Anatomy study note · Head and neck

Orbicularis oris

The sphincter muscle of the lips, encircling the oral opening.

Key points

• Sphincter of the mouth.
• Many fibres from buccinator.
• Facial nerve.
• From the second (hyoid) pharyngeal arch → facial nerve.
• Skeletal muscle: multinucleated, peripheral nuclei, striated.
• Epimysium → perimysium → endomysium.

The full note in the atlas also covers

Origin · Insertion · Action · Nerve supply · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 12, PDF pp. 1519, 1536–1539
• Inderbir Singh’s Human Embryology, ch. 9, PDF pp. 120, 122, 125
• BRS Cell Biology & Histology, 7th ed., ch. 8, PDF pp. 135–144

More from the head and neck

• Palate
• Palatine tonsil
• Palatopharyngeus
• Parathyroid glands
• Parietal bone
• Parietal lobe
• Parotid gland
• Pharyngeal constrictors
• Pharynx
• Phrenic nerve
• Pineal body
• Piriform cortex

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