Layers

Question 1

Layers for lumbar puncture?

Answer 1

Done at level L4-5 (spinal cord terminates at L1-2)

1. Skin
2. Subcutaneous tissue
3. Supraspinous ligament
4. Interspinous ligament
5. Ligamentum flavum
6. Epidural space
7. Dura mater
8. Arachnoid mater
9. Subarachnoid space

Question 2

Layers for an Epidural?

Answer 2

Epidural done at L3

1. Skin
2. Subcutaneous tissue
3. Supraspinous ligament
4. Interspinous ligament
5. Ligamentum flavum
6. Epidural space

Question 3

Layers of midline laparotomy?

Answer 3

Skin.
Subcutaneous fatty layer (Camper's fascia)
Membranous fascia (Scarpa's)
linea alba
transversalis fascia
extraperitoneal fat
peritoneum (avoid falciform ligament above the umbilicus)
Below arcuate line= no posterior sheath

Question 4

Layers of Gridiron incision?

Answer 4

Skin
Subcutaneous fatty layer
Membranous fascia
External oblique
Internal oblique
Transversus abdominis
Transversalis fascia
Preperitoneal fat
Parietal peritoneum

Question 5

Layers of Pfannelsteil incision?

Answer 5

skin, 
superficial fascia (fatty (camper and (bucks) membranous), 
deep fascia, 
anterior rectus sheath, 
rectus abdominis muscle,
 transversalis fascia,
 extraperitoneal connective tissue, 
peritoneum.

Question 6

Layers of inserting a chest drain?

Answer 6

Safe triangle: mid axillary line of the 5th intercostal space. It is bordered by:
Anterior edge latissimus dorsi, the
lateral border of pectoralis major,
a line superior to the horizontal level of the nipple, and the apex below the axilla.

1. Skin
2. Subcutaneous fascia and fat
3. External intercostal muscles
4. Internal intercostal muscles
5. Innermost intercostal muscle
6. Endothoracic fascia
7. Parietal pleural
8. Pleural space

(Visceral pleura + lung)
VAN- intercostal branches run on underside of rib

Question 7

Layers of tracheostomy?

Answer 7

skin
subcutaneous tissue
fat
(may divide isthmus of thyroid gland)
pretracheal fascia (superficial and deep)
trachea

Question 8

Layers for scrotal exploration?

Answer 8

The layers that will be encountered are (in order):

1. Skin
2. Dartos fascia and muscle
3. External spermatic fascia
4. Cremasteric muscle and fascia
5. Internal spermatic fascia
6. Parietal layer of the tunica vaginalis

The layers of the spermatic cord and scrotum are a popular topic in the MRCS exam.
A mnemonic which may help:
Some Damned Examiner Called It The Testes (skin dartos external fascia cremaster internal fascia tunica Testes)