Digastric Muscle

• Origin:
  • Anterior Belly: Digastric fossa of the mandible.
  • Posterior Belly: Mastoid notch of the temporal bone.
• Insertion: Intermediate tendon attached to the body of the hyoid bone.
• Nerve Supply:
  • Anterior Belly: Nerve to mylohyoid (branch of the trigeminal nerve, CN V3).
  • Posterior Belly: Facial nerve (CN VII).
• Arterial Supply:
  • Anterior Belly: Branch of the submental artery.
  • Posterior Belly: Muscular branch of the posterior auricular artery and occipital artery.
• Action: Raises the hyoid bone and base of the tongue, steadies the hyoid bone, and opens the mouth by lowering the mandible.

Veins of the Face

The Supratrochlear Vein

• This vessel begins on the forehead from a network of veins connected to the frontal tributaries of the superficial temporal vein.
• It descends near the medial plane with its fellow on the other side.
• These veins diverge near the orbits, each joining a supraorbital vein to form the facial vein near the medial canthus (angle of the eye).

The Supraorbital Vein

• This vessel begins near the zygomatic process of the temporal bone.
• It joins the tributaries of the superficial and middle temporal veins.
• It passes medially and joins the supratrochlear vein to form the facial vein near the medial canthus.

The Facial Vein

• This vein provides the major venous drainage of the face.

• It begins at the medial canthus of the eye by the union of the supraorbital and supratrochlear veins.
• It runs inferoposteriorly through the face, posterior to the facial artery, but takes a more superficial and straighter course than the artery.
• Inferior to the margin of the mandible, the facial vein is joined by the anterior branch of the retromandibular vein.
• The facial veins ends by draining into the internal jugular vein.

The Superficial Temporal Vein

• This vein drains the forehead and scalp and receives tributaries from the veins of the temple and face.
• In the region of the temporomandibular joint, this vein enters the parotid gland.

The Retromandibular Vein

• The union of the superficial temporal and maxillary veins forms this vessel, posterior to the neck of the mandible.
• It descends within the parotid gland, superficial to the external carotid artery but deep to the facial nerve.
• It divides into an anterior branch that unites with the facial vein, and a posterior branch that joins the posterior auricular vein to form the external jugular vein.

Muscles of the Soft Palate

The Levator Veli Palatini (Levator Palati)

• Superior attachment: cartilage of the auditory tube and petrous part of temporal bone.
• Inferior attachment: palatine aponeurosis.
• Innervation: pharyngeal branch of vagus via pharyngeal plexus.

• This cylindrical muscle runs inferoanteriorly, spreading out in the soft palate, where it attaches to the superior surface of the palatine aponeurosis.

• It elevates the soft palate, drawing it superiorly and posteriorly.
• It also opens the auditory tube to equalise air pressure in the middle ear and pharynx.

The Tensor Veli Palatini (Tensor Palati)

• Superior attachment: scaphoid fossa of medial pterygoid plate, spine of sphenoid bone, and cartilage of auditory tube.
• Inferior attachment: palatine aponeurosis.
• Innervation: medial pterygoid nerve (a branch of the mandibular nerve).

• This thin, triangular muscle passes inferiorly, and hooks around the hamulus of the medial pterygoid plate.
• It then inserts into the palatine aponeurosis.

• This muscle tenses the soft palate by using the hamulus as a pulley.
• It also pulls the membranous portion of the auditory tube open to equalise air pressure of the middle ear and pharynx.

The Palatoglossus Muscle

• Superior attachment: palatine aponeurosis.
• Inferior attachment: side of tongue.
• Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.

• This muscle, covered by mucous membrane, forms the palatoglossal arch.

• The palatoglossus elevates the posterior part of the tongue and draws the soft palate inferiorly onto the tongue.

• Superior attachment: hard palatThe Palatopharyngeus Musclee and palatine aponeurosis.
• Inferior attachment: lateral wall of pharynx.
• Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.

• This thin, flat muscle is covered with mucous membrane to form the palatopharyngeal arch.
• It passes posteroinferiorly in this arch.

• This muscle tenses the soft palate and pulls the walls of the pharynx superiorly, anteriorly and medially during swallowing.

The Musculus Uvulae

• Superior attachment: posterior nasal spine and palatine aponeurosis.
• Inferior attachment: mucosa of uvula.
• Innervation: cranial part of accessory through the pharyngeal branch of vagus, via the pharyngeal plexus.

• It passes posteriorly on each side of the median plane and inserts into the mucosa of the uvula.
• When the muscle contracts, it shortens the uvula and pulls it superiorly.

Muscles Around the Nose

The Nasalis Muscle

• This muscle consists of a transverse (compressor naris) and alar (dilator naris) parts.
• It is supplied by the buccal branch of the facial nerve.

The External Ear

• The auricle (L. auris, ear) is the visible, shell-like part of the external ear.
• It consists of a single elastic cartilage that is covered on both surfaces with thin, hairy skin.
• The external ear contains hairs, sweat glands, and sebaceous glands.
• The cartilage is irregularly ridged and hollowed, which gives the auricle its shell-like form.
• It also shapes the orifice of the external acoustic meatus.

The Ear Lobule

• The ear lobule (earlobe) consists of fibrous tissue, fat and blood vessels that are covered with skin.
• The arteries are derived mainly from the posterior auricular artery and the superficial temporal artery.
• The skin of the auricle is supplied by the great auricular and auriculotemporal nerves.

• The great auricular nerve supplies the superior surface and the lateral surface inferior to the external acoustic meatus with nerve fibres from C2.
• The auriculotemporal nerve supplies the skin of the auricle superior to the external acoustic meatus.

The External Acoustic Meatus

• This passage extends from the concha (L. shell) of the auricle to the tympanic membrane (L. tympanum, tambourine). It is about 2.5 cm long in adults.
• The lateral 1/3 of the S-shaped canal is cartilaginous, whereas its medial 2/3 is bony.

• The lateral third of the meatus is lined with the skin of the auricle and contains hair follicles, sebaceous glands, and ceruminous glands.
• The latter glands produce cerumen (L. cera, wax).

• The medial two-thirds of the meatus is lined with very thin skin that is continuous with the external layer of the tympanic membrane.

• The lateral end of the meatus is the widest part. It has the diameter about that of a pencil.
• The meatus becomes narrow at its medial end, about 4 mm from the tympanic membrane.
• The constricted bony part is called the isthmus.

• Innervation of the external acoustic meatus is derived from three cranial nerves:

1. The auricular branch of the auriculotemporal nerve (derived from the mandibular, CN V³).
2. The facial nerve (CN VII) by the branches from the tympanic plexus.
3. The auricular branch of the vagus nerve (CN X).

The Tympanic Membrane

• This is a thin, semi-transparent, oval membrane at the medial end of the external acoustic meatus.
• It forms a partition between the external and middle ears.
• The tympanic membrane is a thin fibrous membrane, that is covered with very thin skin externally and mucous membrane internally.

• The tympanic membrane shows a concavity toward the meatus with a central depression, the umbo, which is formed by the end of the handle of the malleus.
• From the umbo, a bright area referred to as the cone of light, radiates anteroinferiorly.

• The external surface of the tympanic membrane is supplied by the auriculotemporal nerve.
• Some innervation is supplied by a small auricular branch of the vagus nerve (CN X); this nerve may also contain some glossopharyngeal and facial nerve fibres.

The Oropharynx

• The oral part of the pharynx has a digestive function.
• It is continuous with the oral cavity through the oropharyngeal isthmus.
• The oropharynx is bounded by the soft palate superiorly, the base of the tongue inferiorly, and the palatoglossal and palatopharyngeal arches laterally.

• It extends from the soft palate to the superior border of the epiglottis.

The Palatine Tonsils

• These are usually referred to as "the tonsils".
• They are collections of lymphoid tissue the lie on each side of the oropharynx in the triangular interval between the palatine arches.

• The palatine tonsils vary in size from person to person.
• In children, the palatine tonsils tend to be large, whereas in older persons they are usual small and inconspicuous.
• The visible part of the tonsil is no guide to its actual size because much of it may be hidden by the tongue and buried in the soft palate.