Week 2 - Thoracic muscles

Question 1

What happens to the central tendon when the diaphragm contracts

Answer 1

It is pulled inferiority increasing the vertical thoracic space

Question 2

Diaphragm Attachments, Action, NS

Answer 2

Attachments:

Superficial: inner border of costal margin,
posterior abdominal wall & superior
lumbar vertebrae
Deep: central tendon

Action: the central part descends during
inspiration; primary muscle of inspiration

NS: Phrenic nerve C345

Question 3

Damage above C4

Answer 3

Usually causes death as the phrenic nerve can’t send nerve impulses to diaphragm to breath

Question 4

Passive mechanisms during expiration

Answer 4

1. Elastic recoil of lung when diaphragm relaxes
2. Visceral contents move back superiorly once diaphragm relaxes

Question 5

Is inhalation passive or active contraction?

Answer 5

Active

Question 6

Is exhalation passive or active contraction?

Answer 6

Passive

Question 7

Intercostals Attachments, Action, NS

Answer 7

Attachments:
Superior: inferior border of superior ribs
Inferior: superior border of inferior ribs

Action: Majority of fibres elevate ribs
during inspiration
Stops intercostal spaces from being drawn
inwards, when diaphragm moves
downward

NS: intercostal nerve

Question 8

External intercostal direction

Answer 8

Hands in pant pocket

Question 9

Internal intercostal direction

Answer 9

Hands in jacket pocket (medial to lateral inferiorly)

Question 10

Minor muscles of respiration

Answer 10

Serratus posterior superior (inspiration & proprioception), serratus posterior inferior (forced expiration & proprioception, levatores costarum (inspiration)

Question 11

Forced inspiration accessory muscles

Answer 11

Scalenes, sternocleidomastoid, pec major, pec minor, external intercostals, serratus anterior, lats

Question 12

Rectus Abdominis Att., Action, Function, NS

Answer 12

Attachments:
Superior: xiphoid process & 5-7
costal cartilages
Inferior: pubic symphysis & pubic
crest

Action: trunk flexion, compression of
abdominal viscera

Function: stabilise pelvic tilt
(antilordosis)

NS: thoraco-abdominal nerve

Question 13

External oblique Att., Action, NS

Answer 13

Attachments:
Lateral: external surface ribs 5-12
Medial: linea alba, pubic tubercle,
lateral inguinal ligament, anterior
iliac crest

Action: trunk flexion & rotation,
compression & support
abdominal viscera

NS: thoraco-abdominal nerve

Question 14

Internal Oblique Att., Action, NS

Answer 14

Attachments:
Lateral: thoracolumbar fascia,
anterior iliac crest, lateral inguinal
ligament
Medial: inferior border of ribs 10-12,
linea alba, pecten pubis via conjoint
tendon

Action: trunk flexion & rotation,
compression & support abdominal
viscera

NS: thoraco-abdominal nerve & 1 st
lumbar nerve

Question 15

Transverse abdominis Att., Action, NS

Answer 15

Attachments:
Lateral: lateral inguinal ligament, inner
anterior iliac crest, thoracolumbar
fascia, lower 6 costal cartilages and their ribs
Medial: linea alba, aponeurosis of
internal oblique, pubic crest, pecten
pubis via conjoint tendon

Action: compression & support
abdominal viscera

NS: thoraco-abdominal nerve & 1 st
lumbar nerve

Question 16

What is the linea alba

Answer 16

Medial attachment for:
External oblique
Internal oblique
Transverse abdominis

Question 17

Action of abdominal muscles

Answer 17

Trunk lateral flexion:
Ipsilateral contraction of
internal & external obliques

Trunk rotation:
- contralateral contraction of
external oblique
- ipsilateral contraction of
internal oblique

Rectus abdominis - trunk flexion

Transverse abdominis - compression of abdominal viscera

Rotating left in crunch - right external, left internal contraction

Question 18

Function of abdominal muscles

Answer 18

Support trunk

Respiration: forced expiration (coughing, sneezing)

Bodily functions: vomiturition, defecation, flatus, micturition, parturition