L8 Diaphragm and Nerves of Thorax Flashcards
Diaphragm
Muscular base of thorax
Left and Right Crux = crua
=own nerve supply
Left dome (lower due to heart) Right dome (higher due to liver)
Allows for pressure and volume change
-Contracts= descends inferiorly = increased volume, decreased pressure, inhale
= less space in abdomen, higher pressure, aids venous return with IVC
Diaphragm Ligaments
Posterior attachment of the diaphragm
Centre: MediAN Arcuate Ligament/Aortic Hiatus
Middle: MediAL arcuate ligaments
Outer: LATERAL arcuate ligaments
Structures passing through diaphragm
IVC= T8 Oesophagus= T10 Aorta= T12
Diaphragm nerve supply
Phrenic Nerve
- somatic nerve from neck
- runs anteriorly re hilum
Crus
Right Crus Extend further + comes across onto Left side
Left Crus contained on Left side
Central Tendon
Tendonous region in the centre where 2x pleura meet
1) IVC T8 comes through
- tendon doesnt have alot of contractility, doesnt move, therefore IVC wont get compressed/blood continues to flow, as diaphragm contracts and descends
2) Right Phrenic nerve (Same opening as IVC)
- spreads out in radial fashion, supply Right side of diapraghm
Phrenic Nerve
C3-5 (cervical). somatic nerve, can control diaphragm moving (hold breath). Anterior to Hila of Lung
- some fibres off to pericardium
- supplies diaphragm from under surface
1) Right Phrenic nerve come through same opening in central tendon as IVC - spreads out in radial fashion
- supplies right side of diaphragm
2) Left Phrenic nerves enters via Left crus. pierces and spreads out across undersurfaces
Oesophagus
T10
comes through Right Crus of diaphragm, forming Sling around
-Sphincter for oesophagus (no true anatomical sphincter)
-closes the muscular tube for the majority of the time so stomach contents arent regurgitated back up
+ vagus nerve
-surround oesophagus in plexus (hard to tease off), then continues to abdomen
Vagus nerves
T10, with the Oesophagus, comes through Right Crus of diaphragm
- Parasymp supply to thorax and abdomen
- Cranial nerves, neck + thorax
- surround oesophagus in plexus (hard to tease off), then continues to abdomen
- Anterior and Posterior Vagal Trunks come from Left and Right vagus nerves
Aorta
T12
Midline, behind MediAN arcuate ligament
-can be compresses as doesnt come through muscular part of diaphragm = blood can flow freely
Thoracic Duct
Carrier majority of Lymphatic fluid back into venous system
- drains all lower limbs of abdomen
- cysterna kily continuation
Lower Limb muscle under MediAL arcuate ligament
Psoas major
-posterior abdominal wall
Lower limb muscle under the Lateral arcuate ligament
Quadratus Lumborum
Overriding Autonomic control re Breathing
Phrenic somatic control
- can consciously stop diaphragm from moving and hold your breath
- autonomic control return of breathing once pass out after holding breath long enough
Phrenic nerve Dermatome
C3-5 = chest + shoulder
Irritation of phrenic nerve = shoulder pain
-Intraabdominal nerve pain
1) inflamed gallbladder
2) pancreatitis
-irritation in intra-abdominal space = pain signal via Shoulder Tip pain
Classes of Nerves
- Somatic (Peripheral nerves)
(Intercostal nerves, Phrenic nerve)
-e.g. brachial plexus
-pain, motor, sensory
-controllable - Autonomic (visceral)
-make a plexus altogether
-regulates visceral functions
a) PARAsymp (Vagus)
-1. Brainstem cranial nerves III, VII, IX, X
-Vagus/wandering nerves
-2. Sacral spinal nerves (S2-S4) (from cauda equina). pelvic control.
b) Sympathetic (sympathetic chain) (T1-L2 spinal nerves)
- T1-T5 (supply to Cardiac + Pulmonary plexuses)
- T6-L2 (supply to splanchnic nerves)
What are the 4x nerves of the thorax?
- Intercostal Nerve (somatic)
- Phrenic nerve (somatic)
- Vagus (Para)
- Sympathetic chain (Symp)
Sympathetic chain
Only sympathetic supply (head - pelvis)
Lateral to vertebral column
Symp. branches come from each spinal level, and form chains w. ganglia at each level
-any interruption to these nerve in thorax can give signs that are much further afeild (face = tumour in thorax)
Autonomic Sympathetic nerves
Fight or Flight
- relaxes bronchioles
- increased HR heart rate
- increased CO
Parasympathetic nerves
- bronchiole constriction (less air in)
- decreased HR heart rate
- decreased CO
Sternal wires
on chest x-ray
chest has previously been opened up (e.g. for cardiac bypass)
-major
Lopsided diaphragm
markedly different
damaged phrenic nerve
Nerve= contraction = descent/downwards diaphragm
Nerve damage= diaphraghm doesnt move/doesnt descent remains high
Horner’s Syndrome
relatively common
weird face
-all on same side
1. PTosis- eyelid droops/ lost control/eye half closed
2. Meiosis - pupil constricts (not reactive to light) (pin point pupil)
3. Anhydrosis - lack of sweating dry half face) (hydro=water)
All controlled by sympathetic chain from chest. Hints tumour/lesion in chest compressing sympathetic chain info flow into head and neck
