Mod 4: Lecture 1 - Anatomy of the Head and Neck Flashcards Preview

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Muscles of Facial Expression

- in the subcutaneous tissue of the anterior and posterior scalp, face, and neck
- move the skin and change facial expressions to convey mood
- most muscles attach to bone or fascia and produce their effects by pulling the skin
- all muscles of facial expression develop from mesoderm in the second pharyngeal arches


Muscles: Occipitofrontalis
1. Attachments
2. Action
3. Innervation

1. - flat digastric muscle with occipital and frontal bellies
---- share a common tendon: the epicranial aponeurosis
- occipital belly attaches to the superior nuchal line
- frontal belly inserts into the skin and subcutaneous tissue of eyebrows and forehead
2. - independent contraction of the
---- occipital belly: retracts the scalp
---- frontal belly: protracts the scalp
3. - facial nerve


Muscles: Mouth, Lips, and Cheeks

- Orbicularis Oris: sphincter around the mouth
- Buccinator: cheek
- Elevators, retractors, and evertors of the upper lip
- Depressors, retractors, and evertors of the lower lip


How do the muscles of the mouth, lips, and cheek contribute to facial expression and social function?

- see video


Muscles: Orbicularis Oris
1. Attachments
2. Action
3. Innervation

- encircles the mouth within the lips, controlling entry and exit through the oral fissure
- also important during articulation (speech)
1. - medial maxilla and mandible, and angle of mouth
- inserts within the mucous membrane of the lips
2. - tonic: closes the mouth
- phasic: compresses and protrudes lips
3. facial nerve


1. Attachments
2. Action
3. Innervation

- thin, flat, rectangular muscle
1. - attaches laterally to the maxillae and mandible, opposite to the molar teeth
- occupies a deeper, more medially placed plane than the other facial muscles
---- passes deep to the mandible so that it is more closely related to the buccal mucosa than the skin of the face
2. - smiling
- keeps the cheek taut, thereby preventing it from folding and being injured during chewing
- helps the cheeks resist the forces generated by whistling and sucking
3. - facial nerve


Buccinator and Obicularis Oris

- anteriorly, the fibers of the buccinator mingle medially with the fibers of the obicularis oris
- the force of the two muscles compress the cheeks and lips against the teeth and gums
- the two muscles work with the tongue to keep the food between the occlusal surfaces of the teeth during chewing
---- prevent food from accumulating in the oral vestibule


Bell's Palsy

- something to do with the buccinator muscle
- see video


1. Attachments
2. Action
3. Innervation

- broad, thin sheet of muscle in the subcutaneous tissue of the neck
1. - subcutaneous tissue of supra and infraclavicular regions
- base of mandible, skin of cheek, and angle of mouth and obicularis oris
2. - from superior attachment: tenses the skin, producing vertical skin ridges
- from inferior attachment: helps depress the mandible and draw the corners of the mouth inferiorly, as in a grimace
3. facial nerve


Levator Anguli Oris
1. Attachments
2. Action
3. Innervation

1. - originates from the maxilla immediately inferior to the infrorbital foramen
- inserts into the angle of the mouth, blending with the fibers of the orbicularis oris muscle
2. - lifts the angles of the mouth
3. - facial nerve


Depressor Anguli Oris
1. Attachments
2. Action
3. Innervation

- triangular muscle
1. - originates from the mandible
- 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
2. pulls the angles of the mouth downward
3. facial nerve


Zygomaticus Major and Minor
1. Attachments
2. Action
3. Innervation

1. - arise from the zygomatic bone
- fibers angle downward and medially to insert into the angle of the mouth and blend with the orbicularis oris muscle
2. - draws the angle of the mouth upward and backward
---- toward the zygomatic bone --> smile
3. facial nerve


Eye: Orbicularis Oculi
1. Attachments
2. Action
3. Innervation

1. - originates from medial orbital margin and lacrimal bone
- inserts into skin around orbit
2. two parts with different actions
- palpebral: blinking
- orbital: forceful closing
3. facial nerve


Parotid Gland

- enclosed within a tough fascial capsule, the parotid sheath
- wedged between the ramus of the mandible and the mastoid process
- fatty tissue between the lobes of the gland assures flexibility of the gland
---- to accommodate the motion of the mandible
- apex of the gland is posterior to the angle of the mandible
---- behind the jaw
- base is related to the zygomatic arch


Embedded with the parotid gland, from superficial to deep, are the...

- Parotid Plexus of the Facial Nerve (CN VII) and its branches
- Retromandibular Vein: drainage from superficial face
- External Carotid Artery


Blood Supply to the Face

- Arch of Aorta ---> brachiocephalic trunk, left common carotid artery, and left subclavian artery
-Brachiocephalic Trunk ---> right common carotid artery and right subclavian artery
- Right/Left Common Carotid Artery ---> right/left internal carotid and right/left external carotid


Internal Carotid Arteries

- ascends deep to the parotid gland, the digastric muscle, and the muscles attached to the styloid process
- become the main artery of the brain and orbit


External Carotid Arteries

- supply structures external to the skull
---- with some exceptions such as the middle meningeal artery
- runs posterosuperiorly to the region between the neck of the mandible and the earlobe
---- where it is embedded in the parotid gland


Neck Osteology

- Temporal Bone: side skull bone
---- mastoid and styloid processes
- Mandible: lower jaw
- Hyoid: floating bone in neck
- Clavicle: collar bone
- Sternum: breast bone


Larynx Structures

Visceral Structures on the Neck - From Superior to Inferior:
-Epiglottis: blocks the trachea so food can't enter
----- cartilage
- Hyoid: bone, located right below the epiglottis
- Thyroid Cartilage: a thick sheet that wraps around above the trachea
- Cricoid Cartilage: a ring-shaped band
- Arytenoid Cartilage: posterior to the cricoid
- Tracheal Cartilages: wrap around the trachea


Function of Larynx Structures

- sound production
- pressure valve


Sound Production

- cartilages rotate to adjust tension and length of vocal ligaments


Thyroid and Parathyroid Glands

- Thyroid: spongy tissue that wraps around the neck
---- Parathyroid: four little tiny glands that are on the thyroid
- Functions:
---- regulation of metabolism
---- regulation of growth and development
---- regulation of nervous system activity


Regions of the Pharynx

- Nasopharynx: top region, behind the nasal cavity and above the mouth, where a postnasal drip comes from
- Oropharynx: small region at the back of the mouth
- Laryngopharynx: the throat


Functions of the Pharynx

- conducts air to larynx/trachea
- conducts food to esophagus


Clinical Correlation: Tracheostomy

- see video


Sternocleidomastoid Muscle
1. Attachments
2. Action
3. Innervation

1. - mastoid process of temporal bone
- sternum and clavicle
2. - unilateral: lateral flexion to the same side, rotation to the opposite side
- bilateral: cervical flexion
3. - accessory nerve (CN XI)
---- C2, C3 sensory


Scalene Muscles
1. Attachments
2. Action
3. Nerve

1. - transverse processes of cervical vertebrae
- first two ribs
2. - bilateral: assist in neck flexion, raise first two ribs
3. - ventral rami of cervical nerves


Suprahyoid Muscles

- Mylohyoid: under chin
- Digastric
---- anterior: hyoid to point of chin
----- posterior: hyoid to point of jaw
- Stylohyoid
- Geniohyoid


Infrahyoid Muscles

- Omohyoid
---- omo = scapula
- Sternohyoid
- Sternothyroid
- Thyrohyoid