anatomy group :D

THOUSANDS OF APOLOGIES

2007-07-23T08:53:00.000-07:00

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

2007-05-30T07:40:00.000-07:00

(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

2007-05-22T21:51:00.000-07:00

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

2007-05-22T21:30:00.000-07:00

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

2007-05-22T02:20:00.000-07:00

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

2007-05-22T00:49:00.000-07:00

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

2007-05-21T21:52:00.000-07:00

(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

2007-05-15T17:19:00.000-07:00

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

2007-05-14T05:48:00.003-07:00

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

2007-05-11T10:05:00.000-07:00

(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

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

Boundaries and Contents of the Orbit

2007-05-11T09:42:00.000-07:00

(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

Eyeball

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

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

i. sensory nerves: branches of trigeminal nerve

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

Lacrimal apparatus: production, movement & drainage of fluid from surface of eyeball

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)

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

Innervations: Optic nerve (CN II), frontal nerve, lacrimal & nasociliary (V₁), oculomotor (III), Trochlear (IV), Abducent (VI), sympathetics and parasympathetics (ciliary ganglion)
Extraocular muscles
Adipose tissue and fascia
Specific nerves & vessels associated with each of these structures

Ophthalmic artery (10 branches)
2 venous channels: superior & inferior ophthalmic veins

Describe the maxillary and mandibular nerves.

2007-04-28T20:20:00.003-07:00

Maxillary nerve(V2) has 3 branches:
1)Zygomaticotemporal branch
2)Zygomaticofacial branch
3)Infra-orbital branch

-it exit the skull via foramen rotundum

Zygomaticotemporal
-exit zygomatic bone
-supply small area of anterior temple above the zygomatic arch

Zygomaticotfacial
-exit zygomaticofacial foramen
-supply skin on zygomatic bone

Infra-orbital
-exit maxilla via infra-orbital foramen and immediately divide into multi branch
-supply lower eye lid, side of nose, cheek and upper lip

Mandibular nerve (V3) has 3 branches as well:
1)Auriculotemporal branch
2)Buccal branch
3)Mental branch

-it exit the via foramen ovale

Auricotemporal
-enter the face posterior to the temporalmandibular joint
-passes through the parotid gland
-ascend just anterior to the ear
-supply external acoustic meatus & tympanic membrane & large area if temple

Buccal
-on the surface of buccinator muscle
-supply the cheek

Mental
-exit mandible via mental foramen
-immediately divide into multi branch
-supply skin and mucous membrane of lower lip and skin of chin

Contributed by Lawrence Oh

Anatomy Tasks : The Neck

2007-04-26T06:47:00.000-07:00

a. Review the anatomy of the typical and atypical cervical vertebrae. (Shanthini)
b. Review atlanto-occipital and atlanto-axial articulations. (Lawrence)
c. Review trapezius & sternocleidomastoid & their relation to investing fascia (John); Explain how they define the anterior & posterior triangles. (Chris)
d. Explain how anterior triangle is subdivided; describe it's clinical significance. (Madhura)
e. Outline the features of the viscera of the neck - thyroid gland, cervical trachea & cervical oesophagus. (Ji Keon & Vivian)
f. Outline the fascial compartments of the neck & their contents. (Sri)

Please Note!
Special task for Christine: (Deep Fascia Regions) - Demonstrate the surface anatomy of the temporal, infratemporal & deep styloid regions and indicate clinical situations when this knowledge may be useful.

John

Temporal Fossa

2007-04-25T22:56:00.000-07:00

The temporal fossa is a fan-shaped space that covers the lateral surface of the skull.

Boundaries:

Superior Margin: Pair of temporal lines (Superior and inferior temporal lines) that arch from the zygomatic process of the frontal bone to the supramastoid crest of the temporal bone
Lateral Margin: Temporal fascia, a fan-shaped aponeurosis overlying the temporalis muscle
Anterior Margin: Posterior surface of the zygomatic process of the frontal bone and the frontal process of the zygomatic bone
Inferior Margin: Zygomatic arch laterally; Infratemporal crest of the greater wing of the sphenoid medially

Contents:

Temporalis muscle:
Fanshaped muscle that orginates from the superior temporal line;
Fibres converge inferiorly to form a tendon which attaches to the anterior surface of the coronoid process of the mandible;
A powerful elevator of the mandible, retracts the mandible as well.
Innervated by the deep temporal nerves and blood supplied by the deep temporal arteries and middle temporal artery

Deep Temporal Nerves:
Usually 2 in number; originates from the anterior branch of the mandibular nerve(V3) in the infratemporal fossa;
Pass superiorly, around the infratemporal crest of the sphenoid bone, deep to the temporalis muscle to innervate it

Zygomaticotemporal Nerve:
Branch of the zygomatic nerve, a branch of the maxillary nerve (V2);
Originates in the pterygopalatine fossa; Penetrates temporal fascia to supply skin of the temple

Deep Temporal Arteries:
Usually 2 in number; Originate from the maxillary artery in the infratemporal fossa;
Travel superiorly with the deep temporal nerves; Anastomoses with Middle temporal arteries

Middle Temporal Artery:
A branch of the superficial temporal artery; Branches out just superior to the root of the zygomatic arch; Penetrates under the temporal fascia and goes deep to temporalis muscle; Supplies temporalis muscle and anastomoses with deep temporal arteries

Source: Gray's Anatomy for Students
Contributed by John Lee

Facial Nerve Palsy and Bell's Palsy

2007-04-24T09:34:00.001-07:00

Hi everyone, sorry for putting this up so late. Remember Dr Lakshmi was asking us about the difference between a Facial nerve Palsy and a Bell's Palsy during the Facial and Parotid Regions Practical?

Well, hope what I found below will be able to shed some light on the confusion.

Facial nerve paralysis, or facial nerve palsy refers to the paralysis of the facial muscles. This disorder can have numerous causes. These includes
Trauma: such as birth trauma, skull base fractures, facial injuries, middle ear injuries, or surgical trauma.
Nervous system disease: including Opercular syndrome, Millard-Gubler syndrome.
Infection: of the ear or face, or Herpes Zoster of the facial nerve (Ramsey-Hunt syndrome).
Metabolic: diabetes mellitus or pregnancy.
Tumors: acoustic neuroma, schwannoma, cholesteatoma, parotid tumors, glomus tumors.
Toxins: alcoholism or carbon monoxide poisoning.

If no apparent cause can be found in a patient with facial nerve paralysis, then it is said to be idiopathic and the patient is diagnosed as having Bell's palsy (a diagnosis of exclusion). In other words, Bell's palsy is an idiopathic facial paralysis.

As the name suggests, there is no known etiology behind Bell's palsy as yet. Some schools of thought suggest that Bell's palsy is caused by a viral infection of the facial nerve with the most likely virus being the herpes simplex virus.

Bell's palsy is usually a self-limiting, non-life threatening condition that spontaneously remits within six weeks. The incidence is 15-40 new cases per 100,000 people per year in the US. It is one of the most common neurological disorders affecting the cranial nerves. There is no predominant age or racial predilection; however it is 3.3 times more common during pregnancy and slightly more common in menstruating females. In general, the incidence increases with advancing age.

The typical symptoms of Bell's palsy include:
Unilateral acute paralysis of facial muscles. The paralysis involves all muscles, including the forehead.
About half the time, there is numbness or pain in the ear, face, neck or tongue.
There is a preceding viral illness in 60% of patients.
There is a family history of Bell's palsy in 10% of patients.
Less than 1% of patients have bilateral problems.
There may be a change in hearing sensitivity (often increased sensitivity).

The proposed mechanism of injury of the facial nerve in Bell's palsy is:
Primary viral infection (herpes) sometime in the past.
The virus lives in the nerve (trigeminal ganglion) from months to years.
The virus becomes reactivated at a later date.
The virus reproduces and travels along the nerve.
The virus infects the cells surrounding the nerve (Schwann cells) resulting in inflammation.
There immune system responds to the damaged Schwann cells which and causes inflammation of the nerve and subsequent weakness or paralysis of the face.
The course of the paralysis and the recovery will depend upon the degree and amount of damage to the nerve.

Facial nerve palsy or Bell's palsy? You tell me! =)

Source: http://www.medicinenet.com/facial_nerve_problems/page3.htm

Contributed by: John Lee

Deep Facial Regions - Anatomy Tasks

2007-04-24T09:27:00.000-07:00

This is just a reminder for the tasks that we are going to do on thursday, after the 2pm lecture.

1. Describe the temporomandibular joint. (Ji Keon)
2. Describe the muscles of mastication. (Shanthini)
3. Describe the maxillary artery and it's major branches. (Vivian)
4. Describe the maxillary and mandibular nerves. (Lawrence)
5. Describe the boundaries and contents of the temporal (John), infratemporal (Sree), and deep styloid regions (Madhura).
6. Group and list the foramina of these regions (temporal, infratemporal and deep styloid) ; describe contents. (Chris)
7. Demonstrate the surface anatomy of the regions and indicate clinical situations when this knowledge may be useful. (Christine)

Otalgia

2007-04-24T08:37:00.000-07:00

Otalgia is defined as ear pain. Two separate and distinct types of otalgia exist. Pain that originates within the ear is primary otalgia; pain that originates outside the ear is referred otalgia.

Typical sources of primary otalgia are external otitis, otitis media, mastoiditis, and auricular infections. Most physicians are well trained in the diagnosis of these conditions. When an ear is draining and accompanied by tympanic membrane perforation, simply looking in the ear and noting the pathology can make the diagnosis. When the tympanic membrane appears normal, however, the diagnosis becomes more difficult.

Referred otalgia is a topic unto itself. Although many entities can cause referred otalgia, their relationship to ear pain must be identified. A categorical discussion of the workup, treatment, prognosis, demographics, and other issues is impossible because the various pathologies responsible for creating referred otalgia are so diverse.

By definition, referred otalgia is the sensation of ear pain originating from a source outside the ear.

To better understand referred otalgia, the physician first must understand the anatomic distribution of nerves associated with the ear. Irritation of these nerves, as well as irritation of distant branches of these nerves, can cause the perception of pain within the ear.

Pathophysiology: The sensory innervation of the ear is served by the auriculotemporal branch of the fifth cranial nerve, trigeminal nerve (CN V), the first and second cervical nerves, the tympanic (Jacobson) branch of the glossopharyngeal nerve, the auricular (Arnold) branch of the vagus nerve, and the sensory branches of the facial nerve. Neuroanatomically, the sensation of otalgia is thought to center in the spinal tract nucleus of CN V. Not surprisingly, fibers from CNs V, VII, IX, and X and cervical nerves 1, 2, and 3 have been found to enter this spinal tract nucleus caudally near the medulla. Hence, noxious stimulation of any branch of the aforementioned nerves may be interpreted as otalgia.

Causes: Dental disorders are the most common cause of referred pain to the ear. Of this group of disorders, temporomandibular dysfunctions account for the majority of patients. The auriculotemporal branch of the trigeminal nerve mediate pain, which is often perceived deep within the ear.

Within the oral cavity, the sensory innervation becomes quite complex. The tongue receives fibers from the glossopharyngeal nerve, the facial nerve, the trigeminal nerve and the vagus nerve posteriorly. All these nerves have distributions in the ear as well.

Sinusitis is another very common source of ear pain. The neural pathway is along V2, and the auriculotemporal nerve of V3, of CN V. Because the trigeminal nerve supplies the nasal cavity, patients with inflammatory mucosal contact points and nasal obstruction may develop symptoms in their ears.

Neck problems can also refer pain to the ears. These disorders include cervical osteoarthritis, cervical myofascial pain syndrome, and traumatic injuries. The cervical spine is sensitive and well supplied by the cervical nerve roots. Muscular pain from the trapezius or sternocleidomastoid may project postauricularly to the mastoid and occipital area.

Sensory branches of the vagus and glossopharyngeal nerves supply mucosal areas in the upper aerodigestive tract such as the nasopharynx, oropharynx, laryngopharynx, and larynx. The vagus continues caudally and supplies sensory enervation to the bronchus, esophagus, and heart as well. Irritative lesions at any of these sites may lead to secondary otalgia.

Tonsillitis and pharyngitis are very common causes of earaches in children. Less commonly, laryngitis, laryngeal tumors, esophagitis, and even angina pectoris may manifest as otalgia.

Sometimes, pain may be from irritation of the nerves themselves without an inciting source. These disorders are termed neuralgias. Neuralgias are typified by lancinating pain in the distribution of the involved nerve.

Source: http://www.emedicine.com/ent/topic199.htm

Contributed by John Lee

Palsies of the CN III, IV, VI

2007-04-24T03:49:00.000-07:00

by Ji Keon LOOI

Oculomotor Palsy
Characteristic signs of a complete lesion of CN III:-

Ptosis (drooping) of the superior eyelid, caused by paralysis of the levator palpebrae superioris.

Eyeball (pupil) abducted and directed slightly inferiorly (down and out) because of unopposed actions of the lateral rectus and superior oblique.

No pupillary (light) reflex (constriction of the pupil in response to bright light) in the affected eye

Dilation of pupil, resulting from the interruption of parasympathetic fibers to the sphincter of the pupillae, leaving the dilator pupillae unopposed.

No accommodation of the lens (adjustment to increase convexity for near vision) because of paralysis of the ciliary muscle.

Injury to the Trochlear Nerve
CN IV is rarely paralyzed alone. The nerve may be torn in severe head injuries because of its long intracranial course. Damage to CN IV nerve or its nucleus impair the ability to turn the affected eyeball inferomedially. The characteristic sign of trochlear nerve injury is diplopia (double vision) when looking down (e.g., when going down stairs). Diplopia occurs because the superior oblique normally assists the inferior rectus in depressing the pupil (directing the gaze downward) and is the only muscle to do so when the pupil is adducted. In addition, because the superior oblique is the primary muscle producing intorsion of the eyeball, the primary muscle producing extorsion (the inferior oblique) is unopposed when the superior oblique is paralyzed. Thus the direction of gaze and rotation of the eyeball about its anteroposterior axis is different for the two eyes, especially when looking downward and medially.

Injury to the Abducent Nerve
Because CN VI has a long intracranial course, it is often stretched when intracranial pressure rises, partly because of the sharp bend it makes over the crest of the petrous part of the temporal bone after entering the dura. A space-occupying lesion such as a brain tumor may compress CN VI, causing paralysis of the lateral rectus muscle. Complete paralysis of CN VI causes medial deviation of the affected eye—that is, it is fully adducted owing to the unopposed action of the medial rectus, leaving the person unable to abduct the eye. Diplopia is present in all ranges of movement of the eyeball, except on gazing to the side opposite the lesion.

Source: Moore and Agur; Essential Clinical Anatomy, Lippincott and Williams