Gross Anatomy of Head and Neck Flashcards
What are the three gates beween the mouth and the airways?
1) soft palate elevates to close off nose from mouth
2) epiglottis depresses to close off larynx
3) vocal cords in larynx
What is the action of the genioglossus?
Extrinsic paired muscles push tongue out of mouth. Run from mandible to hyoid + tongue
What is the action of hyoglossus
What are the layers of the scalp and skull?
Skin
Connective tissue
Aponeurosis connecting frontalis and occipitalis muscles
Loose CT
Periosteum
_N.B: _SCA are fused and can shear at the loose CT layer
Periosteum (AKA epicranium)
Outer Table
Diploe (medullary cavity)
Endostium (endostial layer of dura)
Inner Table
Where do emissary veins run?
From the CT underlying the skin of the scalp, through the skull, into the superior saggital sinus.
What are the meningeal coverings of the brain and spinal cord? What spaces are potential? What vessels run where?
Potential Space: epidural containing middle meningeal artery
Dura mater:
- endostial layer (fused to….)
- meningeal layer
Potential Space: subdural containing…
Arachnoid mater
Real space: subarachnoid, inflated by CSF
Pia mater (fused to brain surface
What are the three dural reflections and the herniation syndromes associated with them?
Falx cerebri:
- separates the hemispheres
- Subfalcine herniation (AKA: cingulate): compression of ACA gives lower limb plegia/paralysis
Tentorium
- separates the cerebellum from the rest of the brain
- subtentorial (AKA uncal): triad of mydriasis (III), contralateral plegia (cerebral peduncle), coma (RAS in brainstem)
Sellar diaphragm (no herniation syndrome)
Straight sinus connects superior and inferior saggital sinuses
cavernous sinus receives draininage from orbits
inferior petrosal sinus is sampled in the diagnosis of Cushing’s disease
Sinuses ultimately empty into the internal jugular veins
What structures pass through:
- optic canal
- cribiform plate
These are foramina in the anterior cranial fossa:
- the olfactory “nerve” (CNI) through the cribiform plate
- CN two (three letters, three structures pass through the optic canal), the opthalmic artery and central retinal vein (and sympathetics…)
What structures pass through:
- Superior orbital fissure
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
- Foramen lacerum
These foramina are in the middle cranial fossa:
- Superior orbital fissure–> orbit
- III, IV, V1, VI, superior opthalmic veins
- Foramen rotundum–> pterygopalatine fossa
- V2
- Foramen ovale–> infratemporal fossa
- V3 (“3” kind of looks like a”o”, or Some Random hOle)
- Foramen spinosum –> infratemporal fossa
- Middle meningeal artery (think: an MMA fighter snapping someone’s spine)
- Foramen lacerum (not a true foramen in life)
What passes through:
- internal auditory meatus
- jugular foramen
- hypoglossal canal
- foramen magnum
These are in the posterior cranial fossa:
- internal auditory canal: VII, VIII
- Jugular foramen: IX, X, XI, jugular veins
- hypoglossal canal: XII
- foramen magnum: spinal cord, spinal arteries
Which foramen do the following structures go through:
- each cranial nerve
- opthalmic artery
- superior opthalmic veins
- middle meningeal artery
- jugular veins
- vertebral arteries
I: cribiform plate
II: optic canal (with opthalmic artery, central retinal vein, sympathetics)
III: superior orbital fissure (with IV, V1, VI, opthalmic veins)
IV: SOF
V1: SOF
V2: foramen rotundum
V3: foramen ovale
VI: SOF
VII: internal auditory meatus
VIII: internal auditory meatus
IX: jugular foramen
X: jugular foramen
XI: in through foramen magnus, out through jugular foramen
XII: hypoglossal canal
Greater and lesser wings of sphenoid bones, and medial and lateral pteygoid plates
What is the blood input and output of the cavernous sinus? What is the clinical significance?
Receives blood from the opthalmic veins and other veins, drains into into the superior and inferior petrosal sinuses –> jugular
Lots of anastomoses, site for retrograde infection from face to enter brain (trauma to “danger area of face”).
The cavernous sinus is the only site in the human body where an artery passes though an entirely venous structure, so it is possible to have an arterio-venous fistula.
The pituitary lies between the two sinuses and an adenoma may compress the nerves
Which meningeal layers is the cavernous sinus located between?
The two layers of dura (periosteal and meningeal)
What structures pass through the cavernous sinus and where are they located?
Lateral wall: CN III, IV, V1 (all go thru SOF) and V2 (travels to rotundum)
Medial wall (with internal carotid + carotid plexus): VI
Which bone is this?
The muscle cone of the orbit..
Components of the lacrimal apparatus and the flow of tears
Lacrimal gland–> conjunctival sac–> tears wash medially across eye–> collected in superior and inferior lacrimal puntum–>lacrimal canaculi–> lacrimal sac–> nasal cavities
What are the areas of transition of the skull?
pterygopalatine fossa
infratemporal fossa
What cranial structures would you be concerned about with a penetrating wound to the medial, roof, floor and lateral wall of the orbit?
Medial: nasal cavity, ethmoid air sinuses
Floor: maxillary sinuses
Roof: anterior cranial fossa
Lateral wall: temporal fossa (temporalis muscle) or communicating branch of VII…
What demarcates the three cranial fossa?
lesser wing of sphenoid
Petrous ridge
Where does the trigeminal ganglion sit? What is housed in the ganglion?
All the GSA of V cell bodies (no synapses because it is a sensory ganglia)
On the greater wing of the sphenoid )?)
What are the modalities in V1? What are the main branches?
All GSA
1) Frontal nerve travels along medial wall of orbit –>divides into–> supratrochlear (travels above trochlea) and supraorbital
2) lacrimal nerve travels along lateral wall of orbit, thru lacrimal galn and out onto face
3) Nasocilliary crosses over II and divides into anterior ethmoid nerve (pins nerve to medial wall) and infratrochlear nerve. Also gives off ciliary branches (sensory to cornea, afferent limb of corneal reflex). Short ciliary branches contain PNS from CN III and are before the nasociliary crosses over II. Long ciliary branches come off after it crosses over II
How does PNS from CNIII get to the eye?
Oculomotor nerve contains preganglionic fibers, exits through supraorbital fissure.
Synapse in motor root ganglion (cilliary ganglion on cillary nerve) and hop into ciliary nerve to become “short ciliary nerves” and enter eye that way to get to constrictor pupillae and cilliary muscle (rounds lens)
What are the muscles of mastication innervated by V3 and what does each do?
There are 4:
- Temporalis: occludes jaw. Originates at upper border of temporal fossa and inserts on the coronoid process of mandible.
- Masseter:occludes jaw, pulling on the lateral side of the mandible. Originates on the zygomatic arch and inserts on the ramus of the mandible
- Lateral pterygoid: fibers are oriented horizontally, so protrudes the mandible.
- Medial pterygoid: occludes jaw, pulling on the medial side of mandible
Just a nice diagram
What are the divisions of the oculomotor nerve and what does each innervate?
Superior division:
- superior rectus, levatro palpebrae superioris
Inferior division
- medial rectus
- inferior rectus
- inferior oblique
- PNS to cilliary ganglion and short ciliary nerves
Extraocular muscles
Lateral extraocular muscles
What is the temporal fossa? What is the orgin, insertion and innervation of the temporalis muscle?
Major contents in the temporalis muscle, a muscle of mastication innervated by deep temporal nerves of V3, originating on the upper border of the temporal fossa, passing underneath the zygomatic arch and inserting on the coronoid process of the mandible
What are the parts of the mandible?
Lingual nerve in relation to muscles
Where is the infratemporal fossa in relation to the temporal fossa?
Where do the lateral pterygoids attach?
Lateral (has 2 heads)
- upper: infratemporal crest–> mandible near TMJ
- lower: lateral plate of pterygoid process –> near TMJ
Where do the medial pterygoids attach?
Medial pterygoid has two heads (superficial and deep)
- Deep head: the medial surface of the lateral pterygoid plate–> ramus of mandible
- Superficial head: maxilla –> ramus of mandible
(medials pterygoids attach to the ramus of the mandible, whereas the lateral pterygoids attach near the TMJ)
What are the important features of the TMJ? What happens everytime you open your mouth?
It’s actually two joints in one. The lower joint is a hinge, the upper joint allows the mandible to slide forward onto the articular tubercle of the mandible. Everytime you open your mouth the mandible slides forward so it can clear structures in the neck posterior to the mandible.
Where does V3 exit the skull and what are the important branches?
Exits through the foramen ovale into the infratemporal fossa
- Auriculotemporal nerve (behind parotid, wraps around middle meningeal artery. GSA to temporal region. )
- Lingual nerve (GSA to the anterior 2/3 tongue (glossopharygeal (IX) does posterior 1/3) (Picks up chorda tympani (from VII) which does SSA (taste) to anterior 2/3 tongue and PNS to all glands below the oral fissure. Synapses in the otic ganglion which is just medial to V3)
- Inferior alveolar nerve (enters mandible and does sensory to the lower mandible and teeth. Terminates as the mental nerve)
- Buccal nerve part of anterior division of V3 (not labelled in diagram)
Branches of the external carotid
What three bones make up the pterygopalatine fossa?
1) Palatine
2) Maxillary
3) Sphenoid (specifically the ?lateral pterygoid plate
What are the 6 canals associated with the pterygopalatine fossa?
1) sphenopalatine foramen (–>nasal cavity, carries nasopalatine n.)
2) foramen rotundum (cranial cavity- V2 comes through here)
3) Pterygoid canal (–> cranial cavity, carries greater petrosal n. (PNS from VII)
4) Pharyngeal canal (–> nasopharynx, carries pharyngeal nerve)
5) Palatine canal (–>roof of oral cavity, carries descending palatine branch)
6) Inferior orbital fissure (–> orbit, carries infraorbital n.)
Where does V2 exit the skull and what are its major branches?
V2 exits through foramen rotundum into the pterygopalatine fossa (PPF).
- infraorbital nerve, tranverses the PPF anteriorly, gets to skin via infraorbital fissure
- descending palatine nerve, traverses the PPF inferiorly, goes through the palatine canal and branches. one goes to soft palate, one goes to hard palate
- nasopalatine nerve, traverses the PPF superiorly, goes through sphenopalatine foramen into the nasal cavity
- pharyngeal nerve traverses the PPF posteriorly, goes through the pharyngeal canal to innervate the nasopharynx
PNS from CN VII (greater petrosal n.) synapses on the pterygopalatine ganglion and travel to the palatine (via. the descending palatine n.), nasal (via. nasopalatine n.) lacrimal (via. communicating branch (all PNS fibers) of zygomaticofacial n. to the lacrimal n. of V1) and pharyngeal glands (via pharyngeal n.)
How does the greater petrosal nerve get from the brainstem to the pterygopalatine fossa?
Exits with CN VII (lateral pontemedullary junction), goes with VII through the interal acoustic meatus at the petrous part of the temporal bone. The greater petrosal comes out of the bone, joins with postganglionic SNS fibers to form “the nerve of the pterygoid canal”. It is supported by cartilage in the foramen lacerum and moves anteriorly to the pterygoid canal –> pterygopalatine fossa.
N.B: wikipedia says greater petrosal nerve (PNS form VII) and SNS together are “the nerve of the pterygoid canal
What are the various compartments of the neck? What structures are contained in the carotid sheath?
clinical correlate: infxn can spread in the retropharyngeal space
Carotid sheath: jugular vein, common carotid artery, vagus
Where are the greater and lesser cornu of the hyoid? How does the hyoid move when swallowing?
The hyoid bone anteriorly and superiorly- it pulls the larynx forward and up so that food only goes in the pharynx
Relationship of internal and external carotids to SCM and to cervical lymph nodes
Internal carotid: runs medial and deep to SCM. Has deep cervical nodes
External carotid: runs external and along the lateral border of SCM. Have superficial cervical chain surrounding it
What are the infrahyoid muscles? What are they innervated by….
AKA “Strap muscles” (named for lower –> higher attachement)
- Thyrohyoid
- Sternothyroid
- Sternohyoid (most supeficial)
- Omohyoid (omo=scapula)
**act to depress hyoid**
What are the suprahyoid muscles? What do they do? What are they innervated by?
They iniate swallowing by pulling the pharynx up and posteriorly (elevate hyoid).
- mylohyoid: forms floor of mouth (V3- think of it as a muscle of mastication)
- digastric (anterior and posterior bellies, runs through “central tendon”, posterior belly attaches near mastoid process) (anterior belly V3 via mylohyoid nerve; posterior belly VII)
- genio-hyoid (hypoglossal nerve)
- stylohyoid (attaches on styloid process of temporal bone) (VII)
Just a nice figure
What is the relationship of the sublingual and submandibular glands to the suprahyoid muscles?
Wraps around the mylohyoid muscle. Lingual nerve passes underneath the submandibular duct.
Where are the jugulo-digastric and jugulo-omohyoid nodes?
What are the important cartilages of the larynx?
The median crico-thyroid ligament (not labelled) is what is cut in emergency ariway opening (=cricothyrotomy)
What is the blood supply of the thyroid?
Superior (from internal carotid) and Inferior thyroid artery (from common carotid)
Inferior thyroid vein
Arteries given off by the external carotid
Maxillary is the one after facial
What are the extrinsic muscles of the tongue (that we need to know), what does each do and where does it attach
Extrinsic tongue muscles:
- genioglossus: from hyoid to genu of mandible
- hyoglossus: all along the border of hyoid to join genioglossus in the midline, tilts tongue side to side
- styloglossus: styloid process of temporal bone and fuses with the genioglossus. Retracts tongue.
What is the innervation and blood supply of the tongue?
Innervation:
- motor: hypoglossal (XII)
- general sensory: anterior 2/3 lingual n. branch of V1, posterior 1/3 is glossopharyngeal
- special sensory: anterior 2/3 chorda tympani (branch of VII) via lingual nerve, posterior 1/3 is glossopharyngeal
Blood supply
- deep lingual vein
- lingual artery (from ext. carotid)
What are the circular muscles of the pharynx?
Circular (x 3)
- Constrictors aid in peristalsis. Attach in different places anteriorly, but posteriorly come together in the pharyngeal raphe which attaches to the pharyngeal tubercle of the skull
- superior
- middle
- inferior
Where does the pharyngotympanic tube run?
AKA eustachian tube runs from middle ear to pharynx. salpingopharyngeal m. stretches the tube and helps equalize pressure. Also important route for otitis media.
What are the muscles of the soft palate?
They look like a spider, with the body being the soft palate and four legs going up (2x tensor, 2x levator) and down (2 x palatopharyngeal, 2x palatoglossus) (veli is latin for soft)
- tensor veli palatini m.: attaches at the base of the skull on both sides, comes staright down then does a 90 degree turn around the amulus of the medial pterygoid plate. Contraction flatttens the soft palate
- levator veli palatini m. originates from the base of the skull and inserts in the midline of the soft palate. elevates soft palate
- palatopharyngeal m. from soft palate to pharynx
- palatoglossus m.
What muscles form the pharyngeal arches? What is found between the arches?
Palatoglossus arch (anterior) and palatopharyngeal arch (and muscles) .
What is Waldeyer’s ring
The ring of tonsils around the pharynx…
What is the epiglottis? What is it’s function? What is the quandrangular membrane?
A flap of tissue that folds down on the larynx to block food from entering the larynx. The lower edge is attached to the quandrangular membrane. The quandrangular membrane itself has a free edge where mucosa folds over forming the false vocal folds.
The true vocal folds in inferior to that and are mucosa folded over the free edge of the crico thyroid ligament (the one you cut in cricothyrotomy). The mucosa balooned out between the false and true vocal folds is called the laryngeal ventricle.
The true vocal folds produce sound, the false vocal folds close during swallowing
What is the flat muscle just deep to the skin in the neck?
platysma
