THOUSANDS OF APOLOGIES

Re: ERROR IN DISTRIBUTING ANATOMY TASK

Dear all,

I am so sorry for not checking the task list thoroughly before asking everyone to select their task so enthusiastically.

So sorry. I think John is still the ideal person in helping us in distributing the task :)

Ji Keon


(Abdominal Acessory Organs - is meant for Week 3, Semester 4)

GASTROINTESTINAL TRACT
*or we will just do this together, as a group discussion
[] Describe the basic structure of hollow viscera including layers,
specialisations, functions & neurovascular supply (Chris)
􀂾 Describe the subdivision of gut into foregut, midgut & hindgut (Christine)
􀂾 Describe the arterial supply & venous drainage of the divisions (Ji Keon)
􀂾 Give an overview of the components of the foregut (Madhura)
􀂾 Give an overview of the components of the midgut (John)
􀂾 Give an overview of the components of the hindgut (Sri)
􀂾 Demonstrate the surface anatomy of the gastrointestinal tract and
indicate clinical situations when this knowledge may be useful (Shantz)

ABDOMINAL ACCESSORY ORGANS

􀂾 Describe the features of the liver & biliary system (Chris)
􀂾 Describe the features of the pancreas (J.K)
􀂾 Describe the relations of the pancreas & clinical implications (Viv)
􀂾 Describe the features of the spleen (Sri)
􀂾 Discuss splenectomy & post-operative sequelae (Law)
􀂾 Review the portal vein (Shantz)
􀂾 Discuss portal hypertension & portosystemic anastomoses (Chris)
􀂾 Describe the features of a plain abdominal x-ray (John)
􀂾 Demonstrate the surface anatomy of the accessory organs and
indicate clinical situations when this knowledge may be useful (Madh)

Pathway of External & Internal Jugular Veins

(hey guys..and girls..erm, reli reli sori for not being able to b there at the prac today..sori!!! here's my part..hope it helps..)

External Jugular Veins
- begins near the angle of the mandible
- union of posterior auricular vein and retromandibular vein
(*revision: retromandibular vein is formed when superficial temporal vein meets maxillary vein)
- crosses SCM obliquely and deep to the platysma
enters the anteroinferior part of the lateral cervical region
pierce the investing layer of deep cervical fascia (posterior of SCM)
- terminates in the subclavian vein

Internal Jugular Veins
- starts at the jugular foramen, a continuation of the sigmoid sinus
the dilated area at the start of the IJV at the jugular foramen is called superior bulb of the IJV
- descends in the carotid sheath with:

• superior to the carotid bifurcation - internal carotid artery
• inferior to the carotid bifurcation - common carotid artery & vagus nerve

- passes throught the anterior cervical region
passes deep to the SCM
passes deep to the gap between the sternal and clavicular head of SCM
- terminates posterior to the sternal end of the clavicle where it merges with the subclavian vein to form the brachiocephalic vein
dilates at the end to form the inferior bulb of the IJV (important because the inferior bulb has a bicuspid valve which permits blood flow to the heart while preventing backflow of blood into the vein)

(Posted by: Vivian)

Paranasal Sinuses

Paranasal sinuses
= air filled extensions of the respiratory part of the nasal cavity into the cranial bones (frontal, ethmoid, sphenoid, maxillary)
function:

• reduce weight of the skull
• warm, humidify and clean air
• help reverberate the voice

Frontal sinuses
- posterior to superciliary arches and root of nose
- detectable by age 7
- usually paired but rarely of equal sizes
separated by a non-median bony septum
- drains through the frontonasal duct into the ethmoidal infundibulum which opens into the semilunar hiatus of the middle nasal meatus
- innervated by supraorbital nerve (CN V1)
*keep in mind that the frontal sinuses are very variable*

Ethmoidal sinuses/cells
- small invaginations of the mucous membrane of the middle and superior nasal meatus
- between medial wall of orbit and nasal cavity (posterior and slightly inferior to frontal sinus)
- known as ethmoidal cells because of its cell-like structure (honeycomb)
- divided into 3 groups

• Anterior ethmoidal cells - drains into middle nasal meatus through the ethmoidal infundibulum
• Middle ethmoidal cells - also known as "Bullar cells" because forms the ethmoidal bulla (swelling on the superior border of semilunar hiatus), open directly into middle nasal meatus,
• Posterior ethmoidal cells - open directly into superior nasal meatus

- innervated by nasociliary nerve (CN V1)
*infection may break the fragile medial wall of the orbit, can cause blindness if severe*

Sphenoidal sinuses
- located in body of sphenoid
separated by a non-median bony septum
- derived from posterior ethmoidal cell at age of 2 years
- opens into sphenoethmoidal recess
- important structures close to it:

• nasal cavity anteriorly
• pituitary fossa and gland superiorly
• cavernous sinus laterally

- innervated by posterior ethmoidal nerve

Maxillary Sinuses
- largest paranasal sinus
- in the body of the maxilla
- apex - towards zygomatic bone
base - lateral wall of nasal cavity
roof - floor of orbit
floor - alveolar part of the maxilla
- drains into maxillary ostium into the middle nasal meatus via the semilunar hiatus
- innervated by superior alveolar nerves (CN V2)
Important things to note about maxillary sinus
1. Infection of the maxillary sinus is common becuase ostia are small and located high on their superomedial walls. Therefore often become obstructed. Also because of the location of the ostia, hard to drain unless it is full.
*Note that apparantly there is cilia present in the maxillary sinus which sweeps the fluid up into the nasal cavity - just like how your cilia sweeps the mucus in the respiratory tract. Fluid accumulates when the cilia fails to work like when there's infection and presence of pus*
2. 3 molar teeth - if removal is not done properly, fragments of the root of the teeth can pierce the sinus, causing infection. Inflammation of the sinus is often accompanied by toothache because supplied by superior alveolar nerves

Note: Important to know where the sinuses open into the nasal cavity

(Posted by: Vivian)

Cervical Trachea and Oesophagus

Trachea
- starts from C6 til sternal angle, bifurcate to R and L bronchus at sternal angle, anterior to oesophagus
- 2.5cm in adults, diameter of pencil in child
- fibrocartilaginous tube, supported by incomplete cartilaginous tracheal rings (to keep airway patent and prevent it from collapsing), posterior part of trachea is the trachealis muscle
- important relations:

• common carotid artery, recurrent laryngeal nerves and thyroid lobes laterally
• jugular venous arches and inferior thyroid veins anteriorly (these structures are inferior to isthmus of thyroid gland)
• oesophagus posteriorly

Oesophagus
- starts from C6 til stomach (T11)
- muscular tube (skeletal muscle upper 1/3, smooth muscle lower 1/3, middle 1/3 is a mix of both)
Cervical oesophagus
- start from pharyngoesophageal jxn (lvl of C6) - this is the narrowest part of the oesophagus caused by the cricopharyngeal part of the inferior constrictor muscle = superior esophageal sphincter
- inclines slightly left as it descends
- ends when it enters the superior mediastinum via thoracic inlet (continues as the thoracic oesophagus)
- important relations:

• trachea anteriorly
• cervical vertebrae posteriorly
• thymus glands laterally

- vessels - inferior thyroid arteries and veins
nerves - recurrent laryngeal nerves and cervical sympathetic trunks (from C1-4 anterior rami)
lymphatics - drains into paratracheal lymph nodes and inferior deep cervical lymph nodes

*Please keep in mind this is only the cervical part of the oesophagus..the oesophagus extends til the stomach!!!!

(Posted by: Vivian)

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