Download Anatomy 2 Parotid Gland

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)
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.
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.
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.
Note: Above parotid duct lies temporal
and zygomatic branches of facial nerve
and below duct lies the buccal branch.
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.
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.
Triangle's borders: anterior belly, posterior belly of
Digastric muscle and lower border of mandible.
It’s a mixed gland (serous+ mucus), duct coming from deep part will
open under the tongue in sublingual papillae.
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 preganglionic 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
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 
Remember: Only Structure deep to BOTH muscles is: LINGUAL ARTERY
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
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.
Another Note: between superior and middle constrictor muscles are
3 structures:
123-
Glossopharyngeal nerve
Stylopharyngeus muscle
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.
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.
Veins can cause problems such as
bleeding!
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.)
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