Anatomy Flashcards
Length of colon
150cm
Which part of the colon is retroperitoneal?
- ascending colon
- descending colon
- rectum and anal canal
Length of sigmoid colon
40cm
Arterial supply of ascending colon
- Ileocolic (from SMA)
- Right colic arteries (from SMA)
Arterial supply of transverse colon
- Right 2/3: right marginal branch from SMA
- Left 1/3: left marginal branch from SMA
Arterial supply of descending colon
- Left colic artery (from IMA)
Arterial supply of sigmoid colon
- Sigmoid arteries (from IMA)
What is Marginal Artery of Drummond?
Clinically important vessels that provide collateral supply to colon - maintaining arterial supply in case of occlusion of major vessels. Forms from terminal vessels of SMA and IMA.
Nerve supply of colon
- Midgut-derived (ascending colon and proximal 2/3 of transverse colon) = superior mesenteric plexus
- Hindgut-derived structures (distal 1/3 of the transverse colon, descending colon and sigmoid colon)
= Inferior mesenteric plexus (parasympathetic: pelvic splanchnic nerve; sympathetic: lumbar splanchnic nerve)
How long is the oesophagus?
25cm
Where does the oesophagus start and end at?
- Start at the cricoid cartilage (C6 vertebra)
- End at the stomach (T10 vertebra)
Upper oesophagal sphincter formed by
Cricopharyngeus muscle
Lower oesophageal sphincter formed by
- Increased tone of the muscularis propria
- Fibres of the right diaphragmatic crus
- Angle of His
3 narrow points of the oesophagus
- Cricopharyngeus sphincter
- Aortic arch
- Where the oesophagus pierces through the diaphragm
Layers of oesophagus
- Mucosa
- Submucosa [Meissner’s plexus]
- Muscularis propria (Inner circular, outer longitudinal) [Auerbach Plexus in between]
- Serosa or adventitia
Retroperitoneal part of duodenum
1st inch of the 1st part
Difference between jejunum and ileum
> Jejunum
- Vasa recta longer
- Arcades less
- Has valvular conniventes
> Ileum
- Shorter vasa recta
- Arcades more
- Has Peyer’s patches
Arterial supply of small intestine
> Duodenum
- 1st and 2nd: superior pancreatoduodenal artery (branch of gastroduodenal artery)
- 3rd and 4th: inferior pancreatoduodenal artery (branch of superior mesenteric artery)
> Jejunum & Ileum
- Jejunal and ileal branches of SMA
Inferior mesenteric vein drains blood from
- Rectum
- Sigmoid colon
- Descending colon
- Splenic flexure
Ureter length and diameter
- 25-30cm long
- 3mm in diameter
Relation of inguinal canal
> Floor
- Inguinal ligament
> Roof
- Formed by arching fibers of transversus abdominis and internal oblique
- Become the conjoint tendon medially
> Anterior wall
- External oblique aponeurosis
- Reinforced laterally by internal oblique
> Posterior wall
- Transversalis fascia
Content of spermatic cord
> 3 arteries
- Testicular artery
- Artery to the Vas Deferens
- Cremasteric artery
> 3 nerves
- Autonomic nerve (sympathetic from T10)
- Ilio-inguinal nerve
- Nerve to cremaster ( from genito-femoral nerve)
> 3 important structures
- Vas Deferens
- Pampiniform Plexus of vein
- Processus Vaginalis
Anatomy of anal sphincter
> Internal anal sphincter
- Upper 2/3
- Involuntary smooth muscle
> External anal sphincter
- Lower 2/3
- Voluntary muscle
Arterial supply of anal canal
> Above pectinate line
- Superior rectal artery (branch of IMA)
> Below pectinate line
- Inferior rectal artery
( branch of internal pudendal artery)
Nerve supply of anal canal
> Above pectinate line
- Visceral innervation via inferior hypogastric plexus
> Below pectinate line
- Somatic innervation via inferior rectal nerve (branches of pudendal nerve)
Venous drainage of anal canal
> Above pectinate line
- Superior rectal vein -> inferior mesenteric vein (portal venous system)
> Below pectinate line
- Inferior rectal vein -> internal pudendal vein (systemic venous system)
- Site of varices when portal HPT
Common position of appendix
- Post-ileal (1 or 2 o’clock)
- Pre-ileal (1 or 2 o’clock)
- Pelvic (5 o’clock)
- Sub-cecal (6 o’clock)
- Retrocecal (11 o’clock) [Most common]
Describe branches of portal venous system
- Formed by union of the splenic vein and SMV posterior to neck of pancreas
- IMV join to splenic vein posterior to body of pancreas
Superior mesenteric vein drains blood from
- Small intestine
- Cecum
- Ascending colon
- Transverse colon
Anatomy of pancreas
- Head: lie within c-shaped concavity of duodenum, uncinated process extend to left behind the superior mesenteric vessels
- Neck: lie in front of portal vein
- Body: run upward and left across the midline
- Tail: anterior to left adrenal gland contacting hilum of spleen
Blood supply of pancreas
- Celiac artery -> splenic artery (tail) and superior pancreaticoduodenal artery (head)
- Superior mesenteric artery -> inferior pancreaticoduodenal artery (head)
- Venous drainage via pancreaticoduodenal veins -> portal vein
Arterial supply of breast
> Medial
- Internal thoracic artery (branch of subclavian artery)
> Lateral
- Lateral thoracic and thoracoacromial branches (from axillary artery)
- Lateral mammary branches (from posterior intercostal arteries)
- Mammary branch (from anterior intercostal artery)
Lymphatic drainage of breast
- Axillary nodes (75%) [5 groups]
- Parasternal nodes (20%)
- Posterior intercostal nodes (5%)
Anatomical division of liver
- Separated by falciform ligament into right and left lobe
- 2 accessories lobes arise from right lobe, located at visceral surface of liver: caudate (upper) and quadrate (lower) lobe
- Portal hepatis separate the 2 accessory lobes
Arterial supply of liver
- Hepatic artery proper (25%)
- Hepatic portal vein (75%)
Functional division of liver
- Divide by 1 transverse plane (main branch of portal vein) and 3 sagittal plane (3 main hepatic veins)
- Into 8 segments numbered in anti-clockwise manner around porta hepatis
- Have own vascular inflow, outflow, and biliary drainage
Border of anterior triangle
- Lower border of mandible superiorly
- Midline anteriorly
- Anterior border of the SCM posteriorly
Border of posterior triangle
- Posterior border of the SCM anteriorly
- Anterior border of the trapezius posteriorly
- Clavicle inferiorly
Blood supply of thyroid glands
- Superior thyroid artery (from external carotid)
- Inferior thyroid artery (from thyrocervical trunk)
- Thyroid ima artery - around 10% of people
Symptoms of damaged recurrent laryngeal nerve
- Unilateral damage = hoarseness
- Bilateral damage = dyspnea
Arteries of lower limb
- External iliac artery continues as femoral artery after crossing the inguinal ligament
- Superficial femoral enter the adductor canal and pass through the hiatus in the adductor magnus to reach the popliteal fossa, where it changes its name to popliteal artery
- Popliteal divide at lower border of popliteus into anterior and posterior tibial artery
- Anterior tibial -> dorsalis pedis
- Posterior tibial -> peroneal artery + medial and lateral plantar artery
Course of the great saphenous vein
- Arise from medial side of dorsal venous arch of foot
- Ascends immediately in front of medial malleolus (accompanied by saphenous nerve)
- Ascends obliquely up the medial aspect of thigh
- Pierces the cribriform fascia at the saphenofemoral junction to drain into the femoral vein
Course of small saphenous vein
- Arise from lateral side of the dorsal venous arch of foot
- Passes posterior to the lateral malleolus
- Ascends up the midline of calf
- Pierces the deep fascia over popliteal fossa to drain into popliteal vein
- Accompanied in course by sural nerve
Location of communicating veins
- Saphenofemoral junction
- Hunterian perforator: mid-thigh
- Dodd’s perforator: distal thigh
- Boyd’s perforator: knee
- Calf perforator: at 5, 10, 15cm above medial malleolus
Parts of gallbladder
- Fundus
- Body
- Neck
Describe the biliary tree
- Right and left hepatic ducts -> common hepatic duct
- Joined with cystic duct when descend -> common bile duct
- Joined with main pancreatic duct -> hepatopancreatic ampulla/ ampulla of Vater
Artery supply of gallbladder
- Cystic artery (branch of right hepatic artery)
Calot’s triangle
- Inferior border of liver superiorly
- Cystic duct laterally
- Common hepatic duct medially
Content of inguinal canal
- Males: spermatic cord + ilioinguinal nerve
- Females: round ligament of the uterus + ilioinguinal nerve
Borders of Hesselbach’s triangle
- Lateral: inferior epigastric artery
- Medial: lateral border of rectus abdominis
- Inferior: inguinal ligament
Anatomy of inguinal canal
- 4-6cm long oblique passage above inguinal ligament
- Deep ring: 2cm above the midpoint of the inguinal ligament
- Superficial ring: above and medial to the pubic tubercle
Langer line
- Line of skin tension
- Associated with the distribution of collagen and elastic fibers in the skin
- Predominantly horizontal in abdomen
Location of appendix
- Pre-ileal (1, 2 o’clock)
- Post-ileal (1, 2 o’clock)
- Sub-ileal (3 o’clock)
- Pelvic (5 o’clock)
- Subcecal (6 o’clock)
- Paracecal (10 o’clock)
- Retrocecal (11 o’clock) [Most Common]
Artery supply of appendix
- Appendicular artery (derived from ileocolic artery, a branch of SMA)
Major branches of SMA
Inferior Pancreaticoduodenal artery
- Inferior region of head of pancreas
- Uncinated process
- Duodenum
Jejunal and Ileal artery
Ileocolic artery
- Ileum
- Cecum
- Appendix
- Ascending colon
Right colic artery
- Ascending colon
Middle colic artery
- Transverse colon
Dependent area for pelvic - Supine position
- Morison’s pouch (hepato-renal fossa)
- Pouch of Douglas (retro-uterine pouch)
- Para-colic gutter
Cantlie line
- Vertical line extends from inferior vena cava posteriorly to the middle of gallbladder fossa anteriorly
- Left: segment 2,3,4a,4b
Right: segment 5,6,7,8
Anatomical vs Functional division of liver
> Anatomical division
- Demarcated by falciform ligament
> Functional division
- Demarcated by Cantlie’s line -> more important for reading CT scan and surgery
- Further divide into 8 functional segment
9 layers of abdominal wall
- Skin
- Subcutaneous tissue
- Superficial fascia
- External oblique muscle
- Internal oblique muscle
- Transversus abdominis muscle
- Transversalis fascia
- Preperitoneal adipose and areolar tissue
- Peritoneum
Midline vs Paramedian incision
> Midline
- Cut through skin, subcutaneous tissue, fascia, linea alba, transversalis fascia and peritoneum
> Paramedian
- Cut through skin, subcutaneous tissue, anterior rectus sheath, posterior rectus sheath, transversalis fascia, and peritoneum
- Assess lateral viscera - kidney, spleen, and adrenal glands
- Can damage blood and nerve supply, leading to atrophy of muscle medially
Blood supply of stomach
> Lesser curvature
- Right gastric (branches of common hepatic, from coeliac trunk)
- Left gastric (directly from coeliac trunk)
> Greater curvature
- Right gastro-omental (branches of gastroduodenal artery, from common hepatic)
- Left gastro-omental (branches of splenic artery, from coeliac trunk)
Direct vs Indirect hernia
> Indirect
- Remnants of patent processus vaginalis
- Lateral to the inferior epigastric vessels
- Travelling through the inguinal canal with spermatic cord
- May continue through the superficial inguinal ring into the scrotum
> Direct
- Result of weak posterior wall
- Arise medial to the inferior epigastric vessels
- Not within the spermatic cord
Example of perforator veins
- Saphenofemoral junction
- Hunter veins (at thigh level)
- Dodd’s perforators (inferior 1/3 of the thigh, above the knee)
- Body’s perforator (at or below the knee level)
- Cockett’s perforator (at the level of calf and inferior 2/3 of the leg) - further subdivided into superior, medium and inferior perforators
Mallampati classification
- Class 1: complete visualization of the soft palate
- Class 2: complete visualization of the uvula
- Class 3: visualization of only the base of uvula
- Class 4: soft palate is not visible at all
Lymph nodes at inguinal region
- Divide into 2 groups by their position relative to a horizontal line drawn at the level of termination of the great saphenous veins
- Above line: Superficial inguinal nodes
- Below line: Sub-inguinal nodes (Superficial and Deep)
