Facial Muscles, Spine Joints, and Ligaments: An Anatomical Study

Facial Muscles

Occipitofrontalis muscle (frontal belly): Elevates the brow and wrinkles the forehead.

Procerus muscle: Depresses the medial angle of the eyebrow and wrinkles the root of the nose.

Corrugator supercilii: Draws the eyebrow medially and inferiorly, creating vertical wrinkles between the eyebrows.

Depressor supercilii: Depresses the eyebrow.

Orbicularis oculi: Has three parts: palpebral (gently closes the eyelid), orbital (forcefully closes the eye), and lacrimal (compresses the lacrimal gland, aiding tear production).

Levator labii superioris alaeque nasi: Elevates the upper lip and dilates the nostril.

Levator labii superioris: Elevates the upper lip.

Zygomaticus minor: Elevates the upper lip.

Zygomaticus major: Draws the corner of the mouth superiorly and posteriorly (smiling).

Orbicularis oris: Closes and protrudes the lips.

Nasalis: Has two parts: transverse (compresses the nose) and alar (dilates the nostrils).

Risorius: Draws the corner of the mouth laterally (as in a forced smile).

Depressor anguli oris: Draws the corner of the mouth inferiorly and laterally (frowning).

Depressor labii inferioris: Depresses the lower lip.

Mentalis: Elevates and protrudes the lower lip, wrinkling the chin.

Depressor septi nasi: Depresses the nasal septum and dilates the nostrils.

Occipitofrontalis muscle (occipital belly): Retracts the scalp.

Buccinator: Compresses the cheek against the teeth.

Masseter: Elevates the mandible (closes the mouth).

Temporalis: Elevates and retracts the mandible.

Medial pterygoid: Elevates the mandible and assists in protrusion.

Lateral pterygoid: Depresses and protrudes the mandible; allows for side-to-side movement.

Joints of the Spine

The joints between adjacent vertebral bodies are symphyses (cartilaginous joints).

The joints between the vertebral arches are synovial joints between the articular processes, with accessory ligaments connecting the laminae, transverse processes, and spinous processes.

Special Joints

• Lumbosacral
• Sacrococcygeal
• Atlanto-occipital
• Atlantoaxial

Ligaments and Their Functions

Ligamenta flava (Yellow ligaments): Unite the vertebral laminae and interconnect the edges of the laminae of adjacent vertebrae.

Interspinal ligaments: Unite the spinous processes from the root to the apex.

Supraspinal ligament: Connects the tips of the spinous processes from C7 to the sacrum.

Intertransverse ligaments: Play an important role in the functional stability of the spine.

Iliolumbar ligaments: Strengthen the intertransverse ligaments.