Second Part of the Maxillary Artery (Pterygoid Part)

Location / Relation

Branches and Their Supplies

Key Points

• All branches of the second part accompany branches of V3 (mandibular nerve) - a classic exam point.
• The deep temporal arteries are usually two (anterior and posterior).
• The pterygoid arteries are numerous small vessels supplying both heads of the pterygoid muscles.
• The masseteric artery passes through the mandibular notch (sigmoid notch) to reach the masseter.
• The buccal artery is the only branch that reaches the cheek mucosa and skin.

Overview of All Three Parts (for context)

• Gray's Anatomy for Students, p. 1130

Venous Drainage of the Oral Cavity

1. Tongue

• Begins near the apex of the tongue, visible through the mucosa on the ventral surface
• Runs posteriorly on the underside of the tongue alongside (then separated by) the hyoglossus muscle
• Accompanies the hypoglossal nerve (CN XII) on the external surface of hyoglossus - this vein is prone to injury during hypoglossal nerve dissection
• Joins a sublingual vein (from the sublingual salivary gland) to form the vena comitans nervi hypoglossi
• Drains into the internal jugular vein (or may join the lingual or facial vein first)

• Drain the dorsum and sides of the tongue
• Follow the lingual artery between the hyoglossus and genioglossus muscles
• Drain into the internal jugular vein at the level of the hyoid bone

2. Palate, Teeth, Cheeks, and Gingiva - via Pterygoid Plexus

• Posteriorly via a short maxillary vein into the retromandibular vein
• Anteriorly via the deep facial vein into the facial vein

3. Lips

Summary Flowchart

Tongue (deep & dorsal lingual veins)
        ↓
  Internal Jugular Vein  ←────────────────────────┐
                                                   │
Palate / Teeth / Cheeks / Gingiva                  │
  → Pterygoid Plexus                               │
      ↓ (posterior)          ↓ (anterior)          │
  Maxillary Vein         Deep Facial Vein           │
      ↓                       ↓                    │
  Retromandibular Vein → Facial Vein               │
              ↓                                    │
         Common Facial Vein ───────────────────────┘

Lips → Facial Vein → Common Facial Vein → Internal Jugular Vein

Clinically Important Note: Pterygoid Plexus Connections

• Spread of dental/oral infections to the cavernous sinus (cavernous sinus thrombosis)
• Retrograde spread of anesthetic agents injected under pressure near the pterygoid plexus
• Gray's Anatomy for Students, p. 1131
• Scott-Brown's Otorhinolaryngology, Head & Neck Surgery, Ch. 41
• Cummings Otolaryngology Head and Neck Surgery, Ch. 91

Lymphatic Drainage of the Oral Cavity

• Level Ia - Submental nodes (between anterior bellies of digastric, above hyoid)
• Level Ib - Submandibular nodes (within submandibular triangle)
• Level II - Upper deep cervical nodes (jugulodigastric = most important)
• Level III/IV - Jugulo-omohyoid nodes (at omohyoid-IJV crossing)

1. Tongue

2. Floor of Mouth

3. Lips

4. Cheeks (Buccal Mucosa)

• Drains to submental and submandibular nodes (Levels Ia and Ib)
• The buccal surface extends posteriorly to the pterygomandibular raphe; lesions in this region also tend to drain to Level Ib

5. Teeth and Gingivae

6. Palate

• Venous drainage from the hard palate goes to the pterygoid plexus; lymphatics follow a separate path to upper cervical nodes

7. Final Efferent Pathway

Oral cavity structures
        ↓
Submental (Ia) + Submandibular (Ib) nodes
        ↓
Upper deep cervical - Jugulodigastric nodes (Level II)
        ↓
Mid/lower deep cervical - Jugulo-omohyoid nodes (Levels III/IV)
        ↓
Thoracic duct (left) / Right lymphatic duct (right)
        ↓
Venous system (jugulosubclavian angle)

Clinical Significance

1. Bilateral drainage of the tongue tip, central floor of mouth, and posterior tongue means bilateral neck node dissection may be needed for midline lesions.
2. The jugulodigastric node (Level II) is the first node enlarging in tonsillar, posterior tongue, and oropharyngeal malignancies - it is the sentinel node for much of the upper aerodigestive tract.
3. The jugulo-omohyoid node (Level III/IV) is particularly important for anterior floor of mouth, oropharyngeal, and laryngeal drainage.
4. Retropharyngeal nodes are an important skip route for hard palate tumours - these nodes are not removed in standard neck dissections and must be specifically addressed.
5. Approx. 150 lymph nodes exist on each side of the neck; examination of both sides is mandatory even for clinically unilateral oral cavity lesions.

• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Ch. 41
• Cummings Otolaryngology Head and Neck Surgery, Ch. 91
• S Das Manual of Clinical Surgery, 13th Ed.

Nerve Supply of the Oral Cavity

Overview

1. General sensation (GSA) - predominantly trigeminal nerve (V2 and V3)
2. Special sensation / taste (SA) - facial nerve (VII) via chorda tympani (anterior 2/3 tongue), glossopharyngeal (IX) for posterior 1/3
3. Motor (GSE) - hypoglossal nerve (XII) for tongue; V3 for floor muscles; vagus (X) for soft palate
4. Autonomic - parasympathetic via VII and IX; sympathetic from T1 via superior cervical ganglion

A. SENSORY (GENERAL SENSATION)

1. Maxillary Nerve (V2) - Upper Oral Cavity

2. Mandibular Nerve (V3) - Lower Oral Cavity

B. TASTE (SPECIAL SENSATION)

Key point: The vallate papillae sit ON the sulcus terminalis - they receive taste from CN IX (not VII). CN IX branches also creep anterior to the sulcus terminalis to supply taste from these papillae.

C. MOTOR SUPPLY

Tongue Muscles - Hypoglossal Nerve (CN XII)

• Intrinsic muscles (superior/inferior longitudinal, transverse, vertical)
• Genioglossus (most important - tongue protrusion)
• Hyoglossus (tongue depression)
• Styloglossus (tongue retraction/elevation)
• Exception: Palatoglossus is supplied by the vagus nerve (CN X)

Floor of Mouth

• Mylohyoid and anterior belly of digastric - nerve to mylohyoid (branch of V3)
• Geniohyoid - C1 fibers traveling with CN XII

Soft Palate Muscles - Vagus Nerve (CN X) via Pharyngeal Plexus

• Levator veli palatini, palatoglossus, palatopharyngeus, musculus uvulae
• Exception: Tensor veli palatini - nerve to medial pterygoid (V3)

Lips and Cheeks - Facial Nerve (CN VII)

• All muscles of facial expression including orbicularis oris (lip sealing) and buccinator (cheek muscle) - supplied by facial nerve (CN VII)

D. AUTONOMIC SUPPLY

E. Summary Table by Structure

Clinical Notes

• The lingual nerve passes medial to the lower third molar - at risk during wisdom tooth extraction, causing loss of anterior 2/3 tongue sensation
• Chorda tympani injury (in middle ear surgery or parotid surgery) causes loss of taste from anterior 2/3 tongue + reduced submandibular/sublingual salivation
• CN XII palsy causes tongue deviation toward the side of the lesion (ipsilateral genioglossus paralysis)
• Referred otalgia (ear pain) from oral cavity lesions is via CN IX (posterior tongue/tonsil → tympanic branch of IX → ear)
• Gray's Anatomy for Students, p. 1240
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Ch. 41
• Cummings Otolaryngology Head and Neck Surgery, Ch. 91

First Part of the Maxillary Artery (Mandibular Part)

Location / Relations

Branches

Major Branches

• Ascends vertically from the maxillary artery
• In the infratemporal fossa, passes superiorly between the sphenomandibular ligament (medially) and lateral pterygoid muscle (laterally)
• Passes between the two roots of the auriculotemporal nerve just below the foramen spinosum (classic exam point)
• Enters the cranial cavity through the foramen spinosum
• Inside the skull it runs in the periosteal (outer) layer of dura mater
• Divides into a frontal (anterior) branch and a parietal (posterior) branch
• Is the largest meningeal vessel - supplies most of the dura mater, cranial bone, and bone marrow of the calvaria
• Clinical: Rupture of the anterior branch by a temporal blow causes an extradural (epidural) hematoma - blood collects between dura and inner table of skull, causing a lucid interval then rapid deterioration

• Descends from the maxillary artery
• Before entering the mandible, gives off a mylohyoid branch (accompanies the nerve to mylohyoid in the mylohyoid groove)
• Enters the mandibular canal through the mandibular foramen alongside the inferior alveolar nerve
• Inside the canal it supplies all lower teeth, mandibular bone, and buccal gingivae
• Terminates as two branches:
  • Incisive branch - continues forward to supply incisor teeth
  • Mental artery - exits through the mental foramen to supply chin, lower lip, and labial gingiva

Minor Branches (3 small branches)

Summary Table

Clinical Importance

• Extradural hematoma - the anterior (frontal) branch of the middle meningeal artery runs in a groove on the inner surface of the temporal bone (pterion - thinnest part of skull). A blow here fractures the bone and tears the artery, causing a classic presentation: brief loss of consciousness → lucid interval → rapid deterioration as blood under arterial pressure strips dura from bone.
• The inferior alveolar nerve block (dental anaesthesia) targets the inferior alveolar nerve near the mandibular foramen; the artery accompanies the nerve at this point and inadvertent intravascular injection is possible.
• The accessory meningeal artery provides an important collateral meningeal supply and also communicates with orbital and ophthalmic vessels.
• Gray's Anatomy for Students, p. 1130
• Color Atlas of Human Anatomy Vol. 2, p. 97