03/07/2026
HEAD & NECK ANATOMY
High-Yield Notes — NEET PG / MDS 2027
Original notes with schematic illustrations — not affiliated with or copied from any coaching institute
1. Triangles of the Neck
The neck is divided by the Sternocleidomastoid (SCM) into an Anterior triangle and a Posterior triangle. This is one of the most frequently tested topics — know the boundaries, contents, and subdivisions cold.
Fig 1. Triangles of the neck — schematic (original illustration)
Anterior Triangle — Boundaries
• Anterior: Midline of neck
• Posterior: Anterior border of SCM
• Superior: Lower border of mandible + line to mastoid
• Apex: Suprasternal notch
Anterior Triangle — Subdivisions
• Submandibular (digastric) triangle — submandibular gland, facial artery
• Submental triangle — submental lymph nodes
• Carotid triangle — carotid bifurcation, CN X, XII, sympathetic chain ⭐ HIGH YIELD
• Muscular triangle — infrahyoid muscles, thyroid, parathyroid
Posterior Triangle — Boundaries
• Anterior: Posterior border of SCM
• Posterior: Anterior border of Trapezius
• Base: Middle 1/3 of clavicle
Posterior Triangle — Subdivisions
• Occipital triangle — spinal accessory nerve (CN XI) ⭐ clinically important (surgery risk)
• Supraclavicular (subclavian) triangle — subclavian artery, brachial plexus trunks
MNEMONIC — Carotid triangle contents: “VAN + X, XII” — Vein (IJV), Artery (carotid), Nerve (vagus), plus hypoglossal (XII) and accessory (XI) nerves passing through.
2. Skull Base Foramina & Cranial Nerve Exits
Foramen-nerve matching is a guaranteed 1-2 mark question almost every year. Learn it as a table, not prose.
Fig 2. Skull base foramina — schematic (original illustration)
Foramen
Fossa
Contents
Cribriform plate
Anterior
CN I (olfactory fila)
Optic canal
Middle
CN II, Ophthalmic artery
Superior orbital fissure
Middle
CN III, IV, V1, VI + ophthalmic vein
Foramen rotundum
Middle
CN V2 (maxillary)
Foramen ovale
Middle
CN V3 (mandibular), accessory meningeal a.
Foramen spinosum
Middle
Middle meningeal artery, meningeal branch of V3
Foramen lacerum
Middle
Internal carotid artery (passes over, not through)
Internal acoustic meatus
Posterior
CN VII, VIII
Jugular foramen
Posterior
CN IX, X, XI + internal jugular vein
Hypoglossal canal
Posterior
CN XII
Foramen magnum
Posterior
Medulla, spinal root of CN XI, vertebral arteries
MNEMONIC — Jugular foramen (CN IX, X, XI): “Vagus takes Glossopharyngeal and Accessory” = 9, 10, 11 exit together, closely related to the internal jugular vein.
3. Cavernous Sinus ⭐ Repeatedly Asked
Dural venous sinus lateral to the body of the sphenoid bone / pituitary fossa. Structures pass either through its lateral wall or directly through the sinus.
Lateral wall (in order, top to bottom):
• CN III (oculomotor)
• CN IV (trochlear)
• CN V1 (ophthalmic)
• CN V2 (maxillary)
Within the sinus (surrounded by blood, most vulnerable):
• Internal carotid artery (with sympathetic plexus)
• CN VI (abducens) ⭐ first nerve affected in cavernous sinus thrombosis
CLINICAL PEARL: Cavernous sinus thrombosis classically presents with proptosis, chemosis, and ophthalmoplegia — CN VI palsy is often the earliest sign since it lies free within the sinus, unprotected by the dural wall.
4. Thyroid Gland — Quick Recall
Feature
Key Fact
Capsule
True capsule (from gland) + false capsule (pretracheal fascia)
Ligament of Berry
Attaches gland to cricoid cartilage — thyroid moves with swallowing
Blood supply
Superior thyroid a. (external carotid), Inferior thyroid a. (thyrocervical trunk)
Nerve at risk — superior pole
External laryngeal nerve (near superior thyroid vessels)
Nerve at risk — inferior pole
Recurrent laryngeal nerve (close to inferior thyroid artery)
RLN injury
Hoarseness (unilateral); airway compromise (bilateral)
5. Rapid-Fire Facts (Last-Minute Revision)
• Pretracheal fascia encloses thyroid, trachea, esophagus, and infrahyoid muscles
• Danger space of neck lies between alar fascia and prevertebral fascia — communicates with posterior mediastinum
• Great auricular nerve — most commonly injured nerve in parotid surgery (sensory, not facial nerve)
• Facial nerve (CN VII) — divides parotid gland into superficial and deep lobes
• Frey's syndrome — gustatory sweating after parotid surgery, due to aberrant regeneration of auriculotemporal nerve fibers
• Pharyngeal arch derivatives — Arch 1: Trigeminal (V); Arch 2: Facial (VII); Arch 3: Glossopharyngeal (IX); Arch 4/6: Vagus (X)
