HEAD AND NECK IMPORTANT – PAROTID GLAND, THYROID GLAND, TONGUE, TMJ, CAVERNOUS SINUS, FACIAL NERVE, MIDDLE EAR, MUSCLES OF MASTICATION, EXTRAOCULAR MUSCLES, WALDEYER’S RING, LARYNX, PHARYNX

Reading File

Finding Sources

Reading File

Here are your comprehensive Head & Neck notes drawn from Gray's Anatomy for Students, Cummings Otolaryngology, K.J. Lee's Essential Otolaryngology, Scott-Brown's ORL, and Bradley & Daroff's Neurology.

HEAD & NECK - HIGH-YIELD ANATOMY NOTES

1. PAROTID GLAND

Location & Extent

Largest of the three paired salivary glands
Anterior and inferior to the lower half of the ear
Superficial, posterior, and deep to the ramus of the mandible
Extends from the zygomatic arch superiorly to the lower border of the mandible
Posteriorly covers the anterior part of SCM; anteriorly extends halfway across the masseter

Parotid Duct (Stensen's Duct)

Leaves the anterior edge midway between zygomatic arch and corner of the mouth
Crosses the face transversely, turns deep to the buccal fat pad after crossing the medial border of the masseter
Pierces the buccinator muscle
Opens into the oral cavity opposite the second upper molar tooth

Key Structures Passing THROUGH the Parotid (superficial to deep):

Facial nerve [VII] - exits stylomastoid foramen, divides into upper and lower trunks within the gland, then gives 5 terminal branches: temporal, zygomatic, buccal, marginal mandibular, cervical
External carotid artery - gives off posterior auricular artery, then divides into maxillary (passes deep to mandible) and superficial temporal arteries
Retromandibular vein - formed from maxillary and superficial temporal veins within the gland

Clinical Note: Surgical removal of the parotid is technically difficult because of the intimate relationship with the facial nerve. The facial nerve is the key surgical landmark - it splits the gland into superficial and deep lobes (not true anatomical lobes).

2. THYROID GLAND

Location & Structure

Anterior in the neck, below and lateral to the thyroid cartilage
Two lateral lobes + an isthmus (crosses anterior surface of 2nd and 3rd tracheal rings)
Lies deep to sternohyoid, sternothyroid, and omohyoid muscles
Surrounded by the pretracheal fascia (visceral compartment with pharynx, trachea, esophagus)

Embryology

Arises as a median outgrowth from the floor of the pharynx near the base of the tongue
Foramen cecum of the tongue = site of origin
Thyroglossal duct marks path of migration (normally disappears)
Remnants: thyroglossal cyst, fistula, lingual thyroid, pyramidal lobe

Blood Supply

Artery	Origin	Supplies
Superior thyroid	First branch of external carotid	Upper poles; anterior branch anastomoses across isthmus
Inferior thyroid	Thyrocervical trunk (subclavian artery)	Lower poles; supplies parathyroids
Thyroid ima (inconstant)	Brachiocephalic trunk or aortic arch	Anterior tracheal surface

Venous Drainage

Superior thyroid vein → internal jugular vein
Middle thyroid vein → internal jugular vein
Inferior thyroid vein → left/right brachiocephalic veins

Lymphatics: Paratracheal nodes + deep cervical nodes (inferior to omohyoid)

Recurrent Laryngeal Nerves - Critical Surgical Relation

Right RLN: loops around right subclavian artery, ascends in tracheo-esophageal groove
Left RLN: loops around arch of aorta, longer course
Both ascend in the groove between trachea and esophagus to enter the larynx
Run in close proximity to the inferior thyroid artery - at surgical risk during thyroidectomy

3. TONGUE

Surface Anatomy

Sulcus terminalis: V-shaped groove at the junction of anterior two-thirds and posterior one-third
Foramen cecum: pit at the apex of the sulcus terminalis - site of thyroglossal duct origin

Papillae (on anterior 2/3):

Type	Shape	Distribution	Function
Filiform	Thread-like	Bulk of tongue surface	Temperature, texture, pain (CN V3); NO taste
Fungiform	Mushroom-shaped	Diffuse (concentrated anteriorly)	Taste buds on superior surface
Foliate	Folds	Lateral tongue	Taste buds on lateral surface
Circumvallate	Large, V-shaped row	At sulcus terminalis	Taste buds on lateral surface; CN IX taste

Taste Innervation:

Anterior 2/3 - taste via chorda tympani (CN VII) → lingual nerve
Posterior 1/3 - taste via CN IX (glossopharyngeal)
General sensation anterior 2/3: lingual nerve (CN V3)
General sensation posterior 1/3: CN IX
Sensation of epiglottis/vallecula: CN X

Muscles of the Tongue:

Muscle	Origin	Insertion	Action	Nerve
Genioglossus (extrinsic)	Mental spine of mandible	Hyoid + bottom of tongue	Depresses + protrudes tongue	CN XII
Hyoglossus (extrinsic)	Body + greater cornu of hyoid	Side of tongue	Depresses + retracts tongue	CN XII
Styloglossus (extrinsic)	Styloid process	Tip and side of tongue	Retracts + elevates tongue	CN XII
Palatoglossus (extrinsic)	Palatine aponeurosis	Side + dorsum of tongue	Elevates posterior tongue, closes oropharyngeal isthmus	CN X (vagus)
Intrinsic muscles (4 sets)	Within tongue	Within tongue	Alter shape	CN XII

Key Rule: All tongue muscles are supplied by CN XII (hypoglossal) EXCEPT palatoglossus (CN X)

Vascular Supply:

Arterial: lingual artery (2nd branch of external carotid artery)
Venous: lingual veins → internal jugular vein

Frenulum: Fold connecting inferior tongue to the floor of mouth; Wharton's ducts open on either side

4. TEMPOROMANDIBULAR JOINT (TMJ)

Type: Synovial joint

Articulation: Mandibular (glenoid) fossa + mandibular condyle

Unique Features:

Joint space divided into upper and lower cavities by an intra-articular disc
Articular surfaces are fibrous cartilage (NOT hyaline cartilage) - due to intramembranous development
Secondary condylar cartilage present in the head of the condyle until adolescence
Movements influenced by the teeth

Movements:

Upper compartment: Gliding (translational) movements
Lower compartment: Hinge (rotational) movements

Articular Disc: Divides joint into upper and lower compartments

Upper lamina (fibro-elastic)
Lower lamina (non-elastic)
Lateral pterygoid muscle attaches to its anterior surface

Ligaments:

Temporomandibular (lateral) ligament - primary stabilizer
Sphenomandibular ligament - from spine of sphenoid to lingula of mandible
Stylomandibular ligament - from styloid process to angle of mandible

Nerve Supply: Auriculotemporal nerve + masseteric nerve (both from CN V3 mandibular) Blood Supply: Superficial temporal and maxillary arteries

Clinical Note: The neck of the condyle (connecting condyle to ramus) is a frequent fracture site. Proximity to the external auditory meatus means TMJ disorders can mimic ear pain.

5. CAVERNOUS SINUS

Location: Paired dural venous sinuses on either side of the sella turcica/sphenoid body; extends from the apex of the orbit to the apex of the petrous temporal bone

Contents - The "OTSM" Arrangement:

Lateral wall (top to bottom): CN III (oculomotor), CN IV (trochlear), CN V1 (ophthalmic), CN V2 (maxillary)
Running through the sinus itself: CN VI (abducens) - most medially placed, running freely
Internal carotid artery (ICA) - runs through the sinus, with sympathetic plexus

Memory Aid: "O TOM CAT" (Oculomotor, Trochlear, Ophthalmic, Maxillary, Carotid, Abducens, sympatheTic)

Tributaries (blood flows IN from):

Superior ophthalmic vein
Inferior ophthalmic vein
Sphenoparietal sinus
Superficial middle cerebral veins

Drainage (blood flows OUT to):

Superior petrosal sinus → transverse/sigmoid sinus
Inferior petrosal sinus → internal jugular vein
Pterygoid plexus (via emissary veins through foramen ovale)

Dangerous Connections: The facial vein and pterygoid plexus communicate with the cavernous sinus - facial infections (boils, carbuncles in the "danger triangle") can lead to cavernous sinus thrombosis

Clinical Syndromes:

Cavernous Sinus Syndrome: Ophthalmoplegia (CN III, IV, VI) + facial pain/numbness (V1/V2) + Horner's syndrome + proptosis
Tolosa-Hunt Syndrome: Painful idiopathic inflammation of cavernous sinus - responds to corticosteroids
Cavernous Sinus Thrombosis: Septic (S. aureus most common) vs. aseptic; presents with fever, proptosis, periorbital edema, painful ophthalmoplegia
Carotid-Cavernous Fistula (CCF): Pulsating proptosis, bruit, chemosis, orbital congestion

CN VI is the first to be affected in raised ICP (longest intracranial course and freely positioned in the sinus)

6. FACIAL NERVE (CN VII)

Functional Components:

Special Visceral Efferent (SVE): Muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric - all 2nd branchial arch derivatives
General Visceral Efferent (GVE) - via nervus intermedius:
- GSPN (greater superficial petrosal nerve) → pterygopalatine ganglion → lacrimal gland, nasal glands
- Chorda tympani → submandibular ganglion → submandibular + sublingual glands
Special Afferent (SVA): Taste - anterior 2/3 tongue via chorda tympani; palate and tonsils via GSPN
General Somatic Afferent (GSA): Skin of external auditory canal (EAC), conchal auricle

Brainstem Nuclei:

Motor nucleus (SVE)
Superior salivatory nucleus (GVE)
Nucleus of solitary tract (taste - SVA)

Intratemporal Course (within Fallopian Canal):

Meatal/IAC segment: Enters IAC; no fibrous sheath (only arachnoid)
Labyrinthine segment: First, shortest, narrowest; runs superior to cochlea → geniculate ganglion
Geniculate ganglion: First genu; gives off GSPN anteriorly; cell bodies for taste and somatic afferents
Tympanic (horizontal) segment: Runs along medial wall of middle ear, above oval window; most commonly dehiscent here
Second genu: At pyramidal eminence (where stapedius tendon emerges)
Mastoid (vertical) segment: Descends to stylomastoid foramen; gives off chorda tympani and nerve to stapedius

Extratemporal Course:

Exits stylomastoid foramen
Enters parotid gland, divides into upper (temporofacial) and lower (cervicofacial) divisions
Five terminal branches: Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical
Memory Aid: "To Zanzibar By Motor Car" or "Ten Zebras Bit My Calf"

Vulnerabilities (Table from Cummings):

Segment	Key Vulnerability
Labyrinthine	Narrow canal, no epineurium, watershed supply → Bell palsy (viral geniculate ganglionitis)
Geniculate ganglion	Thin/dehiscent bone; tethered by GSPN → fracture, shearing
Tympanic	Dehiscent above oval window; risk in cholesteatoma, otitis media
Mastoid	Variable course; risk in mastoidectomy; lateral to tympanic annulus

Bell Palsy: Most common cause of acute facial paralysis; MRI shows enhancement of distal IAC and labyrinthine segment; imaging not typically required unless atypical features

7. MIDDLE EAR

Structure:

Air-filled, mucous membrane-lined space in the temporal bone
Between the tympanic membrane (laterally) and the lateral wall of the inner ear (medially)
Develops from the first pharyngeal pouch (foregut extension)

Divisions:

Hypotympanum: Below tympanic annulus
Mesotympanum: Space medial to the TM; extends from ET opening anteriorly to facial nerve posteriorly
Epitympanum (attic): Superior recess

Boundaries:

Wall	Composition	Important Structures
Tegmental (roof)	Tegmen tympani (thin bone)	Separates from middle cranial fossa
Jugular (floor)	Thin bone	Separates from internal jugular vein
Membranous (lateral)	Tympanic membrane + bony lateral wall of epitympanic recess	TM = cone of light, umbo, pars flaccida/tensa
Labyrinthine (medial)	Bony wall	Promontory, oval window (stapes), round window
Mastoid (posterior)	Opens into aditus ad antrum	Facial nerve, pyramidal process
Carotid (anterior)	Opens into ET	Internal carotid artery medial to ET opening

Ossicular Chain:

Malleus → connected to tympanic membrane (handle), articulates with incus
Incus → middle bone; articulates with malleus (synovial) and stapes (synovial)
Stapes → footplate in oval window

Eustachian Tube (ET):

45° angle from middle ear to nasopharyngeal opening at torus tubarius
Proximal 1/3: bony (in petrous bone)
Distal 2/3: fibrocartilaginous, collapsed at rest
Tensor veli palatini opens the tube during swallowing/yawning
Narrowest point: bony-cartilaginous junction
ICA closely associated with the medial wall at the tympanic opening

Muscles in the Middle Ear:

Tensor tympani: Attached to handle of malleus; innervated by CN V3 (medial pterygoid nerve); dampens vibration
Stapedius: Attached to neck of stapes; innervated by CN VII; protective reflex against loud sounds; paralysis → hyperacusis

8. MUSCLES OF MASTICATION

All 4 primary muscles of mastication are innervated by CN V3 (mandibular nerve)

Muscle	Origin	Insertion	Primary Action	Nerve
Masseter	Zygomatic arch + maxillary process of zygomatic bone	Angle + lateral surface of mandibular ramus, coronoid process	Elevation + protrusion	Masseteric n. (V3)
Temporalis	Superior/inferior temporal lines (parietal, frontal, sphenoid bones)	Coronoid process of mandible	Elevation + retraction	Deep temporal n. (V3)
Lateral pterygoid	Superior head: greater wing of sphenoid; Inferior head: lateral pterygoid plate	Superior head: pterygoid fovea of condyle; Inferior head: pterygoid fovea/ramus	Depression, protrusion, side-to-side (contraction of both = protrusion; one side = lateral excursion)	Lateral pterygoid n. (V3)
Medial pterygoid	Deep head: medial lateral pterygoid plate; Superficial head: pyramidal process of palatine + maxillary tuberosity	Medial angle of mandible	Elevation + side-to-side	Medial pterygoid n. (V3)

Functional Summary (from Cummings):

Motion	Muscles
Jaw CLOSING (elevation)	Masseter, temporalis, medial pterygoid, superior head lateral pterygoid
Jaw OPENING (depression)	Inferior head lateral pterygoid, anterior belly digastric, mylohyoid, geniohyoid
Protrusion	Masseter + lateral pterygoid
Retraction	Temporalis (posterior fibers)
Side-to-side (grinding)	Lateral + medial pterygoid (contralateral)

Additional "muscles of mastication" - jaw openers (CN V3 except geniohyoid):

Digastric (anterior belly): CN V3 (inferior alveolar) - depression + retraction
Mylohyoid: CN V3 - depression
Geniohyoid: CN XII (hypoglossal) - depression

9. EXTRAOCULAR MUSCLES

Six Muscles and Primary Actions:

Muscle	Primary Action	Nerve
Medial rectus (MR)	Adduction (moves eye inward)	CN III
Lateral rectus (LR)	Abduction (moves eye outward)	CN VI
Superior rectus (SR)	Elevation (also intorsion + adduction)	CN III
Inferior rectus (IR)	Depression (also extorsion + adduction)	CN III
Superior oblique (SO)	Intorsion (primary); also depression + abduction	CN IV
Inferior oblique (IO)	Extorsion (primary); also elevation + adduction	CN III

Mnemonic for nerve supply: "LR6 SO4 rest 3" (Lateral Rectus = VI, Superior Oblique = IV, rest = III)

Six Cardinal Directions of Gaze (Yoke Muscles):

Direction	Right eye	Left eye
Right	LR	MR
Left	MR	LR
Up-right	SR	IO
Down-right	IR	SO
Up-left	IO	SR
Down-left	SO	IR

Orbital Blowout Fracture:

Most commonly traps inferior rectus (IR), second most common: inferior oblique (IO)
Presents with limited upward gaze and diplopia (not paralysis - mechanical entrapment)
Forced duction test: grasp globe with forceps near limbus and rotate; if it moves freely = paralysis; if restricted = entrapment
More common in younger patients (greenstick fracture, smaller defect)

All extraocular muscles originate from the annulus of Zinn (common tendinous ring) EXCEPT the inferior oblique (originates from the orbital floor near the lacrimal fossa)

CN III palsy: Down and out eye, ptosis, dilated unreactive pupil (if compressive - "surgical CN III palsy") CN IV palsy: Vertical diplopia, worse going down stairs; patient tilts head to opposite side CN VI palsy: Horizontal diplopia, eye deviated medially (LR paralysis); first nerve affected in raised ICP

10. WALDEYER'S RING

Definition: A ring of lymphoid tissue encircling the pharyngeal inlet

Components:

Pharyngeal tonsil (adenoid) - in nasopharynx (roof and posterior wall)
Tubal tonsils - around the pharyngeal opening of the Eustachian tubes
Palatine tonsils - between the anterior (palatoglossal) and posterior (palatopharyngeal) pillars in the oropharynx - the most commonly referred to "tonsils"
Lingual tonsil - on the posterior/base of the tongue
(Lateral pharyngeal bands may also be included)

Clinical Significance:

Most common site of head and neck lymphoma (from Grainger & Allison's Radiology)
Strong link between Waldeyer's ring lymphomas and GI tract involvement (synchronous/metachronous) - up to 20% are MALT type; endoscopy + FDG PET/CT staging recommended
Tonsils most commonly affected - asymmetric mucosal thickening on CT/MRI; circumferential or multifocal pattern suggests NHL
NHL comprises 12% of paranasal sinus tumors
MRI is preferred for evaluating head and neck lymphoma extent

Palatine Tonsil Blood Supply:

Main supply: tonsillar branch of the facial artery
Also: ascending palatine, ascending pharyngeal, lingual, and lesser palatine arteries
Dangerous bleed post-tonsillectomy: Tonsillar branch of facial artery (or post-pharyngeal branch in superior pole)

11. LARYNX

Cartilages (9 total):

Unpaired (3): Thyroid, cricoid, epiglottis
Paired (3 pairs): Arytenoids, corniculates, cuneiforms

Cartilage	Type	Notes
Thyroid	Hyaline	Largest; "Adam's apple"; angle 90° in male, 120° in female
Cricoid	Hyaline	Only complete ring in the airway; narrowest point in adults
Epiglottis	Elastic fibrocartilage	Attached to thyroid cartilage by thyroepiglottic ligament
Arytenoids	Hyaline	Sit on cricoid; vocal process (attach vocal cord) + muscular process
Corniculates	Elastic	Sit on apex of arytenoids (Santorini's cartilages)
Cuneiforms	Elastic	In aryepiglottic fold (Wrisberg's cartilages)

Membranes & Ligaments:

Thyrohyoid membrane: Connects thyroid cartilage to hyoid bone; pierced by superior laryngeal artery and internal laryngeal nerve
Cricothyroid membrane (conus elasticus): Emergency surgical access (cricothyrotomy)
Cricotracheal ligament: Connects cricoid to first tracheal ring
Quadrangular membrane: Between epiglottis and arytenoids; lower free edge = vestibular ligament (false vocal cord)
Conus elasticus: Upper free edge = vocal ligament (true vocal cord)

Compartments:

Supraglottis (vestibule): Epiglottis → false vocal cords (vestibular folds)
Glottis: True vocal cords (rima glottidis between them)
Infraglottis: Below true cords to lower border of cricoid

Muscles - Intrinsic (all innervated by RLN except cricothyroid):

Muscle	Action
Posterior cricoarytenoid (PCA)	ONLY abductor of vocal cords (opens glottis) - "safety muscle"
Lateral cricoarytenoid (LCA)	Adducts vocal cords
Transverse arytenoid	Adducts vocal cords
Thyroarytenoid	Relaxes vocal cords
Cricothyroid	Tenses vocal cords

Nerve Supply:

Superior laryngeal nerve (SLN) from vagus:
- External branch: motor to cricothyroid muscle
- Internal branch: sensory to larynx above vocal cords; enters through thyrohyoid membrane
Recurrent laryngeal nerve (RLN): Motor to all intrinsic muscles except cricothyroid; sensory below vocal cords
RLN injury: unilateral = hoarseness; bilateral = stridor/respiratory distress

Blood Supply:

Superior laryngeal artery (from superior thyroid artery) with internal laryngeal nerve through thyrohyoid membrane
Inferior laryngeal artery (from inferior thyroid artery)

Lymphatics:

Above vocal cords → deep cervical (upper) nodes (rich lymphatic supply → early supraglottic spread)
Below vocal cords → paratracheal + deep cervical (lower) nodes
Vocal cords: VERY sparse lymphatics → local disease stays localized longer

12. PHARYNX

Subdivisions:

Region	Extent	Key Structures
Nasopharynx	Base of skull → soft palate	Adenoids (pharyngeal tonsil), Eustachian tube openings (torus tubarius), fossa of Rosenmüller (lateral recess - most common site of nasopharyngeal carcinoma)
Oropharynx	Soft palate → hyoid/valleculae	Palatine tonsils, base of tongue (lingual tonsil), valleculae, posterior pharyngeal wall
Hypopharynx (laryngopharynx)	Hyoid → lower border of cricoid	Pyriform sinuses, post-cricoid region, posterior pharyngeal wall

Muscles of the Pharynx:

Constrictors (external layer):

Muscle	Origin	Nerve	Notes
Superior constrictor	Pterygoid hamulus, pterygomandibular raphe, mandible, tongue	CN X (pharyngeal plexus)	Passavant's ridge (closes nasopharynx in swallowing)
Middle constrictor	Hyoid bone (greater/lesser cornu)	CN X
Inferior constrictor	Thyroid + cricoid cartilages	CN X + external SLN	Lower fibers = cricopharyngeus (Killian's triangle = Zenker's diverticulum site)

Longitudinal muscles (elevate pharynx):

Stylopharyngeus - CN IX (only pharyngeal muscle innervated by CN IX)
Palatopharyngeus - CN X
Salpingopharyngeus - CN X

Waldeyer's ring is integral to the pharynx - see section 10 above

Killian's Triangle / Dehiscence:

Gap between the oblique fibers of the inferior constrictor (thyropharyngeus) and the horizontal cricopharyngeus muscle
Site of Zenker's diverticulum (pharyngeal pouch) formation

Blood Supply:

Ascending pharyngeal artery (from external carotid)
Tonsillar branch of facial artery
Palatine arteries

Nerve Supply (Pharyngeal Plexus):

Motor: CN X (pharyngeal branches) - all constrictors and most elevators
Sensory: CN IX (mostly) + CN X
Exception: stylopharyngeus = CN IX (motor)

QUICK-REFERENCE: KEY NERVE-MUSCLE ASSOCIATIONS

Nerve	Muscles Supplied
CN V3 (mandibular)	All 4 muscles of mastication, tensor veli palatini, tensor tympani, anterior belly digastric, mylohyoid
CN VII (facial)	Muscles of facial expression, stapedius, stylohyoid, posterior belly digastric
CN IX	Stylopharyngeus ONLY
CN X	Most pharyngeal muscles, cricothyroid (external SLN), intrinsic laryngeal via RLN
CN XI	SCM, trapezius
CN XII	All tongue muscles except palatoglossus
CN III	All extraocular muscles except LR and SO
CN IV	Superior oblique
CN VI	Lateral rectus

Sources: Gray's Anatomy for Students | Cummings Otolaryngology Head and Neck Surgery | K.J. Lee's Essential Otolaryngology | Scott-Brown's Otorhinolaryngology Head & Neck Surgery | Bradley and Daroff's Neurology in Clinical Practice | Grainger & Allison's Diagnostic Radiology

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