Suprahyoid Region Lect 1, Anat Module 4

Front 1

Describe the descending pathway of the hypoglossal nerve.

Back 1

• The hypoglossal nerve leaves the skull through the hypoglossal canal and descends almost vertically in the neck to a level just below the angle of the mandible.
• Here it angles sharply forward and crosses the external carotid artery
• It continues forward and crosses the lingual artery
• The hypoglossal travels deep to the mylohyoid muscle to reach the tongue.

Front 2

Where are the muscles of facial expression?

Back 2

-on the subcautaenous tissue of anterior, posterior scalp, face and neck
-muscles move sin and change expression to reflect mood.

-most attach to bone or fascia and produce effects by pulling the skin.
-All muscles of expression develop from mesoderm in 2nd pharyngeal arch.

Front 3

Describe facial swelling

Back 3

• The face has no distinct deep fascia and the subcutaneous tissue between the cutaneous attachments of the facial muscles is loose
• The looseness of the subcutaneous tissue enables fluid and blood to accumulate in the loose connective tissue

Front 4

Describe occiptofrontalis attachments, action, and innervation

Back 4

• The occipitofrontalis is a flat digastric muscle, with occipital and frontal bellies that share a common tendon, the epicranial aponeurosis
• The occipital belly attaches to the superior nuchal line
• The frontal belly inserts into the skin and subcutaneous tissue of eyebrows and forehaad
• Action: Independent contraction of the occipital belly retracts the scalp and contraction of the frontal belly protracts it
• Innervation: – Occipital belly: Posterior auricular branch
of facial nerve
– Frontal belly: Temporal branches of facial nerve

Front 5

Describe the 5 layers that the scalp is composed of?

Back 5

"SCALP"

1. Skin: thin, except in the occipital region, containing many sweat and sebaceous glands and hair follicles.
2. Connective tissue: forms the thick, dense, richly vascularized subcutaneous layer that is well supplied with cutaneous nerves.
3. Epicranial aponeurosis: the broad, strong, tendinous sheet that serves as the attachment for the occipitofrontalis muscle
4. Loose areolar tissue
5. Pericranium: a dense layer of connective tissue that forms the external periosteum of the neurocranium

Front 6

Name the muscles in the mouth, lips, and cheeks

Back 6

Muscles of the mouth, lips and
cheeks include:
• The orbicularis oris, the sphincter around the mouth.
• The buccinator in the cheek.
• Elevators, retractors, and evertors of the upper lip.
• Depressors, retractors, and evertors of the lower lip.

Front 7

Describe attachments, action, and innervation of orbicularis oris

Back 7

• The orbicularis oris, encircles the mouth within the lips, controlling entry and exit through the oral fissure
• The orbicularis oris is also important during articulation (speech)
• Attachments: – Medialmaxillaandmandible,and
angle of mouth
– Insertswithinthemucous membrane of the lips
• Action:
– Tonic:closesmouth
– Phasic:compressesand protrudes lips
• Innervation:
– Buccal and marginal mandibular branches of facial nerve 15

Front 8

Describe attachments, action, innervation of buccinator muscle

Back 8

• The buccinator is a thin, flat, rectangular muscle that attaches laterally to the alveolar processes of the maxillae and mandible, opposite the molar teeth, and to the pterygomandibular raphe, a tendinous thickening of the buccopharyngeal fascia. Anteriorly, its f8ibers belnd with the orbicularis oris muscle fibers.
• It occupies a deeper, more medially placed plane than the other facial muscles, passing deep to the mandible so that it is more closely related to the buccal mucosa than the skin of the face.
• The buccinator is innervated by the
buccal branch of facial nerve
• The buccinator, active in smiling, also keeps the cheek taut, thereby preventing it from folding and being injured during chewing.
Anteriorly, the fibers of the buccinator mingle medially with those of the orbicularis oris, and the tonus of the two muscles compresses the cheeks and lips against the teeth and gums.
• The following muscles work together to
keep food between the occlusal surfaces of the teeth during mastication

Front 9

Mobius syndrome

Back 9

Mobius syndrome is a rare birth defect caused by the absence or underdevelopment of the 6th and 7th cranial nerves)
In this report, a 7-year-old-boy with Mobius syndrome is presented. He had asymmetry of facial expression.....and severe tooth decay.
After dental treatment, the periodic re-care visits should be done according to the eruption pattern.

Front 10

Describe attachments, action, and innervation of the platysma

Back 10

• The platysma is a broad, thin sheet of muscle in the subcutaneous tissue of the neck.
• Attachments: – Subcutaneoustissueofsupra-
and infraclavicular regions
– Baseofmandible,skinofcheek, angle of mouth and orbicularis oris
• Action
– Fromsuperiorattachment,tenses the skin, producing vertical skin ridges
– Frominferiorattachment,helps depress the mandible and draw the corners of the mouth inferiorly, as in a grimace.
• Innervation: – Cervical branch of facial nerve

Front 11

Describe attachments, action, and inneravation levator anguli oris

Back 11

• The levator anguli oris muscle originates from the canine fossa of the maxilla immediately inferior to the infraorbital foramen.
• It inserts into the angle of the mouth, blending with fibers of the orbicularis oris muscle.
• Action: Lifts the angles of the mouth.
• Innervation: Buccal br. of facial nerve

Front 12

Describe attachments, action, and innervation of depressor anguli oris

Back 12

• The depressor anguli oris is
a triangular muscle
• It originates from the external oblique line of the mandible.
• The ascending fibers converge at the apex to insert into the angle of the mouth from below and blend with the fibers of the orbicularis oris muscle.
• Action: Pulls the angles of the mouth downward
• Innervation: Marginal mandibular branch of facial nerve

Front 13

Describe the attachments, action, and innervation of zygomaticus major

Back 13

• The zygomaticus major muscle arises from the lateral aspect of the zygomatic bone.
• Its fibers angle downward and medially to insert into the angle of the mouth and blend with the orbicularis oris muscle.
• Action: draws the angle of the mouth upward and backward.
• Innervation: Buccal branch of facial nerve (+ some fibers from zygomatic branch)

Front 14

Describe attachments, action, nad innervatin of zygomatiuc minor.

Back 14

• The zygomaticus major muscle arises from the anterior aspect of the zygomatic bone.
• Its fibers angle downward and medially to insert into the skin of the upper lip
• Action: Assists in elevation of the the upper lip
• Innervation: Buccal branch of facial nerve

Front 15

Describe the attachments, action, and innervation of the risorius

Back 15

• The risorius muscle is a thin muscle that arises from parotid and masseteric fascia, and buccal skin
• The risorius muscle inserts transversely into the angle of the mouth
• Action: Retracts the angle of the mouth posteriorly
• Innervation: Mandibular and/or Buccal br. of facial nerve (highly variable)

Front 16

Describe the attachments, action, and innervation of the levator labii superioris

Back 16

• The levator labii superioris muscle arises originates from the inferior orbital margin.
• It inserts into the upper lip • Action: Raise the upper lip.
• Innervation: Buccal br. of facial nerve

Front 17

Describe the attachments, action, and innervation of the depressor labii inferioris

Back 17

• The depressor labii inferioris muscle arises from the lowest portion of the oblique line of the mandible
• It inserts into the skin of the lower lip
• Action: Depresses the lower lip
• Innervation: marginal mandibular br. of facial nerve

Front 18

Muscles of eye

Describe attachments, action, and innervation of orbicularis oculi

Back 18

• Originates from medial orbital margin and lacrimal bone
• Inserts into skin around orbit
• Two parts with different actions: Palpebral (blinking)
– Orbital (forceful closing)
Innervation: temporal and zygomatic branches of facial nerve

Front 19

Forehead muscle

Describe attachments, action, and innervation of the corrugar supercilli

Back 19

• Attachments
– Medial end of supercilliary arch (ridge superior to the supraorbital margin)
– Skin overlying the supercilliary arch and supraorbital margin
• Action: Draws eyebrows medially and inferiorly
• Innervation: Temporal br. of facial nerve

Front 20

Describe attachments of chin mentalis, action, and innervation

Back 20

• Attachments:
– Body of mandible anterior to the roots of inferior incisors
– Skin of chin
• Action: – Elevates and protrudes
lower lip
• Innervation:
– Marginal mandibular br. of facial nerve

Front 21

Describe attachments of levvator superioris alaeque nasii and alar part of nasalis

Back 21

– Attachments: • Frontalprocessofmaxilla • Alarcartilage
– Action • Depressesalalaterally
(dilates nasal aperture)
– Innervation:Buccalbr.of facial nerve

Front 22

Describe attachments, action, and innervation of procerus and transverse part of nasalis

Back 22

– Attachments:
• Fasciaondorsumofnose and lateral nasal cartilage
• Skinofinferiorforehead between brows
– Action
• Depressesmedialendof brow, wrinkles dskin on dormsum of nose
– Innervation:Buccalbr.of facial nerve

Front 23

Describe the parotid gland

Back 23

• The parotid gland is enclosed within a tough fascial capsule, the parotid sheath, derived from the investing layer of deep cervical fascia
• The parotid gland has an irregular shape because the area occupied by the gland, the parotid bed, is anteroinferior to the external acoustic meatus, where it is wedged between the ramus of the mandible and the mastoid process
• Fatty tissue between the lobes of the gland assures the flexibility the gland must have to accommodate the motion of the mandible.
• The apex of the parotid gland is posterior to the angle of the mandible, and its base is related to the zygomatic arch.

Front 24

Where does the parotid duct pass?

Back 24

The parotid duct passes horizontally from the anterior edge of the gland and at the anterior border of the masseter, the duct turns medially, pierces the buccinator, and enters the oral cavity through a small orifice opposite the 2nd maxillary molar tooth.

Front 25

1) What is embedded within the parotid gland, superficial to deep?
2) What is on the parotid sheath and within the gland?

Back 25

1) – parotid plexus of the facial nerve (CN VII) and its branches
– retromandibular vein
– external carotid artery.
2) parotid lymph nodes

Front 26

What gives rise to the parotid plexus?

Back 26

␣ The temporofacial and cervicofacial trunks of the facial nerve give rise to the parotid plexus
␣Extensive variations exist but five terminal branches typically emerge as follows:
* Temporofacial trunk: gives rise to temporal, zygomatic and buccal branches
* Cervicofacial trunk: gives rise to buccal, mandibular and cervical branches.

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