Session 1 - General Organisation of the Head and Neck Flashcards
General muscles of the head (2 groups)
Muscles for facial expression
Muscles of mastication
Nerve supplying the muscles of facial expression
Facial nerve (Cranial nerve VII)
Nerve supplying the muscles of mastication
The mandibular branch of the trigeminal nerve (Cranial nerve V)
Which joint does the muscles of mastication act upon?
The temporomandibularjoint
What are the five key cranial branches of the facial nerve?
Two Zanzibar Buy Motor Car
Temporal branch Zygomatic branch Buccal branch Mandibular branch Cervical branch
What facial component does the facial nerve branches have an important relationship with?
The parotid gland. They all pierce it so if there is a problem with the parotid gland that can cause facial nerve weakness.
What does the trigeminal nerve do?
Supplies sensory to the face + supply motor function to muscles of mastications.
What are the branches of the trigeminal nerve?
Ophthalmic branch (Va) Maxillary branch (Vb) Mandibular branch (Vc)
Which of the trigeminal branches supply motor function?
Mandibular branch (Vc)
What is the main arterial supply of the head and neck?
What are it’s branches?
Common carotid artery
And its branches:
Internal carotid artery and external carotid artery
What is the main vein draining the head and neck?
Internal jugular vein (important for jugular venous pressure)
Most important muscles of the neck
Trapezius Sternomastocleido Platysma Suprahyoid muscles Infrahyoid muscles Scalene muscles
Innervation of platysma
Cervical branch of the facial nerve (CN VII)
Innervation of trapezius
Accessory nerve (CN XI)
Innervation of sternocleidomastoid
Accessory nerve (CN XI)
Anatomical borders of the anterior triangle of the neck
Midline of the neck
Inferior margin of the mandibular
Anterior margin of the sternocleidomastoid
Anatomical borders of the posterior triangle of the neck
(Anterior) Posterior border of the sternocleidomastoid
(Posterior) Anterior border of the trapezius
(Inferior) Clavicle
(Floor) Scalene muscles
Most important muscle of the suprahyoids?
Action of the suprahyoids.
Innervation of the suprahyoids.
Digastric (posterior and anterior belly) muscle
Elevates the hyoid bone and depresses the mandible
Cranial nerves (will suffice for now)
Most important muscle of the infrahyoids?
Action of the infrahyoids
Innervation of the infrahyoids
Omohyoid muscle (strap muscles) (inferior and superior bellies)
Depress and stabilise the hyoid bone
Innervated by the cervical nerves (C1-C3)
Anatomical borders of the carotid triangle.
Sternocleidomastoid
Superior belly of omohyoid
Posterior belly of digastric
What are the pros of the fascial compartments of the neck?
Form natural planes
Ease of movement between the compartments like when swallowing
Can restrict infection spreading
What are cons of fascial compartments of the neck?
Can also permit spread of infection
What is the space called that allows spread of infection?
Retropharyngeal space
How does the retropharyngeal space allow spread of infection?
It can cause infection to go superior to oropharynx etc.
Also can cause infection to spread inferiorly to the thorax and cause mediastinum
What are the two main groups of cervical fascia?
Deep and superficial fascia
What are the 4 types (sometimes 5) deep cervical fascia?
Investing layer Pretracheal layer Prevertebral layer Carotid sheath And sometimes also included the buccopharyngeal layer
What does the investing layer enclose?
It splits to enclose the sternocleidomastoids, the trapezius, the submandibular and the parotid salivary glands.
What is the pretracheal layer attached to?
To the hyoid bone and descends inferiorly to extend into the thorax and blend with the fibrous pericardium.
The pretracheal layer has two sub layers, which?
A muscular layer and a visceral layer
What does each layer enclose?
Muscular = infrahyoid
Visceral = thyroid gland, oesophagus and trachea
The pretracheal layer then runs posteriorly to form what?
The buccopharyngeal fascia.
It is associated with the pharynx and the oesophagus and runs from base of the skull to the diaphragm.
Three main components that the carotid sheath encloses.
Common carotid artery
Internal jugular vein
Vague nerve (CN X)
What are the most common infective sources of the deep space neck infections?
Spread from teeth, pharynx, middle ear or sinuses.
Between which layers of fascia can you find the retropharyngeal space?
Between the buccopharyngeal fascia and the prevertebral fascia
Up until 3-4 years of age what does the retropharyngeal space mostly consist of?
Lymph nodes which drain most of the nose, oral cavity and upper pharynx.
Symptoms of retropharyngeal abscess.
Visible bulge on inspection of the oropharynx Sore throat Difficulty swallowing Stridor Reluctance to move ones neck Fever
What would a lump which moves upon swallowing tell you?
That there is either a thyroglossal duct cyst (congenital and usually appear early on in life)
Or a tumour/pathology of the thyroid gland.
Why would the thyroid gland move up on swallowing?
Because it is enclosed in the pretracheal faschia. The pretracheal fascia also encloses the hyoid bone which moves up on swallowing.
This means that the thyroid gland will move as well as it is enclosed in the same fascial layer.
How can an enlarged thyroid gland sometimes extend?
Retrosternally through the root of the neck.
This is because the lower limit of the pretracheal fascia extends into the thorax.
Symptoms of retrosternally extended thyroid gland swelling (goitre).
Breathlessness Stridor Facial oedema (due to compressed venous drainage)
What will injury of pathology of the facial nerve on an ipsilateral side cause?
That side of the face to ‘droop’.
What is the most common non-traumatic facial paralysis of the facial nerve?
Inflammation of the facial nerve also called Bell’s palsy.
If there is ipsilateral facial droop associated with ipsilateral parotid enlargement, what is this an indication of?
Parotid cancer. Very rare to be a benign tumour.
What are the muscles of mastication?
Temporalis
Masseter
Medial pterygoid
Lateral pterygoid
Action of the muscles of mastication.
Temporalis, masseter and medial pterygoid clench the jaw (elevated the mandible).
Lateral pterygoid opens the jaw (Laaaaaaa-lateral (onomatopoeitic))
How can the muscles of mastication be palpated?
Masseter by feeling the corner of your jaw as you clench your teeth.
Temporalis by feeling over the area of your temples as you clench your jaw.
Pterygoids are not palpable.
Origin of the pterygoids.
Pterygoid plates at the base of the skull.
Which muscles collectively depress the mandible?
The infrahyoids like omohyoid, the lateral pterygoid and also gravity.
Critical structures passing between the scalenes.
Brachial plexus
Subclavian vessels
Subclavian artery (anterior and middle scalenes)
Phrenic nerve
Muscles of facial expression.
Orbicularis oris Orbicularis oculi (Orbital and palpebral) Occipitofrontalis Temporalis Masseter Buccinator Zygomatics Risorius
What are the muscles of facial expression innervated by? (Some exceptions from the flashcard before)
The facial nerve (CN VII)
Some by mandibular branch of the trigeminal nerve.
Action and innervation of orbicularis oris.
Purses/pouts lips
Buccal branch of CN VII
Action and innervation of orbicularis oculi both orbital and palpebral.
Orbital: Forcefully shuts eyes
Palpebral: closes the eyes gently like blinking.
Temporal branch of CN VII
Action and innervation of occipitofrontalis.
Elevates eyebrows and wrinkles the forehead.
Facial nerve (possibly temporal branch)
Action and innervation of temporalis.
Elevates the mandible and retracts the jaw.
Innervated by the mandibular branch of the trigeminal nerve (CN V)
Action and innervation of masseter.
Main elevator of the mandible.
Innervated by the mandibular branch of the trigeminal nerve (CN V)
Action and innervation of zygomaticus major and minor.
Draws the angles of the mouth lateral and superiorly.
It makes you smile when your mouth is open.
Major: zygomatic and buccal branches of the facial nerve (CN VII)
Minor: buccal branch of the facial nerve (CN VII)
Action and innervation of risorius.
Pulls corner of mouth laterally.
Smile with a closed mouth.
Innervated by the buccal branch of the facial nerve (CN VII)
Action and innervation of buccinator.
Compresses cheeks against the teeth when masticating.
Trumpeters used them to blow up cheeks.
Innervated by the buccal branch of the facial nerve (CN VII)
Patient with Bell’s palsy. Why is the patient still able to open and close her jaw as normal?
Because the trigeminal nerve is intact which is the main nerve innervating muscles of mastication.
Which nerve is affected in Bell’s palsy?
Facial nerve (CN VII)
