General Organisation of Head and Neck Flashcards
What does the head consist of?
- Scalp
- Skull
- Brain and its coverings (meninges)
- Special sense organs
- Muscles
- Cranial nerves and their branches
- Glands
- Blood vessels
- Lymphatics
What is true of many of the structures of the head?
They also run through the neck
What are the structure of the head that run through the neck in close relationship with?
- Thyroid gland
- Pharynx
- Larynx
- Trachea
- Oesophagus
- Cervical vertebrae
Where does the neck extend?
- Between the lower margin of the mandible superiorly
- To suprasternal notch of manubrium and upper border of clavicle inferiorly
What is the necks overall function?
Connects head to rest of body
What happens to structures in the neck?
They are compartmentalised by concentric fascial layers creating compartments running through the neck
What are the functions of the fascial planes of the neck?
- Form natural planes
- Ease of movements between structures
- Contains spread of infection
When is ease of movement between structures in the neck important?
During swallowing
Give an example of where fascial planes of the neck contain the spread of infection
Superficial skin infection in skin of neck cannot track deeper
What are the layers of fascial planes of neck?
- Superficial fascial layer
- Three deep cervical fascial layers
Where is the superficial fascial layer found?
Just below the skin
What is the superficial fascial layer made up of?
Largely fatty tissue, with;
- External jugular vein
- Cutaneous nerves
- Superficial lymph nodes
- Platysma muscle
What are the deep cervical fascial layers named according to?
What they do, or the structures they’re surrounding
What are the names of the three deep cervical fascial layers?
- Investing layer
- Pretracheal layer
- Pre-vertebral layer
What does the investing cervical fascial layer do?
Surrounds the entire neck, like a collar
What is the superior margin of the investing cervical fascial layer attached to?
- Entire lower border of mandible (midline to angle)
- Mastoid process
- Superior nuchal line
- External occipital protuberance in the posteiror midline
What does the investing cervical fascial layer attach to posteriorly?
- Spinous process of vertebrae
- Ligamentum nuchae
What does the investing layer of cervical fascia attach to inferiorly?
- Upper border of manubrium
- Upper surface of clavicle
- Acromion
- Spine of scapula
What does the investing layer of cervical fascia split to enclose?
- Sternocleidomastoid
- Trapezius
- Submandibular salivary gland
- Parotid salivary glands
Is the pre-tracheal layer of cervical fascia thick or thin?
Thin
What is the pre-tracheal layer of cervical fascia limited to?
Anterior part of neck
What is the pretracheal layer of cervical fascia attached to in superiorly?
Hyoid bone
What happens to the pre-tracheal layer of fascia inferiorly?
It extends into the thorax, where it binds with the fibrous pericardium
What does the pre-tracheal layer of cervical fascia consist of?
- Muscular layer
- Visceral layer
What does the muscular layer of the pretracheal cervical fascia do?
Encloses the infrahyoid muscles
What does the visceral layer of the pre-tracheal cervical fascia do?
Encloses;
- Oesophagus
- Thyroid gland
- Trachea
What does the visceral layer of pre-tracheal fascia do around the thyroid gland?
Splits around it to form a ‘false capsule’
What does the pre-vertebral layer of cervical fascia do?
Forms a sheath for the vertebral column and muscles associated with it
Where does the prevertebral layer of cervical fascia extend?
Base of cranium to 3rd thoracic vertebrae
How does the prevertebral layer of cervical fascia extend laterally?
As the axillary sheath
What does the axillary sheath surround?
- The brachial plexus of nerves
- Axillary vessels
What is the carotid sheath?
A tubular, fibrous structure
What is the carotid sheath formed from?
All three layers of deep cervical fascia
Where does the carotid sheath extend?
From base of cranium, through root of neck, to arch of aorta
What does the carotid sheath create?
A compartment for a number of neurovascular structures running between head and thorax
What structures run through the carotid sheath?
- Common carotid artery
- Internal jugular vein
- Vagus nerve (CN X)
What does the fascial compartmentilisation of structures in the neck give rise to?
Potential spaces between fascial planes
Where does the retropharyngeal space lie?
Between the prevertebral layer of fascia and the fascia surrounding the fascia (more specificially, the buccopharyngeal fascia)
What does the retropharyngeal space initially contain?
Lymph nodes
Up until when does the retropharyngeal space contain lymph nodes?
Up until age 3-4
What is the retropharyngeal space helpful in?
- Allow pharynx to move freely on vertebral column
- Expanding during swallowing
What is the problem with the retropharyngeal space?
Infection can collect
What areas in the neck are readily palpable (sometimes visible)?
- Thyroid cartilage (Adam’s Apple)
- Cricoid cartilage
What is the function of cartilage in the neck?
Supports underlying larynx
Where is the thyroid gland found?
At the base of the neck
Is the thyroid gland palpable?
Not unless enlarged
What is the purpose of the hyoid bone in the neck?
Attachment of lots of muscles, including strap like infrahyoid muscles
What course do the infrahyoid muscles take?
They descend from the hyoid bone
What is the neck divided into by anatomical borders?
Two triangles
What are the borders of the anterior triangle?
- Superior - Inferior margin of mandible
- Medial - Midline of neck
- Lateral - Anterior margin of sternocleidomastoid
What structures are associated with the anterior triangle?
Structures coursing between the head and thorax
What are the border of the posterior triangle?
- Inferior - Clavicle
- Medial - Posterior margin of sternocleidomastoid
- Lateral - Anterior margin of trapezius
What structures are associated with the posterior triangle?
Those coursing between thorax/neck and upper limb
Give an example of a structure associated with the posterior triangle?
Trunks of brachial plexus
Why are the anatomical triangles of the neck helpful?
Because different structures are found in them
What can diseases affecting the thyroid gland cause?
- Enlargement of the gland
- Discrete lumps
What can help localise a pathology to the thyroid gland?
Asking a patient with a swelling/lump in their neck to swallow, and observing wether it moves
Why will swelling/lumps associated with the thyroid gland move when swallowing?
The thyroid gland is enclosed by pre-tracheal fascia, which is attached to hyoid bone. The hyoid bone and larynx move up when swallowing, so hyoid bone will too, and any swelling or lump will involving this gland
What is an enlarged thyroid gland termed?
A goite
Where can a goite sometimes extend?
Retrosternally, through the root of the neck
Why can a goite sometimes extend through the root of the neck?
Because the lower limit of pre-tracheal fascia extends into the thorax
What can retrosternal extension of a goite lead to?
Compression of other structures running through the root of the neck
What structures can be compressed in a retrosternal extension of goite?
- Trachea
- Venous blood vessels
What symptoms can compression of the tracheal by a retrosternally extending goite lead to?
- Breathlessness
- Stridor
What symptoms can compression of venous blood vessels due to a retrosternally extending goite lead to?
Facial oedema, due to decreased venous drainage from head and neck
What do the layers of deep cervical fascia form?
Natural cleavage plates
What is the function of the natural cleavage plates formed by deep cervical fascia?
- Allows structure to move and pass over one another with ease
- Allows easy seperation of tissues during surgery
- These layers determine the direction and extent to which any infection occuring within the neck may spread
Where can infection develop, regarding the fascial planes of the neck?
- Retropharyngeal space
- Pre-tracheal space
What is infection in the retropharyngeal and pre-tracheal space usually secondary to?
Throat infection
What can potentially result from an infection in the retropharyngeal space and pre-tracheal space?
Can spread from neck into thorax, down as far as posterior mediastinum, which risks the development of mediastinitis
What is the problem with mediastinitis?
Life threatening
Is mediastinitis common?
No, it is rare
What may infection in the retropharyngeal or pre-tracheal space develop into?
Abscess
What is important when someone has an abscess caused by infection in retropharyngeal or pre-tracheal space?
Recognise and treat early
Why must an abscess in the retropharyngeal or pre-tracheal space be recongised and treated early?
Carries significant morbiditity and mortality
How may an abscess caused by infection in the retropharyngeal or pre-tracheal space present?
- Visible bulge on inspection of oropharynx
- Sore throat
- Difficulty swallowing
- Stridor
- Neck stiffness
- High temperature
What risks the insertion of bacteria into the pre-tracheal space?
Inserting surgical airways
What are most of the arteries supplying the face branches of?
The external carotid arteries
How does the external carotid artery terminate?
As superficial temporal artery and maxillary artery
What happens to the external carotid artery after termination?
It gives rise to a number of branches
What important branche does the external carotid artery give rise to before termination?
Facial artery
Why is the facial artery important?
It is the major arterial supply of the face
Where can the pulse of the facial artery be palpated?
As the artery winds around the inferior border of the mandible
Where does the facial artery have many anastomoses?
With other arteries of the face
What is the result of the facial artery having many anastomoses with other arteries of the face?
In the event of laceration of artery on one side, it is necessary to compress both arteries to stop bleeding
What runs with the facial artery?
The facial vein
What course does the facial vein take?
From medial angle of eye, to inferior border of mandible
What does the facial vein constitute?
The major venous drainage of the face
What does the facial vein drain into?
The internal jugular vein
What forms the external jugular vein?
- Superficial temporal vein
- Maxillary vein
- Other veins
What do the internal and external jugular veins drain into?
Subclavian vein
What are the major muscles and groups of the head and neck?
- Sternocleidomastoid
- Trapezius
- Muscles of facial expression
- Muscles of the cheek (buccinators)
- Occipitofrontalis muscle
- Muscles of mastication
- Superficial muscle of neck and chin (platysma)
- Muscle of ear
What is the sternocleidomastoid innervated by?
Accessory nerve (CN XI)
What is the origin of the sternocleidomastoid?
Mastoid process
What happens to the body of the sternocleidomastoid?
It splits into two heads, sternal and clavicular
Where does the sternocleidomastoid insert?
- Sternal head into sternum
- Clavicular head into clavicle
Where does the sternocleidomastoid lie relative to the platysma?
Deep
Is the sternocleidomastoid palpable and visible?
Yes, especially when tensing the muscle
What is the action of the sternocleidomastoid?
- When acting unilaterally, lateral flexion of neck, moving ear towards shoulder, and rotates chin superiorly
- When acting bilaterally, flexion at neck and extension at joint between base of skull and cervical vertebrae (atlanto-occipital joint)
What does the trapezius arise from?
- Back of skull
- Nuchal ligament
- Spinous process of vertebrae
Where does the trapezius insert?
- Lateral 1/3 of clavicle
- Acromion
- Spine of scapula
Why does the trapezius have many actions?
Due to it being a very broad muscle
What actions of the trapezius are important when considering the neck?
Elevates and rotates the shoulders, ‘shrugging’ them
Is the trapezius muscle visible?
Superior border is visible when shoulders shrugged against resistance
What is the trapezius supplied by?
The accessory nerve (CN XI)
What to the sternocleidomastoid and trapezius form?
Important anatomical boundaries of the neck
What are the muscles of facial expression supplied by?
The facial nerve (CN III)
How do many of the muscles of facial expression act?
As dilators and sphincters
Give 4 muscles of facial expression
- Orbicularis oculi
- Levator palpebrae superioris
- Orbicularis oris
- Dilator muscles of lips
What are the parts of the orbicularis oculi?
- Palpebral part
- Orbital part
What does the palpebral part of the orbicularis oculi do?
Performs gentle closure of eyelid
What does the orbital part of the orbicularis oculi do?
Closes more forcefully
What does the levitor palpabrae superioris do?
Elevates the upper eyelid
What is the innervation of the levator palpebrae superioris?
- Oculomotor nerve (CN III)
- Superior tarsal muscle (located within the LPS) is innervated by sympathetic nervous system
What does the orbicularis oris do?
Purses the lips
What do the dilator muscles of the lips do?
Opens the mouth
What do the muscles of the cheek do?
- Keep cheek taut
- Aid in chewing
What are the muscles of the cheek supplied by?
Facial nerve (CN VII)
Give a muscle of the cheek
Buccinator
What does the buccinator do?
Pulls cheek inwards against teeth
What is the function of the buccinator pulling cheeks inwards against the teeth?
Prevents accumulation of food in the area
What is the occipitofrontalis muscle supplied by?
Facial nerve (CN VII)
What are the muscles of mastication supplied by?
Mandibular division of trigeminal nerve (branch of CN IV)
What do the musles of mastication act to do?
Open and close the jaw
Are there more or less muscles of mastication than muscles of facial expression?
Less
Give 4 muscles of mastication
- Medial and lateral pterygoids
- Masseter
- Temporalis
What does the lateral pterygoid do?
- Acting bilaterally, protract the mandible, moving jaw forward
- Acting unilaterally, produce side to side movement of jaw
What does the medial pterygoid do?
Elevates the mandible, closing the mouth
What does the temporalis muscle do?
- Elevates the mandible, closing the mouth
- Retracts the mandible, pulling the jaw posteriorly
What is the platysma supplied by?
Facial nerve (CN VII)
Describe the shape of platysma
Broad, sheet like
Where does platysma lie?
- Anteriorly in the neck
- Very superficial
What are the actions of platysma?
- Draws corner of mouth inferiorly
- Draws skin of neck superiorly if teeth are clenched
What are the muscles of the ear supplied by?
Facial nerve (CN VII)
Where do the muscles of the face lie?
In subcutaneous tissue
What do most muscles of the face attach to?
Bone or fascia
How do the muscles of the face produce their effects?
By pulling the skin
What orifaces to the muscles of the face surround?
- Mouth
- Eyes
- Nose
What happens to the facial nerve once it has exited the cranium?
It enters the substance of the parotid gland
What happens to the facial nerve in the parotid gland?
It divides into its five extracranial branches
What will injury or pathology involving the facial nerve cause?
Muscle weakness of muscles of facial expression on ipsilateral side
What is the most common non-traumatic cause of facial paralysis?
Bell’s palsy
What is Bell’s palsy?
Inflammation of facial nerve near its exit from the cranium at the stylomastoid foramen
What does inflammation of the facial nerve cause?
Oedema and compression of nerve in intracranial facial canal
What is the clinical relevance of the facial nerve in the parotid gland?
As the facial nerve and its branches run through the parotid gland, and lie relatively superficial, they are vulnerable to damage in injuries to face, and in disease or surgery of the parotid gland
Where do cranial nerves arise from?
Brainstem, or slightly above
Where to the cranial nerves leave the skull?
- Those supplying face leave through front of skull
- Those supplying neck leave through base of skull
What cranial nerve is the trigeminal nerve a branch of?
V
What are the key branches of the trigeminal nerve?
- Opthalmic
- Maxillary
- Mandibular
What does the mandibular nerve do?
Supplies motor innervation to the muscles of mastication
What is the importance of the trigeminal nerve?
Main sensory nerve of the face and scalp
Draw a diagram illustrating the cutaneous distribution of the trigeminal nerve
What aspects of the trigeminal nerve can be tested?
- Sensory supply
- Motor supply
How is the sensory supply of the trigeminal nerve tested?
- Ask patient to close their eyes
- Introduce cottom wisp into areas of face supplied by three divisions of trigeminal nerve
This detects tactile sensory competence
How is the motor supply of the trigeminal nerve tested?
- Ask patient to clench their jaw, and palpate;
- Superior to zygomatic arch
- Inferiorly
- Ask patient to open mouth and deviate mandible to left and right
What is being felt for when palpating superior to zygomatic arch in trigeminal nerve testing?
Temporalis
What is being felt for when palpating inferiorly in trigeminal nerve testing?
Masseter
What is being tested for when asking patient to open mouth and deviate mandible to left and right in trigeminal nerve testing?
Competence of medial and lateral pterygoid muscles
What cranial nerve is the facial nerve derived from?
VII
What are the key branches of the facial nerve?
- Temporal
- Zygomatic
- Buccal
- Marginal mandibular branches
- Cervical
What does the temporal branch of the facial nerve innervate?
- Frontalis
- Orbicularis oculi
- Corrugator supercilli
What do the zygomatic branches of the facial nerve innervate?
Orbicularis oculi
What do the buccal branches of the facial nerve innervate?
- Orbicularis oris
- Buccinator
- Zygomaticus
What do the marginal mandibular branches of the facial nerve innervate?
Mentalis
What does the cervical branch of the facial nerve innervate?
Platysma
What are the non-motor functions of the facial nerve?
- Special sensory to the tongue, for taste
- Provides parasympathetic innervation to lacrimal glands and salivary glands
What can pathology of the parotid gland cause, regarding the facial nerve?
Can also affect the nerve, causing paralysis of facial expression
How is the facial nerve tested?
- Test corneal reflex
- Ask patient to;
- Raise eyebrows
- Close eyes, and keep them closed against resistance
- Puff their cheeks
- Reveal their cheeks
When is the corneal reflex absent?
In damage to trigeminal/opthalmic nerve, or facial nerve
What is the corneal reflex?
Involuntary blinking of eyelids, stimulated by tactile, thermal, or physical stimulation of cornea
Why must both side of the face be tested in facial nerve testing?
As they are paired nerves
ADD PICTURES
