Schedule

Lab 26 - First Pharyngeal Arch PRE-LAB

Suggested readings from
Gray's Anatomy for Students, 2nd ed.
Ch. 8, 920-946; 1071-1079

Suggested readings from Langman's Medical Embryology, 11th ed.

Ch. 16: 265-287

Please review this material before lab. Feel free to return to this material during the lab as needed.

1. CRANIUM
Review the anatomy of the base (inferior view) of the cranium.

  • The mandible and the temporal bone form the temporomandibular joint (TMJ), which contains:
    • The mandibular fossa (concavity on the squamous portion of the temporal bone)
    • The articular tubercle (downward projection of the anterior border of the mandibular fossa)
    • The head of the madibular condyle (see below)
  • Review the downward projecting lateral and medial pterygoid plates from the greater wing of the sphenoid.
    • Note the hamulus on the medial pterygoid plate.

 

 

 

2. MANDIBLE

The mandible consists of a horizontal body and a vertical ramus.

  • The angle of the mandible is found between the body and the ramus. The masseter muscle attaches on the lateral side of the mandibular angle, while the medial pterygoid muscle attaches on the medial side.
  • On the ramus of the mandible, identify:
    • The head of the madibular condyle (part of the TMJ)
    • The neck of the mandibular condyle (attachment of the lateral pterygoid muscle on the pterygoid fovea)
    • The coronoid process (attachment of the temporalis muscle)
    • The mandibular notch (passage for the mandibular nerve and vessels)
    • The mandibular foramen (opening of the mandibular canal for the inferior alveolar nerve and vessels)
    • Lingula (attachment of the sphenomandibular ligament)
    • Mylohyoid groove (passage for the nerve to the mylohyoid muscle)
  • On the body of the mandible, identify:
    • The sublingual fossa (fovea for the sublingual gland)
    • The submandibular fossa (fovea for the submandibular gland)
    • The digastric fossa (attachment of the anterior belly of the digastric muscle)
    • The genial tubercle/mental spine (attachment of the geniohyoid muscle)
    • The mylohyoid line (attachment of the mylohyoid muscle)
    • Mental foramen (exit for the mental nerve and vessels)
    • Mental process (chin)
    • Alveolar process (sockets for the teeth to insert the bone)

 

3. LIGAMENTS OF THE TEMPOROMANDIBULAR JOINT

  • Review the three ligaments associated with the TMJ
    • Lateral ligament
    • Sphenomandibular ligament
    • Stylomandibular ligament

 

 

4. TEETH

  • 32 teeth in adults:
    • 16 in the maxilla and 16 in the mandible (8 in each quadrant)
      • in each quadrant (adult):
        • Incisors (2)
        • Canine (1)
        • Premolars (2)
        • Molars (3)

  • 20 deciduous teeth in children
    • No premolars and only 2 molars in each quadrant

 

 

 

5. SUMMARY OF THE MANDIBULAR MOVEMENTS

All muscles that move the mandible are innervated by a branch of CN V3 except for the geniohyoid muscle (innervated by C1 spinal nerve).

Protrusion (protrude chin)

  • Lateral pterygoid muscle (assisted by the medial pterygoid muscle)

Retraction (retrude chin)

  • Temporalis muscle (posterior fibers)
  • Masseter muscle (deep portion)
  • Geniohyoid muscle
  • Digastric muscle

Transverse movements (side-to-side movement, grinding and chewing)

  • Masseter muscle (deep portion)
  • Medial pterygoid muscle
  • Lateral pterygoid muscle

Elevation (adduction, closing of the mouth)

  • Temporalis muscle
  • Masseter muscle
  • Medial pterygoid muscle

Depression (abduction, opening of the mouth)

  • Gravity
  • Lateral pterygoid muscle
  • Suprahyoid muscles
    • Anterior belly of digastric muscle
    • Geniohyoid muscle
    • Mylohyoid muscle

 

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Updated 12/13/12 - Velkey