ANATOMY FINAL EXAM

Boundaries of the Temporal Fossa

Boundaries of the Temporal Fossa

1. Posteriorly and superiorly by the superior and inferior temporal lines

2. Anteriorly by the frontal and zygomatic bones

3. Laterally by the zygomatic arch

4. Inferiorly by the infratemporal crest

5. Floor of temporal fossa is formed by portions of four cranial bones: frontal, parietal, temporal, and sphenoid

6. Temporalis fascia forms the roof and extends from the superior temporal line to the zygomatic arch

Boundaries of the Infratemporal Fossa

• Laterally: ramus of the mandible

• Medially: lateral pterygoid plate

• Anteriorly: posterior aspect of the maxilla

• Posteriorly: tympanic plate and the mastoid and styloid processes of the temporal bone

• Superiorly: inferior surface of the greater wing of the sphenoid bone

• Inferiorly: where the medial pterygoid muscle attaches to the mandible near its angle

Contents of the Infratemporal Fossa

superficial

• Inferior part of the temporalis muscle

• Lateral pterygoid muscles

• Maxillary artery

deep

• Pterygoid venous plexus

• medial pterygoid muscle

• Mandibular, inferior alveolar, lingual, buccal, and chorda tympani nerves and the otic ganglion

Temporalis

Proximal attachment: Floor of temporal fossa. Deep temporal fascia

Distal attachment: coronoid process and ramus of mandible

Action on mandible: elevates mandible, closing jaw; retracts mandible

Innervation: Anterior trunk of mandibular nerve via deep temporal nerves

Blood Supply: Superficial temporal and deep temporal branches of maxillary

Masseter

Proximal attachment: maxillary process of zygomatic bone and zygomatic arch

Distal attachment: angle and lateral surface of ramus of mandible

Action on mandible: elevates mandible; some contribution to protrusion

Innervation: Anterior trunk of mandibular nerve via masseteric nerve

Blood supply: Transverse facial artery and masseteric branches from maxillary and facial arteries

Lateral Pterygoid

Proximal attachment: Superior head – infratemporal surface of greater wing of sphenoid, Inferior head – lateral pterygoid plate

Distal attachment: Superior head – joint capsule and articular disc of TMJ, Inferior head – pterygoid fovea

Action on mandible: Bilaterally – protrudes mandible; Unilaterally and alternating– larger lateral chewing movements

Innervation: Anterior trunk of mandibular nerve via nerves to lateral pterygoid

Blood Supply: Pterygoid branch of maxillary artery

Medial Pterygoid

Proximal attachment: lateral pterygoid plate; tuberosity of maxilla

Distal attachment: medial surface of ramus of mandible, inferior to mandibular foramen (“mirror image” of masseter)

Action on mandible: Bilaterally – elevates and protrudes mandible; unilaterally and alternately – small grinding movements

Innervation: Anterior trunk of mandibular nerve via nerve to medial pterygoid

Blood supply: Pterygoid branches of facial and maxillary arteries

Branches of the Mandibular N.

• Mandibular nerve

  • Descends through foramen ovale to enter the infratemporal fossa

  • Divides into anterior and posterior trunks

  • Posterior trunk is larger and gives rise to:

    • Auriculotemporal

    • Inferior alveolar

    • Lingual

  • Anterior trunk is smaller and gives rise to:

    • Buccal

    • Branch to temporalis

    • Branch to masseter

    • Branch to medial pterygoid

    • Branch to lateral pterygoid

Once the inferior alveolar nerve passes through the mandibular canal it forms the

Inferior Dental Plexus which contains the mental nerve

Before entering the mandibular foramen the inferior alveolar nerve gives off

Nerve to mylohyoid

The lingual nerve gives sensation to

anterior 2/3 of tongue, the floor of the mouth, and lingual gingivae

The chorda tympani nerve carries two types of fibers for different functions. What are they?

1. Carries taste fibers from the anterior 2/3 of tongue

   Carries presynaptic parasympathetic secretomotor fibers for submandibular and sublingual glands

What type of joint is TMJ?

Modified hinge type synovial

Permits movement in three planes

What are the articular surfaces of TMJ?

Head of mandible

Articular tubercle of temporal bone

Mandibular fossa

What prevents posterior dislocation of the TMJ?

Postglenoid tubercle and the lateral ligament

What are the two extrinsic ligaments of the TMJ?

1. Stylomandibular ligament

   1. Thickening of the fibrous capsule of the parotid gland

   2. Runs from styloid process to angle of mandible

2. Sphenomandibular ligament

   1. Runs from spine of sphenoid to the lingula of the mandible

   2. Primary passive support and “swing rope” of mandible

What muscles mandate the movement of the TMJ?

What are the borders of the pterygopalatine fossa?

Posterior wall: pterygoid process of sphenoid

Anterior wall: posterior aspect of the maxilla

Medial wall: perpendicular plate of palatine bone

Roof: greater wing of sphenoid

Floor: pyramidal process of palatine bone

Superior end opens into the inferior orbital fissure

Inferior end is closed except for the palatine foramina

What are the various communications of the pterygopalatine fossa?

Laterally with infratemporal fossa through the pterygomaxillary fissure

Medially with nasal cavity through the sphenopalatine foramen

Anterosuperiorly with the orbit through the inferior orbital fissure

Posterosuperiorly with the middle cranial fossa through the foramen rotundum

Posteriorly with the middle cranial fossa through the pterygoid canal

Posteroinferiorly with the nasopharynx through the pharyngeal canal (aka palatovaginal canal)

Nerves of the Pterygopalatine Fossa

The branches of the pterygopalatine ganglion and the maxillary nerve. Note: For simplicity, this schematic does not show: the contribution of the facial nerve (CNVII) to the pterygopalatine ganglion, the posterior superior alveolar nerves, or the nerve of the pterygoid canal.

Where do parasympathetic fibers transverse through the pterygopalatine fossa?

Parasympathetic fibers to the pterygopalatine ganglion come from facial nerve by way of the greater petrosal nerve

Greater petrosal joins with lesser petrosal in the foramen lacerum region to form the nerve of the pterygoid canal that passes to the pterygopalatine fossa

Parasympathetic fibers synapse in the ganglion

Where do sympathetic fibers transverse through the pterygopalatine fossa?

Deep petrosal nerve arises form the sympathetic plexus on the internal carotid

Conveys postsynaptic fibers from cell bodies in the superior cervical sympathetic ganglion

Do not synapse in pterygopalatine ganglion but join branches of the ganglion

Both sympathetic and parasympathetic pass to the pterygopalatine ganglia and glands in the nasal cavity, palate and superior pharynx

slay this is satan

What is the function of the cranial meninges? What are the three layers?

• Functions:

  • Protect the brain

  • Create an enclosed space for CSF

  • Provide supporting framework for vasculature

• Composed of:

  • Dura mater

  • Arachnoid mater

  • Pia mater

What are the three meningeal spaces? Describe their location and contents.

1. Dura-cranial interface (extradural or epidural “space”)

   1. Between cranium and periosteal layer of dura

   2. Not continuous with spinal epidural space

2. Dura-arachnoid interface (subdural “space”)

   1. Between meningeal layer of dura and arachnoid mater

   2. Like spinal layers, not a true space as pressure from CSF holds arachnoid right up against dura

3. Subarachnoid space

   1. Between arachnoid and pia

   2. Only true space, contains CSF arteries and veins

What are the two layers of the dura mater?

• Composed of two layers:

  • Periosteal layer

    • Formed from periosteum of internal surface of calvaria

    • Continuous with the periosteum of external surface at foramina

  • Meningeal layer

    • Fibrous membrane

    • Continuous with dura of spinal cord

• Has it’s own blood supply and innervation

What are the dural infoldings?

1. Falx Cerebi

   1. Separates left and right hemisphere

2. Tentorium Cerebelli

   1. Separates occipital lobes from cerebellum, creating two supratentorial compartments and one infratentorial compartments

3. Falx Cerebelli

   1. Partially separates the cerebellar halves

4. Diaphragma Sellae

   1. Circular sheet of dura attaching between clinoid processes

   2. Forms a partial roof over hypophysial fossa

   3. Pierced by the pituitary stalk

   4. Anterior ‘limbs’ create the cavernous sinus

Confluence of Sinuses

meeting place for superior sagittal, straight, occipital and transverse sinuses; located at the internal occipital protuberance

Superior Sagittal Sinus

at attached edge of falx cerebri; runs from crista galli to confluence; receives superior cerebral veins via communication with lateral venous lacunae

Inferior Sagittal Sinus

runs in free edge of falx cerebri; ends in straight sinus

Straight Sinus

formed from union of inferior sagittal and great cerebral vein; runs at attachment of falx cerebri to tentorium cerebelli

Transverse Sinus

run inferior to attached side of tentorium cerebelli; runs laterally from confluence; becomes sigmoid sinus at the posterior aspect of petrous part of temporal bone

Sigmoid Sinus

s-shaped course through posterior cranial fossa; traverses the jugular foramen to become the IJV

Occipital Sinus

run in attached border of falx cerebelli; ends in confluence; communicates inferiorly with internal vertebral venous plexus

Cavernous Sinus Pathway

large venous plexus on each side of sella turcica; extends from superior orbital fissure to apex of petrous part of temporal bone; receives blood from superior and inferior ophthalmic, superficial middle cerebral and sphenoparietal veins; drains to superior and inferior petrosal sinuses

Intercavernous Sinus

channels anterior and posterior to stalk of pituitary gland; allows for communication between left and right cavernous sinuses

Superior Petrosal Sinus

runs from cavernous sinus to junction of transverse/sigmoid sinuses; lies in anterolateral attached margin of tentorium cerebelli

Inferior Petrosal Sinus

runs from cavernous sinus to sigmoid sinus at jugular foramen; run in groove between petrous part of temporal and basilar part of occipital bone; basilar plexus joins the inferior petrosal sinuses from each side and communicates with internal vertebral venous plexus

Cavernous Sinus Contents

• Internal carotid artery and its small branches

• Carotid plexus of sympathetic nerves

• Abducent nerve (CN VI), Oculomotor nerve (CN III), trochlear nerve (CN IV), two divisions of trigeminal nerve (CN V)

• REMEMBER OTOMCAT

What is the main arterial supply to the dura?

Middle Meningeal Artery

Where does the middle meningeal artery enter and exit the cranium?

Enters through the foramen spinosum and exits through the foramen spinosum or foramen ovale

Innervation of the Dura

• Dura is pain sensitive. Source for headaches.

• Anterior meningeal branches of ethmoid nerves (CN V1) – anterior cranial fossa, anterior falx cerebri

• Meningeal branches of maxillary (CN V2) – anterior and middle cranial fossa

• Meningeal branches of mandibular (CN V3) – anterior and middle cranial fossa

• Tentorial nerve (branch of CN V1) – roof of posterior cranial fossa and posterior part of falx cerebri

• Nerves from C2 and C3 (via spinal nerves, vagus nerve (CN X) or hypoglossal nerve (CN XII) – floor of posterior cranial fossa. Pain in the posterior floor can cause refered pain behind the ears or back of the neck

Which is vascular/avascular; cranial pia, cranial arachnoid?

Cranial Pia: Highly Vascularized

Cranial Arachnoid: Avascular

What are subarachnoid cisterns?

Areas on base of brain where pia and arachnoid mater are widely separated

Contain CSF, and soft tissue structures like arachnoid trabeculae, vasculature and cranial nerve roots

What are the four lobes of the brain?

Frontal – the anterior most lobe, extends to the central sulcus posteriorly and the lateral sulcus inferiorly; anterior most portion is the frontal pole

Parietal – from the central sulcus to the parieto-occipital sulcus (best viewed on medial surface), sits above lateral sulcus

Occipital – most posterior lobe behind the parieto-occipital sulcus; posterior most portion is the occipital pole

Temporal – inferior to lateral sulcus, anterior to parieto-occipital sulcus; anterior most portion is the temporal pole

What are the three portions of the brainstem?

Midbrain - most rostral portion; at junction of middle and posterior cranial fossae; associated with CN III and IV

Pons – caudal to midbrain; lies in anterior part of posterior cranial fossa; associated with CN V

Medulla oblongata – most caudal portion; continuous with spinal cord; in posterior cranial fossa; associated with CN IX, X, XII

CN XI, XII, XIII associated with pons-medulla junction.

Describe the flow of CSF in the brain.

1. CSF is primarily produced in the choroid plexus, a network of blood vessels in the ventricles of the brain, especially the lateral and fourth ventricles. The choroid plexus filters blood plasma and secretes CSF, which is a continuous process.

2. From the choroid plexus, CSF flows through the ventricular system of the brain, which includes the lateral ventricles, third ventricle, cerebral aqueduct, and fourth ventricle.

   1. The cerebral aqueduct connects the third ventricle to the fourth ventricle, allowing CSF to move between these compartments.

3. CSF exits the fourth ventricle through small openings called the foramina of Luschka (two lateral openings) and the foramen of Magendie (a midline opening). These foramina allow CSF to enter the subarachnoid space, which is the space between the arachnoid mater and the pia mater, surrounding the brain and spinal cord.

4. CSF circulates within the subarachnoid space, bathing the brain and spinal cord in nutrients and providing a cushioning effect. It also helps to remove waste products from the brain and maintain a stable environment for neural function.

5. CSF is absorbed back into the bloodstream through structures called arachnoid granulations or villi, which are protrusions of the arachnoid mater into the venous sinuses. These structures allow for the reabsorption of CSF into the venous blood, completing the circulation cycle.

Extradural (epidural) Hemorrhage

Occurs when blood from a torn meningeal artery collects between the calvaria and periosteal layer of the dura

Usually caused by a blow to the head (fracture of the pterion as it overlies the anterior branch of middle meningeal artery)

As blood pools it forms an extradural (epidural) hematoma that can cause pressure on the brain

Symptoms: initially a brief concussion, followed by lucidity (for hours), then drowsiness and coma

Blood needs to be drained and vessel repaired

Dural Border Hematoma

Occurs as blood collects creating a space between the dura and arachnoid maters

Hemorrhage is usually caused by hard blow to head that jerks the brain causing a hemorrhage

Usually damage is done to the venous system, most commonly superior cerebral vein (as it enters the sagittal sinus)

Symptoms include confusion, dizziness, headache, and possibly issues with balance, nausea/vomiting, loss of consciousness or seizures

Subarachnoid Hemorrhage

Collection of blood in the subarachnoid space, usually arterial

Often from rupture of a saccular aneurysm, sometimes due to head trauma (involving cranial fractures and cerebral lacerations)

Causes severe headache, stiff neck and possibly loss of consciousness

Stroke (Differentiate between the four types)

• Generally caused by an abrupt blockage in a major cerebral artery

  • Thrombotic – arteries in brain are diseased or damaged subsequently becoming blocked

  • Embolic – artery becomes blocked due to a clot that formed elsewhere and traveled to brain

  • Hemorrhagic stroke - Occurs when a vessel is ruptured, can be at the site of a saccular aneurysm

  • Berry aneurysm – occurring in vessels of or near cerebral arterial circle

Stroke Susceptibilities & Risks

Risk increases with age

Higher rate in women

Higher rate in African-Americans

Higher incidence in those with hypertension, heart disease, smoking, diabetes

Meningitis

• Inflammation of the meninges surrounding the brain

  • Symptoms: Fever, HA, Stiff neck, Photophobia, N/V, confusion/altered mental state

• Can have several different causes

  • Bacterial – 70% are children under 5. Life threatening. Vaccines are available for some kinds of bacterial meningitis

  • Viral – Most people who have the virus will not develop meningitis

  • Fungal - Rare

  • Parasitic - Rare

  • Drug – Induced – Rare. NSAIDS and some antibiotics

Transtentorial Herniation

Transtentorial herniation is a medical condition characterized by the displacement of brain tissue through the tentorial notch, which is a narrow opening in the skull that separates the cerebellum from the cerebral hemispheres. The tentorium cerebelli is a fold of the dura mater, the tough outer layer of the meninges that surround the brain.

When there is increased intracranial pressure due to various reasons such as tumors, hemorrhage, or swelling of the brain, the brain tissue may be forced downward through the tentorial notch. This can lead to compression of vital structures in the brain, including the brainstem.

There are different types of transtentorial herniation, including:

1. Central (or "downward") Transtentorial Herniation: In this type, the brain tissue is displaced downward through the tentorial notch, putting pressure on the midbrain and other structures.

2. Uncal (or "lateral") Transtentorial Herniation: This occurs when the innermost part of the temporal lobe, the uncus, herniates through the tentorial notch. This can compress the third cranial nerve and lead to specific neurological symptoms.

Structure of the Orbit

Bones within the Orbit Space

Base – outlined by the orbital margin and surrounds the orbital opening

Superior wall – Frontal bone and lesser wing of sphenoid

Medial wall – ethmoid, maxilla, lacrimal and sphenoid bones

Inferior wall – (floor) maxilla, palatine and zygomatic bones

Lateral wall – formed by frontal process of zygomatic bone and greater wing of sphenoid.

Apex – at the optic canal in lesser wing of sphenoid

Palpebra Composition

• Skin

• Subcutaneous tissue

• Orbicularis oculi

• Tarsus - dense connective tissue plates

• Superior and inferior tarsus

• Tarsal glands

Loss of sympathetic innervation to the Palpebra would result in

Partial Ptosis

Conjunctiva

inner surface of the lids  conjunctiva lining the eyeball

Chalazion

Blockage and inflammation of a tarsal gland

On the inner surface of the eyelid

Stye

Blockage and inflammation of sebaceous and sweat glands

On the edge of the eyelid

Lacrimal Gland

• Has its own fossa

• Ducts are on the superior fornix of the conjunctiva (upper eyelid)

• Gland → Duct → Puncta → Canaliculi → Sac

Lacrimal Apparatus Innervation

Sensory via Lacrimal N. (V1)

Secretomotor:

• Parasympathetic via VII and then V

  • Preganglionic axons (VII) to Pterygopalatine ganglion

  • Postganglionic axons via V2 V1

• Sympathetic innervation -

  • Postganglionic axons from superior cervical ganglion

Layers of the Eyeball

• Outer fibrous layer: sclera (posterior) and cornea (anterior, transparent)

• Middle vascular layer : choroid (posterior) and iris and ciliary body (anterior).

• Retina: Sensory neural layer

• Optic portion (posterior) and nonvisual portion (anterior)

Two parts of the uvea

1. Choroid: Dense Vasculature

2. Ciliary Body

   1. Muscle: Accommodation for near vision

   2. Processes: Attachment of zonular fibers

Iris

The central opening in the iris is the pupil.

Two sphincters for pupil

1. Sphincter Pupillae: Arranged in a circular pattern

2. Dilator Pupillae: Arranged in a radial pattern

Optic Disc

where neurovasculature enters/exits the eye. Insensitive to light = blind spot

Macula

contains the fovea centralis which is the area of most acute vision (can only be seen when using red-free light)

Describe the path of light within the eye.

1. Lens would form a round shape in the absence of ciliary muscles

2. In relaxed state (no nerve stimulation), lens is stretched and can refract light for distance vision

3. Parasympathetic stimulation via oculomotor nerve (CN III) cause a sphincter like contraction reduces stretching on lens and allows it to refract light for near vision

   Thickness of lens increases with age and lens shape changes become restricted after age 40

Orbicularis Oculi

Palpebral portion: involuntarily closes eyelids gently

Innervation – CN VII

Levator palpebrae superior

Raises eyelid

Innervation – CN III

Superior Tarsal Muscle

Innervation - Superior Cervical Ganglion

The four Rectus Muscles

Rectus Muscles:

• Medial Rectus Muscle: This muscle is responsible for moving the eye medially (towards the nose).

• Lateral Rectus Muscle: This muscle moves the eye laterally (towards the temple).

Both the medial and lateral rectus muscles play a crucial role in horizontal eye movements.

• Superior Rectus Muscle: This muscle primarily elevates the eye, externally rotates, and adducts.

• Inferior Rectus Muscle: The inferior rectus muscle depresses, externally rotates, and adducts.

The superior and inferior rectus muscles are involved in vertical eye movements.

The Two Oblique Muscles

Oblique Muscles:

• Superior Oblique Muscle: The superior oblique muscle is responsible for depressing and abducting the eye (moving it downward and outward).

  • Origin: From the Sphenoid and passes through the trochlea.

• Inferior Oblique Muscle: This muscle elevates and abducts the eye (moving it upward and outward).

  • Origin: Orbital surface of the maxilla

  • Insertion: Just under lateral rectus.

The oblique muscles contribute to diagonal eye movements.

Extrinsic Eyeball Muscle Innervation

1. Medial Rectus

   1. C 3

2. Lateral Rectus

   1. C 6

3. Superior Rectus

   1. CN 3

4. Inferior Rectus

   1. CN 3

5. Superior Oblique

   1. C 4

6. Inferior Oblique

   1. C 3

Which structures pass through the common tendinous ring?

Optic Nerve, Ophthalmic A., Nasociliary branch of Ophthalmic N., Abducent N., Superior & Inferior Branch of Oculomotor N.

What are the three branches of the opthalmic nerve?

1. Nasociliary N.

   1. Eyeball, eyelids, nose, anterior cranial fossa

2. Lacrimal N.

   1. Lacrimal Gland, Conjunctiva

3. Frontal N.

   1. Supratrochlear, Supraorbital

Which cranial nerves are responsible for the pupillary light reflex?

2 & 3

Which cranial nerves are responsible for the corneal reflex?

absence is CN V1, impairment is CN VII

What muscles compose the external layer of the pharynx?

Superior, Middle, and Inferior pharyngeal constrictor

What muscles compose the internal longitudinal layer of the pharynx?

Palatopharyngeal, Stylopharyngeus, Salpingopharyngeus

What are the four constrictor gaps of the pharynx?

1. Between superior constrictor and cranium

2. Between superior and middle constrictors

3. Between middle and inferior constrictors

4. Inferior to inferior constrictor

Stylopharyngeus Innervation

Glossopharyngeal N.

Nasopharynx

• Pharyngeal orifice of pharyngotympanic tube

  • Tubal and pharyngeal (adenoid) tonsils

What are the muscles within the Nasopharynx?

Torus Tubarius, Torus Levatori, Levator Veli Palatini, Salpingopharyngeus (within the salpingopharyngeal fold)

Tonsil problems can arise due to….

An infected adenoid

Boundaries of the Oropharynx

Soft palate, base of tongue, and palatoglossal and palatopharyngeal arches

What are the three stages of deglutition (swallowing)?

Stage 1: voluntary bolus compression

Stage 2: involuntary superior contraction

Stage 3: involuntary pharyngeal constrictors contraction

What can happen during a palatine tonsillectomy?

Because of rich blood supply, bleeding commonly arises from external palatine vein and tonsillar artery.

It is also common to injury CN IX which accompanies the tonsillar artery due to the thin wall. This can cause loss of taste to the posterior 1/3 of the tongue as well as loss of afferent limb of gag reflex.

Where is oropharyngeal squamous cell carcinoma?

• Base and posterior 1/3 of tongue

• Tonsils

• Soft palate

• Posterior and lateral pharyngeal walls

Laryngopharynx Boundaries

Extends from epiglottis to inferior border of cricoid cartilage

Laryngopharynx Landmarks

Middle and inferior pharyngeal constrictors, palatopharyngeus, stylopharyngeus

How does the layngopharynx communicate with the larynx?

Via the laryngeal inlet in the piriform fossa

Foreign bodies in the laryngopharynx can be especially bad because…

Sharp objects may pierce mucous membrane and injure internal laryngeal nerve

Superior laryngeal nerve vulnerable during object removal

What is the main arterial supply to the pharynx?

Ascending pharyngeal artery (ECA), Inferior Thyroid Artery (Subclavian portion of TCT)

What is the main venous drainage of the pharynx?

Pharyngeal Veins → Internal Jugular Vein

Where does the pharynx drain to?

Deep cervical nodes → Retropharyngeal, Paratracheal, Infrahyoid nodes

Where does the palatine tonsil lymph drain to?

Jugulodiagastric nodes

What supplies motor to the pharynx?

CN X via pharyngeal branches

What supplies sensory fibers to the three different parts of the pharynx?

Naso: V2

Oro: IX

Laryngo: X