1 Demonstrate the organization of the three layers of the pericardial sac and explain their role in the occurrence of pericardial tamponade



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Anatomy Second Semester Oral Quiz Review 01/29/2013

1) Demonstrate the organization of the three layers of the pericardial sac and explain their role in the occurrence of pericardial tamponade.

The pericardial sac begins externally with a tough fibrous layer of dense connective tissue. Internal to that is the serous parietal pericardium, and, like the lung, there is a visceral pericardium attached directly to the organ parenchyme, that here, is the myocardium.


Pericardial tamponade is an acute type of pericardial effusion. Due to the tough outer layer of the pericardial sac, there is a finite space that fluid may accumulate in, and while it does so, puts a great deal of pressure on the ventricles, reducing stroke volume. The cause of the effusion can be myocardial rupture, pericarditis, trauma, neoplasm, and cardiac surgery. Pressure is relieved by pericardiocentesis (needle inserted from the skin by ultrasound guidance)
2) Demonstrate the transverse and oblique sinuses of the pericardium, describing their borders (arterial and venous) and explain their use in cardiac surgery.
After the pericardial sac has been opened anteriorly, a finger can be passed through the transverse pericardial sinus posterior to the aorta and pulmonary trunk. The transverse pericardial sinus is between the venous and arterial mesocardia, namely, the ascending aorta and pulmonary artery cranio-ventrally and the superior vena cava dorsally.
The transverse pericardial sinus is especially important to cardiac surgeons. By passing a surgical clamp or placing a ligature around these vessels, inserting the tubes of a coronary bypass machine, and then tightening the ligature, surgeons can stop or divert the circulation of blood in these large arteries while performing cardiac surgery.
The oblique pericardial sinus lies posterior to the heart (dorsal) and is bounded

Anteriorly by serous pericardium of the left atrium

Posteriorly by the parietal pericardium of the pericardial sac

Superiorly and laterally by the reflection of serous pericardium around the four pulmonary veins, SVC & IVC

Lift the apex of the heart and place fingers posterior to the heart to identify the oblique pericardial sinus. This space is utilized during cardiac surgery to manually massage and manipulate the heart.
3) Demonstrate the four borders of the heart seen in the anterior view (inferior, superior, left or right pulmonary) and describe the structures composing each border.

Right border (from superior to inferior)

SVC

Right atrium



IVC

Left border (from superior to inferior)

Arch of the aorta (aortic knob on film)

Pulmonary trunk (knob)

Left auricle

Left ventricle


4) Demonstrate the four surfaces of the heart (anterior, posterior, left & right lateral, inferior & superior) ….[that’s six for those counting] and describe the structures composing each surface.
Superior: where the great vessels are located

Inferior (floor): directed downward and dorsally, is formed by both ventricles

and rests on the central tendon

Right Lateral: Right atrium, ventricle and vena cavae

Left Lateral: Left auricle, atrium and ventricle

Posterior: Left atrium, vena cavae, pulmonary veins, coronary sinus

Anterior: The apex of the heart, formed by both ventricles, and the left

auricle and right atrium compose the anterior aspect of the heart.


5) Demonstrate the components present in the right atrium and right ventricle and explain the clinical aspects of right sided failure.
The right atrium receives venous, oxygen-poor blood, from the systemic circulation via the superior vena cava (SVC), inferior vena cava (IVC), and (posteriorly) the coronary sinus. The pectinate muscles extend from the crista terminalis (vertical muscular ridge on the internal surface of the anterior right atrial wall.) The crista terminalis separates the rough pectinate surface from the smooth surface posterior, termed the sinus venarum. The fossa ovale is also visible, a region of the interatrial septum, which, in the patient’s embryonic life, served as a right-to-left shunt, known as the foramen ovale. The smooth interior portion of the anterior right atrial wall is what remains of the sinus venarum.
The right ventricle receives from blood from the right atrium via the tricuspid valve. The chordae tendineae are ligaments that connect each cusp to the papillary muscles, closing each cusp when the papillary muscles are contracting. The valve has a septal, anterior and posterior valve. Tracking the anterior papillary muscle inferiorly, one can locate the muscular moderator band (aka septomarginal trabeculae) and follow it to the ventricular septum. The moderator band carries the right bundle branch from the AV node. The trabeculae carnea is the term for the musculature of the right ventricular wall. The conus arteriosus is the narrowing, smooth walled portion of the ventricle located left and superiorly, leading to the pulmonary valve, which also has three cusps; anterior, right and left cusps.
When the right ventricle begins to lose efficiency (losing ejection fraction)
Common clinical symptoms of right-sided heart failure:

Dyspnea


Peripheral edema

Jugular vein distension (JVD)

Nocturia

Hepatomegaly

Common causes of right-sided heart failure:

Coronary artery disease (CAD)

Left-sided heart failure

COPD or chronic bronchitis / emphysema alone

Congestive Heart Failure (CHF)

Pulmonary embolism (PE)

Valvular disease / damage / defect

Anemia (associated)

Hyperthyroidism
6) Demonstrate the components present in the left atrium and left ventricle and explain the clinical findings in left sided failure.
The left atrium receives oxygen-rich blood from the pulmonary venous system (2 veins per lung). These pulmonary veins dump into the posterior region of the left atrium. Blood passes from the left atrium to the left ventricle via the mitral valve (aka bicuspid valve).
The left ventricle receives oxygen-rich blood and is responsible for pumping that into the systemic circulation. With a much thicker myocardium than the right ventricle, the left also has two papillary muscles, (one per mitral cusp). Blood is ejected through the aortic (semilunar) valve into the ascending aorta. From the ascending aorta, you can see the 3 sac-like depressions called aortic sinuses. From these sinuses you can find the coronary artery and vein branch points.
Left-sided heart failure is associated with these symptoms & findings:

Increased work to breath

Rales or crackles upon auscultation (lung bases)

Pulmonary edema

Pulmonary effusion

Cyanosis

Cough, frothy

Hemoptysis

Needs to elevate head

Decreased urine production

Fatigue, weakness

Paraoxysmal nocturnal dyspnea

Weight gain

Laterally displaced heart apex beat

Gallop rhythm

Common causes of left-sided heart failure:

MI

Myocarditis



High blood pressure

Valvular damage, defect, disease

Hypothryroidism
7) Demonstrate the course of the great vessels in and out of the heart and explain the two ‘crosses’ present in the heart.

Identify them on your own heart:

Pulmonary veins

Pulmonary arteries

Ascending aorta

Inferior & Superior Vena Cavae
The two crosses of the great vessels are (1) between the pulmonary veins and the vena cavae and (2) aorta and the pulmonary trunk (45° from floor)
(Thanks reader)
8) Describe and identify the sites of auscultation of the cardiac sounds on your partner.
A(ortic) region: Between 2nd & 3rd intercostal spaces, immediately lateral to

sternum (RUSB)

P(ulmonary) region: Left 2nd intercostal space, immediately lateral to

sternum (LUSB)

T(ricuspid) region: 4th to 6th intercostal spaces, at lower left sternal border

(LLSB)


M(itral) region: between 5th and 6th intercostal spaces on the left

mid-clavicular line


Note!
The below image shows the tricuspid region too far to the right. Please note the auscultation of the tricuspid is on the left border, not right.



1.) Demonstrate the major coronary arteries (see pictures below @ #2) and discuss the mechanism for generating systole in the coronary system
During systole, the contraction of the ventricular musculature compresses and occludes the coronary vasculature. At the moment of contraction, blood is pushes into the venous system to the coronary sinus. Also, some blood is pushed back into the epicardial vessels (superficial, large portions of coronary arteries), which act as capacitors.
2.) Describe the cardiac veins and demonstrate their presence where possible on the heart



3.) Describe the conductile system of the heart and demonstrate its components wherever possible on the heart.
Beginning with the sinoatrial node, which is located on the lateroposterior aspect of the right atrium. (may be visible on exterior surface). The SA node is the pacemaker of the heart and demonstrates phase 4 depolarization, a.k.a. automaticity. A given depolarization travels next to the atrioventricular node, located between the atria & ventricles. The AV node shows the slowest conduction velocity, which permits complete ventricular filling before the contraction of the myocardium occurs.
The impulse then travels through the bundle of His, which runs along the interventricular septum as right and left bundle branches. At the apex of the heart, the bundle branches lead to the Purkinje fiber system. The Purkinje fibers provide electrical conduction to the ventricles, transmitting a paced interval.
4.) Describe the sympathetic innervation of the heart and demonstrate its components wherever possible on the heart and great vessels.
(See answer for #5 below)
5.) Describe the sympathetic innervation of the heart and demonstrate its components wherever possible on the heart and great vessels.
Sympathetic Innervation

Preganglionic: T1 to T4(T5)

Postganglionic: Cervical ganglia and cardiac sympathetic nerves

Parasympathetic Innervation

Preganglionic: vagal nuclei and vagal cardiac nerves

Postganglionic: Cardiac ganglia and cardiac plexus

Related anatomy

The cardiac plexus is divided into two regions

Superficial

Posterior to arch of aorta, anterior to pulmonary trunk

Formed by superior cardiac branch of left sympathetic trunk and lower superior cervical cardiac branch of the left vagus nerve

Deep


Anterior to tracheal bifurcation, posterior to arch of aorta, superior to pulmonary arterial split

Formed by cardiac nerves by the cervical ganglia of sympathetic trunk and the cardiac branches of the vagal and recurrent laryngeal nerves

Splits into left and right branches

If possible, locate the vagus, recurrent laryngeal, sympathetic trunk (T1-T4/5) & splanchnic nerves

Note, the left vagus nerve innervates the AV node & the right vagus innervates the SA node
6.) Demonstrate the approximate location of the four cardiac valves on a PA chest film and describe the auscultation points for each valve.
As you can see below: (not a PA chest film) but helpful

Follow the anterior 3rd rib on the right (aortic valve)

Follow the anterior 3rd rib of the left (pulmonary valve)

Follow the anterior 5th rib on the right (tricuspid valve)

Follow the anterior 4th rib on the left (mitral/bicuspid valve)

The locations for auscultation are more clearly seen in the photo, the valve locations are a bit difficult to see, but they’re there.





Demonstrate the branches of the ophthalmic division of the trigeminal nerve and describe the nerve fiber components or specific function of those branches
Ophthalmic nerve fibers carried

Somatic afferent (GSA)

Sensation to the

Upper face

Ciliary body

Cornea


Iris

Portions of nasal mucosa

Sphenoidal sinus

Frontal sinus

Tentorium cerebelli

Posterior dura mater

Posterior area of falx cerebri
Branches of the ophthalmic division of the trigeminal nerve

Nasociliary nerve

Branch to sensory root of ciliary ganglion

Sensation from eye ball components

Posterior ethmoidal nerve

Sensation from posterior ethmoidal air cells

Long ciliary nerve

Carry sympathetic fibers from stellate ganglion to the

dilator pupillae muscle

Sensation from sclera, choroid, iris, cornea

Infratrochlear nerve

Sensation from skin just medial to palpebral fissure

Anterior ethmoidal nerve

Sensation from anterior ethmoidal air cells

Frontal nerve

Supratrochlear nerve

Sensation from

midline, inferior forehead

conjunctiva

skin of upper eyelid

Supraorbital nerve

Sensation from

Frontal sinus

Conjunctiva

Skin of the forehead (2 branches)

Lacrimal nerve

Sensation to the lacrimal gland & conjunctiva

Recurrent meningeal branch to tentorium, falx


Demonstrate the branches of the maxillary division of the trigeminal nerve and describe the nerve fiber components or specific function of those branches
Maxillary nerve fibers carried

Somatic afferent (GSA)

Sensation to

Maxillary

Nasal cavities

Sinuses


Palate

Mid-face


Visceral efferent pathway (GVE)

Lacrimal nerve (V1) conveys parasympathetic fibers from CN VII originating by the zygomatic branch of V2 from the pterygopalatine ganglion


Branches of the maxillary division of the trigeminal nerve

Pathway


Passes from trigeminal ganglion through the cavernous sinus and exits via foramen rotundum

Crosses pterygopalatine fossa

Enters orbit at infraorbital fissure

Traverses the infraorbital groove and emerges on the face via the infraorbital foramen

In the cranium

Middle meningeal nerve

From pterygopalatine fossa

Infraorbital nerve

Zygomatic nerve

Nasal branches

Superior alveolar nerves (posterior superior, middle superior)

Palatine nerves (greater & lesser palatine nerves)

Pharyngeal nerve

In the infraorbital fissure

Anterior superior alveolar nerve

Infraorbital nerve

On the face

Inferior palpebral nerve

Superior labial nerve
Demonstrate the branches of the mandibular division of the trigeminal describe the nerve fiber components or specific functions of those branches
Mandibular nerve fibers carried (via foramen ovale)

Special visceral efferent (BE)

To muscles of mastication

Visceral efferent (GVE)

Lingual nerve to chorda tympani
Branches of mandibular division of trigeminal

From main trunk

Meningeal branch (enters cranium via foramen spinosum)

Sensory to the dura mater

Medial pterygoid nerve (motor)

Tensor tympani

Tensor veli palatine

Anterior division

Masseteric nerve (motor)

Deep temporal nerves (ant & post) motor

Buccal (sensory!!) nerve

Lateral pterygoid nerve (motor)

Posterior division

Auriculotemporal nerve (sensory)

Parasympathetic fibers from CN IX to the parotid gland

Lingual nerve (sensory)

parasympathetic fibers from CN VII

Inferior alveolar nerve (sensory)

Motor to

Mylohyoid muscle

Anterior digastic muscle
Demonstrate the muscles of mastication, including their specific action, attachments, innervation and suggest muscle strength tests to determine function
Masseter muscle

Action: elevation and protraction of the mandible

Superficial head

Origin: Zygomatic process of maxilla, anterior 2/3 zygomatic

arch

Insertion: Angle and lower half of ramus of mandible



Deep head

Origin: posterior 1/3 of zygomatic arch

Insertion: upper half of ramus, coronoid process of mandible

Innervation: Masseteric Nerve, from V3

Strength testing: Ask patient to clench their teeth, and then open

mouth, while palpating the masseter muscle


Temporalis muscle

Action: elevation and retraction of the mandible

Origin: temporal lines of parietal bone, temporal fossa

Insertion: runs medial to zygoma to the coronoid process of

Mandible

Innervation: deep temporal nerves, from V3

Strength testing: Ask patient to clench teeth, open mouth, while

palpating the temporalis muscle (via temples)


Lateral pterygoid muscle

Actions:

bilateral - depression & protrusion of mandible

unilateral – contralateral excursion of mandible

Superior head

Origin: infratemporal surface/crest of greater wing of

sphenoid bone

Insertion: Articular disc, TMJ capsule

Inferior head

Origin: lateral surface of lateral pterygoid plate

Insertion: neck of mandibular condyle

Innervation: lateral pterygoid nerve, from V3

Strength testing: ask patient to open their mouth against

resistance, then ask to move mandible laterally

against resistance
Medial pterygoid muscle

Actions:

Bilateral – elevation of mandible

Unilateral – assist ‘laterals’ in contralateral excursion

Superficial head

Origin: Maxillary tuberosity

Deep head (much larger)

Origin: medial surface of lateral pterygoid plate

Common Insertion: Medial angle of the mandible

Innervation: nerve to medial pterygoid, via V3

Strength testing: ask patient to open mouth and clench teeth while

palpatng the masseteric region. (Resistive lateral

excursion tests both pterygoids).
Demonstrate the branches of the facial nerve and describe the nerve fiber components or specific function of those branches
Facial nerve fibers carried

Special visceral efferent (BE)

Facial nucleus

Facial expression musculature

Stylohyoid muscle

Posterior belly of digastric muscle

Stapedius muscle

Visceral efferent (GVE)

Superior salivatory nucleus

Synapse at pterygopalatine and submandibular ganglion

Lacrimal gland

Submandibular gland

Glands of nasal mucosa & both palates

Sublingual glands

Small salivary glands of the tongue dorsum

Also, visceral efferents form the parotid plexus

Special visceral afferent

Nucleus of the solitary tract (NST)

Chorda tympani, carrying gustatory fibers from tongue

(taste)


Somatic afferent (GSA)

Sensation from

Auricle

Skin of auditory canal



Outer tympanic membrane

Via CN VII to the principal sensory nucleus of CN V


Branching inside petrous portion of temporal bone

Greater petrosal nerve (GVE)

Stapedial nerve (BE)

To stapedius muscle

Chorda tympani (GVE, SA)

Branching outside the cranium

Posterior auricular branch

Branch to digastric & stylohyoid

Temporal branch*

Zygomatic branch*

Buccal branch*

Marginal branch*

Cervical branch*

*superficial branches to muscles of facial expression
Below:picture shows the labeling of each branch of the superficial facial nerve, post-parotid.

Demonstrate two dissection approaches to the pterygopalatine ganglion, including which structures must be removed or displaces in order to see the walls of the pterygopalatine fossa
Note: Only going from my experience with my donor on this answer
1.) Anterior approach

Reflect the masseter muscle, tendon of temporalis

Remove the superior portion of the mandible, from the angle to the TMJ

Examine the nerve and vascular components present between the medial and lateral pterygoid muscles

2.) Posterior approach

Must have ‘face-off’ cut performed on your cadaver

Posterior to trachea, anterior to styloid processes of skull and longus musculature

Position the face ‘face-down’ and approach the ganglion from the posterior

The medial pterygoids are appreciable, as is the maxillary artery and its divisions. The ganglion is located between the two pterygoid muscles, so carefully pick or reflect the medial pterygoid to reveal the nerves
1.) Demonstrate the pterygopalatine ganglion and associated nerves and discuss the outward clinical manifestations of pterygopalatine ganglion failure and pterygopalatine ganglion hyperfunction (sphenopalatine neuralgia). Contrast with submandibular ganglion and otic ganglion failure.
Pterygopalatine ganglion branches

Nasopalatine

Greater palatine

Lesser palatine

Pharyngeal branch of maxillary nerve

Failure

Numb canines, lateral incisors, molars

Numb hard palate

Difficulty swallowing



Sphenopalatine Neuralgia

Ice cream headache

Also, cluster headache patterns have been described by hyperfunction of this ganglion

Otic ganglion failure

The otic ganglion supplies parasympathetic innervation to the parotid gland

Failure here would manifest itself through a lack of enzymatic saliva supplied to the oral cavity

Submandibular ganglion failure

Failure to produce saliva (produces nearly 70% of saliva to mouth)


2.) Demonstrate the muscles of the tongue and describe their innervation (nerves and specific fibers carried).
Extrinsic (BE nerves)

Genioglossus muscle



Hypoglossal nerve

From mandible

Hyoglossus muscle

Hypoglossal nerve

From hyoid bone

Styloglossus muscle

Hypoglossal nerve

From styloid process

Palatoglossus muscle

Pharyngeal branch of vagus nerve

From palatine aponeurosis



Intrinsic (All Hypoglossal nerve, BE fibers)

Superior longitudinal muscle

Along superior surface of tongue

Inferior longitudinal muscle

Lines the sides of tongue

Verticalis muscle

Middle of tongue, joins both longitudinal muscles

Transversus muscle

Divides the middle of the tongue
3.) Describe the act of swallowing, paying attention to voluntary acts vs involuntary components, including which muscles are used during use phase and their innervation.
A.) Oral Phase

This phase is voluntary whose sole purpose is to prepare a bolus from the food placed in the mouth, aside from parasympathetic salivation

Moistening

Parasympathetic (chorda tympani: CN VII, lesser petrosal: CN IX)

Mastication

Voluntary motor (V3) and buccinators (VII)

Trough formation

Intrinsic muscles force bolus to posterior tongue (XII)

Movement of bolus to posterior oropharynx

Once the bolus reaches the palatoglossal arch, as propelled by intrinsic and extrinsic tongue muscles (XII), the pharyngeal phase (involuntary, takes over)



B. Pharyngeal Phase (involuntary reflex)

Closure of the nasopharynx

Soft palate is tensed, (tensor palatini, (V3))

Soft palate is elevated, (levator palatini, (XI, X)

Approximation of pharynx towards posterior soft palate

Palatopharyngeus m (IX, X)

Superior constrictor (IX, X)

Pharynx prepares to receive bolus

Pharynx is pulled superiorly, forward by

Stylopharyngeus (IX)

Salpingopharyngeus (IX, X)

Palatopharyngeus (IX, X)

Opening of the auditory tube

Actions of levator palatini, tensor palatini, and salpingopharyngeus open auditory tube

Pressure equalizes between nasopharynx & middle ear

Closure of the oropharynx

Kept shut by palatoglossus (IX, X)

Laryngeal closure & elevation

Vocal fold closure, adduction, is essential to avoid aspiration during swallowing

Lateral cricoarytenoids (X, recurrent laryngeal)

Oblique, transverse heads of arytenoids (X, recurrent laryngeal)

Creates a swallowing apnea

Swallowing occurs during expiration usually

Laryngeal elevation by

stylopharyngeus

salpingopharyngeus

palatopharyngeus

inferior constrictor

Hyoid elevation

Digastric and stylohyoid m. (V & VII)

Bolus transits pharynx

Movement occurs by pharyngeal peristalsis

Sequential contraction by superior, middle and inferior constrictor muscles

C. Esophageal Phase (Involuntary)

Esophageal peristalsis

Bolus is propelled first by striated muscle (recurrent laryngeal, X)

Then by smooth muscle, (X), at a rate of 3-5cm/s

Relaxation of upper and lower esophageal sphincters necessary

Relaxation phase

The larynx, hyoid, pharynx move inferiorly mostly by elastic recoil of muscles that constricted earlier
4.) Demonstrate the structures within the tympanic (middle ear) cavity, including ossicles, musculature and neurovascular components, including identification of which type of fibers the nerves carry.
Ossicles

Malleus (bound to tympanic membrane)

Incus (connecting arm to stapes)

Stapes (most likely not seen on dissection)



Muscles

Stapedius (CN VII)

Tensor tympani (CN V: medial pterygoid nerve, from V3)

Neurovasculature

Chorda tympani (GVE, SA)

Sensory taste fibers from anterior 2/3 of tongue

Presynaptic parasympathetic fibers to the submandibular ganglion, providing secretomotor innervation to the submandibular and sublingual salivary glands

* Sensation from the middle ear is provided by the glossopharyngeal nerve
5.) Describe otitis media and why it affects children more often than adults, specifically in relation to the structures that can be demonstrated in the cadaver dissections.
Otitis media is an inflammation of the middle ear / Eustachian tube. It affects children more than adults for two developmental reasons. Initially, the young skull has a very short external auditory meatus and a horizontally-oriented Eustachian tube. Therefore, there isn’t an immunoprotective advantage of hair and cerumen with a lengthened external auditory meatus and when a pathogen causes AOM (acute otitis media) in a child, the smaller and horizontal Eustachian tube makes it very difficult for the middle ear to drain itself of pathogen and associated fluids.

Above, see the difference locations of the external auditoy meatus between the fetal and adult skull.


6.) Demonstrate the structures of the inner ear and describe the innervation (specific fibers carried) and vascular supply within the petrous part of the temporal bone.
Cochlea (basic anatomy)

Oval window

Round window

Spiraling tubular organ, subdivided into 3 tubes

Scala tympani

Scala media

Organ of Corti, endolymph-filled

Scala vestibuli

Modiolus is the central axis of the spiral, contains spiral ganglia from CN VIII (SA)

Helicotrema, at apex of media and vestibuli



Vestibule

Saccule


up and down head movements

Utricle


Linear, horizontal head movements

Semicircular canals

3 loops, oriented in 3D (x,y,z) dimensions


All sensed by vestibular branch of CN VIII
Vascular supply to the inner ear is provided by the labryrinthine artery, a branch from the basilar artery.
7.) Demonstrate the craniovertebral joints and describe the attachments of the alar ligament, cruciform ligament and tectorial membrane / posterior longitudinal ligament within the vertebral canal.
Alar ligament

from sides of dens to tubercles of medial occipital condyle

Cruciform ligament

Vertical portion, from body of axis to basilar occiput

Transverse portion, posterior to dens, from one side of atlas to the other

Tectorial membrane / PLL

Tectorial membrane is an extension of the PLL superiorly

Fixed at posterior surface of the atlas

Attaches to the basilar groove of occiput, anterior to foramen magnum, and is continuous with the dura

1. Demonstrate the extraocular muscles of the eye, including identification of their attachments and innervation.

Notes:


All rectus musculature + the superior oblique originate from the annulus and insert of different aspects of the eyeball.

The actions of each muscle are not required for this objective (see #2)

Don’t forget about the superior oblique’s course through the trochlea
2. Describe the extraocular muscle strength test (H pattern) to determine isolated function of individual muscles. Put one of your peers through this test and identify which muscle is tested in each position.
The below image is for the left eye. Mirror image of this would be the right eye. Practice with a friend. The oblique muscle actions are isolated when the eye is adducted, and the inferior superior rectus muscles are isolated when abducted.



3. Demonstrate the nerves of the orbit, identify the branches and indicate which specific fibers those branches carry.
CN II: optic nerve (SA)

CN III: oculomotor nerve (BE)

Superior ramus to levator palpebrae superioris & superior rectus

Inferior ramus to rest of oculomotor muscles

CN IV: trochlear nerve to superior oblique m (BE)

CN V:

Ophthalmic (GSA)

Nasociliary (GSA)

Anterior & posterior ethmoidal

Infratrochlear

Long ciliary nerve

Lacrimal (GSA)

Communicates with zygomatic branch from maxillary nerve (V2) which provides post-synaptic parasympathetic innervation (pterygopalatine ganglion) to the lacrimal gland (GVE)

Frontal (GSA)

Supratrochlear n.

Supraorbital n.

CN VI: Abducens nerve to lateral rectus m
4. Demonstrate the arterial supply and venous drainage of the orbit, including sites of anastomosis.


The first branch of the internal carotid artery (ICA) is the ophthalmic artery. From the ophthalmic artery, we have an orbital group of branches and an ocular group of branches.

Orbital

Lacrimal


Supraorbital

Ethmoidal branches

Internal palpebral

Frontal


Nasal

Ocular

Long & short ciliary branches

Anterior ciliary

Central retinal

Muscular

Anastamoses (with branches of the ECA)

Note the picture, the anastomoses include the two eyelid arches and at the infraorbital region with the facial artery



Venous Drainage

Vortex veins

They drain the actual eye, superior drains into superior ophthalmic vein, inferior vortex veins drain into the inferior ophthalmic vein.

Superior & inferior ophthalmic veins

Drain into the cavernous sinus



5. Demonstrate the lacrimal gland, including discussion of its innervation in regards to specific branches and fibers. Be able to detail the drainage of tears from the orbit.
Situated on the superior lateral aspect of the eyeball, the lacrimal gland has both parasympathetic and sympathetic fibers.

Parasympathetic

Originating from the lacrimal nucleus supplying the facial nerve, the facial nerve gives off the greater petrosal nerve.

Meets the deep petrosal nerve and travels to the pterygopalatine ganglion

Once through the infraorbital fissure, the zygomatic branch carries these post-synaptic fibers to the lacrimal nerve to the gland



Sympathetic

Originating from the superior cervical ganglion (stellate) and travels along middle meningeal artery

Merge with deep petrosal nerve, which joins the greater petrosal (see above)

Does not synapse in pterygopalatine ganglion

Continue with the zygomatic branch to the lacrimal**

Tear Drainage

Two regions of ductage; orbital and palpebral

Tears from eye are collected in the lacrimal punta, which are small holes in the eyelid

These pass tears to the lacrimal sac, which drains via the nasolacrimal duct into the inferior nasal meatus


6. Demonstrate the cavernous sinus and the cranial nerves in its lateral wall. Describe potential routes of infection that can impact this space.
The lateral wall of the sinus is occupied by cranial nerves III, IV, V1, V2.
Infection is possible by the following routes:

From the external face (danger area of the face)

Routed through the superior or inferior ophthalmic veins

Or deep facial vein, pterygoid plexus of veins @ foramen ovale

Infection can spread by cavernous sinus thrombosis, which will originate from:

Sphenoid sinus

Ethmoidal air cells

Nasal furuncle



Dental infections



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