MUSCLES OF THORACIC WALL with details

1. MUSCLES OF THORACIC WALL
By : Dr Raheel Ahmad

2. INTERCOSTAL SPACE
• Space between the ribs contains three muscles of
respiration:
1) External intercostal
2) Internal intercostal
3) Innermost intercostal
• Innermost intercostal muscle is lined internally by the
endothoracic fascia and parietal pleura.
• Intercostal nerves and blood veins run between the
internal and innermost intercostal muscles.
• Arranged in order from above downward : intercostal
vein, intercostal artery and intercostal nerve.

4. DIAPHRAGM
• Most important muscle of repiration. Dome shaped.
• Origin of diaphragm is divided into three parts:
1. Sternal part: arising from posterior surface of the
xiphoid process.
2. Costal part: arising from the deep surface of the lower
six ribs and their costal cartilages.
3. Vertebral part: arising from vertberal column.
• NERVE SUPPLY:
The phrenic nerve

6. INTERCOSTAL MUSCLES
• EXTERNAL INTERCOSTAL:
Origin : Inferior border of the rib above
Insertion: superior border of the rib above
Nerve supply: Intercostal nerve
Action: Except first rib, they raise ribs during
inspiration and thus increase anteroposterior
and transverse diameter of thorax, last rib
fixed by abdominal muscle lower ribs during
expiration.

7. CONTT….
• INTERNAL INTERCOSTAL MUSCLE:
ORIGIN: inferior border of the rib above.
Insertion: superior border of the rib above
Nerve supply: Intercostal nerve
ACTION: assist external intercostal muscle

8. LEVATORES COSTARUM
ORIGIN: transverse process of seventh cervical
and eleventh thoracic vertebra
INSERTION: superior border of the ribs
NERVE SUPPLY: posterior rami of the thoracic
spinal nerve
ACTIONS: Elevate ribs

9. SERRATUS POSTERIOR SUPERIOR
ORIGIN: upper thoracic spines
INSERTION: Lower ribs
NERVE SUPPLY: Intercostal Nerve
ACTION: Elevate ribs

10. SERRATUS POSTERIOR INFERIOR
ORIGIN: Lower thoracic and upper lumbar spine
INSERTION: lower ribs
NERVE SUPPLY: Intercostal nerve
ACTIONS: Lowers Ribs