Thorax Flashcards
Thoracic Musculature
- Intercostal Muscles (External, Internal, Innermost)
- Subcostal Muscles
- Transversus thoracis muscle
- Levator costarum muscle
- Diaphragm
External Intercostal Muscles Origin
Superior attachments - inferior margin of rib above
External Intercostal Muscles Insertion
Inferior attachment - superior margin of rib below
External Intercostal Muscles Innervation
Intercostal nerves T1-T11
External Intercostal Muscles Action
Moves ribs superiorly; most active during inspiration
Internal Intercostal Muscles Origin
Inferior attachment: Superior margin of ribs below deep to attachment sits of external intercostals
Internal Intercostal Muscles Insertion
Superior attachment - Lateral edge of costal groove of rib above
Internal Intercostal Muscles Innervation
Intercostal nerves T1-T11
Internal Intercostal Muscles Action
Moves ribs inferiorly; most active during expiration
Innermost Intercostal Muscles Origin
Inferior attachment - Internal aspect of superior margin of rib below
Innermost Intercostal Muscles Insertion
Superior attachment - Medial edge of costal groove of rib above
Innermost Intercostal Muscles Innervation
Intercostal nerves T1-T11
Innermost Intercostal Muscles Action
Moves ribs inferiorly; most active during expiration
Transverse Thoracis Muscles Origin
Posterior xiphoid process and body of sternum
Transverse Thoracis Muscles Insertion
Into inner aspect of costal cartilages of ribs 2-6
Transverse Thoracis Muscles Innervation
Intercostal nerves T2-T6
Transverse Thoracis Muscles Action
Depress costal cartilages of ribs 3-6 and at in exhalation; secure internal thoracic blood vessels to the anterior wall
Diaphragm Muscle Origin
- Origin (three parts:
- Sternal: Part dorsal to xiphoid process
- Costal: Part from inner surface of lower 6 ribs
- Lumbar: Part by two cura (crus Singular) - Dome shaped musculotendinous septum between thorax and abdominal cavities
- Right is longer attached to sides of vertebral bodies L1-L3
- Left is shorter attached to sides of vertebral bodies L1-L2
- Connected across the midline by Median Arcuate ligament, passing anterior to the aorta
- Medial lumbocostal arch (medial arcuate ligament) attached medially to L1 and L2 and laterally to L1 (Psoas major involvement)
- Lateral Lumbocostal arch (lateral arcuate ligament) attached medially to L1 and laterally to rib 12 (quadratus Lumborum involvement)
Diaphragm Muscle Innervation
Phrenic Nerve (C3, C4, C5)
Diaphragm Muscle Action
- flattens during inhalation to increase thoracic volume
- Relaxes during exhalation to decrease thoracic volume
Subcostal Muscle (Intracostal) Origin
Internal surface of rib
Subcostal Muscle (Intracostal) Insertion
Internal surface of rib on the 2nd or 3rd rib above
Subcostal Muscle (Intracostal) Innervation
Intercostal nerves T1-T11
Subcostal Muscle (Intracostal) Action
Move ribs inferiorly; act with internal interncostals
