Monday, 15 January 2018

Anatomy One Liners

Anatomy One-Liners
1) Ascending colon 12.5cm long
- from the caecum to the inferior surface of  the right lobe of the liver
- usually retroperitoneal
(2) Transverse colon 50cm long 
- from the right colic flexure to the left colic flexure
- suspended by transverse mesocolon attached to the anterior border of the pancreas
(3) Descending colon - 25cm long
- from left colic flexure to the sigmoid colon
- it is narrower than ascending colon
- usually, it is retroperitoneal
(4) Sigmoid colon 37.5cm long
- from pelvic brim to the third piece of the sacrum, where it becomes rectum
- suspended by sigmoid mesocolon

Mesentery:- The mesentery of the small intestine (or) mesentery proper is a broad, fan-shaped fold of peritoneum which suspends the coils of jejunum and ileum from the posterior abdominal wall
Root of mesentery - 15cm long
- directed obliquely downwards and to the right
- It extends from the duodenojejunal flexure on the left side of vertebra L2 to the upper part of the right sacroiliac joint
- It crosses the following :
(1) Third part of duodenum where the superior mesenteric vessels enter into it
(2) The abdominal aorta
(3) The inferior vena cava
(4) The right ureter
(5) The right psoas major

The free or intestinal border is 6meter long, thrown into pleats.

Development of diaphragm by
1. Septum transverum
2.pleuro peritoneal membrane
3.somites (3-5th)
4.ventral pleural sac
5.mesentry of esophagus

Tonsil develop embryologically from 2nd pharyngeal pouch
Parathyroid is developed from 3rd & 4th brachial pouches
Footplate of stapes is developed from otic capsule
Umbilical vesicle attain full development in 4th week of fetus
Urachal fistula result from persistent allantois
Tensor tympani and tensor palatine supplied by trigeminal.Levator palatine supplied by the superior laryngeal nerve.
Derivatives of pharyngeal pouch
1st- tubotympanic recess
3rd-inf parathyroid, thymus
4th-sup parathyroid, thyroid
5th-ultimobranchial body

Mesodermal derivatives of branchial arch
1st-malleus, incus, anterior ligament of malleus, sphenomandibular ligament
2nd-stape, styloid process, stylohyoid ligament, lesser cornu of hyoid, sup part of the hyoid
3rd-greater cornu of hyoid, lower part of the body of hyoid
4n6th-laryngeal cartilage
1st pharyngeal arch cartilage-Meckel cartilage
2nd pharyngeal arch cartilage-Reichert cartilage

TYMPANIC membrane dev from all the three germ layers
Pinna dev from 1st n 2nd pharyngeal arches
Footplate and annular ligament from otic capsule
Left umbilical vein-ligamentum teres
Ductus afteriosus-ligamentum arteriosum
Ductus venosus-ligamentum venosum
Septum primum n secondum-fossa ovalis n annulus ovalis respective
Distal umbilical art-median umb ligament
Proximal -sup vesical art
Foregut forms -Oesophagus
- The stomach
- Upper part of duodup to upto the opening of
common bile duct
Midgut forms - Rest of the duodenum
- Jejunum
- The ileum
- The appendix
- The caecum
- The ascending colon
- The right two - thirds of transverse colon
Hindgut forms -Left one-third of transverse colon
- The descending colon
- The sigmoid colon
- Proximal upper part of the rectum

Nerve supply of anal canal
(1) Above the pectinate line
- Sympathetic - Inferior hypogastric plexus - L1 & L2
- Parasympathetic- pelvic splanchnic S2, S3, S4
- Pain is carried by both of them
(2) Below the pectinate line
- somatic
- Inferior rectal S2,S3,S4 - nerves
(3) Sphincters - Internal sphincter - contraction - sympathetic nerve / relaxation - parasympathetic. N
External sphincter - inferior rectal nerve & by perineal branch of 4th sacral. N

Genital tubercle forms - clitoris
- urethral folds forms - labia minora
- genital swelling form - labia majora
- urogenital membrane gets ruptured to form the vestibule

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