L8 Diaphragm and Nerves of Thorax Flashcards Preview

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Flashcards in L8 Diaphragm and Nerves of Thorax Deck (23):


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

Oesophagus= T10
Aorta= T12


Diaphragm nerve supply

Phrenic Nerve
-somatic nerve from neck
-runs anteriorly re hilum



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



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



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

1. Somatic (Peripheral nerves)
(Intercostal nerves, Phrenic nerve)
-e.g. brachial plexus
-pain, motor, sensory
2. 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?

1. Intercostal Nerve (somatic)
2. Phrenic nerve (somatic)
3. Vagus (Para)
4. 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)


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