Lab 6

Question 1

State the fascicle direction for the following muscles:

a. ) External intercostal muscle
b. ) Internal intercostal muscle
c. ) Innermost intercostal muscle

Answer 1

a. ) External intercostal muscle - inferomedial.
b. ) Internal intercostal muscle - inferolateral.
c. ) Innermost intercostal muscle - inferolateral.

Question 2

Which intercostal muscle(s) are incomplete anteriorly/ posteriorly? What replaces these spaces?

Answer 2

External intercostal muscle is incomplete anteriorly, where it is covered by the external intercostal membrane.
Internal intercostal muscle is incomplete posteriorly, where it is covered by the internal intercostal membrane.

Question 3

List muscles involved with forced inspiration.

Answer 3

"STEPS". 
S - Sternocleidomastoid. 
T - Thoracic diaphragm. 
E - External intercostals. 
P - Parasternal (interchondral) part of internal intercostals. 
S - Scalenes.

Question 4

List muscles involved with forced expiration.

Answer 4

“TAI”.
T - Transversus thoracis.
A - Abdominal muscles (RE, EAO, IAO).
I - Interosseus part of internal intercostals.

Question 5

What are the peripheral attachments of the respiratory diaphragm?

Answer 5

Anteriorly - xiphoid process.
Posteriorly - medial and lateral arcuate ligaments.
Laterally - inferior 6 costal cartilages.
Inferiorly - lumbar vertebral bodies (via crura, and median arcuate ligament).

Question 6

Which hemidiaphragm sits higher then the other, and why?

Answer 6

The right hemidiaphragm sits higher then the left as the liver is on the right side of the body (in space which would otherwise be occupied by the diaphragm).

Question 7

What major connective tissues attach to the central tendon:

a. ) Superiorly
b. ) Inferiorly

Answer 7

a. ) Superiorly - fibrous pericardium.

b. ) Inferiorly - coronary ligament (of liver).

Question 8

What structure passes through the central tendon and at which vertebral level?

Answer 8

The inferior vena cava passes through the vena caval aperture in the central tendon, at the level of T8.

Question 9

Explain the structural differences between the right and left crura.

Answer 9

Right crura - attaches to VB of L1 - L3; creates a loop in which the centre is the oesophageal hiatus.
Left crura - attaches to VB of L1 - L2.

Question 10

Name at least two structures that pass through the right crus and at which vertebral level?

Answer 10

Vertebral level - T12.

Structures - descending aorta, VAGUS nerve.

Question 11

Over which muscle do the following ligaments span:
a.) Medial arcuate ligament
b,) Lateral arcuate ligament

Answer 11

a.) Medial arcuate ligament - psoas major.

b,) Lateral arcuate ligament - quadratus lumborum.

Question 12

What are the bony attachments of each arcuate ligaments?

a. ) Medial
b. ) Lateral

Answer 12

a.) Medial arcuate ligament - VB’s of L1 and L2, to the TVP of L1.
b,) Lateral arcuate ligament - TVP of L1 to the tip of the 12th rib.

Question 13

What structures form the aortic hiatus?

Answer 13

The median arcuate ligament and the VB of L1.

Question 14

What structure unites the left and right crura of the diaphragm?

Answer 14

The median arcuate ligament.

Question 15

To which embryological section (epaxial or hypaxial) of the embryo do the abdominal flank muscles
belong?

Answer 15

Abdominal muscles are hypaxial.

Question 16

Between which two muscles is the neurovascular plane situated in the abdomen?

Answer 16

Between the IAO and TA.

Question 17

Which muscles contribute to the formation of the sheath and what parts do they contribute to?
1.
2.
3.

Answer 17

1. External abdominal oblique - anterior layer.
2. Internal abdominal oblique - anterior and posterior layers.
3. Transversus abdominus - posterior layer.

Question 18

Which fascial structure separates the posterior layer of the rectus sheath from the peritoneum?

Answer 18

Transversalis fascia.

Question 19

What layer does the transversalis fascia become in the spermatic cord?

Answer 19

Transversalis fascia becomes the internal spermatic fascia.

Question 20

What does the following structure contain:

Median umbilical fold.

Answer 20

Median umbilical fold contains the median umbilical ligament, also known as the obliterated urachus.

Question 21

What does the following structure contain:

Medial umbilical fold(s).

Answer 21

Medial umbilical fold contains the medial umbilical ligaments, which are remnants of the umbilical arteries.

Question 22

What does the following structure contain:
Lateral umbilical fold.

What structures are the demarcation point for this structure?

Answer 22

Lateral umbilical fold contains inferior epigastric artery.

The vascular structures lying underneath (inferior aspect) to the peritoneal fold.

Question 23

For the following muscle, answer the fields below: 
EAO. 
a.) Origin 
b.) Insertion 
c.) Action

Answer 23

EAO.

a. ) Origin - lower 8 ribs.
b. ) Insertion - linea alba, pubic tubercle, iliac crest.
c. ) Action - contralateral rotation, aid flexion, abdominal compression.

Question 24

For the following muscle, answer the fields below: 
IAO. 
a.) Origin 
b.) Insertion 
c.) Action

Answer 24

IAO.

a. ) Origin - thorocolumbar fascia, iliac crest, inguinal ligament.
b. ) Insertion - lower 4 ribs, linea alba, pubic crest (via conjoint tendon).
c. ) Action - ipsilateral rotation, aid flexion, abdominal compression.

Question 25

For the following muscle, answer the fields below: 
TA. 
a.) Origin 
b.) Insertion 
c.) Action

Answer 25

TA.

a. ) Origin - iliac crest, thorocolumbar fascia, inguinal ligament.
b. ) Insertion - linea alba, pubic crest (via conjoint tendon).
c. ) Action - abdominal compression only.

Question 26

State what each of the following abdominal wall structures become in the spermatic cord:

a. ) Parietal peritoneum
b. ) Transversalis fascia
c. ) Transverse abdominus
d. ) Internal abdominal oblique
e. ) External abdominal oblique

Answer 26

a. ) Parietal peritoneum - tunica vaginalis.
b. ) Transversalis fascia - Internal spermatic fascia.
c. ) Transverse abdominus - nil.
d. ) Internal abdominal oblique - cremaster muscle.
e. ) External abdominal oblique - external abdominal oblique.

Question 27

Consider the conjoint tendon.
With which other muscle does internal oblique join to form this tendon? Where does this tendon attach to medially, and whats it’s function?

Answer 27

Conjoint tendon = aponeurosis’ of TA + IAO. Attaches to pubic crest medially, functions to strengthen the inguinal canal.

Question 28

For the following muscle, answer the fields below: 
Rectus abdominus. 
a.) Origin 
b.) Insertion 
c.) Action

Answer 28

Rectus abdominus.

a. ) Origin - pubic symphysis and crest.
b. ) Insertion - xiphoid process, costal cartilage (runs whole length of anterior abdominal wall).
c. ) Action - flexion, abdominal compression.

Question 29

State the attachment points for the inguinal ligament.

Answer 29

ASIS -> pubic TUBERCLE.

Question 30

The inguinal canal is the canal between the superficial and deep inguinal rings.

Answer 30

Deep inguinal ring - hiatus in transversalis fascia.

Superficial inguinal ring - hiatus in the aponeurosis of the EAO (which makes sense as its superficial!).

Question 31

What structures pass through the inguinal canal?

Answer 31

Both sexes - ilioinguinal nerve.
Females - round ligament of uterus.
Males - spermatic cord.

Question 32

Classify the following joint:

Pubic symphysis.

Answer 32

The pubic symphysis is cartilagenous, symphysis, slightly moveable.
(hint: it’s literally in the fucking name).

Question 33

Classify the following joint:

Anterior sacroiliac joint.

Answer 33

The anterior sacroiliac joint is synovial, uniaxial, gliding.

Question 34

Classify the following joint:

Posterior sacroiliac joint.

Answer 34

The posterior sacroiliac joint is fibrous, syndesmoses, slightly moveable.

Question 35

What muscular structure forms the roof of the perineum?

Answer 35

The pelvic diaphragm (coccygeus + levator ani groups).

Question 36

What is the collective function of the levator ani group?

Answer 36

Stabilization of the abdominal and pelvic organs, controlling the opening and closing of the levator hiatus, as well as preserving urinary and bowel continence.