3 basic functions
o    protection of respiratory tract during swallowing food/air pathways cross.
    epiglottis provides protection
o    control intra-thoracic pressure (in coughing) -    close off airway to build pressure then rapidly open to release stuff
o    production of sound (in speaking, singing, laughing)

Important structures

o    hyoid bone
o    thyroid cartilage
o    arytenoids cartilage: vocal and muscle process
    sits on slope on posterior side of cricoid - spin and slide
o    cricoid cartilage: signet ring
o    thyroepiglottic ligament

Membranes and ligaments

o    membrane: general; ligament: thickening of membrane
o    folds: free edges of membranes or ligaments
o    names: tell you where located

Important membranes:
    quandrangular/vestibular membrane—from epiglottis to arytenoids
•    inferior edge: false vocal fold
    thyrohyoid membrane
    conus elasticus = cricothyroid = cricovocal
•    superior/medial edge = vocal fold
•    vocal ligaments: true folds, top of cricothyroid membrane

The Masseter Muscle

• This is a quadrangular muscle that covers the lateral aspect of the ramus and the coronoid process of the mandible.

• Origin: inferior border and medial surface of zygomatic arch.
• Insertion: lateral surface of ramus of mandible and its coronoid process.
• Innervation: mandibular nerve via masseteric nerve that enters its deep surface.

• It elevates and protrudes the mandible, closes the jaws and the deep fibres retrude it.

The Arteries of the Face

• The superficial arteries are derived from the external carotid arteries.

The Facial Artery

• This is the chief artery of the face.
• It arises from the external carotid artery and winds its way to the inferior border of the mandible, just anterior to the masseter muscle.
• It hooks around the inferior border of the mandible and grooves the bone. Here the artery is superficial, just beneath the platysma and its pulsation can be felt.

• In its course over the face to the medial angle of the eye, the facial artery crosses the mandible, buccinator muscle, and maxilla.
• It lies deep to the zygomaticus major.

• The facial artery ends by sending branches to the lip and side of the nose.
• The part of the artery that runs along the side of the nose to supply the eyelids is called the angular artery.

The Superficial Temporal Artery

• This artery is the smaller of the two terminal branches of the external carotid artery (the other is the maxillary artery).
• It begins deep to the parotid gland, posterior to the neck of the mandible, and ascends superficial to the posterior end of the zygomatic process of the temporal bone. It then enters the temporal fossa.

• The superficial temporal artery ends in the scalp by dividing into the frontal and parietal branches.

• Pulsation of this artery can be felt by compressing the root of the zygomatic process of the temporal bone.

The Transverse Facial Artery

• This small artery arises from the superficial temporal artery before it emerges from the parotid gland.
• It crosses the face superficial to the masseter muscle, about a fingerbreadth inferior to the zygomatic arch.
• It divides into numerous branches that supply the parotid gland and duct, the masseter muscle, and the skin of the face.

• It anastomoses with branches of the facial artery.

EPITHELIUMS

Epithelial Tissue Epithelial tissue covers surfaces, usually has a basement membrane, has little extracellular material, and has no blood vessels. A basement membrane attaches the epithelial cells to underlying tissues. Most epithelia have a free surface, which is not in contact with other cells. Epithelia are classified according to the number of cell layers and the shape of the cells.

• Epitheliums contain no blood vessels.  There is normally an underlying layer of connective tissue
• Almost all epitheliums lie on a basement membrane.The basement membrane consists of  a basal lamina and  reticular lamina. The reticular lamina is connected to the basal lamina by anchoring fibrils. The reticular lamina may be absent in which case the basement membrane consist only of a basal lamina. The basal lamina consists of a   - lamina densa in the middle (physical barrier) with a lamina lucida on both sides (+charge barrier),The basement membrane is absent in ependymal cells.The basement membrane is not continuous in sinusoidal capillaries.

• Epitheliums always line or cover something
• Epithelial cells lie close together with little intercellular space
• Epithelial cells are strongly connected to one another especially those epitheliums that are subjected to mechanical forces.  

Functions of Epithelium:

→ Simple epithelium involved with diffusion, filtration, secretion, or absorption

→ Stratified epithelium protects from abrasion

→ Squamous cells function in diffusion or filtration

Intramembranous ossification

• Flat bones develop in this way (bones of the skull)
• This type of bone development takes place in mesenchymal tissue
• Mesenchymal cells condense to form a primary ossification centre (blastema)
• Some of the condensed mesenchymal cells change to osteoprogenitor cells
• Osteoprogenitor cells change into osteoblasts which start to deposit bone
• As the osteoblasts deposit bone some of them become trapped in lacunae in the bone and then change into osteocytes
• Osteoblasts lie on the surface of the newly formed bone
• As more and more bone is deposited more and more osteocytes are formed from mesenchymal cells
• The bone that is formed is called a spicule
• This process takes place in many places simultaneously
• The spicules fuse to form trabeculae
• Blood vessels grow into the spaces between the trabeculae
• Mesenchymal cells in the spaces give rise to hemopoetic tissue
• This type of bone development forms the first phase in endochondral development
• It is also responsible for the growth of short bones and the thickening of long bones

Muscles Moving the Auditory Ossicles

The Tensor Tympani Muscle

• This muscle is about 2 cm long.

• Origin: superior surface of the cartilaginous part of the auditory tube, the greater wing of the sphenoid bone, and the petrous part of the temporal bone.
• Insertion: handle of the malleus.
• Innervation: mandibular nerve (CN V³) through the nerve to medial pterygoid.

• The tensor tympani muscle pulls the handle of the malleus medially, tensing the tympanic membrane, and reducing the amplitude of its oscillations.
• This tends to prevent damage to the internal ear when one is exposed to load sounds.

The Stapedius Muscle

• This tiny muscle is in the pyramidal eminence or the pyramid.

• Origin: pyramidal eminence on the posterior wall of the tympanic cavity. Its tendon enters the tympanic cavity by traversing a pinpoint foramen in the apex of the pyramid.
• Insertion: neck of the stapes.
• Innervation: nerve to the stapedius muscle, which arises from the facial nerve (CN VII).

• The stapedius muscle pulls the stapes posteriorly and tilts its base in the fenestra vestibuli or oval window, thereby tightening the anular ligament and reducing the oscillatory range.
• It also prevents excessive movement of the stapes.