Head and neck Flashcards
what bones me up the Calvarium?
Frontal,occipital and two parietal bones
What bones make up the Cranial base?
The frontal,occipital,sphenoid, ethmoid, parietal and temporal bones
What bones form the bones of the face? (14)
Zygomatic(2), maxilla(2), nasal(2), lacrimal(2) and mandible, vomer, inferior nasal conchae(2) and palatine(2) bones.
what type of joint are skull sutures?
fibrous- Synarthroses.
what three main sutures form the ‘H’ on the neurocranium?
Coronal, sagittal and lamboid sutures.
What are the two main fontanelles, and where are they located?
Frontal (the junction of the coronal and sagittal sutures) and occipital (the junction of the sagittal and lambed sutures)
What are the four main points of weakness in the skull?
the pterion, anterior cranial fossa, middle cranial fossa and posterior cranial fossa.
If a person receives a blow to the pterion, what may be damaged?
the underlying middle meningeal artery, which can lead to an extradural haematoma.
What are the four main types of skull fractures and their causes?
- Linear-most common, full thickness fracture with radiating, satellite fractures away from the site of impact.
- Depressed- fracture with depression inwards, they result due to a direct blow.
- basal skull-affects the base of the skull. They present with bruising behind the ears (mastoid ecchymosis) or the eyes (racoon eye’s)
- Diastatic- a fracture along a suture line, they are more common in children.
What are the four parts of the temporal bone?
Squamous, pteromastoid, zygomatic, tympanic and styloid process.
What structures form the external nasal skeleton?
Nasal bone, maxilla, septal cartilages, lateral cartilages, major alar cartilages,minor alar cartilages and fibro-fatty tissue.
What structures form the internal nasal skeleton?
Paired bones- nasal, maxillary and palatine bones
Unpaired bones- Ethmoid and vomer bones.
What are the three bony articulations of the TMJ?
The mandibular fossa, articular tubercle and mandibular head.
What are the three ligaments in the TMJ and what do they do?
- Lateral ligament- prevents posterior dislocation.
- Sphenomandibular ligament
- Stylomandibular ligament- supports the weight of the jaw with the facial muscles.
What muscles cause protrusion and retraction of the jaw?
Protrusion- lateral pterygoid muscle.
Retraction-geinohyoid and digastric muscles
What muscles are responsible for elevation and depression of the jaw?
Depression- mainly caused by gravity, but against resistance, the digastric, geniohyoid and mylohyoid muscles assist.
Elevation- temporalis, masseter, and medial pterygoid muscles.
Describe briefly what occurs in a dislocation of the TMJ?
Usually occurs via a blow to the side of the face, yawning or taking a large bite. The head of the mandible slips out of the mandibular fossa and is pulled anteriorly. The facial and auriculotemporal nerves run close to the joint and can be damaged. Posterior dislocations are rare.
There are many foramina in the cribriform plate, what are the three main ones and what do they transmit?
- Olfactory nerve fibres (CNI) intot he nasal cavity.
- Anterior ethmoidal foramen- anterior ethmoidal artery, nerve and vein.
- Posterior ethmoidal foramen- posterior ethmoidal artery, nerve and vein.
Why does the cribriform plate fracture easily and what are the two main symptoms of such a fracture?
it’s the thinnest part of the anterior cranial fossa.
Anosmia- the olfactory nerve fibres can be sheared, resulting in a loss of smell.
CSF rhinorrhoea- fragments of bone can tear the meningeal coverings causing leakage of CSF into the nasal cavity.
What is the Chiasmatic sulcus?
A groove running between the right and left optic canals
where in the sphenoid does the pituitary gland sit?
in the middle of the Sella trucica is a depression called the hypophyseal fossa.
What do the optic canals transmit and where are they located?
Transmit the optic nerves (CNII) and ophthalmic arteries into he orbital cavities. They are situated anteriorly in the middle cranial fossa.
what are the four foramina which lie laterally to the central part of the middle cranial fossa?
(6-1-2-3)
- Superior orbital fissure- opens anteriorly into he orbit. oculor motor nerve, trochlear nerve, ophthalmic branch of the trigeminal nerve, abducens nerve, ophthalmic veins and sympathetic fibres.
- Foramen rotundum- opens into he pterygopalatine fossa. maxillary branch of the trigeminal nerve.
- the foramen oval- opens into he infra temporal fossa. mandibular branch of the trigeminal nerve and accessory meningeal arteries.
- The foramen spinosum- opens into the infra temporal fossa. middle meningeal artery, middle meningeal vein and a meningeal branch of the trigeminal nerve.
What are the three major foramina in the temporal bone?
- Hiatus of the greater petrosal nerve- greater petrosal nerve (branch of the facial nerve), and the petrosal branch of the middle meningeal artery.
- hiatus of the lesser petrosal nerve-transmits the lesser petrosal nerve (a branch of the glossopharyngeal nerve).
- Carotid canal- transversed by the internal carotid artery and deep petrosal nerve.
What is the internal acoustic meatus?
oval opening in the posterior aspect of the petrous part of the temporal bone. It transmits the facial nerve, vestibulocochlear nerve and labyrinthine artery.
What’s transmitted through the foramen magnum? (7)
the medulla of the brain,meninges, vertebral arteries, spinal accessory nerve (ascending), dural veins, anterior and posterior spinal arteries.
What passes through the jugular foramina? (7)
Each transmits the glossopharyngeal nerve, vagus nerves, spinal accessory nerve (descending), internal jugular vein, inferior petrosal sinus, sigmoid sinus and meningial branches of the ascending pharyngeal and occipital arteries.
What is cerebral herniation?
The downward displacement of the cerebellar tonsils through the foramen magnum.
It’s produced by raised inter cranial pressure.
It results in the compression the pons and medulla, which contain the cardiac and respiratory centres and ultimately results in death from cardiorespiratory arrest.
When is the eustachian tube open?
On swallowing
Which layer can the muscles of facial expression be found?
Subcutaneous tissue
What’s special about the insertion of the facial muscles?
They are the only muscles that insert into skin.
What’s the embryonic origin of the facial muscles?
2nd pharangeal arch
What are the two muscles in the orbital group of the muscles of facial expressions and their actions?
- Orbicularis Oculi- palpebral part= gentle closure of the eyes, orbital portion= forceful closure.
- Corrugator Supercilii- draws the eyebrows together.
What happens in an orbital muscle paralysis to the eye?
The lower eyelid droops (ectropion), and the lacrimal fluid can’t be spread over the surface of the eye. This can result in a failure to remove debris, and ulceration of the corneal surface. Exposure keratitis too.
What are the three nasal muscles of facial expression, and their actions?
- Nasalis- transvers= compresses the nares, Alar= opens the nares.
- Procerus- pulls the eyebrows downward to produce transverse wrinkles over the nose.
- Depressor Septi Nasi- Pulls the nose inferiorly, opening the nares.
What are the two main oral muscles and their actions?
- Orbicularis oris- purses the lips
- Buccinator- pulls the cheeks inwards against the teeth, preventing accumulation of food in that area.
What are the two groups of minor oral muscles?
- Lower group- depressor angel kris, depressor labii inferiors and the mentalis.
- Upper group- risers, zygomaticus major, zygomaticus minor, elevator labii superioris, levator superiors ileac nasa and elevator anguli oris.
What are the main symptoms of paralysis of the oral muscles?
- Difficulty eating
- Tissue around the mouth and cheeks sag.
- Skin is drawn to the opposite side when smiling
Where do the muscles of mastication originate from (embryologically)?
1st pharyngeal arch
what are the muscles of mastication innervated by?
Branch of the Trigeminal nerve
What are the three (4) muscles of mastication and their actions?
- Masseter- elevates the mandible, closing the mouth.
- Temporalis-elevates and retracts the mandible
- Medial Pterygoid- elevates the mouth
- Lateral Pterygoid- acting bilaterally, they protract the mandible, pushing the jaw forward. Unilateral action produces the ‘side to side’ movement of the jaw.
What are the four muscles of the tongue?
Geniohyoidus, Genioglossus, hyloglossus and styloglossus.
What is the anterior 2/3 of the tongue innervated by?
- touch- A branch of the trigeminal nerve, the anterior lingual nerve.
- taste- A branch of the facial nerve, the chorda tympani.
What is the posterior 1/3 of the tongue innervated by?
both touch and taste are supplied by the glossopharyngeal nerve
What nerve supplies the motor control of the tongue?
The hypoglossal nerve except the palatoglossus, which is supplied by the vagus nerve.
What is the blood supply to the tongue?
the lingual artery, and a branch from the facial artery- the tonsillar artery.
Through what vein is the tongue drained via?
The lingual vein.
At what levels do the brachiocephalic trunk and common carotid split?
- Brachiocephalic trunk- right strenoclavicular joint
- common carotid- thyroid cartilage (C4) in the carotid triangle.
Where does the external carotid artery end and what are it’s terminal branches
Parotid gland
-superficial temporal and maxillary artery
Before terminating, what are the six branches the external carotid gives off?
- Superior thyroid artery
- Lingual artery
- Facial artery
- Ascending pharyngeal artery
- Occipital artery
- Posterior auricular artery
What are the arteries that supply the scalp and what are they branches of?
- Posterior auricular, occipital and superficial temopral arterier- all branches of the external carotid.
- Supra-orbital and supratrochlear arteries- all branches of the internal carotid artery.
What features of the scalp make a laceration bleed excessively?
- The walls of the arteries are tightly bound to the underlying connective tissue, preventing them from constricting to limit blood loss.
- there are numerous anastomoses
- deep lacerations involve the epicranial aponeurosis, which is worsened by the opposing pulls of the occipital and frontal muscles.
Why does the bony cranium not undergo a vascular necrosis?
it receives it’s blood supply from the middle meningeal artery, which scalp lacerations don’t interfere with.
What structures does the middle meningeal artery supply and what happens if it’s lacerated?
- supplies the skull and the dura mater.
- in an injury to the pterion can lacerate the MMA, causing blood to accumulate between the dura mater and the skull- an extradural haematoma.
- treated by diuretics in minor cases and drilling burr holes in extreme heamorrhages.
Through what structure does the internal carotid enter the cranial cavity?
The carotid canal in the petrous part of the temporal bone.
What structures does the internal carotid artery supply?
- The brain
- The eyes
- The forehead
Where do the vertebral arteries arise from?
Subclavian arteries, medial to the anterior scalene muscles.
What structures in the cervical vertebrae do the vertebral arteries pass up through?
Foramen transversarium
Through what structures do the vertebral arteries enter the cranial cavity?
foramen magnum
What do the vertebral arteries become and what do they supply?
Basilar arteries which supply the brain.
From which artery do the thyrocervical trunk originate?
The right and left subclavian arteries
What are the branches of the thyrocervical trunk and what do they supply?
- inferior thyroid, thyroid gland–> ascending cervical, the posterior prevertebral muscles.
- transverse cervical artery, crosses the base of the carotid triangle, and supplies the trapezius and rhomboid muscles.
- suprascapular- posterior shoulder area.
How can the venous drainage of the head be split and what are the main vessels that do this?
- Brain and meninges- dural venous sinuses
- Scalp and face- internal and external jugular veins
- Neck- anterior jugular veins
The union of what two veins form the external jugular veins?
- Posterior auricular vein- superior scalp and posterior to the outer ear.
- retromandibular vein- formed by the maxillary and superficial temporal veins which drain the face.
Where do the posterior auricular and retromandibular veins combine?
immediately posterior to the angle of the mandible, and inferior to the outer ear.
Describe the anatomical relationship of the external jugular veins to the sternocleidomastoid.
It runs anteriorly to the SCM, crossing it in oblique, posterior and inferior direction.
Does the external jugular vein pass superior or inferiorly to the clavicle?
Inferiorly.
As the external jugular vein passes down the neck, what tributary veins does it receive? (3)
- Posterior external jugular vein
- transverse cervical
- suprascapular veins
What happens when the external jugular vein is severed?
the lumen is held open due to the thick layer of investing fascia. Air is drawn in, producing cyanosis and can eventually stop the blood flow to the right atrium. Pressure can be applied, stopping the bleeding and the entry of air.
What area does the anterior jugular vein drain?
The anterior aspect of the neck.
What’s the communication between the anterior jugular veins called?
The jugular venous arch.
Where does the internal jugular vein originate?
In the cranial cavity, as a continuation of the sigmoid sinus. It starts as a dilation, called the superior bulb.
Through what structure does the internal jugular vein exit the skull via?
the jugular foramen
Describe the anatomical relationship of the internal jugular vein to the carotid sheath, the SCM and common carotid arteries.
- within the carotid sheath
- deep to the SCM
- lateral to the common carotid artery
Where does the IJV combine with the subclavian vein?
posterior to the sternal end of the clavicle.
Where is the inferior bulb of the IJV and why is it important?
Immediately before it’s termination, it has a valve to stop back flow of blood.
During it’s descent, what veins join onto the IJV? (5)
- Fascial
- lingual
- occipital
- superior thyroid
- middle thyroid
What general structures drain into the IJV? (6)
- anterior face
- trachea
- thyroid
- oesophagus
- larynx
- muscles of the neck
What are dural venous sinuses and their role?
Spaces between the periosteal and meningeal layers of the dura mater which are lined by endothelial cells. They collect venous blood from the veins that drain the brain and bony skull, and drain into the IJV.
where are the cavernous sinuses located?
the lateral aspect of the body of the sphenoid bone.
from what structures do the cavernous sinus receive blood from? (3)
- Superior and inferior ophthalmic veins
- middle superficial cerebral veins
- the sphenoparietal sinus
What vessels pass throught the cavernous sinus? (2)
- Internal carotid artery (cools blood before it supplies the brain)
- Abducens nerve
Which nerves are located in the wall of each sinus, and why is this of clinical importance?
- Oculomotor
-Trochlear
-Ophthalmic (V1)
-Maxillary (V2)
they are at risk if the sinus becomes infected.
How is the facial vein connected to the cavernous sinus and why is this of clinical importance?
Via the superior ophthalmic vein, the vein is valveless so blood can reverse its direction and flow from the facial vein to the cavernous sinus. This provides a pathway from which a facial infection can spread to the venous sinuses.
How many cervical vertebrae are there?
7
What are the three characteristic features of cervical vertebrae?
- Triangular vertebral foramen
- Transverse foramen (transmit the vertebral artery, vein and sympathetic nerves)
- Bifid spinous process
How does the C1 Atlas differ from the other cervical vertebrae? (4)
- no vertebral body/ spinous process
- articular facet anteriorly which articulates with the dens of the axis.
- lateral masses on either side of the vertebral arch, which provide an attachment for the transverse ligament of the atlas.
- posterior arch has a groove for the vertebral artery and C1 spinal nerve.
What feature makes the C2 Axis easily identifiable?
Its dens (odontoid process), which articulates with the articular facet of the atlas, creating the medial atlanto-axial joint, which allows for rotation of the head (no).
What are the two types of joint unique to the cervical spine?
- Lateral atlanto-axial joints- articulation between the inferior facets of the lateral masses of C1 and the superior facets of C2. Plane type synovial joints.
- Medial atlanto-axial joint- articulation of the dens of the C2 with the articular facet of c1. Pivot type synovial joint.
What is the joint between the spine and cranium?
atlanto-occipital joints. between the superior facets of the lateral masses of the atlas and the occipital condyles at the base of the cranium. Condyloid type synovial joints, allow flexion at the head (yes).
What are the two joints that are present throughout the whole vertebral column?
- vertebral bodies, a symphyses joint joints by the intervertebral disks.
- vertebral arches, formed by the superior and inferior articular processes of adjacent vertebrae, a plane type synovial joint.
What’s significant about the relationship between the vertebral artery and C7?
it runs around the vertebra, instead of passing through the transverse foramen. The vertebral vein and sympathetic plexus still run in the foramen.
What’s significant about the vertebral artery and the Atlas?
it runs along the groove for the vertebral artery instead of the transverse foramen.
The 7 cervical vertebrae have 8 sets of paired nerves, how does this happen?
The C7 vertebrae has a set of nerves extending from above (C7) and below (C8).
What are the four common types of cervical injury?
- Jeffersons fracture of the atlas
- Hyperextension injury
- Hangman’s fracturs
- Dens Fracture
Describe a Jefferson fracture of the atlas.
- Vertecal fall onto extended neck (diving into a shallow pool)
- compression of the lateral masses of the atlas between the occipital condyles and the axis. Driving them apart, and potentially fracturing the anterior/posterior arches (polo).
- The transverse ligament of the atlas may also be ruptured.
- unlikely there will be any damage to the C1 level as the foramen is large.
Describe a hyperextension injury.
- rear end traffic collision
- anterior longitudinal ligament of the spine is damaged.
- in more severe cases, fractures can occur to any of the cervical vertebrae as they are suddenly compressed.
- the vertebral foramen is large so spinal chord damage is common.
- The worst case scenario- dislocation/subluxation at the C2. C2 moves anteriorly to C3. This can lead to quadriplegia and death.
- More commonly , subluxation occurs at the C6/C7 in 50% of cases.
Describe a hangmans fracture.
Fracture of the pars interarticularis, which is the bony column between the superior and inferior articular facets of the axis.
-likely to be lethal as the fracture fragments or force are likely to rupture the spinal chord.
Describe a Dens fracture.
- 40% of the fractures of the axis
- commonly caused by traffic collisions and falls
- unstable
- high risk of a vascular necrosis and take a long time to heal
Name the four suprahyoid muscles
- stylohyoid
- digastric
- mylohyoid
- geniohyoid
what is the action and innervation of the stylohyoid?
- Initiates a swallowing action by pulling the hyoid bone in a posterior and superior direction.
- Facial nerve (VII)
what is the action and innervation of the digastric?
- It has two muscular bellies, connected by a tendon.
- depresses the mandible and elevates the hyoid
- the anterior belly is innervated by the trigeminal nerve
- the posterior belly is innervated by the facial nerve.
what is the action and innervation of the mylohyoid?
- firms the floor of the oral cavity
- elevates the floor of the mouth and the hyoid bone.
- trigeminal nerve.
what is the action and innervation of the geniohyoid?
- deep to the myohyoid
- depresses the mandible and elevates the hyoid bone
- C1 roots that run within the hypoglossal nerve.
What are the four infrahyoid muscles and what two divisions can they be split into?
- superficial plane- sternohyoid, omohyoid
- deep plane- sternothyroid, thyrohyoid
what is the action and innervation of the sternohyoid?
- depresses the hyoid bone
- anterior rami of C1-3, carried by a branch of the ansa cervicalis.