What is the difference between the viscerocranium and the neuro cranium
Viscerocranium - bones of the face
Neurocranium - Bones surrounding the brain
To remind you of all the MSK you’ve forgotten, how many cervical vertebrae are there? Specific features?
7 - foramina in transverse processes, relatively small bodies
From top to bottom list the four notable structures in the neck that are in line with the trachea
Hyoid bone
Thyroid cartilage
Cricoid cartilage
Thyroid gland
Name the three notable muscles in the neck
Platysma
Sternocleidomastoid
Trapezius
Other than muscle function, what is worth remembering about the SCM and Trapezius muscles
Their borders form important anatomical boundaries of the neck
Platysma: shape and position?
Broad, sheet-like, v. superficial (within superficial fascia), overlies SCM
Platysma: action?
Draws corners of mouth inferiorly and skin of neck superiorly (if teeth clenched)
Platysma: innervation?
Facial Nerve - CN VII
SCM: attachments and position?
Mastoid process, Clavicle and Sternum
Deep to platysma but palpable and visible
SCM: action? (unilateral AND bilateral please)
Unilateral - lateral flexion of the neck (i.e. ear to shoulder while rotating chin superiorly)
Bilateral - flexion at neck, extension at atlanto-occipital joint
SCM: innervation?
Accessory nerve - CN XI
As Trapezius is in MSK as well let’s do it all in one
Arises - back of skull, nuchal ligament, spinous processes of vertebrae
Attaches - lateral 1/3 of clavicle, acromion, spine of scapula
Actions - shrugs, rotates scapula
Nerve - Acessory CN XI
What are the borders of the anterior triangle of the neck?
Midline of the neck
Anterior margin of SCM
Inferior margin of mandible
What are the borders of the posterior triangle?
Anterior margin of trapezius
Clavicle
Posterior margin of SCM
What is the function of the fascial planes in the neck?
Organises structures into compartments
Ease of movement while swallowing
Containing spread of infection
How many layers of cervical fascia are there?
5 - 1 superficial and 4 deep
What are the contents of the superficial layer of fascia?
Loose connective tissue Fat Platysma Cutaneous nerves Lymph nodes Superficial blood vessels
Name each of the deep layers, superficial to deep if you please
Investing
Pretracheal
Prevertebral
Carotid Sheath(s)
Investing layer: what does it surround?
All neck structures -
It splits into 2 in order to completely surround the SCMs and Traps
Investing layer: attachments?
Hint: 7
External occipital protuberance, superior nuchal line, hyoid bone, clavicle, manubrium, scapular spine, ligamentum nuchae
Pretracheal layer: position?
anteriorly in neck - spans between hyoid bone and thorax (fuses there with pericardium)
Pretracheal layer: what structures are contained within it?
Hint: 4
Trachea, oesophagus, thyroid gland and infrahyoid muscles
What are the infrahyoid muscles?
4 muscles (obviously) located inferiorly to the hyoid bone that work to depress the hyoid bone or thyroid cartilage
What can the pretracheal layer be subdivided into?
Hint: 2 parts
Muscular and visceral parts;
Muscular - encloses the infrahyoids
Visceral - encloses the rest
Prevertebral layer: what does it surround?
The vertebral column and its associated muscles
Prevertebral layer: attachments?
base of skull, transverse processes and vertebral bodies of vertebral column as well as ligamentum nuchae and endothoracic fascia of ribcage
Prevertebral fascia: other anatomical significance?
Hint: boundaries
Forms the floor of the posterior triangle of the neck AND the axillary sheath
Carotid sheaths: what are they?
Paired structures formed from contributions of the other deep layers
Carotid sheaths: what do they contain?
Hint: 4
Common carotid artery (bifurcates in it)
Internal jugular vein
Vagus nerve
Cervical lymph nodes
Carotid sheaths: clinical relevance?
Their organisation into a column running from the skull base to the thoracic mediastinum creates a pathway for infection to spread (mediastinitus)
Retropharyngeal and pre-tracheal spaces: why?
Allow spread of infection within them - e.g. tracheostomy could introduce bacteria into pretracheal space
What are the two broad sets of muscles of the face and their respective innervation?
Muscles of facial expression - Facial nerve CN VII
Muscles of mastication - Trigeminal nerve CN V
What other function does the trigeminal nerve have? Which branches are involved?
Sensory to the face and scalp (Roughly top to bottom) Opthalmic Maxillary Mandibular
What is the cranial nerve number of the facial and trigeminal nerves?
Trigeminal - V
Facial - VII
Name the terminal branches of the facial nerve
Hint: 5
Temporal Zygomatic Buccal Marginal mandibular Cervical
Facial nerve: other functions?
SS (special sensory) tongue
Parasympathetic innervation to salivary and lacrimal glands
Clinical relevance: how can the fascial layers aid in diagnosing goitres?
The thyroid gland is enclosed in pretracheal fascia, in turn attached to the hyoid which moves up in swallowing, therefore so will a goitre
Clinical relevance: signs of a retrosternal goitre?
Compression = breathlessness, stridor, facial oedema
How is the facial nerve tested?
Forehead creasing, keeping eyes shut against resistance, revealing the teeth and puffing out the cheeks
How is the trigeminal nerve tested?
Sesory testing with cotton buds
Corneal reflex
Orbicularis oculi: action an innervation?
Closes the eyelid and scrunches the eye
Facial nerve
Levator palpebrae: action and innervation?
Opens the eyelids
Oculomotor nerve CN III
Orbicularis Oris: action?
Purses lips
Buccinator: action?
Compresses cheeks against teeth and is involved in blowing (not that kind)
Pterygoids, lateral and medial: actions?
Clenching jaw and moving it anteriorly
Temporalis: action?
Crushing food in molars
What is the scalp?
The 5 layers of skin and subcutaneous tissue that cover the bones of the cranial vault
Now name the layers of the scalp. Hint: SCALP is a pseudo-mnemonic
Skin (Dense) Connective tissue (Epicranial) Aponeurosis Loose areolar connective tissue Periosteum
Why does the scalp bleed so much?
The dense connective tissue layer has lots of blood vessels that are tightly attached preventing them from constricting if lacerated
Which muscles are connected by the epicranial aponeurosis?
Occipitalis and frontalis
Clinical relevance: scalp infections?
Can spread to cranial cavity via emissary veins, could cause meningitis
Scalp: arterial supply?
Opthalmic and external carotid
Scalp: which branches of external carotid are involved?
Roughly anterior to posterior; superficial temporal, occipital, posterior auricular
Scalp: superficial venous drainage?
Follows arterial supply via veins with the same names
Scalp: deep veous drainage?
Pterygoid venous plexus - draining into the maxiallry vein
Scalp: additional venous drainage?
Hint: anastomoses
Scalp veins connect to diploic veins of the skull via valveless emissaary veins connecting scalp to dural venous sinuses
Scalp: innervation?
Hint: 6 nerves from 2 sources
4 fromTrigeminal; supratrochlear, supraorbital, zygomaticotemporal and auriculotemporal
2 from cervical nerves; lesser and greater occipital nerves (C2 & 3)