Anatomy 2

Parotid Gland: "refer to previous sheet for extra details."

Its pyramidal in shape, apex is toward pharynx. Its Medial surface is

divided into Anterio-medial and posterio-medial and its posterio-medial

surface forms the parotid bed.

Parotid bed (V.imp): meaning that gland is sleeping on structures and

they are:

1- Facial nerve and its 5 branches (Most Superficial structure)

2- Retromandibular vein

3- External carotid artery (most deep structure)

Parotid gland is covered by 2 capsules in which the outer capsule is tough

and fibrous..Therefore during infections, it will enlarge and cause pain;

enlargement is limited by the capsule.

During a viral infection such as Mumps; Rest, Vitamins and sedative

drugs are used to treat infection since mumps can cause sterility of

ovaries if not treated.

Also during Parotid cancer, the gland will enlarge affecting its anatomy.

Note: External carotid gives its 2 terminal branches at neck of

mandible and they are: maxillary and superficial temporal.

Retromandibular vein: is formed in parotid and it’s the middle

structure in parotid bed. It's formed from maxillary and superficial

temporal veins at lower border of gland. Its anterior division joins

facial vein forming common facial vein and then drain into internal

jugular vein. Its posterior division joins posterior auricular vein

forming external jugular vein that drains into subclavian vein.

Surface Anatomy:

Parotid Duct crosses masseter muscle then pierces buccinator and is 1

finger below zygomatic arch. Then this duct open in vestibule at level of

upper second molar.

This duct can become blocked by stones. Lemon is given to patient and

excessive secretions can be seen plus swelling, confirming the block of

gland.

Clinical Point:

Stem of facial nerve divides the parotid into Superficial and deep lobes

and is then branched into 5 branches that supply muscles of facial

expression. After surgery to parotid, surgeon should make sure that no

nerve branch is injured or facial palsy might form. He is supposed to ask

the patient to due few movements to make sure he is fine..

Examples: patient is told to close his eye to insure working orbicularis

occuli muscle..if an eye didn’t close this might lead to dryness of cornea.

He is also told to blow out to check orbicularis oris muscle..if he didn’t

blow, drooping of saliva might take place due to injury to that muscle. He

is also told to show his teeth for buccinator muscle activity.

HOWEVER, patient should be able to clench his teeth even if he has

facial palsy as this movement is controlled by muscles of mastication that

are supplied by mandibular nerve NOT Facial.

Anatomical relations (V.Imp):

Anteriomedial and posteriomedial structures related to parotid are very

important.

Note: Above parotid duct lies temporal

and zygomatic branches of facial nerve

and below duct lies the buccal branch.

Anteriomedial structures related to parotid are:

1- Ramus of mandible

2- Masseter muscle

3- Medial pterygoid muscle.

Posteriomedial structures related to parotid are:

1- Stylohyoid muscle

2- Posterior belly of Digastric.

3- Most important: one third of carotid sheath containing internal

carotid, internal jugular vein and externa carotid artery.

4- Last 4 cranial nerves.

Auricolotemporal nerve is found in upper part of gland and carry

sensory plus secretomotor (parasympathetic).

Secretomotor Innervation of gland:

Parasympathetic secretomotor supply arises from the Glossopharyngeal

nerve. The pre-ganglionic from the lesser petrosal nerve, then to otic

ganglion and the post-ganglionic fibers are from the Auricolotemporal

nerve. Parotid lymph nodes can also be seen.

Submandibular Gland:

Is Located in Digastric or Submandibular triangle.

It’s a mixed gland (serous+ mucus), duct coming from deep part will

open under the tongue in sublingual papillae.

Triangle's borders: anterior belly, posterior belly of

Digastric muscle and lower border of mandible.

Mylohyoid muscle -originating from mylohyoid line of mandible- divides

gland into superficial part and deep part. Mylohyoid also separates the

sublingual fossa from Submandibular fossa which lies beneath it.

Superficial part itself is divided into 2 parts:

1- Upper part hidden in Submandibular fossa

2- Lower part below the lower border of mandible.

Secretomotor Innervation of gland:

Parasympathetic secretomotor supply is from the facial nerve. The pre-

ganglionic fibers form the chorda tympani joining lingual nerve, then to

submandibular ganglion and the postganglionic fibers pass directly to the

gland OR through lingual nerve.

Submandibular anatomical relations:

Hypoglossus and mylohyoid muscles are both related to deep part of

gland.

Structures found between mylohyoid and Hypoglossus:

1- Submandibular deep part

2- Submandibular ganglia

3- Submandibular duct

4- Lingual nerve

5- Hypoglossal nerve

Remember: Only Structure deep to BOTH muscles is: LINGUAL ARTERY

Note: BECAREFUL this Question always comes in the exam and

it might be asked indirectly.. For Example:

"Structures deep to mylohyoid" or "Structures superficial to

Hypoglossus" or "structures between Hypoglossus and

mylohyoid"…SO TAKE CARE

Triple relation between lingual nerve and Submandibular duct:

Lingual nerve is at first superficial to duct, then comes below it and as

they open to mouth at end its medial to it.

Note: Chorda tympani joins the lingual nerve at the far beginning

Sublingual Gland:

The right and left gland meet at midline and are covered by mucosa.

Gland is mostly mucus. Duct opens directly into mouth or through

Submandibular duct

Medial structures related to it:

1- Lingual nerve (most medial)

2- Submandibular duct

3- Genioglossus muscle

Posterior and below is the mylohyoid muscle.

Its parasympathetic innervation is the same as Submandibular.

PHARYNX:

Is made up of 3 parts: Nasopharynx, oropharynx and laryngopharynx

(also called hypopharynx).

It’s a muscular tube that originates from the base of skull below sphenoid

and occipital base till the 6th cervical vertebrae. It then continues as

esophagus.

Difference between pharynx and esophagus is that pharynx is

open anteriorly where as esophagus is a complete muscular tube.

It has a length of 5 inches and is funnel in shape meaning it's wide

superiorly and narrow inferiorly.

Pharynx is made up of 3 constrictor muscles; superior, middle and

inferior in which one overlaps the other and so the inferior constrictor

muscle has the widest base of them all.

Together with those constrictor muscles we have stylopharyngeus muscle

and salpyngopharyngeus.. They are all innervated by Pharyngeal plexus

EXCEPT Stylopharyngeus muscle by GLOSSOPHARYNGEAL NERVE.

These muscles are inserted into Pharyngeal raphe which is a tough

fibrous tissue that originates from pharyngeal tubercle located anterior to

foramen magnum.

Constrictor muscles are circular in shape for peristaltic movements and to

help propagation of bolus where as stylopharyngeus and

salpyngopharyngeus are longitudinal in shape. They all have the same

action EXCEPT a small part from inferior constrictor muscle.

Inferior constrictor muscle is made up of 2 parts:

1- Upper oblique part

2- Lower part called Cricopharyngeus muscle; this muscle is circular

and is always contracted to prevent passage of AIR! It only opens

when bolus reaches it. It acts as sphincter for the esophagus and

that’s why it’s the only part having different action than other

muscles of pharynx

Killian's dehiscence: is the area on the posterior pharyngeal wall

between the upper propulsive part of the inferior constrictor and the

lower sphincteric part, the Cricopharyngeus.

Origin and insertion of Pharynx muscles:

1) Superior constrictor

Origin: Medial pterygoid plate, pterygoid hamulus, pterygomandibular

ligament, mylohyoid line of mandible

Insertion: Pharyngeal tubercle of occipital bone, raphe in midline

posteriorly

Innervation: Pharyngeal plexus

Action: Aids soft palate in closing off nasal pharynx, propels bolus

downward

2) Middle constrictor

Origin: Lower part of stylohyoid ligament, lesser and greater cornu of

hyoid bone

Insertion: Pharyngeal raphe

Innervation: Pharyngeal plexus

Action: Propels bolus downward

3) Inferior constrictor

Origin: Lamina of thyroid cartilage, cricoid cartilage

Insertion: Pharyngeal raphe

Innervation: Pharyngeal plexus

Action: Propels bolus downward

4) Cricopharyngeus

Origin: Lowest fibers of inferior constrictor muscle

Insertion: Sphincter at lower end of pharynx

5) Stylopharyngeus

Origin: Styloid process of temporal bone

Insertion: Posterior border of thyroid cartilage

Innervation: Glossopharyngeal nerve

Action: Elevates larynx during swallowing

6) Salpingopharyngeus

Origin: Auditory tube

Insertion: Blends with palatopharyngeus

Innervation: Pharyngeal plexus

Action: Elevates pharynx

7) Palatopharyngeus

Origin: Palatine aponeurosis

Insertion: Posterior border of thyroid cartilage

Innervation: Pharyngeal plexus

Action: Elevates wall of pharynx, pulls palatopharyngeal arch medially

Inferior of the Pharynx:

A) In NasoPharynx:

1- Choanae: is the posterior opening of nasal cavity

2- On the lateral wall is the opening of the Eustachian tube, the

elevated ridge of which is called the tubal elevation.

Remember: infection or vomiting in babies can reach middle ear

from this tube and lead to Otitis Media.

3- Salpyngopharyngeal fold is a vertical fold of mucous membrane

covering the salpyngopharyngeus muscle.

B) Oral Pharynx:

Have the tonsils in it lateral walls

Relation between epiglottis and tongue:

They are related by 3 folds; medial glossoepiglottic fold and 2 lateral

glossoepiglottic folds. In between these folds lies the vallecula.

While bolus is in mouth; base of tongue goes downward pushing

epiglottis down and the aryepiglottic fold has aryepiglotticus muscle

that contracts, and larynx move upwards by Suprahyoid muscle.

This will lead to complete closure of larynx. The soft palate will close

the nasopharyngeal isthmus.

Some of the food slides down through the Piriform fossa. Piriform

fossa is a depression of mucosa that is anterior to pharynx or

posterior to larynx. Foreign bodies can lodge in this depression

especially Fish bones.

Sensory supply of pharyngeal mucous membrane:

Nasal pharynx: The maxillary nerve (V2)

Oral pharynx: The Glossopharyngeal nerve

Laryngeal pharynx (around the entrance into the larynx): The internal

laryngeal branch of the Vagus nerve

Another Note: between superior and middle constrictor muscles are

3 structures:

1- Glossopharyngeal nerve

2- Stylopharyngeus muscle

3- Mandibulo-pharyngeal ligament.

Blood Supply of the Pharynx:

Ascending pharyngeal, tonsillar branches of facial arteries, and branches

of maxillary and lingual arteries

Lymph Drainage of the Pharynx:

Directly into the deep cervical lymph nodes or indirectly via the

retropharyngeal or paratracheal nodes into the deep cervical nodes.

Note: Vagus nerve gives rise to Superior laryngeal nerve. In

turn superior laryngeal divides into:

1- Internal branch; found inside larynx and is sensory. It

penetrates the membrane between middle and inferior

constrictor muscles.

2- External branch; outside larynx. It supplies the

CRICOTHYROID muscle.

Palatine Tonsils:

The palatine tonsils are two masses of lymphoid tissue, each located in

the depression on the lateral wall of the oral part of the pharynx between

the palatoglossal and palatopharyngeal arches.

Its medial surface is covered by mucous membrane (stratified squamous

non-keratinized epithelium). Crypts can be seen on medial surface due to

infections.

Its lateral surface is covered by capsule. During tonsillectomy lateral

capsule is opened and by the use of surgeon's finger, tonsil is pulled out

and then ligation of tonsillar artery and vein takes place.

External palatine Vein or also called "Para-tonsillar Vein"

descends from the soft palate in this tissue to join the

pharyngeal venous plexus. Patient is kept under observation

with ice cream given to cause vasoconstriction of vessels.

However, bleeding might take place sometimes as this vein

pierces the superior constrictor muscle and so need to be

ligated. This vein can't be seen easily except after operation.

Note: tonsillitis is the inflammation of tonsils due to an

infection. This infection is usually due to Streptococcus species.

If infection is continuous meaning takes place more than 4

times per year.. Tonsillectomy is recommended. This is

because streptococcus infection can become chronic affecting

heart and causing endocarditis, it can also cause inflammation

in knee joint and in kidneys.

Lateral to the superior constrictor muscle lie the styloglossus

muscle, the loop of the facial artery, and the internal carotid artery.

(msh 3arfeh hay esh elha dakhal bl nos.)

Veins can cause problems such as

bleeding!

Blood Supply of tonsil

Artery: The tonsillar branch of the facial artery.

Veins: The veins pierce the superior constrictor muscle and join the

external palatine, the pharyngeal, or the facial veins.

Lymph Drainage of the Tonsil

The upper deep cervical lymph nodes, just below and behind the angle of

the mandible.

Waldeyer's Ring of Lymphoid Tissue:

The lymphoid tissue that surrounds the

opening into the respiratory and digestive

systems forms a ring

The lateral part of the ring is formed by

the palatine tonsils and tubal tonsils

(lymphoid tissue around the opening of

the auditory tube in the lateral wall of the

Nasopharynx)

The pharyngeal tonsil(Adenoid) in the roof

of the Nasopharynx forms the upper part,

and the lingual tonsil on the posterior third

of the tongue forms the lower part.

Remember: Enlargement of adenoids in

babies can lead to snoring and difficulty in breathing and should be

removed.

Please refer to the slides as the doctor didn’t mention everything in

them!! Imagine that :P!

Good Luck

Done by:

Sara Kussad