Anatomy Flashcards
What are the structures 1-5?
- Thyroid gland
- Thyroid cartilage
- Carotid sheath
- Vagus nerve
- Oesophagus
What are the proximal and distal borders of the trachea?
Proximal at lower border of cricoid cartilage (C6)
Distal termination at sternal angle (T4) where it bifurcates into 2 main bronchi
What forms the walls of the trachea?
Fibrous tissue reinforced by 15-20 incomplete semicircular cartilaginous rings.
What type of mucosa lines the trachea?
Respiratory epithelium - ciliated pseudostratified columnar epithelium
What lies immediately posterior to the trachea?
Oesophagus with the recurrent laryngeal nerve
What major vascular structures traverse the trachea anteriorly?
The brachiocephalic artery and left brachiocephalic vein
What is the blood supply to the trachea?
Inferior thyroid artery (arterial supply) - arises from thyrocervical trunk
Inferior thyroid veins (venous drainage) and these drain into right and left brachiocephalic veins
What nerve supplies the trachea?
Recurrent laryngeal branch nerves (brances of the vagus) with an additional sympathetic supply from the middle cervical ganglion
Name structures 1-6
- Nerve to subclavius
- Long thoracic nerve
- Musculocutaneous nerve
- Axillary nerve
- Median nerve
- Radial nerve
What are the origins of the brachial plexus?
Anterior primary rami of C5,6,7,8 and T1
What is the course of the brachial plexus?
- emerges as five roots
- lies anterior to scalenus medius and posterior to scalenus anterior
- trunks lie at the base of the posterior triangle of the neck and pass over the first rib, posterior to the third part of the subclavian artery, to descend behind the clavicle
- divisions form behind the middle third of the clavicle
What are the branches of the lateral cord of the brachial plexus?
- Lateral pectoral nerve to pectoralis major
- Musculocutaneous nerve to corachobrachialis, biceps, brachialis and the elbow joint. It continues as the lateral cutaneous nerve of the forearm, supplying the radial surface of the forearm
- Lateral part of the medial nerve
What are the branches of the medial cord?
- Medial pectoral nerve
- Medial cutaneous nerves of the arm and forearm
- Ulnar nerve
- Medial part of median nerve
Which nerves may be missed using the axillary approach?
- intercostobrachial nerve supplying the superomedial surface of the arm (intercostobrachial nerve can be blocked by subcutaneous infiltration)
- musculocutaneous nerve
What are complications are associated with supraclavicular nerve blocks?
- Intravascular injection of local anaesthetic
- Temporary and permanent nerve damage
- Bleeding
- Failure
- Phrenic nerve palsy
- Recurrent laryngeal nerve palsy
- Pneumothorax
Label the great veins of the neck
- Facial vein
- Anterior jugular vein
- RIJ vein
- Right brachiocephalic vein
- Right subclavian vein
- Right vertebral vein
- External jugular vein
- Posterior auricular vein
What sinuses combine to form the internal jugular vein?
- sigmoid sinuses
- inferior petrosal sinuses
These form the internal jugular vein which then pases through the jugular foramen at the base of the skull.
Where does the internal jugular vein terminate?
Behind the sternoclavicular joint as it unites with the subclavian vein to form the brachiocephalic vein
What is the relationship between the internal jugular vein and the carotid artery?
The internal jugular vein lies posterior to the carotid artery at the level of C2, posterolateral at C3 and then lateral to the artery at C4.
The vein and artery are contained within the carotid sheath along with the vagus nerve.
Which veins combine to form the external jugular vein?
- posterior auricular vein
- posterior division of the retromandibular vein
Where do the anterior and external jugular veins join?
They pierce the deep fascia of the neck, usually posterior to the clavicular head of sternocleidomastoid, and unite before draining into the subclavian behind the midpoint of the clavicle
Label the structure of the ACF
- Biceps
- Radial nerve
- Brachial artery
- Median nerve
- Radial artery
- Ulnar artery
- Pronator teres
- Brachialis
What are the borders of the ACF?
Proximally - a line between the humeral epicondyles
Laterally - brachioradialis
Medially - pronator teres
The floor - supinator and brachialis
The roof - deep fascia with median cubital vein and median cutaneous nerve on top
What are the contents of the ACF?
Median, radial and posterior interosseous nerves, the brachial artery (dividing into radial and ulnar arteries) and the biceps tendon.
What is the path of the radial nerve through the antecubital fossa?
- descends in the upper arm, lying between the medial and long heads of the triceps
- enters the ACF between the lateral epicondyle of the humerus and the musculospiral groove
- runs lateral to biceps and under brachioradialis
- then divides into superficial and deep branches
Where does the ulnar nerve traverse the elbow joint?
Ulnar nerve arises medial to axillary artery.
Continues medial to brachial artery, lying on corachobrachialis, to the midpoint of humerus
Here it leaves the anterior compartment by passing posteriorly through medial intermuscular septum.
It lies between the intermuscular septum and the medial head of triceps, passing posterior to the medial humeral epicondyle, and enters the forearm between the 2 heads of flexor carpi ulnaris.
What nerves are you targeting in an ankle block?
4 cutaneous branches of the sciatic nerve:
- posterior tibial
- sural
- deep peroneal
- superficial peroneal
- also one cutaneous branch of the femoral nerve - saphenous nerve
From which spinal nerve do the nerves blocked by an ankle block originate?
Posterior tibial = L5-S3
Sural = L5 - S2
Deep peroneal = L4 - S2
Superficial peroneal = L4 - S2
Saphenous = L3 - L4
Where on a foot do you put local anaesthetic for an ankle block?
What are the indications for an ankle block?
Any foot or toe surgery
What local anaesthetic mixtures can you use for an ankle block?
2% lignocaine
- 5% bupivicaine
- 5% ropivicaine
(speed of onset + duration dictate choice)
Why is adrenaline in an ankle block contraindicated?
Due to the risk of peripheral ischaemia (same as hand blocks)
Label this diagram of the Circle of Willis
- Anterior cerebral artery
- Opthalmic artery
- Superior cerebellar artery
- Basilar artery
- Vertebral artery
- Anterior spinal artery
- Pontine arteries
- Posterior communicating artery
- Internal carotid artery
- Middle cerebral artery
- Anterior communicating artery
Which arteries supply the Circle of Willis?
The internal carotids and both vertebral arteries (which form the basilar artery)
Where do the arteries supplying the Circle of Willis enter the skull?
Internal carotids enter via the carotid canal while the vertebral arteries enter through the foramen magnum
What is normal cerebral blood flow?
15% of cardiac output = 750 ml/min
(50ml/100g/min)
How does blood flow to the grey and white matter differ?
Grey has a higher proportion of blood flow to white (70ml/100g/min vs 20ml/100g/min)
What factors affect cerebral blood flow?
- MAP
- arterial PO2
- arterial PCO2
- cerebral metabolic rate
- body temp
- anaesthetic agents - volatiles, ketamine, propofol
Describe the production and circulation of CSF
- 150ml of CSF which is constantly circulating from brain to spinal cord
- produced in choroid plexuses of lateral, 3rd + 4th ventricles at a rate of 500ml/24hrs
- passes from lateral ventricle to third ventricle via foramen of Munro
- from 3rd-4th ventricle via Sylvian aqueduct
- leaves 4th ventricle through foramina of Luschka laterally
- foramen Magendie medially
- absorbed by arachnoid villi in brain and in spinal arachnoid villi
Label the canals/foramina of the Base of Skull and state which nerves pass through them.
- Optic canal
- optic nerve (II), opthalmic artery, sympathetic nerves
- Cribiform plate
- olfactory nerve (I)
- Foramen rotundum
- maxillary division of trigeminal nerve (V)
- Foramen ovale
- mandibular branch of trigeminal nerve (V), accessory meningeal artery
- Foramen spinosum
- middle meningeal vessels, meningeal branch of mandibular nerve
- Internal auditory meatus
- facial nerve (VII), vestibulocochlear nerve (VIII)
- Hypoglossal canal
- hypoglossal nerve (XII)
- Foramen magnum
- medulla oblongata, vertebral arteries, spinal arteries
What are the branches of the trigeminal nerve and what do they do?
- provides sensory to the face and scalp through three branches
- opthalmic
- maxillary
- mandibular
- opthalmic branch leaves trigeminal ganglion and travels through superior orbital fissure
- provides sensory branches (lacrimal frontal and nasociliary) to supply sensation to anterior aspect of the scalp and superior parts of face incl. cornea
- maxillary branch passes through foramen rotundum and supplies sensation to mid-face
- mandibular branch - mixed sensory/motor, exits skull via foramen ovale
- sensory innervation to mandibular area, up to temporomandibular joint and temple, anterior 2/3rds of tongue
- motor supply to masseter, temporalis, pterygoid muscles
How do you test the trigeminal nerve?
- test for light touch, pinprick and temperature in the 3 separate distributions
- test the corneal reflex
- ask the patient to clench their jaw and palpate masseter and temporalis muscles for volume and tone
- open mouth and observe for mandibular deviation
- test lateral jaw movement against resistance
What are the functions of cranial nerve VII?
Facial Nerve.
Exits the skull via the internal auditory meatus along with vestibulocochlear nerve (VIII).
Motor
- most facial muscles
- frontalis, orbicularis oculi, orbicularis oris, platysma, stapedius
- allows blinking, frowning, smiling
Sensory
- taste to anterior 2/3 tongue
- secretory function to lacrimal gland, nose and mouth, submandibular and sublingual salivary glands
What are the structures 1-4?
- Central tendon of diaphragm
- Inferior vena cava hiatus
- Aorta/aortic hiatus
- Oesophagus/oesophageal hiatus
At what levels are the 3 diaphragmatic foramina?
T8 - inferior vena cava
T10 - oesophagus
T12 - aorta
What do each of the 3 diaphragmatic foramina transmit?
IVC hiatus
- IVC
- phrenic nerve (right)
Oesophageal
- oesophagus
- left gastric vessels
- vagus nerve
Aortic hiatus
- aorta
- azygos vein
- thoracic duct
What is the function of the diaphragm?
Principle muscle of respiration and separates abdominal cavity from thorax
What is the diaphragm composed of?
Sheet of skeletal muscle composed of central tendinous part and peripheral muscular part
What are the attachments of the diaphragm?
Sheet of skeletal muscle composed of a central tendinous part and peripheral muscular part
What are the diaphragms attachments?
Central tendon
- pericardium superiorly
Muscular part
- attached posteriorly to psoas muscle and quadratus lumborum via arcuate ligaments
- medially to xiphisternum
- anteriorly to costal cartilages of lower 6 ribs
What is the nerve supply to the diaphragm?
Phrenic nerve (C3,4,5)
What is a Bochdalek hernia?
Congenital diaphragmatic hernia.
Disruption of diaphragm during fetal development allows abdominal viscera to push into thoracic cavity.
Can cause pulmonary HTN and hypoplastic lungs, resulting in resp distress of newborn.
Carries mortality of 35-60%
Label 1-7
- Left common carotid artery
- Left subclavian artery
- Left coronary artery
- Right coronary artery
- Brachiocephalic trunk
- Right subclavian artery
- Right common carotid artery
Name vessels 1 - 5.
- Left coronary artery (main stem)
- Circumflex artery
- Right coronary artery
- Left interventricular (anterior descending) branch
- Right marginal branch
What is the venous drainage of the heart?
Via the coronary sinus.
It’s the main vein of the myocardium running left to right in the posterior aspect of the coronary groove.
It recieves blood from the great, middle and small cardiac veins as well as the left marginal and posterior ventricular veins.
A smaller percentage (20-30%) occurs via the anterior cardiac and thebesian veins, which drain directly into the right atrium
Where do the left and right coronary arteries arise from?
The left arises from the left posterior aortic sinus while the right arises from the anterior aortic sinus
What is the innervation of the heart?
Via the autonomic nervous system from superficial and deep cardiac plexuses.
The sympathetic supply is from presynaptic fibres of T1-5 and postsynaptic fibres from cervical sympathetic chain ganglia.
The parasympathetic supply is derived from the vagus nerve.
What signs and symptoms might arise from reduced blood flow to the right coronary artery?
RCA supplies the RA and RV as well as some posterior wall of LV and anterior 2/3rds of interventricular septum.
Also supplies much of the conducting system of the heart.
Ischaemia in this will result in either nothing to general malaise, sweating, fatigue, SOB, chest pain.
Signs - anxiety, tachycardia, arrhythmias, hypotension, pulmonary oedema and tachypneoa.
Label structures 1 - 6.
- Lateral corticospinal tract
- Vestibulospinal tract
- Fasciculus cuneatus
- Posterior spinocerebellar tract
- Lateral spinothalamic tract
- Anterior spinothalamic tract
What are the functions of the spinothalamic tracts?
Anterior spinothalamic
- ascending pathway that transmits contralateral sensations of touch and pressure
Lateral spinothalamic
- ascending pathway that transmits contralateral sensations of pain and temperature
What is the blood supply to the spinal cord?
Anterior spinal artery
- lies on anterior median fissure and recieves it’s supply from the vertebral arteries at the foramen magnum, supplies anterior part of cord
Posterior spinal artery
- formed from the posterior cerebellar arteries
- supplies posterior cord and tends to be smaller than anterior
Other spinal arteries - radicular arteries
- branches of vertebral, intercostal, lumbar or sacral arteries
Why is the spinal cord vulnerable to ischaemia from disruption to anterior or posterior spinal arteries?
Because there are no anastomoses between the blood supply
What is the artery of Adamkiewicz?
Also known as the arteria radicularis magna is one of the radicular arteries arising from the lower thoracic region. It is of importance because it has a major role in the blood supply to the lower half of the spinal cord.
What is the venous drainage of the spinal cord?
Via lateral, anterior and posterior venous plexuses.
They unite to drain into larger regional vessels such as the azygos vein, vertebral, lumbar and sacral veins.
What is anterior spinal artery syndrome?
Results from infarction or ischaemia of the anterior spinal artery.
It presents with paralysis and loss of pain and temperature sensation below the level of the insult. Proprioception is usually preserved.
How many pairs of spinal nerves are there?
31 pairs
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
What are the anterior primary rami?
Give cutaneous and motor supply to the limbs and the anterior
and lateral parts of the neck, thorax and abdomen.
What do the posterior primary rami do?
The posterior primary rami give sensory and motor supply to the muscles and skin of the back.
What are the features of spinal shock?
Presents with loss of sensory and motor function below the level of the lesion.
May be accompanied by:
- hypotension
- bradycardia
Initial period of hyporeflexia. Then some reflexes return over the next week or so with a period of hyperreflexia appearing within 4-6 weeks.
After 6 weeks there can be hyperreflexia and spasticity as well as autonomic dysfunction.
What is autonomic dysreflexia?
Usually associated with spinal cord injury above T6 level.
Can result in extreme hypertension, compensatory bradycardia, flushing, sweating and headaches.
Often triggered by painful stimuli below level of cord lesion.
What does the cribiform plate transmit?
- olfactory nerve
- covered by mininges containing CSF
- anterior + posterior ethmoidal arteries and nerves
What does the optic canal transmit?
- optic nerve passing to the superior orbital foramen
- opthalmic artery
- meninges
What goes through the foramen spinosum?
- Middle meningeal artery
- Meningeal branch of mandibular nerve
- Zygomatic branch of facial nerve
What goes through the foramen ovale?
- mandibular branch of trigeminal nerve
- accessory meningeal artery
What goes through the foramen rotundum?
Maxillary branch of trigeminal nerve
What goes through the foramen lacerum?
Internal carotid artery pierces the posterior wall and ascends in it’s upper part
What is contained in the jugular foramen?
- inferior petrosal sinus
- glossopharyngeal nerve IX, vagus nerve X, accessory nerve XI
- sigmoid sinus, continuous with the internal jugular vein
What goes through the hypoglossal canal?
Hypoglossal nerve
What goes through the foramen magnum?
Spinal cord, lower part of medulla
Spinal artery
Vertebral artery
What goes through the carotid canal?
Internal carotid artery
What goes through the stylomastoid foramen?
Facial nerve
Stylomastoid branch of posterior auricular artery
What goes through the internal auditory meatus?
Facial nerve, motor and sensory
Vestibulocochlear nerve
Labyrinthine vessels
Label this spinal cord
A. Lateral corticospinal tract
B. Anterior corticospinal tract
C. Tectospinal tract
D. Fasciculus gracilis
E. Fasciculus cuneatus
F. posterior spinocerebellar tract
G. Anterior spinotcerebellar tract
H. Lateral spinothalamic tract
I. Anterior spinothalamic tract
What is the length of the spinal cord?
45cm
What is grey matter in the spinal cord?
Occupies the central H area. Made of nerve cells.
Divided into:
- 2 posterior horns carrying posterior columns, sensory fibres from the posterior roots
- 2 anterior horns carrying anterior columns, motor cells, which leave in the ventral roots
- in the thoracic region there are 2 lateral horns carrying sympathetic nerves
What is the white matter in the spinal cord?
Composed of medullated nerve cells in the longitudinal orientation. Divided into 3 columns. Posterior, anterior and lateral.
Posterior columns
- 2 ascending tracts - fasciculus gracilis and fasciculus cuneatus run to the medulla, synapses cross to the thalamus, then to sensory cortex
- transmits fine touch + proprioception
Lateral columns
- ascending - lateral spinothalamic tract
- transmits pain and temperature
Anterior columns
- 2 ascending tracts
- anterior and posterior spinocerebellar tracts
- transmit proprioception from muscle and joint
- anterior spinothalamic tract
- transmits light touch and pressure
- descending tracts
- pyramidal tract is major motor pathway
- corticospinal tracts
- lateral + anterior corticospinal
- reticulospinal tract
- tectospinal tract
- rubrospinal tract
- vestibulospinal tract
Label this brachial plexus
A. Ulnar
B. Radial
C. Musculocutaneous
D. Lateral cord
E. Medial cutaneous nerve of the forearm
F. Median nerve
G. Medial cutaneous nerve of the arm
What is the brachial plexus formed from?
Union of the anterior primary rami of the lower 4 cervical nerves and the anterior primary rami of the first thoracic nerve (C5 - T1)
Where do the nerve roots for the brachial plexus emerge from?
Intervertebral foramina
What roots form the upper trunk of the brachial plexus?
C5 and 6
What is the root which forms the middle trunk?
C7
What nerve roots form the lower trunk of the brachial plexus?
C8 and T1 nerve roots
What lies in the posterior triangle of the neck?
The roots and trunks of the brachial plexus.
Covered by skin, patysma and deep fascia.
Superficially the plexus is crossed by the external jugular vein and the supraclavicular nerves.
Where do the trunks of the brachial plexus emerge from?
The space between the scalenus anterior and scalenus medius muscles. The space becomes wider in the anteroposterior plane as the muscles approach their insertion on the 1st rib.
Where does the brachial plexus leave the next?
Crossing the clavicle near it’s midpoint.
What are the indications for a supraclavicular brachial plexus block?
As a sole anaesthetic or a supplement to GA for surgeries in the shoulder, arm and forearm.
Where is the insertion point for a supraclavicular block?
1cm above the midclavicular point, lateral to the insertion of the clavicular head of sternocleidomastoid and lateral to subclavian artery pulsation.
What are CI to a supraclavicular block?
- short stiff neck
- large goitre
- previous radiotherapy to neck
- recurrent laryngeal nerve palsy
- pneumothorax on other side
What does stimulation of the radial nerve (C7, 8) do?
Elicits extension of elbow, wrist and finger
What does stimulation of the ulnar nerve (C8, T1) do?
Elicits wrist flexion and medial deviation
What does stimulation of the median nerve (C5-8) do?
Elicits wrist flexion, finger flexion and thumb opposition
What are the landmarks for an interscalene block?
Posterior triangle, posterior to sternomastoid.
Transverse processes, particularly C6 at the level of the cricoid cartilage.
What are the landmarks for a supraclavicular block?
Posterior to the subclavian artery as it passes over the clavicle.
What are the landmarks for an axillary block?
Palpate the axillary artery as high as possible in the axilla between corachobrachialis and teres minor.
In an axillary block, which arm nerves can be missed?
Intercostobrachial nerve supplying the superior and medial surface of the arm, musculocutaneous nerve supplying the radial side of the forearm.
Which 2 major branches of the plexus are blocked by the axillary approach?
Median and ulnar nerves
What problems can arise from an axillary block?
- miss the circumflex, radial and muscular cutaneous nerve of forearm, leaves sensation on radial side of forearm
- miss intercostal brachial nerve, sensation on superior and medial arm
- complications - haematoma, IV injection, failure due to injection outside the sheath
What are the problems and complications of an interscalene block?
Problems: failure to block C8/T1 the hand and superior/medial upper arm.
Complications
- epidural, spinal, IV - vertebral artery injection
- phrenic nerve block
- recurrent laryngeal nerve
- Horner’s syndrome
- pneumothorax
What complications can arise from a supraclavicular block?
- IV injection and CNS/CVS effects
- pneumothorax
- stellate ganglion block
- Horner’s syndrome
- phrenic nerve block
- back tracking of LA to epidural space
What is the maximum dose of lidocaine?
3mg/kg without adrenaline
6mg/kg with adrenaline
What is the max dose of bupivicaine?
2mg/kg/4hrs
What is the max dose of prilocaine?
6mg/kg plain
9mg/kg with adrenaline
