Session 1 Flashcards
What are the coverings of the brain called
Meninges
Where do cranial nerves arise from
Central nervous system (mainly brainstem)
Blood vessels supplying the head and neck structures arise from or drain into branches of
large arteries (common carotids) and veins (subclavian veins)
Neck extends from and to
From lower margin of mandible (jaw) to suprasternal notch of manubrium and upper border of clavicle
Structures in the neck are compartmentalised by layers of
Cervical fascia
What are the layers of cervical fascia
Superficial cervical fascia and 4 deep cervical fascia layers
What is the superficial cervical fascial layer
loose connective tissue largely containing adipose
What lies within the superficial cervical fascial layer
superficial blood vessels e.g. anterior and external jugular veins, cutaneous nerves, superficial lymph nodes and platysma muscle
What are the layers of deep cervical fascia
Investing layer, pretracheal layer (middle), and the prevertebral layer (deep)
Carotid sheath- formed by parts of others
What does the carotid sheath do
Encircles several key neurovascular structures running between head and thorax
Pretracheal fascia is sometimes described collectively as the
Middle layer of deep cervical fascia
Prevertebral fascia is sometimes described as
Deep layer
What does the investing layer do
Surrounds the entire neck like a collar
Investing layer splits to enclose the
Sternocleidomastoid and trapezius muscles, submandibular and parotid salivary glands
Investing layer superior margin is attached to
mandible, mastoid process, superior nuchal line, external occipital protuberance
Investing layer inferior margin attached to
Manubrium, clavicle acromion, spine of scapula
What is the pretracheal layer attached to
Hyoid bone, extends into thorax and blends with fibrous pericardium
What does the pretracheal layer consist of
Muscular layer enclosing the infrahyoid muscles
Visceral layer enclosing thyroid gland (false capsule), trachea and oesophagus
What is buccopharyngeal fascia
Pretracheal fascial layer as it continues posteriorly to surround the muscles of the pharynx and oesophagus- fascia associated with the pharynx and oesophagus
Where does the buccopharyngeal fascia layer run from
Base of skull to diaphragm,
What is the carotid sheath
Tubular, fibrous structure that extends from base of the skull through root of neck to arch of aorta
What does the carotid sheath contain
Common carotid artery, internal jugular vein, cranial nerve CN and vagus nerve CN X
Where does the prevertebral layer extend from
Base of cranium to 3rd thoracic vertebra
Pre vertebral layer extends laterally as the
Axillary sheath- surrounds axillary vessels and brachial plexus of nerves running into upper limb
Clinical correlate of deep cervical fascia
Form natural cleavage panes that allow structures to move over and pass one another, allow easy separation during surgery
What to fascial layers determine
Direction and extend to which an infection in the neck may spread, depending on whether it develops within the compartments or between fascial layers
Fascial compartmentalisation of structures in neck gives rise to
Potential spaces between fascial planes
When do spaces in neck distend
Deep neck infections
Common infective source of deep neck space infections
Teeth, pharynx, sinuses
Deep neck space infections key points
Rare but pose significant risk to life
Where is the retropharyngeal space found
Between the prevertebral layer of fascia and the buccopharyngeal fascia
Key problem with retropharyngeal space
Space extends to length of neck, into mediastinum so retropharyngeal infections can spread inferiorly into thorax- can cause mediastinitis (life threatening)
Pro of retropharyngeal space
Pharynx free movement over surface of pre vertebral fascia
Abscess in retropharyngeal space usually secondary to
Infection involving upper respiratory tract
Abscess in retropharyngeal space spreadys to involve the
Retropharyngeal lymph nodes (in supra-hyoid region in young children), atrophied by adults
Retropharyngeal abscess adults cause
Penetrating injury of oesophagus, bacteria can enter from aero digestive tract
Retropharyngeal abscess signs and symptoms
Visible bulge on inspection of oropharynx, sore throat, difficulty swallowing, strider, reluctance to move the neck, high temperature
Thyroid gland disease test
Ask patient to swallow and observe whether lump moves- localises pathology to thyroid gland
Thyroid gland anatomy
Enclosed by pre-tracheal fascia, attached to hyoid bone.
What happens during swallowing
Hyoid bone and larynx move up hence thyroid
Where can an enlarged thyroid gland sometimes extend to
Retrosternally- through root of neck into superior thorax, via thoracic inlet
Retrosternal extension of goitre can risk
Compression of other structures running through narrow thoracic inlet (trachea and venous blood vessels)
Symptoms of retrosternal extension of goitre and compression
Facial plethora (from compression impending venous drainage from head and neck), breathlessness, stridor (tracheal compression)
Test to detect retrosternal goitre
Pemberton manoeuvre- raising arms above head causes narrowing of thoracic inlet, causes fascial plethora
2 major muscles of the neck
Sternocleidomastoid and trapezius
Important 3 triangles in neck
Anterior, posterior and carotid
Key other muscles of neck
Suprahyoid and infrahyoid groups of muscles (most attach to hyoid bone)
2 contribute towards boundaries of carotid triangle
Which group of muscles in the neck act as accessory muscles of respiration
Scalene muscles- form floor of posterior triangle
Critical structures that pass close to scalene muscles
Brachial plexus (trunks of plexus), subclavian vessels (pass between anterior and middle scalenes as they run into upper limb),
Phrenic nerve- arises from within neck, carrying spinal nerve routes C3,4,5, descends along surface of anterior scalene before entering into thorax
Most important muscles of the supra and infra hyoid muscle groups
Digastric and Omohyoid- contribute to boundaries of carotid triangle
2 types of muscles of face and head
Muscles of facial expression and muscles of mastication
Most muscles of fascial expression lie within the
Subcutaneous tissue and have attachments to the bone and often each other
Broadly speaking the muscles of fascial expression act as
Sphincters or dilators around bony cavities (except for buccinators which keep cheek taut to keep food in oral cavity)
What innervates all the muscles of fascial expression including plates a
Branches of facial nerve
Facial nerve is
Cranial nerve 7
Facial nerve route
Exits base of skull to become extracranial
Once facial nerve exits skull it runs through
Substance of parotid gland - nerve is vulnerable to damage in facial injuries and disease or surgery of parotid gland
Within parotid gland the facial nerve divides into
5 key terminal extracranial branches
Injury or pathology affecting the facial nerve and its extracranial branches will cause
Weakness of muscles of facial expression on ipsilateral side (same side) causing that side to droop
Most common non-traumatic cause of facial paralysis is
Inflammation of the facial nerve (Bell’s palsy)
Inflammation of the facial nerve causes
Oedema and compression of nerves
Weakness of the facial muscles on one side in association with an ipsilateral parotid gland enlargement is
Highly likely to be parotid cancer- rare for benign infective inflammatory conditions to cause this
How many muscles of mastication
4
Muscles of mastication act to
Move the mandible at the temporomandibular joint (TMJ) when chewing food
All muscles of mastication are supplied by
Branches from the mandibular division of the trigeminal nerve (branch of CN V)
Muscles of mastication
Temporalis, masseter, 2 pterygoids
Which muscles of mastication are not palpable
Pterygoid- lie deep to mandible, origin is pterygoid plates (have 2 different actions on jaw open and close)
All the muscles of mastication except one act to
Elevate the mandible (close jaw)
Action of depressing mandible
Lateral pterygoid and suprahyoids
(Laaa = open mouth)
Which bones form the cheek bone
Zygomatic and zygomatic arch
What is the jaw bone
Mandible
Big bone in middle of face
Maxilla
Where is occipitofrontalis
Forehead
Where is orbicularis occuli
Eye socket and eyelids
Where is orbicularis or is
Mouth
Where is buccinator
Wall of cheek
What makes up the occipitofrontalis
2 muscle bellies- joined by epicranial aponeurosis
Frontal and occipital
Frontal belly inserts into skin of eyebrow, blends with muscles around orbits (no bony attachments)
What is the action of the occipitofrontalis
Raises eyebrows and wrinkles skin of forehead
What makes up orbicularis oculi
Flat constrictor- orbital and palpebral parts (eyelid)
What does the orbital part of the orbicularis oculi do
Squeezes eyelids together slightly
What does palpebral part of orbicularis oculi do
Gently closes eyelid (involuntary blinking)
Critical role of orbicularis oculi
Protects eye and keeps front of eye moist (tear film)
Orbicularis oris origin and insertion
Origin is maxilla And mandible
Inserts into skin and membrane of lips
Actions of orbicularis oris
Purses lips together (facial expressions and speech)
Seals mouth closed (keeps food inside oral cavity)
Buccinator actions
Holds cheek in towards teeth, contracted to expel air against pursed lips
Dilators of mouth
Risorius and zygomaticus major - smile
What is platysma
Arises from fascia overlying anterior chest (pectoralis and deltoid)
Where does platysma insert
Lower part of mandible, subcutaneous tissue on skin of lower face
Where does platysma run and what does it do
Runs very superficially in neck and tenses skin of anterior neck (acts to lower inferior lips)
All muscles of facial expression innervated by
Extracranial branches of the facial nerve (cranial nerve 7)
What are the 5 key extra-cranial branches of facial nerve (relationship to parotid gland)
Two Zebras Bit My Cock
Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical
What is used to indicate severity of ipsilateral facial muscle weakness or paralysis
House-Brackmann Scale (1-6)
What is important to asses in facial paralysis
Eye occlusion- inability to fully close eye = eye protection required/referral to opthalmologist
3 key divisions of trigeminal nerve (cranial nerve 5)
Va ophthalmic
Vb maxillary
Vc mandibular (also motor to muscles of mastication)
Temporalis runs from
Superficial temporal fossa to part of mandible
Masseter runs from
Zygomatic arch to mandible
Pterygoids work together to
Move mandible side to side
Thyroid gland palpability
Lower part of neck, not usually palpable unless enlarged
What nerve supplies platysma
Facial
What nerve supplies Sternocleidomastoid
Accessory
Sternocleidomastoid origin and insertion
Origin- clavicle and sternum
Inserts- mastoid process
Action of Sternocleidomastoid
Rotates head so chin turns to opposite side, act together to flex neck
What’s torticollis
Involuntary contraction of SCM causing asymmetrical head/neck position
What nerve supplies trapezius
Accessory nerve
Origin and insertion of trapezius
Origin- Occipital bone, nuchal ligament
Insertion- lateral 1/3 clavicle and acromion of scapula
Actions of trapezius
Elevates shoulder and stabilises scapula
What can lead to trapezius muscle wasting and weakness
Spinal accessory nerve injury
What forms anterior triangle
Midline of neck, inferior margin of mandible and anterior margin of Sternocleidomastoid
What forms the posterior triangle
Posterior margin of Sternocleidomastoid, anterior margin of trapezius, middle 1/3 of clavicle
general structures where are associated with anterior triangle
Between head and thorax
general structures where are associated with posterior triangle
Thorax/neck and upper limb
Which neurovascular bundle lies under the SCM
Vagus nerve, IJV and CCA, surrounded by carotid sheath,
(Internal jugular vein always most lateral, Common carotid artery always more middle, Vagus nerve always tucked in at back)
Boundaries of carotid triangle
Digastric (posterior belly), Sternocleidomastoid and omohyoid (superior belly)
Where is carotid sheath and its contents found
Carotid triangle
What is below thyroid cartilage
Cricoid cartilage and then thyroid gland
Boundaries of posterior triangle
Trapezius, clavicle and Sternocleidomastoid
What runs in the roof of the posterior triangle
External jugular vein (very superficial)
Neurovascular structures in posterior triangle
Brachial plexus (communicates with upper limb) , also contains subclavian artery and vein
Pneumonic for carotid sheath
IC 10 CC in the IV
Internal carotid, Vagal nerve, common carotid, internal jugular vein (level 4)
Which side is affected and which facial nerve
Left side, left facial nerve palsy (ipsilateral)
Why can she still open and close her jaw as normal despite having facial nerve palsy
Masicators are supplied by trigeminal nerve
