sub-mandibular glands and submandibular calculi

Submandibular glands

• paired salivary glands
• smaller than parotid glands but larger than sublingual glands
• hook shaped, divided to deep and superficial part
• larger arm

o larger arm of hook is below the mylohyoid muscle therefore outside the boundaries of the oral cavity

o superficial part of the gland

o against a shallow impression on the medial side of the mandible

· smaller arm

o deep part

o loops around inferior margin of the mylohyoid muscle to enter and lie within the floor of the oral cavity

o lateral to the surface of the hyoglossus muscle

· submandibular duct

o emerges from the medial side of the deep part of the gland in oral cavity

o passes forward to open on the summit of a small sublingual papilla inside base of frenulum of tongue

o the lingual nerve loops under the submandibular duct from lateral to medial

o nerve descends anteromedially through floor of oral cavity into tongue

vessels

· supplied by branches of facial and lingual arteries

· veins drain into lingual and facial veins

· lymph of submandibular glands drain into submandibular nodes and then into deep cervical nodes

innervation

• chorda tympani branch of facial nerve

Salivary duct calculus is a concretion of mostly calcium mineral salts (calculus) that forms within the ducts. The resulting blockage and inflammation (sialitis) causes immense pain on eating when saliva production increases and infection of the salivary gland may ensue.

The majority form in the submandibular gland.

Where do salivary gland stones occur?

About 8 in 10 salivary stones form in one of the submandibular glands. It is thought that the 'uphill' drainage and the slightly thicker saliva that is made in these glands is why stones are more likely to form there. (The larger parotid glands drain saliva sideways into the mouth. They also make saliva that is 'thinner' than the submandibular glands.)

What are the symptoms of salivary stones?

The common symptoms are pain and swelling of the affected gland at mealtimes. This occurs if the stone completely blocks a duct. You normally make extra saliva during a meal which pours into the mouth. However, the saliva cannot pass into the mouth if the duct is blocked by a stone. The pain can be sudden and intense just after starting a meal. Swelling soon follows. The pain and swelling ease over about 1-2 hours after a meal.

However, most stones do not block a duct completely. A stone may only partially block saliva flow, or not block the flow at all if it is embedded in the body of the gland. In these situations the symptoms can vary and include one or more of the following.

• Dull pain from time to time over the affected gland.
• Swelling of the gland. Swelling may be persistent, or vary in size from time to time.
• Infection of the gland may occur causing redness and pain. This may develop into an abscess (ball of infection and pus) and make you feel quite unwell.
• No symptoms at all. A stone may be found by chance on an x-ray taken for another reason

oral cavity and pharynx

ORAL CAVITY

-part of the oral region
-where the food is ingested
-the voluntary action of swallowing is initiated in oral cavity.
-divided into :

i) oral vestibule : slit-like space between teeth and buccal gingivae and lips and cheek (the area
in front of the teeth)
ii)oral cavity proper : space between upper and lower dental arches (the area behind the teeth up to oropharynx )

PHARYNX

-posterior to nasal and oral cavities
-from cranial base --> inferior border of cricoid cartilage (anteriorly), inferior border of C6
(posteriorly)
-widest ( opposite hyoid)
-narrowest (inferior border of pharynx where it is continuous with esophagus)
-interior of pharnx

i) nasopharynx - choanae --> soft palate (pharyngeal tonsil)
ii)oropharynx- soft palate ---> superior border of epiglottis (palatine tonsil + lingual tonsil)
iii)laryngopharynx - superior border of epiglottis ---> inferior border of cricoid cartilage (C4-C6 posteriorly)

pharyngeal muscles

1) external layers-superior constrictor
-middle constrictor
-inferior constrictor
-function: constrict walls of pharynx during swallowing
2) internal layers-palatopharyngeus
-slapingopharyngeus
-stylopharyngeus
-function: elevate pharynx and larynx during swallowing and speaking

Nerves

-all innervated by pharyngeal branch of vagus nerve and pharyngeal plexus eXCEPT
stylopharyngeus (CNIX) and tensor veli palatini (CNV3)
-inferior constrictor is also innervated by external and recurrent laryngeal nerve of vagus

Artery
-tonsillar artery (branch of facial artery)

Vein
-external palatine vein (paratonsil vein) --> enters pharyngeal venous plexus

Waldeyer's Tonsillar Ring

(Named after Heinrich Wilhelm Gottfried von Waldeyer, 1836 - 1921, German anatomist)

Anatomy

Ring of lymphoid tissue, formed by the lingual tonsil, palatine tonsils, and nasopharyngeal tonsils (also called adenoids). It appears during the first few months after birth, is prominent during childhood, and gradually involves from puberty on. Normal lymphoid tissue of Waldeyer's ring appears as homogeneous soft tissue, sometimes lobulated.

Clinical Applications

· Congenital
If no adenoids are seen by the age of 6 months, a problem with the immune system should be suspected.

· Inflammation
Hypertrophy of the nasopharyngeal tonsil and palatine tonsils is commonly seen in children. Hypertrophy of the adenoids commonly causes dysfunction of the eustachian tube, which on its turn causes serous otitis media. Hypertrophy of the palatine tonsils may cause dysphagia (difficulty swallowing) and breathing difficulties; these symptoms are less commonly seen with lingual tonsil hypertrophy.

· Tumour
Waldeyer's ring is a common site for extranodal non Hodgkin lymphoma head and neck manifestation. Primary squamous cell carcinoma head and neck may hide in crypts within lymphoid tissue of Waldeyer's ring.

Tonsillectomy & Adenoidectomy

Tonsillectomy is defined as the surgical excision of the palatine tonsils while adenoidectomy refers to the surgical excision of the adenoids or nasopharyngeal tonsils.

These are some of the risks and complications of tonsillectomy and adenoidectomy:

• Failure to alleviate every episode of sore throat, or resolve subsequent or concurrent ear or sinus infections/nasal drainage. Possible need for additional surgery.
  
• Failure to improve the nasal airway or resolve snoring, sleep apnea, or mouth breathing.
  
• Bleeding. Bleeding may be classified as intraoperative, primary (occurring within the first 24 hours), or secondary (occurring between 24 hours and 10 days).
  
• Infection, dehydration, and/or prolonged pain which could lead to the necessity for hospital admission for fluids and/or pain control.
  
• A permanent change in voice or nasal regurgitation.
  

Source: http://www.medcyclopaedia.com/library/topics/volume_vi_2/w/waldeyers_ring.aspx
http://www.medicinenet.com/tonsillectomy/article.htm

Contributed by John Lee

Review of Trapezius & Sternocleidomastoid Muscle + their Relation to Investing Fascia

Review of Trapezius:

- An extrinsic or superficial muscle of the back.

Functions: Assist in rotating the scapula during the abduction of the humerus above the horizontal; Upper fibres elevate, middle fibres adduct and lower fibres depress scapula.

Sri: The classification of the fibres are based on their structure i.e. upper fibres are descending fibres; middle fibres transverse & lower fibres are ascending.

Origin: Superior nuchal line, external occipital protuberence, ligamentum nuchae, spinous processes of CVII to TXII.

Insertion: Lateral 1/3 of clavicle, acromion, spine of scapula

Innervation: Motor - accessory nerve(CN XI); Proprioception - C3 and C4

Review of Sternocleidomastoid (aka Sternomastoid muscle)

Function: Individually - tilts head towards shoulder on same side; rotates head to turn face to opposite side, Acting together - draw head forwards

Origin: Sternal head- Upper part of anterior surface of manubrium
Clavicular head- Superior surface of medial 1/3 of the clavicle

Insertion: Lateral 1/2 of superior nuchal line, Lateral surface of mastoid process

Innervation: Accessory nerve (CN XI) and branches from anterior rami of C2 to C3 (C4)

Relations to Investing Fascia:

Posteriorly, the investing fascia attaches to the ligamentum nuchae and the spinous process of CVII. As this fascial layer moves anteriorly, it splits to enclose the trapezius muscle, reunites into a single layer to form the roof of the posterior triangle, spilts again to surround the sternocleidomastoid muscle, and reunites again to join its twin from the other side.

Contributed by John Lee

Source: Gray's Anatomy for Students

Atlanto-occipital and Atlanto-axial joint

Atlanto-occipital joint

-(articulation between the atlas and the occipital bone) consists of a pair of condyloid joints.

ligaments connecting the bones are:
1.Two Articular capsules
- synovial joint of condyloid type, loose capsules

2.Posterior atlantoöccipital membrane
broad but relatively weak
extend from anterior arch of atlas to posterior margin of foramen magnum

3.Anterior atlantoöccipital membrane
- broad, densely woven fibre ( strong)
- centrally they are continuous with anterior longitudinal ligament
- extend from anterior arch of atlas to anterior margin of foramen magnum

The movements permitted in this joint are:
1.flexion and extension, which give rise to the ordinary forward and backward nodding of the head
2.slight lateral motion to one or other (tilting of head)

Atlanto-axial articulation

-articulation of the atlas with the axis

three articulation facet:

2 lateral atlanto-axial joint (right and left)
- betweeen inferior facet of lateral mass of atlas and superior facet of axis.
- gliding type synovial joint

1 median atlanto-axial joint
- between den of axis and anterior arch of atlas
- pivot joint

movement permitted at this joint:
1.rotation of head
- cranium and atlas rotate on axis as a unit
- the dens of C2 is the pivot that is held in the socket formed by the tranverse ligament of the atlas

Ligament connecting the bone:
1.Superior and inferior longitudinal ligament (cruciate ligament)
- pass from transverse ligament to occipital bone superiorly and to body of C2 inferiorly
2.Alar ligament
-extend from side of transverse ligament to lateral margin of foramen magnum
3.Tectorial membrane
- strong superior continuation of posterior longitudinal ligament across the median atlanto-axial joint through foramen magnum to the centre floor of cranial cavity.
- run from C2 to internal surface of occipital bone covering alar and transverse ligament
4.Transverse ligament
- extend between the tubercles of the medial aspects of the lateral mass of C1 verterbrae


Contributed by Lawrence Oh

Boundaries and Contents of the Deep Styloid Region

(Pages & figures cited are from Drake et al, Gray's Anatomy for Students, Intl edition 2005)

Boundaries

Lateral: styloid process (pg 907)
Medial: posterolateral wall of pharynx
Anterior: infratemporal region
Posterior: atlas & axis aka C1, C2
Superior: base of skull
Inferior: posterior belly of digastric muscle (pg 907)

Contents

1. Internal carotid artery (pg 911)
2. Internal jugular vein (pg 913 fig. 8.162 & fig. 8.163; same for for following contents)
3. Glossopharyngeal nerve (IX)
4. Vagus nerve (X) & branches
5. accessory nerve (XI)
6. hypoglossal nerve (XII)
7. sympathetic trunk & superior cervical ganglion (pg 932)

Boundaries and Contents of the Orbit

(Legend: inn. - innervation)

Boundaries

• Below the anterior cranial fossa
• Anterior to the middle cranial fossa
• 4 walls (consisting of bones):
• roof (superior wall)
• medial wall
• lateral wall
• floor (inferior wall)

Contents

1. Eyeball
1. Eyelids:
   

   i. Skin, superficial fascia, thin layer of connective tissue, obicularis oculi

   ii. Orbicularis oculi: inn. facial nerve, closes eyelids

   1. palpebral part (in eyelids): medial palpebral ligament; lateral palpebral ligament

   2. orbital part: surrounds orbit

   3. lacrimal part: fibers on the medial border; attach to posterior lacrimal crest

   iii. Orbital septum: deep to palpebral part of orbicularis oculi; attaches to upper eyelid (levator palpebrae superioris) and lower eyelid (tarsus)

iv. Tarsal plates

1. large superior tarsus (upper eyelid)

2. smaller inferior tarsus (lower eyelid)

3. attaches to lateral palpebral ligament & medial palpebral ligament

4. tarsal glands: modified sebaceous glands; secrete oily substance that increase viscosity of tears and decrease rate of evaporation of tears from surface of eyeball

5. levator palpebrae superioris: raises eyelid; inserts into the anterior surface of superior tarsus; inn. oculomotor nerve

6. superior tarsal muscle: inferior surface of levator palpebrae superioris to upper edge of superior tarsus; inn. sympathetic fibres

2. conjuctiva: thin membrane covering posterior surface of each eyelid
3. glands: sebaceous & sweat glands associated with eyelash follicles
4. vessels
5. layers of the eyeball (e.g. sclera etc)
6. innervation:

i. sensory nerves: branches of trigeminal nerve

ii. motor nerves: facial nerve, oculomotor nerve, sympathetic fibers

2. Lacrimal apparatus: production, movement & drainage of fluid from surface of eyeball
1. Lacrimal gland & ducts

i. Position: anterior in the superolateral region of orbit

ii. Larger orbital part: in lacrimal fossa

iii. Smaller palebral part: inferior to levator palpebrae superioris

iv. Two parts are divided by levator palpebrae superioris

v. Ducts empty into lateral part of the superior fornix of conjunctiva (conjunctival sac)

2. Lacrimal lake: fluid then accumulates here
3. Lacrimal canaliculi: fluid drains into here (one canaliculus associated with each eyelid) via lacrimal punctum (opening)
4. Lacrimal sac: canaliculi join together to enter this sac
5. Nasolacrimal duct: each time you blink, lacrimal sac is compressed; fluid flows into this duct
6. Inferior meatus of nasal cavity: fluid ends up here
7. Innervation:

i. Sensory: lacrimal branch of ophthalmic nerve aka lacrimal nerve

ii. Parasympathetic: fibers joins the lacrimal nerve

iii. Sympathetic: follows similar path to parasympathetic except these fibers originate in the superior cervical ganglion; travel along the plexus surrounding the internal carotid artery

3. Innervations: Optic nerve (CN II), frontal nerve, lacrimal & nasociliary (V₁), oculomotor (III), Trochlear (IV), Abducent (VI), sympathetics and parasympathetics (ciliary ganglion)
4. Extraocular muscles
5. Adipose tissue and fascia
6. Specific nerves & vessels associated with each of these structures
1. Ophthalmic artery (10 branches)
2. 2 venous channels: superior & inferior ophthalmic veins