Anatomy Flashcards
1
Q
Describe the anatomy and branches of Brachial plexus
A
Brachial plexus is made of anterior division of C5 - T1 spinal nerves. It has roots, trunks, divisions, cords and brances (Read The Damn Comic Book)
These Roots lie between the scalenus medius and scalenus anterior
Roots form 3 trunks which lie in the posterior triangle. Superior trunk forms from C5C6, Middle trunk from C7 and inferior trunk from C8T1
Trunks from anterior and posterior divisions behind the clavicle
Divisions form cords around the second part of the axillary artery (cords are named accordign to their position around axillary artery).
Lateral cord - Ant div of superior and middle trunks
Posterior cord - Posterior divisions of sup, middle and inf trunks
Medial trunk - ant div of inf trunk
Branches:
From Roots:
- Dorsal Scapular Nerve (c5)
- Nerve to subclavius C5,6
- Long thoracic nerve C5,6,7 (serratus anterior)
From Trunks:
- Suprascapular nerve C5,6
From Cords:
- Lateral Cord (MLL)
- Musculocutaneous nerve
- Lateral pectoral nerve
- Lateral root of median nerve
- Posterior cord (ULTRA)
- Upper and lower subscapualr nerve
- Thoracodorsal nerve
- Radial nerve
- Axillary nerve
- Medial cord (MMMMU)
- Medial pectoral nerve
- Medial cutaneous nv of arm
- Medial cutaneous nv of forearm
- Medial root of median nerve
- Ulnar nerve
2
Q
Branches of axillary artery
A
The three parts of the axillary artery are divided by the relationship to pectoralis minor.
- The first part (above pec. minor)
- The superior thoracic artery
- The second part (behind pec. minor)
- The Thoracoacromial artery
- Clavicular
- Deltoid
- Acromial
- Pectoral
- The lateral thoracic artery
- The Thoracoacromial artery
- The third part (below pec. minor)
- The subscapular artery (largest br.)
- Gives off circumflex scapular to become thoracodorsal artery
- The anterior circumflex humeral artery
- The posterior circumflex humeral artery (passes through quadrangular space with axillary nerve)
- The subscapular artery (largest br.)
3
Q
Describe the course of the phrenic nerve
A
4
Q
Describe the ligaments of liver
A
the liver has 7 ligaments
- coronary ligaments (left and right) - these are peritoneal reflections from the dipgram to the liver. They have an anterior (sup) and posterior (inferior layer that split on the right side to demarcate the bare area of the liver. Medially they are contimous with the faciform ligament
- Trianlgular ligaments (l and R) - extreme lateral end of the coronary ligaments - attached to the diaphragm
- Falciform ligament - From the anterior abd wall to the anterior leaf of coronary ligamnets
- Ligamentum teres - free lower edge of the falciform ligament. Contains the obliterated left umbo vein (drains bllod to the left branch of portal V)
- Ligamnetum Venosum - denoted the obliterated ductus venosus that connects left portal vein to left hepatic vein to bypass liver. Posterior surfce of liver connecting the porta to the left hepatic vein
- Gastrohepatic ligamnet part of the lesser omentum
- Hepatoduodenal ligament - part of lesser omentum
5
Q
branches of femoral artery in groin
A
- Superficial circ iliac
- superficial epigastric
- Superficial external pudendal
- deep internal pud
terminal branches - SFA and profunda
6
Q
What are the boundaries of the ischianal (ischiorectal fossa)? What are the contents?
A
Anteriorly
- fascia covering transversus perineii superficialis
Posteriorly
- Gluteus Max
- Sacrotuberous ligament
Superiorly
- Levator Ani
Inferiorly
- Skin
Medially
- Levator ani
- external sphincter complex
- corrugator custis ani
Laterally
- Obturator interus with overlying fascia
- Ischial tuberosity
Contents
- Fibrofatty tissue
- Inside Alcock’s canal
- Pudendal nerve, art, vein
- Outside Alcock’s canal
- Inferior rectal nerve artery vein
7
Q
What is the blood supply of the breast
A
4 sources:
perforating branches of IMA
perf. branches of post. intercoastal
pectoral branch of thoracoacromial
branches of lateral thoracic
8
Q
relations of pyriformis
A
Superior
- sup gluteal nv and vesses
Inferior
- Inf gluteal nv and vs
- Pudendal nv and int pud vs
- post fem cutaneous nv
- Sciatic nv
Anterior
- scaral plexus
9
Q
what are the usual layers of the GI tract
A
Mucosa
- epithelium
- lamina propria
- Muscularis mucosae
Submucosa
Muscularis Propria
- inner circular
- outer longitudinal
Serosa
10
Q
Describe the fascial layers of neck
A
The neck is enclosed in superficial fascia, deep to whihc lies the deep fascia.
SUPERFICIAL - superficial fascia of neck lies deep to the subcutaneous tissue and encloses the entire neck and contains the platysma.
DEEP FASCIA - has three logitudinal columns that run alon the length of the neck
- Superficial (investing) layer - starts at nuchal line and splits to enclose the trapezius, SCM, straps, parotid and SMG.
- Middle layer - encloses the viscera - larynx, trachea, pharynx, esophagus, thyroid and parathyroids. The anterior and posterior parts of this is also called the pre-tracheal and buccopharyngela fascia
- Deep layer - also called pre-verterbral fascia. This encloses the spine and all its muscles. It has
- an anterior ALAR fascia (between the buccopharyngeal and pre-vertebral fascia)
- Posterior PREVERTEBRAL fascia that lies immidietly anterior to the vertebrae.
- CAROTID SHEATH - all 3 layers of the deep fascia contribute to form the carotid sheath.
11
Q
describe the important surgical spaces of neck for infection
A
The relevant spaces are
- submandibular space -
- parapharyngeal space
- Retropharyngeal space
- True retropharyngeal space (danger space)
- pre-vertebral space
SUBMANDIBULAR
- Between floor of mouth and investing fascia over SMG
- myleohyoid divides this into sublingual and submyelohyiod spaces
- continous laterally with parapharyngeal space
- involved in Ludwigs angina
Parapharyngeal space
- inverted cone lateral to pharynx with base on base of skull and tip on hyoid
- Styloid process (and its muscles) divide this into anterior (nothing) and posterior (IX,X,XI,XII nvs)
- communicates medially with submandibular space
Retropharyngeal space
- True - between buccopharyngeal pfascia and alar fascia
- Extends to the mediastinum and communicates on 2 sides allowing infection to track (danger space)
- Pre-vertebral space - between alar and pre-vertebral fascia.
12
Q
Discuss midgut embryology
A
Midgut embryology is all about the physiological hernia and the reduction thereof by rotation around the SMA-axis. Vitelline duct remnants give rise to a Meckel’s diverticulum.
- The primary intestinal loop enters the extra-embryonic coelom in the umbilical cord in the 6th week.
- Rotation is 270⁰in an anti-clockwise direction (from superior to right to left of the fetus, of which 90 occurs outside the body and 180 occurs inside) and as a result:
- The duodenum passes to the left under the SMA
- The transverse colon sits anterior to everything else
- The caecum ends up in the RIF.
- Return of the gut occurs in a craniocaudal sequence- the cranialmost part returns first.
- Malrotation causes problems with the duodenum/SMA relationship and the position of the caecum & appendix
- The physiological hernia reduces due to
- Normal growth and expansion of the abdominal cavity
- Reduced growth of the liver
- Regression of the mesonephroi
- Vitelline duct remnants form a Meckel’s diverticulum with/without a band or fistula. Meckel’s are found two feet from the IC-valve in 2% of people.
- Omphalocele is failure of reduction of the physiological hernia
- Duplication cysts are usually on the mesenteric side of the intestine and may contain aberrant mucosa.
- Intestinal atresia and stenosis are usually due to vascular accidents. With duodenal atresia consider Down’s syndrome.
13
Q
What are the layers of the primitive embryo and what do they develop into
A
Ectoderm develops into the skin and CNS
Mesoderm has 3 parts (medial to lateral)
- Paraaxial mesoderm - gives rise to the somites (Muscles, bones, cartilage)
- Intermediate mesoderm - gonads and kidneys
- Lateral plate - has 2 layers
- Parietal (somatic lateral plate - parietal peritoneum, blood vessels
- Viseceral / splanchnic plate - visceral peritoneum, stroma and muscles of gut
- Endoderm - epithelium, parenchyma of GIT
14
Q
What are the parts of the embryonic gut
A
The embryonic gut has 4 parts
- Pharyngeal gut - from mouth to the respiratory diverticulum
- Foregut - resp diverticulum to liver bud
- Mid gut - liver bud - junction of prox2/3 and distal 1/3 of tranverse colon
- Hind gut - distal transverse colon to cloacal membrane
15
Q
Development of stomach and duodenum
A
Stomach develops from the primitive fore gut and undergoes 3 critical steps (starting around week 4) to get its final shape and lie:
- it rotates 90 degrees to the right (clockwise when viewed from top) on its longitudinal axis (this creates the lesser sac)
- the posterior wall grows more rapidly than the anterior wall giving rise to the greater and the lesser curves
- Finally it rotates slightly clockwise along it’s longitudinal axis to have an oblique lie.
Duodenum (and Pancreas) are also pulled into the the same rotation by the stomach. This gives rise to the C shape of the duodenum and makes the pancreas a retroperitoneal organ. The duodenum undergoes temporary epithelial obliteration but the lumen re-canalises by the 8th week.
16
Q
Discuss development of pancreas and the resulting abnormalities
A
The pancreas develops from Endodermal tissue around the duodenum as two pancreatic buds (ventral and doral). Due to differential growth of the duodenum, the venrtral bud rotaes to the right (clockwise when viewed from top) to lie below the dorsal bud.
The dorsal bud gives rise to the head, neck, body and tail, the ventral bud gives rise to the lower part of head and the uncinate process.
The ducts of the buds fuse. the final main duct (Wirsung) is made of the ventral duct plus the distal dorsal duct, the proximal dorsal duct can persist as the accessory pancreatic duct (santorini)
Pancreatic divisum is failure of fusion of the dorsal and ventral buds. This predisposes to pancreatitis. 4 types are recgnized:
- Divisum - no connection between ventral and dorsal ducts
- Absent ventral duct
- Flimsy connection between dorsal and ventral ducts
- Reverse divisum - opposite of 1 (ventral bud superior to dorsal and disconnected)
Annular pancreas - dvelopmental anaomaly in rotation of ventral bud leading to ring like configuration around duodenum
- extraduodenal - can cause stenosis
- Intraduodenal - annular panc fused with muscle tissue of duodenum and draining via multiple small ducts - can cuase ulceration
Agensis
17
Q
Discuss hindgut embryology
A
- The terminal hindgut enters the cloaca from which the bladder and urethra also form. The cloacal membrane near the proctodeum separates the ectoderm from the endorderm),
- The primitive cloaca connects with the allantois, the hindgut and the mesonephros
- The urorectal septum grows to join the cloacal membrane thereby separating the cloaca in a urogenital sinus and anorectal canal.
- The place where the urorectal septum meets the clocal membrane becomes the perneal body.
- The anal membrane ruptures in the 9th week.
- The upper part of the anal canal is endodermal in origin, but the lower third is ectodermal. The junction between them is the pectinate line.
- Imperforate anus is caused by non-perforation of the anal membrane or deviation of the urorectal septum posteriorly. Fistulas occur commonly in this condition and open on the perineum, vagina or urethra.
18
Q
What are the types of esophageal atresia
A
- Esophagus elongates as the embryo grows
- The tracheo-bronchial bud comes off the esophagus and gradually gets separated by development of the tracheo-esophageal spetum.
- Abnormal development of thi septum can cause esophageal atresias with(out) fistula
- Atresia with no fistula (complete atresia or stenosis of esophageal lumen)
- Proximal fistula, distal atresia
- Distal fistula promimal atresia (commonest 84%, causes polyhydramnios)
- Both proximal and distal fistula
- H-shaped fistua
19
Q
What are 1st pharyngeal arch structures
A
- The cartilage forms the maxillary process beneath the eye, as well as the mandibular process. These both regress and all that’s left over is the malleus and incus of the ear bones
- The mesenchyme gives origin to the maxillary, zygomatic and temporal bones through membranous ossification (no cartilage precursors to the skull bones) and the mandible.
- Muscular component: All the muscles of mastication, the anterior belly of digastric and the mylohyoid, the tensor tympani (attached to the malleus) and the tensor palati
- Nerve: Maxillary and Mandibular branch of the trigeminal nerve (V3)
20
Q
What are 2nd pharyngeal arch structures
A
- The cartilage gives rise to the stapes, the styloid process of the temporal bone, the stylohyoid ligament and the lesser horn and upper part of the body of the hyoid bone
- Muscular component: Stapedius (attached to the stapes), stylohoid (from styloid process to hyoid bone), posterior belly of digastric, auricular muscles and the muscles of facial expression
- The facial nerve (VII) supplies all these muscles
21
Q
What are 3rd pharyngeal arch structures
A
- Cartilage: lower part of the body and greater horn of the hyoid
- Muscular: stylopharyngeus muscle
- Nerve: Glossopharyngeal nerve (this nerve, IX, winds around the back of the above muscle prior to both entering the pharynx between the superior and middle constrictors)
22
Q
What are 4th and 6th pharyngeal arch structures
A
- Cartilage: All the cartilages of the larynx come from these two arches – thyroid, cricoid, arytenoid, corniculate and cuneiforms.
- The muscles of the fourth arch: cricothyroid, levator palati, constrictors of the pharynx – innervated by the superior laryngeal nerve (branch of vagus)
- The muscles of the sixth arch are all the intrinsic muscles of the larynx supplied by the recurrent laryngeal nerve.
23
Q
What are the derivatives of the pharyngeal pouches?
A
These pouches are lined by endoderm and gives rise to many things:
First pouch:
- This forms a stalk-from the fourth arch - like diverticulum, the tubotympanic recess, that becomes the Eustachian tube and middle ear cavity. It comes close to the first pharyngeal cleft, only separated by the tympanic membrane.
Second pouch:
- This forms the palatine tonsil in the tonsillar fossa. That’s why branchial cysts -of second cleft origin – may have a fistulous process that ends in the tonsillar fossa – of second pouch origin.
Third pouch:
- Gives rise to the inferior parathyroid gland and the thymus. These parathyroids have a long way to migrate and can therefore end up anywhere (thyroid, mediastinum)
Fourth pouch:
- Gives rise to the superior parathyroid gland. This has a much shorter route of migration so less likely to be ‘lost’.
Fifth pouch:
- Gives rise to the ultimobranchial body that incorporates into the thyroid gland and gives rise to the C-cells that secrete calcitonin. Medullary thyroid cancer originates in this body (hence calcitonin is its tumour marker).
- Proliferation of mesenchyme in the second arch cause it to overgrow/overlap the third and fourth arches. The second arch mesenchyme then fuses with the epicardial ridge in the lower part of the neck. Clefts 2,3 and 4 therefore ‘loses’ their connection with the outside world. When this ‘overgrowth’ is not complete, the clefts of 2,3,or 4 may remain in contact with the outside and form a branchial fistula. If ectoderm from clefts 2,3 or 4 remain after the ‘overgrowth’ of the second arch, a branchial cyst may form, characteristically under the anterior border of sternocleidomastoid. Rarely the cyst will connect the second cledt with the second pouch – a branchial fistula with internal fistula tract to the tonsillar fossa.*
24
Q
Describe the embryology of tongue
A
- From the first pharyngeal arch, on the inside, develops two lateral lingual swellings and a median tuberculum impar.
- A second median swelling, the copula, is formed by mesoderm of the 2nd, 3rd and 4th arches on the inside
- A third median swelling originates from the fourth arch – this is the epiglottic swelling
- Behind the epiglottic swelling is the laryngeal orifice (the tracheobronchial diverticulum) flanked by the arytenoid cartilages.
- The lateral lingual swellings overgrow the tuberculum impar and becomes the anterior two-thirds or body of the tongue. This lingual tissue is invaded by the occipital somites, supplied by the hypoglossal nerve. Therefore the motor supply of the tongue is XII and the sensory supply is lingual and chorda tympani nerves (of V3, the nerve of the first arch. The chorda tympani only hitch-hikes along VII).
- The posterior part of the tongue is mainly from third arch mesoderm, hence supplied by the glossopharyngeal nerve (IX)
- The epiglottis is supplied by the superior laryngeal nerve, the nerve of the fourth arch
25
Anatomy of axillary vein
The axillary vein is a deep vein of the upper limb that is **formed by** the union of the brachial and basilic veins. It **starts at** the lower border of the teres major muscle and ascends medially through the axilla towards the 1st rib, where it is **terminates as** subclavian vein at lateral border of 1st rib. Here it lies anterior to the scalenus anterior tendon.
Along its course, the axillary vein lies **anteromedial to the axillary artery,** partially overlapping it. The **tributaries** of the axillary vein are the subscapular, circumflex humeral, lateral thoracic, thoracoacromial, and cephalic veins, most of which correspond to the branches of the axillary artery.
26
Important aspects of kidney anatomy
LEFT
* hilum at L1
* anterior relations - descending colon and tail of panc
* Lienorenal ligament
* Left renal vein longer than right, recieves gonadal vein at right angle.
RIGHT
* Hilum L2
* Anterior relations - Asc colon and 2nd part of duo
Each weighs about 150 g
calyx -\> pelvis -\> ureter
27
Important aspects of kidney anatomy
LEFT
* hilum at L1
* anterior relations - descending colon and tail of panc
* Lienorenal ligament
* Left renal vein longer than right, recieves gonadal vein at right angle.
RIGHT
* Hilum L2
* Anterior relations - Asc colon and 2nd part of duo
Each weighs about 150 g
calyx -\> pelvis -\> ureter
28
Anatomy of ureter
Abdominal course – begins at L1, lies on Psoas major and crosses anterior to the Genitofemoral nerve and is itself crossed by gonadal vessels.
Left - It is lateral to IMA/V and is crossed by left colic and sigmoid vessels. Crosses pelvic brim at bifurcation of iliac vessels over the SIJ. Apex of sigmoid mesocolon also overlies this.
Right ureter – Posterior relations and relations at pelvic brim are similar except sigmoid mesocolon. Anterior relations – 3rd part of duodenum, right colic and ileocolic vessels and root of small bowel mesentery.
Pelvic ureter – on the left the apex of sigmoid mesocolon overlies it. It then crosses over the external iliac vessels and runs on pelvic side wall anterior to the internal iliac artery. It crosses sequentially the obturator nerve, superior vesical artery, obturator artery and vein. At the level of ischial spine it turn foreard to enter the posterolateral bladder base. In males, just before it entrs the bladder the vas deferens crosses superior to it. In females, it enetrs the base of the broad ligament and is crossed by the uterine artery. It penetrates the lateral cervic al ligament and crosses 1-2 cm lateral to the lateral vaginal fornix (where it is at risk during hystrectomy) before entering the bladder.
29
Blood supply of ureter
The ureter is supplied segmentally by a number of vessels. From superior to inferior these are:
* Renal arteries
* Gonadal arteries
* Aortic branches
* Common iliac arteries
* Internal illiac arteries
* Superior vesical arteries
* Uterine arteries
* Middle rectal arteries
* Vaginal arteries
* Inferior vesical arteries
30
anatomy of lesser sac
* The lesser sac is a sub-section of the peritoneal cavity behind the stomach
* It opens into the greater sac through a slit-like aperture, the Foramen of Winslow, defined by the following boundaries:
* Posteriorly, the IVC
* Anteriorly, the free edge of the gastroheptic ligament with the portal triad within
* Superiorly, the caudate lobe
* Inferiorly, the pylorus and duodenum
* The anterior surface of the lesser sac is made up of the posterior layer of the lesser omentum, the peritoneum of the posterior stomach, and the posterior layer of the gastrocolic ligament
* The posterior surface of the lesser sac is made up of the peritoneum that covers the
* surface of the neck and body of the pancreas
* upper pole of the left kidney
* left adrenal
* commencement of the abdominal aorta
* coeliac trunk
* crura of the diaphragm
* The anterior layer of the transverse mesocolon
* The lesser sac has a superior recess to the right of the oesophagus, where the peritoneum of the crura reflects anteriorly to become the posterior layer of the lesser omentum/gastrohepatic ligament
31
Branches of the internal iliac artery
The internal iliac has an anterior and posterior division.
**Posterior division:**
* Ileolumbar artery
* Lateral sacral artery
* Superior gluteal artery
**Anterior division:**
* 3 x vesical branches
* Superior vesical (persistent part of umbilical artery)
* Inferior vesical
* Obliterated umbilical (continuation of superior vesical)
* 3 x visceral branches
* Uterine artery
* Vaginal artery
* Middle rectal artery
* 3 x parietal branches
* Obturator artery
* Pudendal artery
Inferior gluteal artery
32
muscles supplied by marginal mandibular nerve
depressors of the lip
1. depressor anguli oris
2. depressor labii inferioris
3. mentalis
33
Branches of the facial nerve
Distal to stylomastoid foramen, the following nerves branch off the facial nerve:
* Posterior auricular nerve
* Posterior belly of Digastric
* Stylohyoid muscle
* Five major facial branches (in parotid gland):
* Temporal branch
* Zygomatic branch
* Buccal branch
* Marginal mandibular branch
* Cervical branch
Intracranial branches:
Greater petrosal nerve
Nerve to stapedius
Corda tympani
34
radial nerve
* The radial nerve (C5-T1) is the nerve of the extensor compartments of the arm and forearm, supplying them and the skin over them and the dorsum of the hand
* It is a direct continuation of the posterior cord of the brachial plexus, it travels through the triangular space between the heads of triceps and down the posterior humerus, where it may be injured with shaft fractures
* It pierces the lateral inter-muscular septum in the mid-arm to pass between brachialis and brachioradialis
* It gives off the posterior interosseous nerve (supplies the extensor forearm) and then continues as a purely sensory nerve to the anatomical snuffbox (APL, EPB, EPL)
* At the dorsum of the hand it supplies the radial 2.5 digits to the distal PIPJ.
35
carotid aretery branches
The common carotid divides into the internal and external carotid arteries at the level of the upper border of the thyroid cartilage, approximately at C4.
The internal carotid ascends into the cranium via the carotid canal where it terminates into the anterior and middle cerebral arteries. Importantly it gives of the ophthalmic branch in the carotid canal; embolisation of this vessel manifests as amaurosis-fugax.
The external carotid terminates as the superficial temporal and maxillary arteries within the parotid gland substance. Prior to that it gives off; the ascending pharyngeal branch medially, the superior thyroid, lingual, and facial arteries anteriorly, and the posterior auricular and occipital branches posteriorly. The occipital branch pins down the hypoglossal nerve as it winds superficial to both vessels, and deep to the facial vein.
36
Describe the embrological origin of the diaphragm
The diaphragm develops between 7-10 weeks from 4 sources
The diaphragm takes origin from 4 sources.
1. The **septum transversum** is a thick plate of visceral mesoderm separating the primitive cavities
2. This fuses with the **pleuroperitoneal membranes** that eventually obliterate the pericardio-peritoneal canals
3. It also fuses with the **mesentery of the oesophagus**, in which the crura of the diaphragm develop
4. Muscular components migrate from **cervical myotomes C3-C5** carrying with them the phrenic nerve.
37
Where are congenital diaphragmatic hernias most likely to be located
**Morgagni hernia -** Due to defect in fusion between the septum transversum and the coastal cartilages. this is located anteriorly and parasternal
**Bochdalek Hernia -** Due to defect in closure of pleuroperitonel membrane. More common on left because it closes later. They are located posteriorly and needs intervention because they can cause pulmonary hypoplasia
38
What structures pass or pirce through various diaphragmatic ostia?
_Aortic Aperture (T12)_
Contents – Aorta, Azygous vein, Thoracic duct (vein and duct may pierce through the right crus)
_Oesophageal opening (T10)_
Contents – Oesophagus, oesophageal branches of left gastric vessels (and associated lymphatics and veins), Vagal trunks
_Venacaval opening (T8)_
Contents – IVC, right phrenic nerve
_Others_
Hemiazygous vein – left crus
Greater, lesser and least splanchnic nerve – each crus
Sympathetic trunk – behind the medial arcuate ligament
Subcoastal nerves and vessels – behind lateral arcuate ligament
Left phrenic nerve – left dome
Superior epigastric vessels – between the xiphoidal and coastal fibres
Neurovascular bundles of the 7th – 11th intercoastal spaces – between the coastal fibres of the diaphragm and the transversus abdominis
