Thoracic Cage I Flashcards
- If damaged, can result in winged scapula due to lack of innervation of serratus anterior
- May be a complication of mastectomy
Long thoracic nerve
Rib categorization
- True Ribs 1st to 7th pairs
- False Ribs 8th to 12th pairs
- Floating Ribs 11th and 12th pairs only
Structure of Costovertebral joints
A single rib will articulate with 2 vertebra but only with one transverse process
- Costovertebral Joint- Between head of rib and 2 vertebral bodies, at and above rib level.
- Costotransverse Joint- Between tubercle of rib and transverse costal facet of vertebra, at rib level
When structures from the inlet are compressed….
Results in upper limb issues
Thoracic inlet syndrome occurs
Sternal angle of Louis is a landmark for…
Level at Intervertebral disc between T4-T5
Manubriosternal Joint
Costal Cartilage of 2nd Rib
Xyphoid process is a landmark for …
Xiphoid Process- Level at Intervertebral disc between T9-T10
The root/spine of the scapula and the inferior angle of the scapula are landmarks for…
Root of the spine of scapula-Vertebral level T4 & Spine of T3
Inferior angle of scapula-Vertebral Level T8 & Spine T7; Also Overlies Rib 7, “points” to Rib 8
Breast anatomy
- Mammary gland lobules (15-20) –> Lactiferous ducts –> Lacterifous sinus.
- suspensory ligatments- Cooper’s ligaments.
Retromammilary space
- between glands and deep fascia. Allows for breast movement
Breast Blood Supply
Lateral Thoracic A.
internal thoracic A. and branching pectoral from thoraco acromial trunk A.
Breast Lymphatic drainage
75% into axillary nodes
25% via parasternal and clavicular lymphnodes
Pectoralis Major
N: Medial and lateral pectoral nerves
Blood: Pectoral branches of thoraco acromial trunk
Pectoralis Minor
N: Medial pectoral nerve (dives through pec minor)
Blood: Pectoral branches of thoraco acromial trunk
Serratus Anterior
N: long thoracic Nerve (superficial to the muscle)
Blood: Lateral Thoracic A
Rib Elevators of the back…
Serratus posterior inferior
Levator Costarum- (also lengthens spine;rotates and flexes spine) 12 pairs of fan shaped muscle,Transverse Processes C7-T11 to Costal Tubercle and Costal Angle
Rib depressors in the back…
Serratus Posterior inferior
3 Layers of intercostal muscles
External intercostal muscles are most superficial
internal intercostal muscles are in the middle
Innermost intercostal Muscles are the deepest layer
External Intercostal muscles
-1 st layer
- rib elevators
- Fibers run Anterioinferiorly (hands in pockets), from upper to lower ribs
Starts from costal tubercle to costochondral junction
Continues as external (anterior) intercostal membrane to sternum
- Anterior or external membrane
Internal intercostal Muscles
- 2nd layer
- rib depressors in the Costal Region, elevates ribs in the chondral region
- Fibers run Posteroinferiorly (hands in gloves), from upper rib to rib below
- Starts at lateral border of sternum, runs to costal angle
- Continues to vertebrae as internal (posterior) intercostal membrane
- has internal or posterior membrane
Innermost intercostal Muscles:
- 3rd layer, most deep
- Action similar to internal intercostal mm, depressing ribs
- Located internally on posterolateral thoracic walls
- formed by 3 different muscles types
(Thoracic) Diaphragm
- lumbar, costal and sternal attachments
- central tendon
- main muscle of inspiration
- ## Phrenic nerve C3-C5
Muscles of Inspiration
- diaphragm
- external intercostals
- chondral portion of internal intercostals
Muscles of FORCED inspiration
- diaphragm
- external intercostals
- chondral portion of internal intercostals
- SCM
- Scalenes
Muscles of Expiration
- Most of expiration is passive
- Costal portion of internal intercostal muscles
- innermost intercostal muscles
Muscles of FORCED expiration
- Most of expiration is passive
- Costal portion of internal intercostal muscles
- innermost intercostal muscles
- Abdominal muscles
Fascial and plueral layers of the thoracic cavity
- Endothoracic fascia (lines muscles)
- Costal Parietal Plueral (lines the thoracic wall, cervical, costal, diaphragmatic, medialstinal near the heart)
intimately connected with endothoracic fascia - Visceral Plueral (lines the lungs themselves)
VAN
- first 11: Intercostal arteries nerves and veins,
- 12- subcostal VAN
- found in between 2nd and 3rd layers of muscles, and rest along each rib’s costal groove, inferior border of the rib.
- Superior border of the bottom rib is the safest place for chest tubes/needles, etc.
Nerve Supply
- traditional “perfect spinal nerve”, ventral primary rami, both sensory and motor, and line up with dermatomes.
- T10 is the level of the navel
- Intercostal Nerves- comes of thoracic T1- T11
- thoraco-abdominal T7-T11
- T12 is subcostal nerve
Anterior Arterial Supply
- notes: blood supply is split between anterior posterior supply
- internal Thoracic A (branch of the subclavian)
- gives off Anterior intercostal ateries to supply ribs 1-6.
Eventually biphricates into: - Superior epigastric Artery- supplies upper abdomen.
- Musculorphrenic A which supplies spaces 7-9
- floating ribs 10-11- no anterior intercostal spaces- no ateries
Posterior Arterial supply
- Primary from Descending Aorta
- ## Supreme intercostal/superior intercostal from costal cervical trunk from IC space 1 and 2
Anterior venous drainage
- The anterior intercostal veins follow the anterior arteries and drain into the internal thoracic vein
Posterior Venous Drainage
- right side is different from left.
- Azygous system
- right side- drains into Azygous
- Left side: superior side drains into Accessory Hemiazygous, inferior drains into Hemiazygous
- ## both then drain into the azygos
Posterior Venous Drainage
- right side is different from left.
- Azygous system
- right side- drains into Azygous to get to the SVC
- Left side: superior side drains into Accessory Hemiazygous, inferior drains into Hemiazygous
- ## both then drain into the azygos
Costocervical trunk gives rise to…
The Supreme intercostal artery, which is the posterior arterial supply for intercostal spaces 1 and 2
