Cranial Bones and Facial Muscles

Cranial Bones

• 8 bones that form the cranium:
  • Frontal bone
  • Parietal bone (2)
  • Occipital bone
  • Temporal bone (2)
  • Sphenoid bone
  • Ethmoid bone
• Functions:
  • Protect the brain
  • Form the orbit (eye socket)
  • Contain the nasal and oral cavities
  • Attach muscles of facial expression and mastication

Facial Muscles

• 31 muscles of facial expression:
  • Involved in emotional expressions, eating, and speaking
  • Innervated by the facial nerve (CN VII)
• Major facial muscles:
  • Zygomaticus major (smiling)
  • Orbicularis oculi (eye movement)
  • Buccinator ( compressor of cheeks)
  • Mentalis (chin movement)

Oral Cavity

• Boundaries:
  • Roof: hard palate and soft palate
  • Floor: mylohyoid muscle and hyoglossus muscle
  • Walls: buccinator muscle and maxilla
  • Anterior: lips
• Functions:
  • Food intake and processing
  • Speech articulation
  • Saliva production and secretion

Neck Muscles

• 3 main groups of neck muscles:
  • Anterior neck muscles:
    • Sternocleidomastoid muscle
    • Scalene muscles
  • Lateral neck muscles:
    • Sternohyoid muscle
    • Omohyoid muscle
  • Posterior neck muscles:
    • Splenius capitis muscle
    • Suboccipital triangle muscles
• Functions:
  • Movement of the head and neck
  • Support of the head and neck
  • Respiration and speech

Cranial Bones

• 8 bones form the cranium: frontal bone, 2 parietal bones, occipital bone, 2 temporal bones, sphenoid bone, and ethmoid bone
• Functions: protect the brain, form the orbit (eye socket), contain the nasal and oral cavities, and attach muscles of facial expression and mastication

Facial Muscles

• 31 muscles of facial expression involved in emotional expressions, eating, and speaking
• Innervated by the facial nerve (CN VII)
• Major facial muscles:
  • Zygomaticus major (smiling)
  • Orbicularis oculi (eye movement)
  • Buccinator (compressor of cheeks)
  • Mentalis (chin movement)

Oral Cavity

• Boundaries:
  • Roof: hard palate and soft palate
  • Floor: mylohyoid muscle and hyoglossus muscle
  • Walls: buccinator muscle and maxilla
  • Anterior: lips
• Functions:
  • Food intake and processing
  • Speech articulation
  • Saliva production and secretion

Neck Muscles

• 3 main groups of neck muscles:
  • Anterior neck muscles:
    • Sternocleidomastoid muscle
    • Scalene muscles
  • Lateral neck muscles:
    • Sternohyoid muscle
    • Omohyoid muscle
  • Posterior neck muscles:
    • Splenius capitis muscle
    • Suboccipital triangle muscles
• Functions:
  • Movement of the head and neck
  • Support of the head and neck
  • Respiration and speech

Cranial Bones

• 8 bones form the cranium (skull)
• Bones include: frontal, 2 parietal, occipital, 2 temporal, sphenoid, and ethmoid
• Functions:
• Protect the brain
• Form the orbits (eye sockets)
• Contain the nasal and oral cavities
• Attach muscles for facial expressions and mastication

Facial Muscles

• 23 muscles of facial expression
• Innervated by the facial nerve (CN VII)
• Originate from the skull and insert into the skin
• Responsible for:
• Facial expressions (e.g., smiling, frowning)
• Eye movement (e.g., blinking, winking)
• Mouth movements (e.g., eating, speaking)
• Major facial muscles:
• Zygomaticus major (smiling)
• Orbicularis oculi (eye movements)
• Buccinator (blowing, sucking)
• Mentalis (chin movements)

Oral Cavity

• Boundaries:
• Roof: hard palate and soft palate
• Floor: mylohyoid muscle and hyoglossus muscle
• Walls: buccinator muscle and mandible
• Anterior: lips
• Contents:
• Tongue
• Teeth
• Salivary glands (parotid, submandibular, sublingual)
• Oral mucosa (lining of the oral cavity)

Neck Muscles

• Anterior neck muscles:
• Suprahyoid muscles:
  • Digastric muscle (elevation of hyoid bone and larynx)
  • Stylohyoid muscle (elevation of hyoid bone and larynx)
  • Mylohyoid muscle (elevation of hyoid bone and larynx)
• Infrahyoid muscles:
  • Omohyoid muscle (depression of hyoid bone and larynx)
  • Sternothyreoideus muscle (depression of larynx)
  • Thyrohyoid muscle (depression of larynx)
• Lateral neck muscles:
• Scalene muscles (respiration)
• Levator scapulae muscle (elevation of scapula)
• Posterior neck muscles:
• Suboccipital muscles (extension and rotation of head)
• Splenius capitis muscle (extension and rotation of head)