Anatomy

Anatomy

6/8/10

1/2008 - Outline the anatomical relations of the cervical trachea relevant to performing a percutaneous tracheostomy. 

Percutaneous Tracheostomy Anatomy

- cylindrical tube- projects onto the spine- C6 -> T5- moving downwards it courses slightly backwards- first 6 tracheal rings are extrathoracic- length = 10-15cm in adults- blood supply = inferior thyroid artery & veins and bronchial arteries- nerves = vagus and recurrent laryngeal (pain and secretomotor) + sympathetics (blood flow and smooth muscles)

SUPERIORLY - cricotracheal membrane -> circoid cartilage

INFERIORLY - terminates at the bifurcation of the bronchi

ANTERIORLY (superficial -> deep)

- skin- superficial fascia + anterior jugular veins connected by a vein that runs superficially across the lower neck- muscles (sternothyreoideus and sternohyoideus)- isthmus of the thyroid gland (2-4th tracheal rings) + - inferior thyroid veins- deep pretracheal fascia

POSTERIORLY

- oesophagus- recurrent laryngeal nerves

LATERALLY

- right and left lobes of the thyroid- inferior thyroid arteries

POSTEROLATERALLY

- carotid sheath (common carotid, jugular vein, vagus nerve)- recurrent laryngeal nerves (lies in groove between trachea and oesophagus)

Jeremy Fernando (2011)

Jeremy Fernando (2011)

1/2005 - Outline the anatomical structures relevant to the insertion of a femoral venous catheter

Femoral Vein Anatomy

6/8/10SP Notes

- continuation of the popliteal vein- lies in the intermediate compartment of the femoral sheath- accompanies the femoral artery in the femoral triangle- at the inguinal ligament it becomes the external iliac vein

FEMORAL TRIANGLE

- superior: inguinal ligament- medial border: adductor longus- lateral border: sartorius- apex: sartorius crossing the adductor longus muscle- roof: skin subcutaneous tissue, the cribriform fascia and the fascia lata- floor: adductor longus, adductor brevis, pectineus and iliopsoas muscles

LANDMARKS

- anterior superior iliac spine (ASIS)- pubic ramus- inguinal ligament- femoral sheath- medially -> laterally (vein, artery, nerve)

INSERTION POINT

- 1cm below inguinal ligament- 1cm medial to femoral arterial pulsation

STRUCTURES NEEDLE PASSES THROUGH (superficial -> deep)

- skin- subcutaneous tissue- fascia (encloses the femoral vessels)- femoral vein- medial: medial compartment of femoral sheath (femoral canal – lymph vessels, nodes and fatty tissue)- lateral: fibrous septum separating intermediate compartment and lateral compartment (containing femoral artery) and further lateral = femoral nerve- posterior: posterior fascia and pectineus

Jeremy Fernando (2011)

Jeremy Fernando (2011)

2/2005 - Describe the anatomy of the tracheobronchial tree, as seen down a bronchoscope inserted via an endotracheal tube

Bronchoscopic Anatomy

6/8/10See: Sabine’s Notes, My diagram, Bronchoscopy photos

ETT

- via adaptor- clear plastic with markings on ETT- Murphy’s eye

TRACHEA

- mucous membranes- anterior and lateral walls: cartilaginous ‘U’ shaped rings connected by connective tissue- posterior wall: muscle (trachealis, par membranaceus)- length: 10-15c in adults (cricoid -> bifurcation)- diameter: 19-22mm

CARINA

- cartilaginous ring that runs anterior-posteriorly between to main bronchi- lumen narrows slightly as it progresses towards the carina

RIGHT MAIN BRONCHUS

- more vertical orientation than left- bronchus intermedius directly ahead- 1-2cm in is the RIGHT UPPER LOBE BRONCHUS @ 0300

RIGHT UPPER LOBE BRONCHUS

- trifurcation: APICAL, ANTERIOR AND POSTERIOR SEGMENTS- this is the only place that has 3 orifices- 1/250 people have their RIGHT UPPER LOBE BRONCHUS coming directory off CARINA

RIGHT BRONCHUS INTERMEDIUS

Jeremy Fernando (2011)

- come back into RIGHT MAIN BRONCHUS- identify the RIGHT MIDDLE and LOWER LOBE BRONCHI

RIGHT MIDDLE BRONCHUS

- seen at 1200- D shape- MEDIAL and LATERAL SEGMENTS

RIGHT LOWER LOBE

- APICAL SEGMENT @ 0600- four basal segments (MEDIAL, LATERAL, ANTERIOR and POSTERIOR)

-> withdraw back into trachea

LEFT MAIN BRONCHUS

- lies more horizontal than RIGHT MAIN BRONCHUS- it is longer and divides into LEFT UPPER and LEFT LOWER LOBE BRONCHI

LEFT UPPER LOBE BRONCHUS

- divides into SUPERIOR and LINGULAR DIVISION @ 0900- SUPERIOR: gives rise to APICOPOSTERIOR and ANTERIOR segments- LINGULA: gives rise to the SUPERIOR and INFERIOR segments

LEFT LOWER LOBE BRONCHUS

- APICAL SEGMENT @ 0600- 3 BASAL SEGMENTS (LATERAL, ANTERIOR and POSTERIOR)

Jeremy Fernando (2011)

2/1997 - Briefly outline the gross anatomy observed when doing a general bronchoscopy in an endotracheally intubated patient? Sketches may help to illustrate

Bronchoscopic Anatomy

6/8/10See: Sabine’s Notes, My diagram, Bronchoscopy photos

ETT

- via adaptor- clear plastic with markings on ETT- Murphy’s eye

TRACHEA

- mucous membranes- anterior and lateral walls: cartilaginous ‘U’ shaped rings connected by connective tissue- posterior wall: muscle (trachealis, par membranaceus)- length: 10-15c in adults (cricoid -> bifurcation)- diameter: 19-22mm

CARINA

- cartilaginous ring that runs anterior-posteriorly between to main bronchi- lumen narrows slightly as it progresses towards the carina

RIGHT MAIN BRONCHUS

- more vertical orientation than left- bronchus intermedius directly ahead- 1-2cm in is the RIGHT UPPER LOBE BRONCHUS @ 0300

RIGHT UPPER LOBE BRONCHUS

- trifurcation: APICAL, ANTERIOR AND POSTERIOR SEGMENTS- this is the only place that has 3 orifices- 1/250 people have their RIGHT UPPER LOBE BRONCHUS coming directory off CARINA

Jeremy Fernando (2011)

RIGHT BRONCHUS INTERMEDIUS

- come back into RIGHT MAIN BRONCHUS- identify the RIGHT MIDDLE and LOWER LOBE BRONCHI

RIGHT MIDDLE BRONCHUS

- seen at 1200- D shape- MEDIAL and LATERAL SEGMENTS

RIGHT LOWER LOBE

- APICAL SEGMENT @ 0600- four basal segments (MEDIAL, LATERAL, ANTERIOR and POSTERIOR)

-> withdraw back into trachea

LEFT MAIN BRONCHUS

- lies more horizontal than RIGHT MAIN BRONCHUS- it is longer and divides into LEFT UPPER and LEFT LOWER LOBE BRONCHI

LEFT UPPER LOBE BRONCHUS

- divides into SUPERIOR and LINGULAR DIVISION @ 0900- SUPERIOR: gives rise to APICOPOSTERIOR and ANTERIOR segments- LINGULA: gives rise to the SUPERIOR and INFERIOR segments

LEFT LOWER LOBE BRONCHUS

- APICAL SEGMENT @ 0600- 3 BASAL SEGMENTS (LATERAL, ANTERIOR and POSTERIOR)

Jeremy Fernando (2011)

1/1996 - Outline the functions of the vagus nerve

Vagus Nerve – Functions

6/8/10SP Notes

- Xth cranial nerves- paired nerves- neurotransmitters = Ach and Noradrenaline- pre and postganglionic neurons- provides 75% of all the parasympathetic nerve fibers (heart, lungs, oesophagus, stomach, small intestine, proximal half of colon, liver, gall bladder, pancreas, kidneys, upper ureters)

BRANCHIAL MOTOR

-> voluntary control over swallowing- striated muscles of pharynx- striated muscles of larynx (except stylopharyngeus and tensor veli palatini)- palatoglossus muscle of the tongue

SECRETOMOTOR

- efferent fibres which innervate the smooth muscle and glands -> pharynx, larynx, thoracic and abdominal viscera down to the splenic flexure.- parasympathetic tone -> increase gland secretion and smooth muscle contraction (rest and digest)

Cardiovascular

- heart: right vagus -> SA node, left vagus -> AV node, atrial muscle innervated by vagal efferentes (slow HR, decrease contractility and dilate coronaries)- arterial pressure -> slight decrease (requires strong stimulation)- supply to blood vessels in salivary, GI glands and erectile tissue -> vasodilation

Respiratory

- bronchoconstriction and increased secretions- pulmonary vasodilation

Gastrointestinal

- increased peristalsis- increased secretions (gastric, pancreatic, lacrimal)- relax sphincters- hepatic glycogen synthesis- gall bladder contraction

Genitourinary

- detrusor contraction- trigone relaxation- penile erection

Jeremy Fernando (2011)

VISCERAL SENSORY

- provides sensory information from larynx, oesophagus, trachea, abdominal and thoracic viscera- stretch receptors from the aortic arch and chemoreceptors to the aortic bodies

GENERAL SENSORY

- pain, temperature and touch:- skin of ear- external auditory meatus- external tympanic membrane- larynx- pharynx

Jeremy Fernando (2011)

2/1995 - Briefly describe your technique for ICC insertion in adult male with haemopneumothorax and multiple fractured ribs after MVA. What are the risks of insertion and how may they be prevented.

Intercostal Drain Insertion

6/8/10SP Notes

PREPARATION

- exclude contraindications- consent- IV access (analgesia, resuscitation medications or products)- monitoring (SpO2, ECG, BP)- confirm affected side (clinically + CXR)- position: supine with arm abducted and hand under head- local anaesthesia: lignocaine with adrenaline = 7mg/kg

EQUIPMENT

- chlorhexidine- drape- scalpel- forceps- clamp- 2.0 suture- gauze- dressing- 32 Fr drain (blood)- underwater seal drainage system (primed)

INSERTION

- full asepsis (G/G/H/M/C)- landmarks = anterior to mid-axillary line, 5th IC space, nipple line (T4), palpate ribs and ICS- 2-3cm transverse incision on top of rib- blunt dissection down to pleura (just superior to rib -> avoid neurovascular structures)- end point: pleural cavity (hiss or blood)- sweep with finger- insert clamped drain using curved forceps to guide in- connect to UWSD- check for drainage and respiratory swing- suture- sterile dressing

POST INSERTION

- CXR- watch for complications: -> not draining (check for kinking)-> organ injury (lung, liver, spleen, heart, vessel) – careful insertion-> blood loss– careful observation-> surgical emphysema (small hole and good suturing)-> infection (sterile technique)

Jeremy Fernando (2011)

2/1995 - Describe the symptoms and signs of a complete 3rd nerve lesion. Explain the anatomical basis of these effects.

IIIrd Cranial Nerve Lesion

6/8/10SP Notes

- oculomotor nerve- innervates: superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae, cillary muscle and iris sphincter

SYMPTOMS/SIGNS

- “down and out” – because of antagonism of the trochlear nerve (superior oblique) and abducens nerve (lateral rectus)- ptosis – weakness of levator palpebrae- diplopia + strabismus – unable to maintain normal alignment when looking straight ahead- dilated, fixed pupil (anisocoria) + blurred vision – parasympathetic fibres originate from the Edinger-Westphal subnucleus of IIIrd nerve complex

ANATOMICAL BASIS (causes of IIIrd nerve dysfunction)

Nuclear Portion

- column shaped- either side of the midbrain tegmentum- infarction, haemorrhage, neoplasm, abscess

Fascicular Midbrain Portion

- courses ventrally- passes through the red nucleus

Jeremy Fernando (2011)

- emerges from the medial aspect of the cerebral peduncle- infarction, haemorrhage, neoplasm, abscess

Fascicular Subarachnoid Portion

- nerve runs in the subarachnoid space anterior to the midbrain and in close proximity to the posterior communicating artery- aneurysm, meningitis, meningeal infiltration, ophthalmoplegic migraine, compression from ipsilateral or mass effect (uncal herniation)

Fascicular Cavernous Sinus Portion

- the nerve runs through the lateral wall of the cavernous sinus- it enters the sinus just above the petroclinoid ligament and inferior to the interclinoid ligament- tumour, pituitary apoplexy/infarction, vascular (giant intracavernous aneurysm, carotid artery-cavernous sinus fistula, cavernous sinus thrombosis), ischaemia, inflammatory (Tolosa-Hunt Syndrome)

Fascicular Orbital Portion

- it enters the orbit through the superior orbital fissure- it then branches into superior and inferior divisions- superior -> levator palpebrae and superior rectus- inferior -> innervates the rest- axons are mostly uncrossed with 2 exceptions (axons to levator palpebrae are from both sides, those for superior rectus come from the contralateral side)- inflammatory (orbital inflammatory pseudotumour), endocrine (thyroid orbitopathy), tumour (haemangioma, lymphoma)

Jeremy Fernando (2011)

2/1994 - Describe or illustrate the anatomical relationships of the left subclavian vein.

Left Subclavian Vein Anatomy

6/8/10SP Notes

- in an adult: 3-4cm in length an 1-2cm in diameter- formed from the axillary veins at the lateral border of the first rib- joins the brachiocephalic vein to become the superior vena cava

ANATOMICAL RELATIONSHIPS

- superior: clavicle- inferior: pleura- posterior: anterior scalene muscle + subclavian artery- anterior: medial thirst of clavicle (immobilized by small attachments to the rib and clavicle) and subcutaneous tissue of the anterior chest wall- lateral: anterior aspect of the deltoid shoulder muscle- medial: internal jugular and brachiocephalic vein (this take place at the medial border of the anterior scalene muscle and behind the sternoclavicular joint)- the large thoracic duct on the left and small lymphatic duct on the right enter the superior margin of the subclavian vein near the IJ junction

Jeremy Fernando (2011)

2/1993 - Briefly discuss the anatomical basis and interpretation of pupillary signs in a patient paralysed and ventilated following a head injury. List the pharmacological and metabolic factors that may alter signs

Pupillary Signs in Head Injury

6/8/10SP Notes

Pupillary signs in the head injured patient are dependent on a number of factors including:

- integrity of the eyes and retina- optic nerve - oculomotor nerve- trochlear nerve- abducens nerve- the respective nerve nuclei for above nerves- also the structures surrounding the above nerves and nuclei

Puplliary Signs

EQUAL AND REACTIVE TO LIGHT – normal integrity of the above structures

MIOSIS – interruption of the sympathetic innervation or irritation of the conjunctivae or cornea (foreign bodies) -> mediated by the constrictor muscle (preganglionics = oculomotor nerve -> ciliary ganglion -> post ganglionics to constrictor muscles releasing Ach)

MYDRIASIS – parasympathetic innervation originates in the Edinger-Westphal subnucleus of the IIrd nerve -> compressive lesions affect autonomic fibers as they are very superficial in the nerve trunk (sympathetic preganglionics from thoracic region -> superior cervical ganglia -> postganglionic neurons releasing noradrenaline -> dilator muscle in iris

ANISOCORIA – unilateral lesions along any of the above tracts

IRREGULAR SHAPED PUPILS – ophthalmological procedures

OVAL PUPILS – early compression of IIIrd nerve due to increased ICP

ONE EYE ‘DOWN AND OUT’ – dysfunction of the IIIrd cranial nerve or nuclei

Pharmacological Factors

MIOSIS: opioids, alcohol, neurolepticsMYDRIASIS: anticholinergics, catecholamines, cocaine, amphetaminesPUPIL REACTIVITY: opioids, propofol, metoclopramide, haloperidol, droperidol

Metabolic Factors

PaCO2:ACIDOSIS:

Jeremy Fernando (2011)

DIABETES: giant cell arteritis, syphyllis, hypertension -> IIIrd nerve palsy without dilated pupil1/1992 - Briefly discuss the anatomical basis and interpretation of pupillary signs in a patient paralysed and ventilated following a head injury. List the pharmacological and metabolic factors that may alter signs

Pupillary Signs in Head Injury

6/8/10SP Notes

Pupillary signs in the head injured patient are dependent on a number of factors including:

- integrity of the eyes and retina- optic nerve - oculomotor nerve- trochlear nerve- abducens nerve- the respective nerve nuclei for above nerves- also the structures surrounding the above nerves and nuclei

Puplliary Signs

EQUAL AND REACTIVE TO LIGHT – normal integrity of the above structures

MIOSIS – interruption of the sympathetic innervation or irritation of the conjunctivae or cornea (foreign bodies) -> mediated by the constrictor muscle (preganglionics = oculomotor nerve -> ciliary ganglion -> post ganglionics to constrictor muscles releasing Ach)

MYDRIASIS – parasympathetic innervation originates in the Edinger-Westphal subnucleus of the IIrd nerve -> compressive lesions affect autonomic fibers as they are very superficial in the nerve trunk (sympathetic preganglionics from thoracic region -> superior cervical ganglia -> postganglionic neurons releasing noradrenaline -> dilator muscle in iris

ANISOCORIA – unilateral lesions along any of the above tracts

IRREGULAR SHAPED PUPILS – ophthalmological procedures

OVAL PUPILS – early compression of IIIrd nerve due to increased ICP

ONE EYE ‘DOWN AND OUT’ – dysfunction of the IIIrd cranial nerve or nuclei

Pharmacological Factors

MIOSIS: opioids, alcohol, neurolepticsMYDRIASIS: anticholinergics, catecholamines, cocaine, amphetaminesPUPIL REACTIVITY: opioids, propofol, metoclopramide, haloperidol, droperidol

Metabolic Factors

PaCO2:

Jeremy Fernando (2011)

ACIDOSIS:DIABETES: giant cell arteritis, syphyllis, hypertension -> IIIrd nerve palsy without dilated pupil

Jeremy Fernando (2011)