targeted topics Flashcards
Head and neck Lymphatics
Level I: Submental and submandibular nodes
Level Ia: Submental triangle
Level Ib: Submandibular triangle
Level II: Upper jugular nodes
Level III: Middle jugular nodes
Level IV: Lower jugular nodes
Level V: Posterior triangle group
Level Va: Superior posterior triangle group
Level Vb: Inferior posterior triangle group
Level VI: Anterior triangle group
Level VII: Upper mediastinal nodes
Anterior triangle borders:
Mandible, anterior margin of SCM, midline from chin to jugular notch on manubrium
Posterior triangle borders:
Anterior margin of trapezius, posterior margin of SCM, clavicle
Nasal Cavity
Description/Features:
• The nasal cavity is formed by:
o anteriorly: nasal aperture
o laterally: inferior, middle and superior nasal conchae or turbinates
o superiorly: cribiform plate of the ethmoid bone
o inferiorly: palatal processes of the maxilla and horizontal portion of the palatine bone
• In the midline, the nasal cavity is divided into right and left halves by a septum composed of fibrocartilage, the vomer and the perpindicular plate of the ethmoid bone
• Anteriorly it is continuous with the nose at the nasal aperture
• Posteriorly it is continuous with the nasopharynx
• Laterally, the three nasal conchae form three spaces:
o superior meatus
o middle meatus
o inferior meatus
Relations:
• Superior meatus communicates with the posterior ethmoidal air cells and sphenoid sinuses via the spheno-ethmoidal recess
• Middle meatus communicates with the frontal sinus via frontal recess, and the ethmoid and maxillary sinuses via the ostiomeatal complex
• Inferior meatus communicates with nasolacrimal duct
Arterial supply:
• The arterial supply of the nasal cavity is rich and derives from both the internal and external carotid arteries (mnemonic: GASPS)
• Lateral nasal wall
o anterior and posterior ethmoidal arteries (branch of the opthalmic artery)
o sphenopalatine artery (branch of the maxillary artery)
o pharyngeal artery (branch of the ascending pharyngeal artery)
• Septum
o greater palatine artery (branch of the maxillary artery)
o sphenopalatine artery (branch of the maxillary artery )
o anterior and posterior ethmoid branches (branch of the opthalmic artery )
• Floor
o greater palatine artery (branch of the maxillary artery)
o superior labial arteries
• Rich arterial supply results in two anastomotic areas, which are common sites of epistaxis:
o Woodruff area: anastomosis of sphenopalatine and pharyngeal arteries just posterior to the inferior turbinate
o Kiesselbach plexus: anastomosis of the anterior ethmoid, greater palatine, sphenopalatine and superior labial arteries in the anteroinferior nasal septum
Venous drainage:
• Venous plexus drains into the sphenopalatine vein, facial vein, infraorbital veins, ophthalmic veins
• Note that posterior ethmoid veins anastomose with veins of the dura mater and orbit (making this a potential route of spread of infection)
Innervation:
• CN V2: mucous membrane of the nasal septum
• CN I: olfactory by the olfactory nerve
Lymphatic drainage:
• Submandibular, retropharyngeal and deep cervical lymph nodes
Lateral Nasal Blood supply
Lateral Wall • Anterior + Posterior ethmoidal arteries o Superiorly o From ophthalmic artery • Sphenopalatine + branches o From maxillary artery o Passes from PP fossa through sphenopalatine foraman • Alar branch
External jugular
Description/Features:
• Drains the head, face and part of the pectoral region
Origin:
• Posterior auricular vein and posterior division of the retromandibular vein unite to form the EJV at the angle of the mandible
o anterior division of the retromandibular vein drains into the facial vein and subsequently the IJV
Course/Relations:
• Courses inferiorly in the subcutaneous anterolateral neck
• Deep to platysma but superficial to the SCM
• Pierces the deep cervical fascia posterior to the clavicular head of the SCM
• Drain into the subclavian vein
Tributaries:
• PAST
o Posterior external jugular vein
o Anterior jugular vein
o Suprascapular vein
o Transverse cervical vein
Internal Jugular
Description/Features:
• Major venous return from the brain, upper face and neck
Origin:
• Formed by the sigmoid sinus and the inferior petrosal sinus in or just distal to the jugular foramen
Course/Relations:
• Formed by the union of inferior petrosal and sigmoid dural venous sinuses
• Descends in the carotid sheath with the internal carotid artery
• Vagus nerve (CN X) lies between the two
• Receiving tributaries (Mnemonic: Medical Schools Like Confident People)
• Descends into the thorax usually between the heads of the sternocleidomastoid muscle
• Unites with the subclavian vein to form the brachiocephalic vein just posterior to the sternoclavicular joint
Tributaries:
• Middle thyroid vein
• Superior thyroid vein
• Lingual vein
• Common facial vein
• Pharyngeal veins
• Thoracic duct on the left side and the right lymphatic duct on the right side open into the angle of union of the internal jugular and subclavian veins
Relations:
• Surrounded by accompanying jugular lymph nodes
• Relation to internal carotid artery
o C2 - posteriorly
o C3 - posterolaterally
o C4 - laterally
• Vagus nerve (CN X) always situated between the ICA and IJV
• Anteriorly (ie. is crossed by these structures)
o upper third - spinal root of accessory nerve (CN XI)
o middle third- lower root of ansa cervicalis
o lower third - SCM, tendon of omohyoid
• Posteriorly (from superior to inferior as the IJV descends in the neck)
o lateral mass of C1 (atlas)
o middle scalene muscle
o anterior scalene muscle
o pleura of lung apices
Diaphragm
Description/Features:
• Diaphragm is a dome-shaped fibromuscular septum which separates the thoracic from the abdominal cavity
• Important for breathing
Origin:
• Muscle slips can be grouped according to their origins:
o sternal: arises from two strips under the xiphoid process
o costal: arise from the inner surfaces of the costal cartilages of ribs 6-12 on either side (interdigitates with transversus abdominis)
o lumbar: arise from the lubocostal arches and from the crura
• Two paired tendinous lumbocostal arches:
o medial lumbocostal arch (medial arcuate ligament): covers psoas major, attaches to the L2 vertebral body
o lateral lumbocostal arch (lateral arcuate ligament): covers quadratus lumborum, attached to the L1 transverse process tip of the 12th rib
• Crura are tendinous structures the blend with the anterior longitudinal ligament of the vertebral column:
o right crus arises from the vertebral bodies of L1-3
o left crus arises from the vertebral bodies of L1-2
o the crura meet in the midline to form an arch called the median arcuate ligament
Insertion:
• Central tendon: thin, strong aponeurosis situated immediately below and is fused to the fibrous pericardium
Apertures:
• Aortic Hiatus (T12): aorta, azygos vein, thoracic duct
• Oesophageal Hiatus (T10): esophagus, vagus nerves, esophageal arteries/veins from left gastric
• Vena Caval Foramen (T8): IVC, right phrenic nerve
• Medial arcuate ligament: the sympathetic trunk
• Lateral arcuate ligament: the subcostal vessels and nerve
• Left phrenic pierces the left muscle dome
• Greater, lesser and least splanchnic nerves pierce each crus
• Hemiazygos vein passes through the left crus
Action:
• Contraction lowers diaphragm and increases thoracic cavity size
Nerve supply:
• Phrenic nerves (C3-5) supply the ipsilateral hemidiaphragm with motor fibres
• Lower intercostal nerves supply proprioceptive fibres to the margins
Blood supply:
• Inferior and superior phrenic arteries (branches of the aorta)
• Intercostal arteries
• Subcostal arteries
• Some supply from pericardiophrenic and musculophrenic arteries (branches of the internal thoracic artery)
Variants:
• Scalloped or serrated appearance: due to abnormal insertion of individual muscle slips
• Dromedary diaphragm (hump)
• Accessory diaphragm
• Congenital diaphragm defects: Bochdalek, Morgagni, eventration, agenesis, central tendon defect
Coronary Veins
Description/Features:
• The coronary veins return blood from the myocardium back to the right atrium
• Coronary venous anatomy is highly variable, but is generally comprised of:
o coronary sinus:
wide venous channel situated in the posterior part of the coronary sulcus
Drains into right atrium between SVC opening and tricus valve
o cardiac veins (drain into the coronary sinus)
great cardiac vein: ascends to drain along the anterior longitudinal sulcus (adjacent to LAD)
middle cardiac vein: ascends in the posterior longitudinal sulcus (with posterior interventricular artery)
small cardiac vein: runs in the coronary sulcus between the right atrium and ventricle (with RCA)
posterior left ventricular vein: runs on the diaphragmatic surface of the left ventricle
Marginal vein of the left ventricle
oblique vein of the left atrium: descends on the back of the left atrium
o thebesian veins (drain directly into the right atrium)
anterior cardiac veins
venae chordis minimae arise in the muscular wall of the heart
Variant anatomy:
• Coronary sinus may act as a conduit between a persistent left SVC and the right atrium
• Coronary sinus may drain into the left atrium (causing right to left shunt)
• Great cardiac vein may drain into the SVC or left brachiocephalic via the oblique vein of Marshall
• Great cardiac vein may drain into the azygous vein
• Cardiac veins may converge to empty into a common opening or directly into the right atrium
Common Bile Duct
Description:
• Transmits bile into the duodenum
• Along with the cystic duct makes up the extra-hepatic bile ducts
• Cystic duct + common hepatic duct = CBD
• CBD is approximately 8cm long and usually <6mm wide in diameter
Course/Relations:
• The CBD travels initially in the free edge of the lesser omentum (with proper hepatic artery and the portal vein)
• Then courses posteriorly to the duodenum and pancreas to unite with the main pancreatic duct to form the ampulla of Vater
• Drains at the major duodenal papillae on the medial wall of the D2 segment of the duodenum
• Calot triangle (relation)
Arterial supply:
• Upper part: cystic artery
• Lower part: superior pancreatico-duodenal artery
Variants:
• Four main relationships of the CBD with the pancreatic head:
o partially covered posteriorly (most common ~50%)
o completely covered
o completely uncovered
o CBD may pass laterally to the pancreatic head (least common)
Gall bladder and the cystic duct
Description/Features:
• The gall-bladder is a pear-shaped musculomembranous sac
• Divided into a fundus, body, and neck
• Extends from the right border of porta hepatis, inferolaterally
• Gallbladder consists of four layers: serosa, muscularis externa, lamina propria, mucosa
• The cystic duct connects the neck of the gallbladder to the common hepatic duct
• Calot’s triangle is an anatomic space bordered by the CHD medially, the CD laterally and inferior border of liver
o contains Lund’s node (lymph node) which may enlarge in cholecystitis
o may contain cystic artery, accessory right hepatic artery or anomalous bile ducts within triangle (important surgical implications)
Relations:
• Superiorly: liver
• Inferiorly: transverse colon, D2 segment of the duodenum (or pylorus of the stomach)
• Anteriorly: liver, transverse colon, 9th costal cartilage
• Medial: IVC
• The cystic duct travels alongside the cystic artery
Arterial supply:
• Cystic artery (branch of right hepatic artery)
Venous drainage:
• Cystic vein drains directly into the right portal vein
Lymph drainage:
• Nodes at the porta hepatis and portal nodes
• Subsequently to the coeliac lymph nodes
Nerve supply:
• Sympathetic: coeliac plexus (passes along the cystic artery)
• Parasympathetic: vagus nerve
Variant anatomy:
• Morphology
o Phrygian cap: the fundus is sometimes folded back upon itself
o Hartmann pouch (infundibulum): neck is focally dilated and probably pathological / related to cholelithiasis
• Number
o accessory gallbladder
gallbladder bifid / duplication / triplication
cystic duct may also be duplicated / tripled
gallbladder agenesis
• Location
o left-lobe > intrahepatic > retrohepatic
• Cystic duct
o low cystic duct insertion - into the distal-third of the CHD
o medial cystic duct insertion - into the left, not the right, side of the CHD
o parallel cystic duct course - courses parallel to the CHD for at least 2cm
o cystic duct empties into the right posterior hepatic duct
IVC
Description/Features:
• IVC drains venous blood from the lower trunk, abdomen, pelvis and lower limbs to the right atrium of the heart
Origin:
• Formed by the confluence of the two common iliac veins at the L5 vertebral level
Course:
• IVC has a retroperitoneal course within the abdominal cavity
• Runs along the right side of the vertebral column
• Passes through the diaphragm at the caval hiatus at the T8 level
• Has a short intra-thoracic course before draining into the right atrium
Relations:
• Anterior: right common iliac artery, mesentery, right gonadal artery, third part of the duodenum, pancreas, posterior surface of the liver
• Posterior: vertebral column, right crus of the diaphragm, right inferior phrenic / adrenal / renal and lumbar arteries, right sympathetic trunk
• Right: right kidney, right ureter, right adrenal
• Left: aorta
Tributaries:
• T8: paired inferior phrenic veins
• T8: hepatic veins (3)
• L1: right adrenal vein
• L1: renal veins
• L2: right gonadal vein
• L1-L4: lumbar veins
• L5: common iliac veins (origin)
Variants:
• IVC duplication: IVC continues on both sides of aorta
• Transposition of IVC: only one IVC on the left side of the aorta
• Azygos continuation of the IVC
o differential for dilated azygos vein
o hepatic segment of the IVC is absent
o hepatic veins join and drain directly into the right atrium
• Circumcaval ureter: IVC develops passing infront of the ureter, so ureter initially courses behind IVC
Tributaries (mnemonic - I Hate GARLIc)
• T8: inferior phrenic veins
• T8: hepatic veins (3)
• L1: right adrenal vein
• L1: renal veins
• L2: right gonadal vein
• L1-L5: lumbar veins
• L5: common iliac veins (origin)
o median sacral vein drains into left common iliac vein, but occasionally drains into junction of left and right common iliac vein
Levator Ani
Description/Features:
• Levator ani is a musculotendinous sheet that forms the majority of the pelvic floor (other component is the coccygeus muscles)
• Three main components (each of which is paired)
o iliococcygeus muscle
o pubococcygeus muscle
subparts: puboperineal, pubovaginal, puboanal
o puborectalis muscle
Origin:
• Iliococcygeus: arises from the posterior part of the tendinous arch / obturator internus fascia and ischial spine
• Pubococcygeus: inner surface of the pubis, anterior part of the tendinous arch / fascia of the obturator internus
• Puborectalis: arises from the inner surface of the pubic bone
• Coccygeus: ischial spine/lig
Insertion:
• Iliococcygeus: coccyx/anococcygeal lig+raphe
• Pubococcygeus: coccyx/anococcygeal lig+raphe
• Puborectailis: unites behind the anorectal junction to form a sling
Action:
• Supports the pelvic viscera
• Aids in urinary and fecal evacuation
• Maintains continence
Relations:
• Rectum, vagina, urethra penetrate through the diaphragm
• Inferior: forms the roof of the ischioanal fossa (contents: inferior rectal vessels, inferior anal nerves)
• Superior: pelvic organs
Nerve supply:
• Inferior rectal nerve from pudendal nerve (S3, S4)
• Levator ani nerve (S4)
Blood supply:
• Inferior gluteal artery
Variation:
• Thinning / aplasia of one or both sides is common (~50%)
Radial Nerve
Description/Features:
• One of five main branches of the brachial plexus
• Provides motor and sensory innervation to the arm and forearm and sensory innervation to the hand
Origin:
• One of two terminal branches of the posterior cord of the brachial plexus (other being axillary)
• Fibres from C8-T1
Course/Relations:
• Lies posterior to the axillary artery in the axilla
• Enters the posterior compartment of the arm under teres major muscle
• Winds around the radial groove of the humerus (between lateral and medial heads of the triceps) accompanying profunda brachii artery
• Passes through the triangular space with profunda brachii
• Pierces the lateral intermuscular septum to enter the anterior compartment of the arm
• Passes to the forearm by coursing anterior to the lateral epicondyle at the level of the elbow joint
• Enters the cubital fossa, where it divides into superficial and deep branches
• Superficial branch courses towards the wrist lateral to the radial artery and enters the hand, dividing into the dorsal digital cutaneous branches
• Deep branch of the radial nerve winds to the back of the forearm around the lateral side of the radius between the two heads of the supinator and continues downward between superficial and deep layers of muscles to the middle of the forearm as the posterior interosseus nerve
Branches/Supply:
• Muscular twigs in the arm:
o medial and lateral heads of the triceps brachii
o anconeus muscles
o brachioradialis
o extensor carpi radialis longus
• Superficial branch of the radial nerve supplies cutaneous sensation to the:
o dorsal aspect of the hand
o dorsal aspect of the first to third digits
o dorsal lateral aspect of the fourth finger
• Deep branch of the radial nerve (continues as the posterior interosseous nerve):
o extensor carpi radialis brevis
o supinator
o extensor digitorum
o extensor digiti minimi
o extensor carpi ulnaris
o abductor pollicis longus
o extensor pollicis brevis
o extensor pollicis longus
o extensor indicis
• Articular twigs to the elbow and wrist joints
• Posterior cutaneous nerve of the forearm
Variants:
• The radial nerve may communicate with the ulnar nerve in the arm
• The radial nerve may supply the entire dorsum of the hand including the dorsal aspect of all the fingers
Musculocutaneous nerve
Origin:
• Lateral cord of the brachial plexus
• Fibres from C5-C7
Course:
• In the axilla, the musculocutaneous nerve courses laterally away from the axillary artery
• Pierces (and supplies) the coracobrachialis muscle and descends towards the elbow between biceps brachii and brachialis muscles
• In the cubital fossa, it courses lateral to the biceps tendon as the lateral cutaneous nerve of the forearm
Supply:
• Muscular branches: anterior compartment of the arm (coracobrachialis, biceps brachii and brachialis muscles)
• Articular branches: shoulder and elbow joints
• Lateral cutaneous nerve of the forearm (lateral aspect of the forearm)
Median Nerve
Description/Features:
• One of five main nerves that arise from brachial plexus
• Only one to pass through carpal tunnel
• Carpal tunnel syndrome is due to pressure on the median nerve
Origin:
• Lateral and medial cords of the brachial plexus (fibres from C5-T1)
Course/Relations:
• It lies at first lateral to the brachial artery then crosses about the level of the insertion of the Coracobrachialis to its medial side
• Descends in the arm between Biceps brachii and Triceps brachii muscles
• Enters the cubital fossa
• In the forearm it passes between the two heads of the Pronator teres and crosses the ulnar artery
• It descends beneath the Flexor digitorum superficialis, and superficial to the Flexor digitorum profundus
• Travels with four tendons of FDS, four tendons of FDP, tendon of FHL through the carpal tunnel
Major Branches:
• Anterior interosseous nerve
o supplies all the flexor muscles of the forearm apart from flexor carpi ulnaris and the ulnar half of flexor digitorum profundus
• Motor branch in the hand (recurrent branch to thenar, palmar digital to lumbricals)
o supplies thenar muscles and the radial two lumbricals (LOAF muscles)
• Palmar cutaneous branch
o cutaneous innervation to the palmar aspect of the thumb, index and middle fingers and the radial half of the ring finger
• Articular branches to the elbow, wrist, carpal and phalangeal joints
Variants:
• May pass under the Struthers’ ligament (exists in 10-15% people) which extends between a bony process from humeral shaft to the medial epicondyle (passes under here with the brachial artery) - potential site of compression (supracondylar process syndrome)
• High division or bifid median nerve
o bifurcation of the median nerve typically occurs after the nerve exits the carpal tunnel
o 5%-10% individuals the median nerve bifurcates more proximal in the carpal tunnel, wrist or forearm
• During gestation, a median artery that serves the hand retracts. However, in some individuals the median artery does not retract and follows the course next to the median nerve into the hand
• Martin-Gruber anastomoses can occur when branches of the median nerve cross-over in the forearm and merge with the ulnar nerve to innervate portions of the forearm
• Riche-Cannieu anastomoses can occur when there is connection between recurrent branch of the median nerve and deep branch of the ulnar nerve of the hand
• The median nerve or either of its branches may pass behind the axillary artery or brachial artery instead of in front of it
• The site of union between the lateral and medial cords is quite variable and has been found as far down as the elbow
• The two cords (lateral and medial) may enclose the axillary vein as well as the axillary artery
Ulnar Nerve
Description/Features:
• Ulnar nerve is one of the terminal branches of the brachial plexus and has motor and sensory supply to the forearm and hand
Origin:
• Terminal branch of the medial cord of the brachial plexus with nerve root fibres from C8-T1
Course/Relations:
• Arm
o runs medial to the axillary artery and subsequently the brachial artery on the coracobrachialis muscle in the anterior compartment
o posterior to the basilic vein and medial to the medial head then long head of the triceps brachii
o passes posterior to the medial epicondyle of the humerus in the superficial condylar groove in the cubital tunnel (under ligament of Osborne)
• Forearm
o enters the forearm between the two heads of flexor carpi ulnaris
o lies superficial to flexor digitorum profundus, deep to flexor carpi ulnaris, with the ulnar artery
o at the wrist, the ulnar nerve runs lateral to the tendon of flexor carpi ulnaris
• Hand
o enters the hand superficial to the flexor retinaculum and inside Guyon’s canal
o divides into its terminal branches at the level of the pisiform bone
Branches (DD:PMS):
• Muscular branches: arise near the elbow to supply flexor carpi ulnaris and the ulnar half of the flexor digitorum profundus
• Palmar cutaneous branch: supplies skin of the hypothenar eminence
• Dorsal cutaneous branch: arises above the wrist, supplies the dorsum of the hand and the ulnar one and a half fingers
• Superficial branch: supplies palmaris brevis, and the remainder of the skin of the ulnar one and a half fingers
• Deep branch: supplies the three hypothenar muscles and adductor pollicis, all the interossei, the third and fourth lumbricals
Supply:
• Motor:
o FDP, FCU
o hypothenar muscles, adductor pollicis
o all interossei, third and fouth lumbricals
• Sensory:
o articular innervation to elbow, wrist, carpal and phalangeal joints
o cutaneous innervation to ulnar aspect of the hand, 5th finger, medial 4th finger
Variants:
• The branch to the dorsum of the hand may be deficient, and this is compensated for by the radial or the medial antebrachial cutaneous nerves
