Lecture Notes on Internal Intercostals and the Pectoral Girdle

Discussion on trunk anatomy before moving to appendicular muscles.
Emphasis on the importance of muscular structure in relation to respiratory functions.

External Oblique Muscle
- Located on the lateral sides of the abdomen.
- Function: Bends and rotates the trunk.
Internal Oblique Muscle
- Positioned beneath the external oblique.
- Function: Assists in trunk rotation and can compress abdominal contents.
Transversus Abdominis
- Deepest abdominal muscle layer.
- Function: Provides stability and compresses abdominal contents.

Diaphragm
- Main muscle of respiration.
- Inhalation: Contraction of the diaphragm allows air to be drawn into the lungs.
- Exhalation: Relaxation of the diaphragm assists in expelling air.
External Intercostal Muscles
- Assist in inhalation by expanding the rib cage.
- Run in the same directional orientation as the external obliques.
Internal Intercostal Muscles
- Responsible for forced exhalation by depressing the ribs.
- Function: Engage during activities such as blowing air into a balloon.

Composed of the clavicle and scapula.
Role: Stabilizes shoulder joints and allows a wide range of upper limb movements.
Joint Classification: Diarthrotic joint, characterized by a large range of motion, which necessitates muscular support.
Stress on structure: The absence of muscular reinforcement can lead to instability in the girdle, leading to injuries or functional impairments.

Notable that reference to muscle attachment sites varies across textbooks (e.g., ribs 2-5 vs. ribs 3-5).
Importance of recognizing individual anatomical differences, emphasizing that variability exists among individuals (