Lecture 15: Anterior Trunk Muscles

Question 0

Xiphisternal joint is where?

Answer 0

Superior limit of liver. Central tendon of diaphragm

Question 1

Xiphoid process is at what level?

Answer 1

T10 vertebral level. Ossified > 40 yrs old.

Question 2

Dermatomes

What level are the nipple, xiphoid, umbilicus and Inguinal ligament

Answer 2

Region of skin innervated by sensory fibres from a SINGLE spinal nerve. 
Nipple: T4 
 Xiphoid process: T7 
 Umbilicus: T10 
 Inguinal ligament: L1

Question 3

The sternum is at what level?

Answer 3

T5-T9

Question 4

Sternum sternebrae

Answer 4

Sternal body fuses from 4 sternebrae

Fusion complete by 25 years of age.

Question 5

What ribs are true, false and floating ribs?

Answer 5

True

(vertebrocostal)
ribs: 1-7

False

(vertebrochondral)
ribs: 8-10

Floating (free) ribs:
11-12

Question 6

The first rib has two groves for what?

Answer 6

Subclavian veins and artery

Question 7

What makes up the boundaries of the superior thoracic aperture?

Answer 7

T1 vertebra + first ribs + superior border of manubrium

Question 8

What makes up the boundaries of inferior thoracic aperture?

Answer 8

T12 vertebra + ribs 11 & 12 + costal margin + xiphisternal joint.

Question 9

What is Thoracic ‘outlet’ syndrome?

Answer 9

Entrapment of structures passing between the neck and thorax/axilla.
Usually brachial plexus between anterior and middle scalene
E.g Costoclavicular syndrome, pallor and coldness of
upper limb, Diminished radial pulse

Question 10

Sternocostal joints

Answer 10

1st: primary cartilaginous joint
2nd-7th: synovial plane joints
“Dislocated” ribs occur at these joints

Question 11

Costochondral joint

Answer 11

Costochondral:
Primary cartilaginous articulation between ribs and costal
cartilages.

Question 12

Interchondral joints

Answer 12

Interchondral:
Synovial plane joint between costal cartilages of 6th-7th, 7th-8th, 8th-9th.

Fibrous articulation between costal cartilages of 9th-10th ribs.

Question 13

Costochondritis

Answer 13

One of the most common identifiable cause of chest pain in children and adolescents.
• Musculoskeletal chest pain generally reproducible on palpation and is exaggerated by physical activity or breathing.
• Costochondral joint pain due to inflammation.
• Treat with NSAIDs, corticosteroids.

Question 14

Which intercostal is most important for breathing?

Answer 14

External intercostals

Question 15

External intercostals

Answer 15

External intercostals between adjacent ribs LATERAL to

costochondral joint.

Question 16

Only Internal intercostals are between what?

Answer 16

costal cartilages.

Question 17

Intercostal nerves originate where?

Answer 17

Primary ventral rami of first 11 thoracic spinal nerves.

Question 18

12th intercostal space innervated by what nerve!

Answer 18

Subcostal nerve

Question 19

Intercostal neurovascular bundles lie where?

Answer 19

inferior to each rib, running in the costal groove deep to the internal intercostal muscles.

Question 20

Intercostal nerves contain what type of fibres?

Answer 20

motor, sensory and sympathetic fibres.

Question 21

Rectus sheath contains:

Answer 21

rectus abdominis & pyramidalis muscles, superior & inferior epigastric arteries, anterior rami of T7-T12.

Question 22

External oblique origin and insertion

Answer 22

External oblique fibres originate on external surfaces of ribs 5-12 and fan out inferomedially to insert in linea alba.

Question 23

Internal oblique origin and insertion

Answer 23

Internal oblique fibres originate from thoracolumbar fascia and anterior 2/3 iliac crest and fan out superomedially to insert into
linea alba.

Question 24

External spermatic fascia

Answer 24

Superficial inguinal ring breaches the aponeurosis of external oblique. External oblique continues as external spermatic
fascia…..

Question 25

Cremasteric fascia

Answer 25

Derived from fascia of both superficial and deep surfaces of internal oblique muscle.
Cremaster muscle reflexively draws testis superiorly in
the scrotum, particularly when cold.

Question 26

Superior and inferior epigastric anastomoses

Answer 26

Superior epigastric (branches from internal thoracic artery) and inferior epigastric (branches from external iliac artery) arteries anastomose in the rectus sheath to supply the muscles of anterior 
abdominal wall.

Question 27

Umbilical folds

Answer 27

Lateral umbilical fold contains the inferior epigastric vessels!

Medial umbilical folds are remnants of umbilical arteries.

Median umbilical fold is remnant of urachus connecting fetal bladder to umbilicus.

Surgeons making abdominal incisions must be careful not to cut the lateral umbilical fold!!!

Question 28

12th intercostal nerve is also know as?

Answer 28

Sub costal nerve

Question 29

Nerves of thoracic wall

Answer 29

Post-ganglionic 
sympathetic fibres 
distributed (via gray 
rami) to all the 
spinal nerves to 
reach all the blood 
vessels, sweat 
glands and smooth 
muscle of the body 
wall (and limbs).

Question 30

Neurovascular bundles run between which intercostal muscles?

Answer 30

Between internal and innermost intercostal muscles

Question 31

What type of joint is the sternoclavicular joint?

Answer 31

Saddle-type synovial joint

Question 32

What blood vessel supplies rectus abdominis?

Answer 32

Superior epigastric

Question 33

Aponeurosis of internal oblique splits to enclose what?

Answer 33

Rectus abdominis

Question 33

transversus abdominis aponeurosis passes deep to?

Answer 33

Rectus abdominis