulations between costal cartilages and sternum

• Both synovial (2-7) and synchondrosis (1)

Describe the sternoclavicular joint

• Synovial joint

• provides stability

Describe intercostal nerves and what do they innervate?

• Exits intervertebral foramina of the spine

• Goes through intercostal space between internal and innermost intercostals

• Motor innervation= intercostal muscles in thorax and abdominal muscles

• Sensory innervation= overlying skin, pleura and parietal peritoneum

Describe subcostal nerves and what do they innervate?

• inferior to 12th rib

• along posterior wall→ abdominal regions

• Motor innervation= abdominal muscles

• Sensory innervation= hip, lateral gluteal region, lower anterior abdominal wall

Describe the phrenic nerve and what do they innervate?

• Ventral Rami/ C3-C5 (C5 keeps diaphragm alive)

• Anterior root of lung → along pericardium

• Motor innervation: diaphragm

• Sensory innervation: diaphragm, pleura, pericardium, inferior vena cava, and peritoneum

Describe the long thoracic nerve and what do they innervate?

• Posterior to brachial plexus→ superficial to serratus anterior

• Motor innervation: serratus anterior muscle

What are the arteries and veins associated with the vasculature of the anterior thoracic wall?

• Internal thoracic artery

  • Internal thoracic vein

• Intercostal artery

  • intercostal vein

• Subcostal artery

  • subcostal vein

Describe the internal thoracic artery

• Branch off subclavian artery

• Vertically, bilaterally, lateral to sternum along internal surface of rib cage

• Branches to: Anterior intercostals, musculophrenic arteries, superior epigastric artery

Describe the internal thoracic vein

• Formed by the confluence of superior epigastric and musculophrenic veins

• Runs next to the internal thoracic artery

• Empties into the brachiocephalic vein

Describe the Intercostal arteries and veins

• Anterior and posterior intercostal artery/vein meets in the middle and anastomosis (connection/bridge)

• Supplies: intercostal muscles, parietal pleura, skin, breast tissue (in 2nd, 3rd and 4th)

Describe the subcostal artery/vein

• last paired branch of the thoracic aorta

• Supplies some abdominal wall muscles

• Veins drain into azygos system

Describe the structure of the diaphragm

• Separates thoracic cavity from abdominal cavity

Describe the apertures of the diaphragm

Three separate hiatus for vessels:

• Aorta

• Inferior vena cava

• Esophagus

what is the innervation of the diaphragm?

Phrenic nerve

Bony landmarks of typical ribs (3-9)

• Head  - Connects with the thoracic vertebrae costal facets

• Neck

• Tubercle

• Articular facet  - connects with the thoracic vertebrae transverse costal facet

• Costal Angle

• Costal Groove

• Shaft / Body

Bony landmarks of Rib1 (Atypical rib)

• Only 1 articular facet

• Groove for subclavian artery

• Groove for subclavian vein

• Attachment of subclavius muscle

• Scalene tubercle

Bony landmarks for Rib 2 (Atypical rib)

• Similar landmarks to typical ribs

• Serratus anterior tuberosity

bony landmarks for Rib 11-12 (Atypical ribs)

• Only one large articular  facet

• Tubercle is absent

• Costal Groove is absent

• Distal end is pointed and capped in cartilage

Where do Posterior intercostal artery/vein in space 1-2 arise from?

subclavian artery

Where do Posterior intercostal artery/vein in space 3-11 arise from?

thoracic aorta

Where do Anterior intercostal artery/vein in space 1-6 arise from?

Internal thoracic artery

Where do anterior intercostal artery/vein in space 7-9 arise from?

Musculophrenic artery