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I now have solid content from Gray's Anatomy for Students. Let me compile the full, high-yield PCT notes.
Head & Neck Anatomy - PCT High-Yield Notes (MBBS)
Source: Gray's Anatomy for Students
1. SKULL (Bones & Landmarks)
Major skull bones:
- Neurocranium: Frontal, parietal (x2), occipital, temporal (x2), sphenoid, ethmoid
- Viscerocranium (face): Maxilla, mandible, zygomatic, nasal, lacrimal, palatine, inferior nasal concha, vomer
Key foramina and what passes through them:
| Foramen | Contents |
|---|---|
| Foramen magnum | Medulla oblongata, vertebral arteries, spinal accessory nerve [XI] roots |
| Foramen rotundum | V2 (maxillary nerve) |
| Foramen ovale | V3 (mandibular nerve) |
| Foramen spinosum | Middle meningeal artery |
| Foramen lacerum | Internal carotid artery (traverses upper part) |
| Jugular foramen | CN IX, X, XI + internal jugular vein |
| Hypoglossal canal | CN XII |
| Internal acoustic meatus | CN VII + CN VIII |
| Stylomastoid foramen | CN VII (exits skull) |
| Superior orbital fissure | CN III, IV, V1, VI + ophthalmic vein |
| Inferior orbital fissure | V2 (infraorbital nerve), zygomatic nerve |
| Optic canal | CN II (optic nerve) + ophthalmic artery |
2. SCALP - Layers (Mnemonic: SCALP)
| Layer | Details |
|---|---|
| S - Skin | Hair-bearing, dense |
| C - Connective tissue (superficial fascia) | Dense, contains vessels & nerves; wounds gape widely here |
| A - Aponeurosis (epicranial / galea aponeurotica) | Connects frontalis to occipitalis |
| L - Loose areolar tissue | "Danger zone" - infections/blood spread here; emissary veins connect to intracranial sinuses |
| P - Pericranium (periosteum) | Closely adherent to skull outer table |
Key point: The "dangerous layer" (loose areolar tissue) allows spread of infection to the cranial cavity via emissary veins.
3. TRIANGLES OF THE NECK
Boundaries:
- Anterior triangle: Medial border of SCM (lat), inferior border of mandible (sup), midline (med)
- Posterior triangle: SCM (ant), trapezius (post), middle 1/3 clavicle (inf)
Subdivisions of Anterior Triangle:
| Triangle | Boundaries | Key Contents |
|---|---|---|
| Submental | Anterior belly digastric (x2) + hyoid | Small lymph nodes, beginning of anterior jugular vein |
| Submandibular | Anterior + posterior belly digastric + mandible | Submandibular gland, facial artery/vein, CN XII, lingual nerve |
| Carotid | Posterior belly digastric + omohyoid + SCM | Common/internal/external carotid, CN X, CN XII, internal jugular vein |
| Muscular | Omohyoid + SCM + midline | Strap muscles, thyroid, parathyroid, trachea, esophagus |
Posterior triangle contents:
- Accessory nerve [XI] (crosses at junction of upper 1/3 and lower 2/3 of SCM)
- Cervical plexus branches (lesser occipital, great auricular, transverse cervical, supraclavicular)
- Brachial plexus roots (C5-T1 emerge here)
- Subclavian artery (3rd part)
- External jugular vein
4. MUSCLES OF THE NECK
Suprahyoid muscles (raise hyoid during swallowing):
| Muscle | Nerve |
|---|---|
| Digastric - anterior belly | Mylohyoid nerve (from V3) |
| Digastric - posterior belly | Facial nerve [VII] |
| Mylohyoid | Mylohyoid nerve (from V3) |
| Stylohyoid | Facial nerve [VII] |
| Geniohyoid | C1 via CN XII |
Infrahyoid "strap" muscles (depress hyoid):
| Muscle | Nerve |
|---|---|
| Sternohyoid | Ansa cervicalis (C1-C3) |
| Omohyoid | Ansa cervicalis (C1-C3) |
| Sternothyroid | Ansa cervicalis (C1-C3) |
| Thyrohyoid | C1 via CN XII |
Mnemonic for strap muscles: "Some Ointment Stops The itching" (Sternohyoid, Omohyoid, Sternothyroid, Thyrohyoid)
SCM (Sternocleidomastoid):
- Origin: Sternal head (manubrium) + clavicular head
- Insertion: Mastoid process + superior nuchal line
- Nerve: CN XI (spinal accessory) + C2/C3 (proprioception)
- Action: Unilateral = tilts head to same side, rotates face to opposite side; Bilateral = flexes neck
5. DEEP CERVICAL FASCIA - Layers
- Investing layer - surrounds all of neck, encloses trapezius + SCM
- Pretracheal (middle) layer - encloses neck viscera (thyroid, trachea, esophagus)
- Prevertebral (deep) layer - surrounds vertebral column + deep back muscles
- Carotid sheath - contains internal carotid/common carotid artery, internal jugular vein, vagus nerve [X]
6. CRANIAL NERVES - Head & Neck Summary
| CN | Name | Function | Exit from skull |
|---|---|---|---|
| I | Olfactory | Smell | Cribriform plate |
| II | Optic | Vision | Optic canal |
| III | Oculomotor | Eye movement (most), pupil constriction, lid elevation | Superior orbital fissure |
| IV | Trochlear | Superior oblique muscle | Superior orbital fissure |
| V | Trigeminal | Face sensation + muscles of mastication | V1: SOF; V2: F. rotundum; V3: F. ovale |
| VI | Abducent | Lateral rectus | Superior orbital fissure |
| VII | Facial | Muscles of expression, taste (ant 2/3 tongue), lacrimal/salivary glands | Stylomastoid foramen |
| VIII | Vestibulocochlear | Hearing + balance | Internal acoustic meatus |
| IX | Glossopharyngeal | Taste/sensation post 1/3 tongue, parotid gland | Jugular foramen |
| X | Vagus | Pharynx/larynx/thorax/abdomen | Jugular foramen |
| XI | Accessory | SCM + trapezius | Jugular foramen |
| XII | Hypoglossal | All intrinsic tongue muscles | Hypoglossal canal |
7. ORBIT
Bony orbit walls:
- Roof: Frontal bone + lesser wing of sphenoid
- Floor: Maxilla + zygomatic + palatine (thinnest wall - "blowout fractures")
- Medial wall: Ethmoid (lamina papyracea), lacrimal, maxilla, sphenoid (thinnest with ethmoid)
- Lateral wall: Zygomatic + greater wing of sphenoid (strongest wall)
Extraocular muscles (all CN III except):
- Superior oblique - CN IV (trochlear)
- Lateral rectus - CN VI (abducent)
- All others (SR, IR, MR, IO, levator palpebrae) - CN III
"LR6 SO4 AO3" - Lateral Rectus = CN VI, Superior Oblique = CN IV, All Others = CN III
Eyelid layers (superficial to deep):
Skin → Subcutaneous tissue → Orbicularis oculi (CN VII) → Orbital septum → Tarsus + levator palpebrae (CN III)
8. PHARYNX
Three parts:
- Nasopharynx: Post-nasal space; contains adenoids (pharyngeal tonsil); Eustachian tube opens here
- Oropharynx: Palatine tonsils ("the tonsils"); between soft palate and epiglottis
- Laryngopharynx (hypopharynx): C3-C6; leads to esophagus; pyriform fossae on either side of larynx (foreign bodies lodge here)
Nerve supply - Pharyngeal plexus: CN IX (sensory mainly) + CN X (motor to all pharyngeal constrictors, except stylopharyngeus = CN IX)
9. LARYNX
Cartilages:
- Unpaired: Thyroid, cricoid, epiglottis
- Paired: Arytenoid, corniculate, cuneiform
Key points:
- Cricoid is the only complete cartilaginous ring in the airway
- Rima glottidis = space between vocal folds (true vocal cords)
- Vestibular folds = false vocal cords (above true cords)
Nerve supply:
- Superior laryngeal nerve (branch of vagus): External branch → cricothyroid muscle (only extrinsic laryngeal muscle); Internal branch → sensory above vocal cords
- Recurrent laryngeal nerve (branch of vagus): All intrinsic laryngeal muscles + sensory below vocal cords
- Clinical: RLN injury → hoarseness (unilateral) or aphonia (bilateral)
10. THYROID & PARATHYROID
- Thyroid: 2 lateral lobes + isthmus at C2-C4 tracheal rings; blood supply from superior thyroid artery (external carotid) and inferior thyroid artery (thyrocervical trunk from subclavian)
- Berry's ligament: Suspensory ligament of thyroid to trachea; RLN runs just posterior - at risk in thyroid surgery
- Parathyroids: Usually 4 glands; superior pair from 4th pharyngeal pouch; inferior pair from 3rd pharyngeal pouch (descend with thymus)
11. FACE - Muscles of Expression
All innervated by CN VII (facial nerve) - "7 branches" (mnemonic: "Two Zombies Bit My Cat"):
- Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical
Parotid gland:
- Largest salivary gland; secretomotor = CN IX via auriculotemporal nerve
- CN VII passes through (but NOT innervates) the parotid - forms the parotid plexus of nerves
- Stensen's duct opens opposite upper 2nd molar
12. ROOT OF THE NECK - Key Structures
- Ansa cervicalis (C1-C3): Innervates all infrahyoid strap muscles except thyrohyoid
- Phrenic nerve (C3, C4, C5): "C3, 4, 5 keeps the diaphragm alive"; crosses anterior scalene
- Brachial plexus roots (C5-T1): Form trunks in posterior triangle
- Subclavian artery: 3 parts defined by anterior scalene; gives off vertebral, thyrocervical, internal thoracic arteries
- Thoracic duct: Drains into junction of left subclavian + left internal jugular veins
13. ARTERIAL SUPPLY - Key Points
- Common carotid bifurcates at C3/C4 (upper border of thyroid cartilage) into:
- Internal carotid (no branches in neck) → enters carotid canal → supplies brain
- External carotid (8 branches in neck/face) → supplies face/neck structures
- Carotid sinus (at bifurcation): baroreceptor, CN IX
- Carotid body (at bifurcation): chemoreceptor, CN IX + CN X
Quick-Fire PCT Must-Knows
| Fact | Answer |
|---|---|
| Roof of infratemporal fossa | Greater wing of sphenoid |
| Muscle that opens mouth | Lateral pterygoid (depresses mandible) |
| Muscle of mastication NOT in ITF | Masseter (superficial to ramus) |
| Taste - anterior 2/3 tongue | Chorda tympani (branch of CN VII) |
| Taste - posterior 1/3 tongue | CN IX |
| Motor to tongue | CN XII (hypoglossal) |
| Sensory to tongue (anterior 2/3) | Lingual nerve (V3) |
| Opening in thyroid membrane | Internal laryngeal nerve + superior laryngeal vessels |
| Cricothyroid - only muscle supplied by external laryngeal nerve | Tensing/lengthening vocal cords |
| Waldeyer's ring components | Pharyngeal tonsil + tubal tonsils + palatine tonsils + lingual tonsil |
Based on Gray's Anatomy for Students. Good luck on your PCT!
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