Anterior Chest Wall Anatomy

Surface Anatomy & Reference Lines

• Mid-sternal line refers to the vertical line drawn down the middle of the sternum.
• Mid-clavicular line runs vertically down from the midpoint of the clavicle.
• Subcostal line is a horizontal reference line located at the lowest point of the rib cage.
• Axillary lines include the anterior, mid, and posterior axillary lines, which define the boundary of the axilla area.

Thoracic Skeleton

• The thoracic skeleton consists of the sternum, ribs, and thoracic vertebrae.
• Components include the manubrium, body, xiphoid process, true ribs (1-7), false ribs (8-10), and floating ribs (11-12).
• Ribs articulate with the sternum via costal cartilage (true ribs) or indirectly (false ribs).

Vertebrae Mechanics

• Thoracic vertebrae feature articular facets for rib attachment.
• Ribs articulate with their corresponding vertebral bodies at superior and inferior costal facets.
• Ribs 3-9 have a distinctive structure with necks and tubercles for articulation.

Anatomy of Breasts

• Female breast characterized by mammary creases and presence of areola and Montgomery glands.
• Blood supply comes primarily from the subclavian artery, axillary artery, lateral thoracic artery, and internal thoracic artery.
• Lymphatic drainage includes axillary, parasternal, abdominal, and clavicular nodes.

Clinical Findings

• Physical examination findings: Lump indicates cyst or mass, dimpling may suggest injury, retracted nipple could signal congenital issues, and peau d'orange appearance may indicate lymphatic blockage.
• Warmth and redness can occur due to pregnancy, menstrual cycle, or inflammation.

Pectoral Kit

• Pectoralis major has two heads: clavicular and sternocostal, originating from the clavicle and sternum, respectively, inserting on the bicipital groove of the humerus.
• Pectoralis minor stabilizes the scapula, while subclavius anchors the clavicle.
• Serratus anterior facilitates scapular movement and holds it against the thoracic wall.

Muscular Dynamics

• Intercostal muscles comprise external intercostals (elevate ribs during inspiration) and internal intercostals (depress ribs during forced expiration).
• The diaphragm plays a vital role in increasing thoracic cavity volume during breathing.

Respiratory Mechanics

• Inspiration relies on diaphragm contraction and accessory muscles to elevate the rib cage.
• Expiration is typically passive but can involve abdominal muscles for forced expiration to increase abdominal pressure.

Anatomical Variations & Conditions

• Conditions such as polymastia (supernumerary breasts) and gynecomastia (male breast tissue development) highlight anatomical diversity in breast morphology.
• Clinical awareness of breast quadrants aids in localizing malignant tumors during examinations.

Surface Anatomy & Reference Lines

• Mid-sternal line refers to the vertical line drawn down the middle of the sternum.
• Mid-clavicular line runs vertically down from the midpoint of the clavicle.
• Subcostal line is a horizontal reference line located at the lowest point of the rib cage.
• Axillary lines include the anterior, mid, and posterior axillary lines, which define the boundary of the axilla area.

Thoracic Skeleton

• The thoracic skeleton consists of the sternum, ribs, and thoracic vertebrae.
• Components include the manubrium, body, xiphoid process, true ribs (1-7), false ribs (8-10), and floating ribs (11-12).
• Ribs articulate with the sternum via costal cartilage (true ribs) or indirectly (false ribs).

Vertebrae Mechanics

• Thoracic vertebrae feature articular facets for rib attachment.
• Ribs articulate with their corresponding vertebral bodies at superior and inferior costal facets.
• Ribs 3-9 have a distinctive structure with necks and tubercles for articulation.

Anatomy of Breasts

• Female breast characterized by mammary creases and presence of areola and Montgomery glands.
• Blood supply comes primarily from the subclavian artery, axillary artery, lateral thoracic artery, and internal thoracic artery.
• Lymphatic drainage includes axillary, parasternal, abdominal, and clavicular nodes.

Clinical Findings

• Physical examination findings: Lump indicates cyst or mass, dimpling may suggest injury, retracted nipple could signal congenital issues, and peau d'orange appearance may indicate lymphatic blockage.
• Warmth and redness can occur due to pregnancy, menstrual cycle, or inflammation.

Pectoral Kit

• Pectoralis major has two heads: clavicular and sternocostal, originating from the clavicle and sternum, respectively, inserting on the bicipital groove of the humerus.
• Pectoralis minor stabilizes the scapula, while subclavius anchors the clavicle.
• Serratus anterior facilitates scapular movement and holds it against the thoracic wall.

Muscular Dynamics

• Intercostal muscles comprise external intercostals (elevate ribs during inspiration) and internal intercostals (depress ribs during forced expiration).
• The diaphragm plays a vital role in increasing thoracic cavity volume during breathing.

Respiratory Mechanics

• Inspiration relies on diaphragm contraction and accessory muscles to elevate the rib cage.
• Expiration is typically passive but can involve abdominal muscles for forced expiration to increase abdominal pressure.

Anatomical Variations & Conditions

• Conditions such as polymastia (supernumerary breasts) and gynecomastia (male breast tissue development) highlight anatomical diversity in breast morphology.
• Clinical awareness of breast quadrants aids in localizing malignant tumors during examinations.