LAB PRACTICAL 2 - head and neck muscles

Buccinator: Origin

Alveolar process of the maxilla and mandible, and pterygomandibular raphe

Buccinator: Insertion

Decussates at modulus of mouth and interdigitates with opposite side

Buccinator: Action

Aids mastication, tenses cheeks in blowing and whistling, aids closure of mouth

Buccinator: Innervation

Buccal branch of facial nerve (VII)

Frontalis: Origin

Occipital: highest nuchal line and mastoid process. Frontal: superior fibers of upper facial muscles

Frontalis: Insertion

Galeal aponeurosis

Frontalis: Action

Wrinkles forehead and fixes galeal aponeurosis

Frontalis: Innervation

Posterior auricular and temporal branches of facial (VII)

Mentalis: Origin

Incisive fossa on anterior aspect of mandible

Mentalis: Insertion

Skin of chin

Mentalis: Action

Elevates and wrinkles skin of chin

Mentalis: Innervation

Mandibular branch of facial nerve (VII)

Orbicularis oculi: Origin

Medial orbital margin and lacrimal sac (orbital, palpebral and lacrimal parts)

Orbicularis oculi: Insertion

Lateral palpebral raphe

Orbicularis oculi: Action

Closes eyelids, aids passage and drainage of tears

Orbicularis oculi: Innervation

Temporal and zygomatic branches of facial nerve (VII)

Orbicularis oris: Origin

Near midline on anterior surface of maxilla and mandible and modulus angle of mouth

Orbicularis oris: Insertion

Mucous membrane of margin of lips and raphe with buccinator at modiolus

Orbicularis oris: Action

Narrows orifice of mouth, purses lips and puckers lip edges

Orbicularis oris: Innervation

Accessory parts are incisivius labii superiors and inferioris

Zygomaticus major: Origin

Anterior surface of zygomatic bone

Zygomaticus major: Insertion

Modiolus at angle of mouth

Zygomaticus major: Action

Elevates and draws angle of mouth laterally

Zygomaticus major: Innervation

Buccal branch of facial nerve (VII)

Zygomaticus minor: Origin

Lateral infra-orbital margin

Zygomaticus minor: Insertion

Skin and muscles of upper lip

Zygomatics minor: Action

Elevates and everts upper lip

Zygomaticus minor: Innervation

Buccal branch of facial nerve (VII)

Risorius: Origin

Deep fascia of face and parotid

Risorius: Insertion

Modiolus and skin at angle of mouth

Risorius: Action

Retracts angle of mouth

Risorius: Innervation

Buccal branch of facial nerve (VII)

Levator labii superioris: Origin

Medial infra-orbital margin

Levator labii superioris: Insertion

Skin and muscle of upper lip

Levator labii superioris: Action

Elevates and everts upper lip

Levator labii superioris: Innervation

Buccal branch of facial nerve (VII)

Platysma: Origin

Skin over lower neck and upper lateral chest

Platysma: Insertion

Inferior border of mandible and skin over lower face and angle of mouth

Platysma: Action

Depresses and wrinkles skin of lower face and mouth. Aids forces depression of mandible

Platysma: Innervation

Cervical branch of facial nerve (VII)

Corrugator supercilli: Origin

Medial superciliary arch

Corrugator supercilli: Insertion

Skin of medial forehead

Corrugator supercilli: Action

Wrinkles forehead

Corrugator supercilli: Innervation

Temporal branch of facial nerve (VII)

Depressor angle oris: Origin

Outer surface of mandible posterior to oblique line

Depressor angle oris: Insertion

Modiolus at angle of mouth

Depressor angle oris: Action

Depresses and draws angle of mouth laterally

Depressor anguli oris: Innervation

Mandibular branch of facial nerve (VII)

Depressor labii inferioris: Origin

Outer surface of mandible along oblique line

Depressor labii inferioris: Insertion

Skin of lower lip

Depressor labii inferioris: Action

Depresses and draws lower lip laterally

Depressor labii inferioris: Innervation

Mandibular branch of facial nerve (VII)

Digastric: Origin

Anterior belly: digastric fossa on posterior surface of symphysis menti. Posterior belly: base of mastoid process

Digastric: Insertion

Fibrous loop to lesser cornu of hyoid bone

Digastric: Action

Elevates hyoid bone. Aids swallowing and depresses mandible

Digastric: Innervation

Anterior belly: mylohyoid nerve (5). Posterior belly: facial nerve (VII)

Masseter: Origin

Anterior two thirds of zygomatic arch and zygomatic process of maxilla

Masseter: Insertion

Lateral surface of angle and lower ramus of mandible

Masseter: Action

Elevates mandible (enable forced closure of mouth)

Masseter: Innervation

Anterior division of mandibular nerve (V)

Mylohyoid: Origin

Mylohyoid line on internal aspect of mandible

Mylohyoid: Insertion

Anterior three quarters: midline raphe, posterior quarter of body of hyoid bone

Mylohyoid: Action

Elevates hyoid bone, supports and raises floor of mouth, aids in mastication and swallowing

Mylohyoid: Innervation

Mylohyoid nerve (V)

Omohyoid: Origin

Suprascapular ligament and adjacent scapula

Omohyoid: Insertion

Inferior border of body of hyoid bone

Omohyoid: Action

Depresses hyoid bone and hence larynx

Omohyoid: Innervation

Ansa cervicalis nerve ($C1, 2, 3$)

Sternocleidomastoid: Origin

Anterior and superior manubrium and superior medial third of clavicle

Sternocleidomastoid: Insertion

Lateral aspect of mastoid process and anterior half of superior nuchal line

Sternocleidomastoid: Action

Flexes and laterally rotates cervical spine, protracts head when acting together, extends neck when neck already partially extended

Sternocleidomastoid: Innervation

Spinal accessory nerve (lateral roots $C1-5$)

Sternohyoid: Origin

Superior lateral posterior aspect of manubrium

Sternohyoid: Insertion

Inferior border of body of hyoid bone

Sternohyoid: Action

Depresses hyoid bone and hence larynx

Sternohyoid: Innervation

Ansa cervicalis nerve ($C1, 2, 3$)

Sternothyroid: Origin

Medial posterior aspect of manubrium

Sternothyroid: Insertion

Oblique line of laminate of thyroid cartilage

Sternothyroid: Action

Depresses larynx

Sternothyoid: Innervation

Ansa cervicalis nerve ($C1, 2, 3$)

Stylohyoid: Origin

Base of styloid process

Stylohyoid: Insertion

Base of greater cornu of hyoid bone

Stylohyoid: Action

Elevates and retracts hyoid bone, aids swallowing and elevates larynx

Stylohyoid: Innervation

Mandibular branch of facial nerve (VII)

Temporalis: Origin

Temporal fossa between inferior temporal line and infratemporal crest

Temporalis: Insertion

Medial and anterior aspect of coronoid process of mandible

Temporalis: Action

Elevates mandible and posterior fibers retract

Temporalis: Innervation

Deep temporal branches from anterior division of mandibular nerve (V)

Thyrohyoid: Origin

Oblique line of lamina of thyroid cartilage

Thyrohyoid: Insertion

Inferior border of body of hyoid bone

Thyrohyoid: Action

Elevates larynx or depresses hyoid bone

Thyrohyoid: Innervation

$C1$ fibers carried by hypoglossal nerve (XII)

Scalenus anterior: Origin

Anterior tubercles of transverse processes $C3-6$

Scalenus anterior: Insertion

Scalene tubercle on superior aspect of 1st rib

Scalenus anterior: Action

Accessory to inspiration. Lateral flexion of neck when 1st rib is fixed

Scalenus anterior: Innervation

Anterior primary rami of $C5, 6$

Scalenus medius: Origin

Posterior tubercles of transverse processes of $C1-7$

Scalenus medius: Insertion

Superior aspect of neck of 1st rib

Scalenus medius: Action

Accessory to inspiration

Scalenus medius: Innervation

Anterior primary rami of $C3-8$