Head and Neck Practical 1 Flashcards
Describe course of external jugular vein
Formed just inferior to ear, makes it way across angle of mandible and passes superficially across sternocleidomastoid muscle, passes through posterior triangle of neck and drains into subclavian vein
At what vertebral level do we find the hyoid bone?
C3
At what vertebral level do we find the thyroid cartilage?
C4-C5
At what vertebral level do we find the cricoid cartilage?
C6
At what vertebral level do we find the bifurcation of the common carotid artery?
C3-C4
What is this bone?
Mandible
What is this bone?
Hyoid
What is this?
Thyroid cartilage (esp. laryngeal prominence/Adam’s apple)
What area is being pointed to?
Anterior triangle of neck
What area is being pointed to?
Posterior triangle of neck
What muscle is being pointed to?
Sternocleidomastoid muscle - forming division between anterior and posterior triangle
What is the base/superior border of the anterior triangle?
The inferior border of the mandible
What is the anterior border of the anterior triangle?
Midline of neck
What is the posterior border of the anterior triangle?
Anterior border of sternocleidomastoid muscle
Contents of anterior triangle?
- Suprahyoid muscles
- Infrahyoid muscles
- All of these are in anterior triangle except the inferior belly of omohyoid which is found in the posterior triangle
- Common carotid artery
- Internal jugular vein
- Lobes of thyroid gland (deep to infrahyoid muscles)
What is being pointed to?
Inferior belly of omohyoid
What vessel is being pointed to?
Common carotid artery
What vessel is being pointed to?
Internal jugular vein (deep to SCM)
What is being pointed to?
SCM
What forms base of posterior triangle?
Clavicle
What forms anterior boundary of posterior triangle?
Posterior aspect of SCM
What forms posterior boundary of posterior triangle?
Anterior border of trapezius muscle
Contents of posterior triangle?
- Inferior belly of omohyoid
- Trunks of brachial plexus
- Accessory nerve (CN XI)
- Apex of lung
- External jugular vein
What is being pointed to?
A trunk of brachial plexus
What nerve is this?
- accessory nerve (CN XI)
- Pierces SCM as well as the trapezius (innervating both)
What does accessory nerve (CN XI) innervate?
Sternocleidomastoid and trapezius
Part 1:
- Stab wound to right side of neck
- Presents with pain and paresthesia down lateral aspect of right arm
- Difficulty abducting arm
- 4cm wound in right posterior triangle in neck
What structures would you be worried about?
Part 2:
- Plain chest radiograph excluded a pneumothorax
- No elevation of right hemidiaphragm to suggest phrenic nerve injury
- No evidence of spinal cord injury
- Neurological examination of lower limbs was normal
- Peripheral pulses normal in limb and no significant haematoma in neck
- Examination of upper limb revealed light touch sensation was reduced in C5 and C6 dermatomes
- Unable to initiate abduction of shoulder
- Only able to abduct arm when gravity was eliminated
Part 1:
- Contents of posterior triangle e.g:
- Apex of lung
- Trunks of brachial plexus
- Accessory nerve
Part 2:
- Can rule out injury to apex of lung (as no pneumothorax)
- Can rule out injury to spinal cord
- Can rule out injury to blood vessels
- Sensory findings + inability to initiate abduction of shoulder –> implies injury to nerve supplying supraspinatus
- Abduction of arm usually controlled by C5 myotome
- C5 and C6 spinal roots combine to form superior trunk of brachial plexus (found in posterior triangle of neck)
- C5 and C6 fibres combine to form suprascapular nerve which innervates supraspinatus which is responsible for initiating abduction
- Some fibres also contribute to axillary nerve (again reudcing ability to abduct)
What is the ansa cervicalis? What does it innervate?
A loop of nerves that are part of the cervical plexus, formed from contributions from C1, C2 and C3 spinal nerve roots. Innervates:
- sternohyoid
- sternothyroid
- omohyoid muscles (superior and inferior belly)
The only infrahyoid muscle it does not innervate is the thyrohyoid muscle.
What innervates thyrohyoid?
C1 nerve through a branch of the hypoglossal nerve
Where are the infrahyoid muscles located?
Inferior to the hyoid bone
What can the infrahyoid muscles be split into?
2 superficial muscles and 2 deep muscles
What muscle is this?
Omohyoid (has 2 bellies - superior and inferior)
Attachments of inferior belly of omohyoid?
- Arises from scapula
- It is attached to the superior belly by an intermediate tendon, which is anchored to the clavicle by the deep cervical fascia.
Attachments of superior belly of omohyoid?
- the superior belly ascends to attach to the hyoid bone.
What are the superficial infrahyoid muscles?
Omohyoid and sternohyoid
Attachments of sternohyoid?
- Originates from the sternum and sternoclavicular joint.
- It ascends to insert onto the hyoid bone.
What muscle is this (sternohyoid has been reflected)? What are its attachments?
Sternothyroid
- Arises from the manubrium of the sternum
- attaches to the thyroid cartilage.
What muscle is this? What are its attachments?
Thyrohyoid
- Arises from the thyroid cartilage of the larynx
- ascends to attach to the hyoid bone
What are the deeper infrahyoid muscles?
- Thyrohyoid
- Sternothyroid
What are the innervations of the 4 infrahyoid muscles?
- Omohyoid, sternohyoid and sternothyroid –> Anterior rami of C1-C3, carried by a branch of the ansa cervicalis.
- Thyrohyoid –> Anterior ramus of C1, carried within the hypoglossal nerve.
As a group, what is the action of the infrahyoids?
Contract and depress the hyoid bone (bring it down)
Where are the suprahyoid muscles found?
Above the hyoid bone
Anterior view of suprahyoid muscles
What is this muscle?
Mylohyoid - fibres run horizontally
Which muscle forms the floor of the mouth?
Mylohyoid
What is this muscle?
Digastric (anterior belly) - one on each side
Attachments of anterior and posterior belly of digastric?
- The anterior belly arises from the digastric fossa of the mandible.
- The posterior belly arises from the mastoid process of the temporal bone.
- The two bellies are connected by an intermediate tendon, which is attached to the hyoid bone via a fibrous sling.
What is the attachment point between the 2 bellies of digastric?
Hyoid bone
What muscle is this?
Posterior belly of digastric
what slight depression is being pointed to? which suprahyoid muscle inserts here?
Diagastric fossa (one on each side) - anterior belly of diagstric inserts here
What is being pointed to? What suprahyoid inserts here?
internal surface of mastoid process of temporal bone - posterior belly of diagstric inserts here (one each side)
Innervation of anterior belly of digastric?
Mandibular branch of trigeminal nerve (CN V3)
Innervation of posterior belly of digastric?
Branch of our facial nerve (CN VII)
Functions of suprahyoid muscles?
- Elevate hyoid
- Diagstric muscle has additional function –> to lower the mandible on a fixed hyoid
- 2 bellies 2 functions
Digastric view
What passes through the jugular foramen?
- Internal jugular vein
- Vagus nerve (CN X)
- Glossopharyngeal nerve (CN IX)
- Accessory nerve (CN XI)
Is the vagus nerve contained in the carotid sheath?
Yes
Does the left vagus give rise to the recurrent laryngeal in the neck?
No - gives rise in the thorax (only right gives rise in the neck)
Does the vagus nerve convey touch sensation from the laryngopharynx?
True (motor and sensory supply to pharynx and larynx)
What is this vessel? What is it contained in?
Common carotid artery - contained in carotid sheath
What is this nerve? Location related to common carotid artery?
Vagus nerve - found lateral to common carotid artery
What vessel is this? Located related to common carotid artery and vagus nerve?
Internal jugular vein - lateral to both common carotid artery and vagus nerve (also deep to SCM)
Order of contents of carotid sheath?
- Common carotid artery (most medial)
- Vagus nerve (middle)
- Internal jugular vein (lateral)
What is the carotid sheath?
Layer of fascia
What does the common carotid artery bifurcate into?
Internal and external carotid arteries
What does the internal carotid artery supply?
Gives off no branches in neck, instead supplies brain
What does the external carotid artery supply?
Gives off branches in neck and face
What does internal jugular vein drain?
Skull, brain, face
What area is there? Where does it go from/to?
nasopharynx (posterior to nasal cavity) - from nasal cavity to tip of soft palate
View of tip of soft palate
What area is this? Where does it go from/to?
Oropharynx (posterior to oral cavity) - From soft palate to epiglottis
What space is this? Where does it go from/to?
Laryngopharynx (found posterior to larynx) -from epiglottis to oesophagus
Order of swallowing
- Chewing bolus of food in oral cavity –> voluntary movement controlled by muscles of mastication
- Tip of soft palate flips up to close the nasopharynx
- Bolus of food makes way down oropharynx
- Before it gets to laryngopharynx, the epiglottis will flip down to close the larynx
- Therefore, bolus of food is pushed by constrictor muscles of phraynx until it arrives at the oesphagus
The pharynx receives innervation from which cranial nerves?
- CN IX glossopharyngeal (sensory and motor branches)
- CN X vagus nerve (sensory and motor branches)
What does the pharyngeal plexus consist of?
Pharyngeal branches from the glossopharyngeal nerve (CN IX). Pharyngeal branch of the vagus nerve (CN X).
What is this? (directly posterior to laryngeal prominence)
Vocals cords/folds
What is this?
Epiglottis
What is this?
Trachea
What is this superior C shaped bone? (this is model of larynx) What vertebral level is it at?
Hyoid bone at level of C3
What is this she’s pointing at? What verebral level?
Thyroid cartilage - C4 and C5
What can be noticed about the thyroid cartilage when viewing from the back?
Is not closed at the back (not a complete ring) - C shaped
What cartilage is this? What is its shape?
Cricoid cartilage - does form complete ring
What is the arytenoid cartilage? Where is it found?
either of a pair of cartilages at the back of the larynx, used in the production of different kinds of voice quality
What is being pointed to?
Vocal cords (have muscles attached to them)
How are the vocal cords moved?
Muscles of larynx (contract and move vocal cords) to allow opening and closing
Another view of vocal cords
What is found between cricoid and thyroid cartilage?
Cricothyroid membrane
Surface anatomy of cricothyroid membrane
Aside from the cricothyroid membrane, where else can an emergency airway be established?
In trachea itself (tracheostomy) - this is more invasive and requires general anaesthetics
What is being pointed to?
Thyroid gland (butterfly shape) that sits anterior to larynx and deep to infrahyoid muscles
Describe structure of thyroid gland
- 2 lobes (right and left)
- Isthmus (in middle connecting 2 lobes)
Location of isthmus of thyroid gland?
Just below cricoid cartilage, spanning the first few rings of the trachea
Where can the thyroid gland be palpated?
- Put fingers just lateral to larynx, below cricoid cartilage
- Ask patient to swallow which causes thyroid gland to move up and down with the larynx
Arterial supply of thyroid gland?
- Superior thyroid artery - arising from the external carotid artery
- Inferior thyroid artery (ITA) branching from the thyrocervical trunk which branches from the subclavian artery
What is being pointed to?
The superior thyroid artery (one on each side)
What is being pointed to?
Inferior thyroid artery (one on each side)
What nerve is this?
Vagus nerve
On the right side, what does the vagus nerve give rise to in the neck?
Right recurrent laryngeal (given off at the level of the subclavian)
Where does the right recurrent laryngeal travel to? What does it innervate?
ascends back to larynx to provide sensory innervation just below the vocal cords and motor innervation to muscles of the vocal cords
Describe path of left recurrent laryngeal nerve
Arises in thorax and hooks around arch of aorta (not subclavian)
How do the recurrent laryngeal nerves pass in relation to the thyroid gland?
Pass posterior to the thyroid gland
What is important during thyroid gland surgeries ?
Careful not to damage the recurrent laryngeal nerve or any of the vessels that supply the thyroid gland
Does sensation from the larynx above the vocal cords travel in the internal laryngeal nerve?
True
The superior laryngeal nerve also arises in the neck. What does this split into? What does each branch innervate?
Splits into internal and external branches. The external laryngeal nerve innervates the cricothyroid muscle of the larynx. The internal laryngeal provides sensory innervation to the laryngopharynx and superior part of the larynx.
At what level tracheal rings is the thyroid isthmus?
At the level of the 2nd and 3rd tracheal rings (just below cricoid cartilage)
Is the thyroid gland closely related to both recurrent laryngeal nerves?
Yes
Position of vocal cords during breathing?
Open
Position of vocal cords during swallowing?
Closed (adducted)
Position of vocal cords during phonation?
Half open half closed –> allows vibration and controls pitch
Patient presents with:
- Weight loss, anxiety and tremor
- Exophthalmos (protruding eyes)
1) What is diagnosis?
2) How should thryoid gland be examined?
1) Thyrotoxicosis (overactive thyroid gland)
2) Stand behind sitting patient and feel neck just below laryngeal prominence. Ask patient to swallow.
Following thyroid surgery, what is most common cause of a husky voice? What other nearby structures are liable to damage?
a) damage to recurrent laryngeal nerve
b) thyroid arteries
