Head and neck anatomy Flashcards
What are the 2 major functions of the skull?
protect the brain and support facial structures
How can the bones of the head be divided into 2 groups?
Cranial bones and facial bones
What do the cranial bones form?
Roof and base of the skull
What is the roof of the skull known as?
Calvarium
What are all the cranial bones?
Frontal (1), parietal (2), temporal (2), occipital (1), ethmoid (1), sphenoid (1)
Which of the cranial bones for the calvarium?
frontal (1), occipital (1), parietal (2)
What are the facial bones known as?
viscerocranium
What are all the facial bones?
lacrimal (2), maxilla (2), nasal (2), inferior concha (2), palatine (2), vomer (1), zygoma (2), mandible (1)
How many facial bones are there in total?
14
What does the superior part of the skull form?
cranium / neurocranium
What are cranial sutures?
dense fibrous joints made of collage
Function of cranial sutures
allow bones to move over each other during childbirth
What is the name of the cranial sutures between the frontal and parietal bones?
Coronal sutures
What is the name of the cranial sutures between the 2 parietal bones?
Sagittal sutures
What is the name of the cranial sutures between the occipital and parietal bones?
Lambdoid sutures (shaped like Greek letter, lamda)
What are the names of the gaps between cranial bones in newborns?
fontanelles (anterior and posterior)
Where is the anterior fontanelle?
the gap between the developing 2 frontal bones and parietal bones
When does the anterior fontanelle close?
18-24 months
What is the clinical use of the anterior fontanelle?
indicates the intercranial pressure
Where is the posterior fontanelle located?
Between the sagittal and lambdoid sutures
When does the posterior fontanelle close?
6-8 weeks
Which bones make up the cranial base?
ethmoid, frontal, occipital, sphenoid, temporal bone (petrous part)
What is the petrous part of the temporal bone?
The portion of the temporal bone where middle and inner ear sit (hearing and balance)
What shape is the sphenoid bone?
Butterfly shaped
What anatomical feature can be palpated posterior to the ear?
Mastoid process
What does the mastoid process contain?
Mastoid air cells
What can cause inflammation of the mastoid process?
acute otitis media (middle ear infection)
What is the name of the opening at the base of the skull that allows the spinal cord to connect to the brain?
foramen magnum
Which bone contains the foramen magnum?
Occipital bone
Where does the olfactory nerve (CN I) enter the brain?
Through the cribriform plate of the ethmoid bone
Where is the ethmoid bone located?
Posterior to nasal cavity, between 2 orbits
What is the name of the canal in the temporal bone that carries nerves and blood vessels to the inner ear?
Internal auditory meatus
Which cranial nerves pass through the internal auditory meatus?
CN VII (facial) and CN VIII (vestibulocochlear)
Which is the thinnest of the facial bones?
lacrimal bones
Which bone forms the cheekbones?
zygoma
Which bones does the zygomatic bone join with?
Frontal (above), sphenoid (deep), temporal (side), maxilla (antero-inferiorly)
Function of the zygomatic bone (zygoma)
forms a crash-impact barrier that transmits trauma posteriorly to the temporal bone. Protects skeleton of face
Why are middle bones more anterior whereas lateral bones are more posterior?
To create a wider area for binocular vision
Which bones form the cranial vault (top of skull)?
frontal, parietal, occipital, temporal (squamous part - inferior to parietal)
Which part of the temporal bone is softer?
Squamous part
What is the weakest part of the skull?
Pterion
Where is the pterion?
Region of the skull where the frontal, parietal, temporal and sphenoid bones meet
Which blood vessels can rupture if there is trauma to the pterion?
Middle meningeal artery and vein
What happens if the middle meningeal artery / vein ruptures?
It will cause an extra-dural haemorrhage which will result in the dura being pressed off the skull. This can take time so there is a delay in symptoms.
What is the delay in symptoms called during an extradural haemorrhage?
lucid interval
Symptoms of an extradural haemorrhage
reduced consciousness, headache, nausea, vomiting
What are the 3 layers of meninges in the brain (inner to outer)?
Pia mater, arachnoid mater, dura mater
Name for the eye socket
orbit
Where is the opening for the optic canal (CN II)?
The optic foramen located at the apex of the orbit
Which cranial nerves enter through the superior orbital fissure?
Oculomotor (CN III), Trochlear (CN IV), Trigeminal (CN Va - ophthalmic division), Abducens (CN VI)
Which bones make up the superior wall (roof) of the orbit?
Frontal and lesser wing of sphenoid
Which bone separates the orbit from the anterior cranial fossa?
frontal bone
Which bones make up the inferior wall (floor) of the orbit?
maxilla, palatine and zygomatic bones
Which bone separates the orbit from the maxillary sinus?
maxilla
Which bones form the medial wall of the orbit?
Lacrimal, ethmoid, maxilla, sphenoid bone
Which bones separates the orbit from the ethmoid sinus?
ethmoid bone
Which bones form the lateral wall of the orbit?
zygomatic and sphenoid
What forms a boundary around the base of the orbit?
eyelids (orbital rim)
Which cranial nerves supply the extra-ocular muscles?
CN III (oculomotor), CN IV (trochlear), CN VI (abducens)
What is the name of the opening located inferior to the orbit within the maxilla?
Infraorbital foramen
Which nerve passes through the infraorbital foramen?
Infraorbital nerve (terminal branch of CN Vb - maxillary division)
Which nerves are anaesthetised during dental procedures on the upper teeth?
Superior alveolar nerves
Which bones and cartilage form the nasal septum?
Ethmoid bone (posterior), vomer, septal cartilage. (maxilla forms anterior nasal spine)
Which nerve supplies the palate and anterior teeth?
Nasopalatine nerve
Where does the nasopalatine nerve emerge from?
Incisive canal in the palatine process of maxilla
Which bone forms the palate?
Palatine process of the maxilla
What is the origin of the arterial blood supply to the head and neck?
arch of aorta
Which 2 arteries does the common carotid artery divide into?
internal and external carotid artery
What does the internal carotid artery supply?
Supplies 80% of the blood to the brain
Which artery supplies 20% of the blood to the brain?
vertebral artery
What does the external carotid artery supply?
exterior of the head and neck
What are the branches of the external carotid artery?
Ascending pharyngeal, superior thyroid, lingual, facial, occipital, posterior auricular, superficial temporal, maxillary
What does the ascending pharyngeal artery supply?
pharynx
What does the superior thyroid artery supply?
upper aspect of thyroid gland
Which artery branches into the inferior thyroid artery?
subclavian artery
What does the lingual artery supply?
tongue, sublingual salivary gland, gingiva, oral mucosa at floor of mouth
What does the facial artery supply?
face
what does the occipital artery supply?
muscles of posterior neck and skull (over occipital bone)
What does the posterior auricular artery supply?
neck muscles and ear structures
What does the superficial temporal artery supply?
skin and muscle at side of face and scalp, parotid gland, TMJ
What does the maxillary artery supply?
upper teeth
Where does the right common carotid artery arise from?
from the brachiocephalic trunk
Where does the left common carotid artery arise from?
arch of aorta
What artery supplies the sternocleidomastoid?
Lower sternocleidomastoid branch of the occipital artery
Which artery and vein supplies and drains the upper lip?
Superior labial artery and vein
Which artery and vein supplies and drains the lower lip?
Inferior labial artery and vein
Which vein drains the face?
facial vein
Which vein drains the side of the scalp?
superficial temporal vein
Which 2 veins unite and drain into the external jugular vein?
facial vein and retromandibular vein
Which 3 structures pass through the parotid gland?
retromandibular vein, facial artery, facial nerve (CNVII)
Which veins unite to form the retromandibular vein?
maxillary and superficial temporal vein
What does the internal jugular vein drain?
cerebrum, inside of the skull, most of external structures of head and neck
What does the external jugular vein drain?
some external structures e.g. posterior auricular vein and retromandibular vein
What is a cavernous sinus?
A paired dural venous sinus within the middle cranial fossa
Why is the cavernous sinus described as ‘cavernous’?
It is split into septae / small caves (honeycomb structure)
Where is the cavernous sinus located?
In the middle cranial fossa, either side of the sella turcica of the sphenoid bone
Which gland is surrounded by the cavernous sinus?
pituitary gland
Term used to describe a clot in the cavernous sinus
cavernous sinus thrombosis
Causes of cavernous sinus thrombosis
infection spreading from areas such as the orbit, paranasal sinuses and the danger triangle.
Symptoms of cavernous sinus thrombosis
headache, proptosis, photophobia, cranial nerve palsies,
What is proptosis?
Eye bulging
What is photophobia?
sensitivity to bright light
Which artery passes through the cavernous sinus?
internal carotid artery
What is significant about the internal carotid artery passing through the cavernous sinus?
it is the only part of the body where an artery passes through a venous structure
What is the suggested purpose of the artery passing though the cavernous sinus?
heat exchange can occur between the warmer arterial blood and cooler venous circulation
Which nerves pass through the cavernous sinus?
Oculomotor (CNIII), trochlear (CNIV), abducens (CNVI), ophthalmic (CNVa) and maxillary (CNVb) divisions of trigeminal nerve.
Which vein drains the surface of the scalp into the dural venous sinuses?
emissary vein
Between which 2 structures do dural venous sinuses lie?
periosteal and dura mater
Function of dural venous sinuses
collects pools of blood that drain the CNS, face and scalp
Which structure do all dural venous sinuses ultimately drain into?
internal jugular vein
What is found between the arachnoid mater and pia mater?
cerebrospinal fluid (CSF)
How many dural venous sinuses are there?
11
Where is the danger triangle of the face?
corners of mouth to bridge of nose
How can infection potentially spread from an extracranial to an intracranial site?
facial vein anastomoses with ophthalmic veins which drain into the cavernous sinus
What conditions can occur if infection spreads from the danger triangle into an intracranial site?
cavernous sinus thrombosis, meningitis, brain abscess
How can the heart rate be determined using the pulses of arteries?
contraction of left ventricle causes pressure waves in artery which corresponds with the heartbeat
What is a normal heart rate?
60-80 bpm
In which arteries of the head and neck can you feel a pulse?
carotid artery, superficial temporal artery (and its anterior branch), facial artery
Where can you feel the carotid pulse?
either side of trachea
Where can you feel the facial pulse?
mid-way along mandible
Where can you feel the temporal pulse?
anterior to ear or temple
Which set of nerves innervate the head and neck?
cranial nerves and nerves of the cervical plexus
Which cranial nerves innervate the head and neck?
CN V (trigeminal), CN VII (facial), CN IX (glossopharyngeal), CN XII (hypoglossal)
What are the 3 branches of the trigeminal nerve (CN V)?
Ophthalmic (Va), maxillary (Vb), mandibular (Vc)
Function of the ophthalmic division of the trigeminal nerve (CN Va)
sensory innervation to the skin over the forehead
Which nerves join to form the ophthalmic nerve?
frontal, lacrimal and nasociliary nerves
What are the terminal branches of the frontal nerve? (forms CN Va)
supraorbital and supratrochlear nerve
Function of the maxillary nerve (CN Vb)
sensory innervation of the midface (lower eyelids and upper teeth)
Which nerves unite to form the maxillary branch? (CN Vb)
zygomatic, infraorbital, anterior, middle and superior alveolar nerves
What fibres are found in the mandibular division (CN Vc)?
motor and sensory
Function of the mandibular division
innervates the muscles of mastication (motor), sensory innervation to lower third of face and side of face
Which nerves unite to form the mandibular nerve?
auriculotemporal nerve (side of face), lingual nerve (floor of mouth), buccal nerve (cheeks), inferior alveolar nerve (lower teeth) - all sensory
What is the name of the line on the face that relates to the occlusal plane?
Frankfurt line (relevant to prosthodontics)
Where does the Frankfurt line pass along the face?
Inferior margin of orbit and upper margin of external auditory meatus
