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Flashcards in USMLE Road Map - Head I Deck (123):

The cranium consists of ... bones, which form the ...?

8 bones, which form the calvaria and the cranial base.


Bones of the calvaria consist of ...?

2 layers of compact bone separated by the diploe - A layer of bone marrow.


The bones of the cranium are joined by suturues:

1. The coronal suture is formed by the frontal bones and the 2 parietal bones.
2. The sagittal suture is formed by the 2 parietal bones.
3. The lamboidal suture is formed by the 2 parietal lobes and the occipital bone.


The pterion is on the ...?

Lateral aspect of the skull superior to the zygomatic arch and posterior to the lateral wall of the orbit.


The pterion is supeficial to the ...?

Anterior branch of the middle meningeal artery, which supplies the dura and the skull.


The facial skeleton is formed by ... bones, which enclose the orbits, nasal cavity, and paranasal sinuses.

14 bones.


Innervation of the meningeal dura:

1. Most is innervated by the trigeminal.
2. The meningeal dura of the posterior cranial fossa is innervated by the first 3 cervical spinal nerves + meningeal branches of the vagus nerve.


The emissary veins are ...?

Valveless veins that pass through openings in the skull and allow dural sinuses to communicate with extracranial veins.


Most of the blood from the superior sagittal sinus passes through the ...?

Confluence of the sinuses and enters the RIGHT transverse sinus.


Most of the blood from then straign sinus enters the ...?

Left transverse sinus.


Each sigmoid sinus passes through ...?

A jugular foramen, joints with an inferior petrosal sinus, and drains into an internal jugular vein.


The cavernous sinuses are ...?

Dural venous sinuses situated lateral to the body of the sphenoid and the pituitary gland.


The cavernous sinuses receive blood from ...?

Cerebral veins and from the sphenoparietal venous sinuses.


Each cavernous sinus drains into a ...?

Superior and an inferior petrosal sinus.
--> Intercavernous sinuses interconnect the 2 cavernous sinuses.


Structures that courses through the cavernous sinus?

1. The internal carotid artery and its periarterial plexus of postganglionic SNS axons + CN VI course through the middle of each cavernous sinus.
2. V1, V3, III, IV --> Course in the lateral wall of the cavernous sinus.


The superior and the inferior ophthalmic veins are ...?

Emissary veins that link the cavenous sinus with tributaries of the facial vein near the orbit and wit the pterygoid plrxus of veins in the infratemporal fossa.


A thrombosis of the cavernous sinus may result from an ...?

Infection that is transported from the face to the cavernous sinus by the superior ophthalmic vein or the inferior ophthalmic vein.


Thombosis of the cavernous sinus - Patients may initially exhibit:

Internal strabismus resulting from a lesion of the abducens nerve.


Thrombosis of the cavernous sinus - Patients may later exhibit ...?

A loss of all ocular movements because of oculomotor and trochlear nerve involvement and pain and numbness in the face and scalp because involvement of involvement of the ophthalmic and maxillary divisions of the trigeminal nerve.


The basilar plexus of veins are ...?

Emissary veins --> Which link the inferior petrosal sinuses with the internal vertebral plexus in the epidural space of the vertebral canal.


Anterior cranial fossa - Ethmoid bone - Openings:

1. Cribriform plate.
2. Anterior ethmoidal foramen.
3. Posterior ethmoidal foramen.


The cribriform plate transmits ...?

Olfactory nerves (I).


The anterior ethmoidal foramen transmits:

Anterior ethmoidal nerve (nasociliary n. br.) and vessels (ophthalmic a.and v.).


The posterior ethmoidal foramen transmits;

Posterior ethmoidal nerve (nasociliary n. br. and vessels (ophthalmiic a. and v.).


Sphenoid bone - Openings:

1. Optic canal.
2. Superior orbital fissure.
3. Foramen rotundum.
4. Foramen ovale.
5. Foramen spinosum.


Optic canal - Transmits:

1. Optic nerve (II).
2. Ophthalmic artery.


Superior orbital fissure - Transmits:

1. Oculomotor (III).
2. Trochlear.
3. VI.
4. V1 branches --> Nasociliary + frontal and lacrimal nerve.
5. Superior ophthalmic vein.


Foramen rotondum - Transmits:

V2 of the trigeminal nerve.


Foramen ovale - Transmits:

V3 - Motor root of trigeminal nerve.
+ Lesser petrosal nerve (br. of IX).


Foramen spinosum - Transmits:

1. Middle meningeal artery (br. of maxillary a.).
2. Nervus spinosus (meningeal branch of V3).


Temporal bone - Openings:

1. Carotid canal.
2. Hiatus of facial canal.
3. Hiatus for lesser petrosal n.


Carotid canal transmits:

1. Internal carotid artery.
2. Internal carotid plexus (post ganglionic SNS axons from superior cervical ganglion).


Hiatus for facial canal - Transmits:

Greater petrosal nerve (VII).


Hiatus for lesser petrosal n. - Transmits:

Lesser petrosal nerve (IX).


Juncture between the sphenoid, temporal, and occipital bone - Opening:

Foramen lacerum.


Temporal bone - Posterior cranial fossa - Opening:

Internal auditory meatus.


Internal auditory meatus - Transmits:

1. VIII.
2. VII.
3. Labyrinthine artery.


Juncture between temporal and occipital bones - Opening:

Jugular foramen.


Jugular foramen - Transmits:

Anterior compartment: Inferior petrosal sinus.
Intermediate compartment: IX, X, XI.
Posterior compartment: Sigmoid sinus.


Occipital bone - Opening:

1. Hypoglossal canal.
2. Foramen magnum.


Hypoglossal canal - Transmits:

Hypoglossal nerve (XII).


Foramen magnum - Transmits:

1. Spinal cord.
2. Vertebral arteries.
3. Spinal roots of both Accessory (XI) nerves.


Temporal bone (base of skull) - Openings:

1. Stylomastoid foramen.
2. Petrotympanic fissure.


Stylomastoid foramen - Transmits:



Petrotympanic fissure - Transmits:

Chorda tympani n. of CN VII.


Frontal bone - Opening:

Supraorbital foramen.


Supraorbital foramen - Transmits:

1. Supraorbital nerve.
2. V1.
3. Supraorbital artery and vein.


Maxilla - Openings:

1. Infraorbital foramen.
2. Incisive foramen.
3. Pterygomaxillary fissure.


Infraorbital foramen - Transmits:

1. Infraorbital nerve.
2. V2.
3. Infraorbital artery/vein.


Incisive foramen - Transmits:

Nasopalantine nerve and a.


Pterygomaxillary fissure - Transmits:

1. Posterior superior alveolar n. (V2).
2. Maxillary a.


Junction between perpendicular process of palatine and sphenoid bone - Opening:

Sphenopalatine foramen.


Sphenopalatine foramen - Transmits:

1. Nasopalatine nerve (V2).
2. Sphenopalatine a. and v.


Palatine bone - Opening:

1. Greater palatine foramen.
2. Lesser palatine foramen.


Greater palatine foramen - Transmits:

1. Greater palatine nerve (V2).
2. Greater palatine a. and v.


Lesser palatine foramen - Transmits:

1. Lesser palatine nerve (V2).
2. Lesser palatine a. and v. .


Mandible - Openings:

1. Mandibular foramen.
2. Mental foramen.


Mandibular foramen - Transmits:

1. Inferior alveolar nerve (V3).
2. Inferior alveolar a. and v.


Mental foramen - Transmits:

1. Mental nerve (V3).
2. Mental a. and v.


Muscles of facial expression are innervated by ...?

VII - Act as sphincters and dilators of openings on the face.


Muscles of mastication are innervated by the ...?

Mandibular nerve of CN V3 and act to move the mandible at the temporomandibular joint.


The skin of the face and scalp is innervated by ...?

Cutaneous branches of the 3 divisions of the trigeminal nerve and by CERVICAL spinal nerves.


Branches of the ophthalmic division of V1 innervate the ...?

1. The scalp anterior to the vertex.
2. Including the skin of the upper eyelid, dorsum, and tip of the nose.


Branches of the maxillary division (V2) innervate the ...?

1. Cheek, including skin covering the zygomatic arch and maxilla.
2. The lower lid.
3. The upper lid.


Branches of the mandibular division (V3) innervate ...?

1. The lateral aspect of the scalp.
2. Including skin of the lateral face anterior to the external auditory meatus.
3. Skin covering the mandible.
4. Skin of the lower lip.


Branches of cervical spinal nerves innervate skin ...?

Over the angle of the mandible and the scalp posterior to the vertex.


The face and scalp are supplied by branches of the ...?

1. External carotid.
2. Ophthalmic arteries.


The face and scalp are drained by ...?

Tributaries of the retromandibular and facial veins.


The parotid duct crosses ...?

The masseter --> Passes through the biccunator, and opens into the oral cavity near the second upper molar.


The parotid gland is traversed by ...?

1. Muscular branches of the facial nerve.
2. The retromandibular vein.
3. The external carotid artery.


A tumor of the parotid gland may compress the ...?

Muscular branches of the facial nerve and cause weakness of muscles of facial expression on the side of the tumor.


The parotid gland is innervated by ...?

Preganglionic PNS axons in the IX nerve and by postganglionic PNS axons from the otic ganglion.


The mucosal secretions of the sinuses drain mainly into ...?

Meatuses, or air-filled channels, between the conchae and the lateral wall of the nasal cavity.


The superior meatus is the site of drainage of ...?

The posterior ethmoidal cells.


The middle nasal meatus is the site of drainage of the ...?

1. Anterior and middle ethmoid air cells.
2. The frontal sinus.
3. The maxillary sinus.


The inferior meatus contains the ...?

Opening of the nasolacrimal duct, which drains tears from the lacrimal sac in the medial part of the orbit.


The sphenoethmoidal recess is the site of drainage of the ...?

Sphenoid sinus.


The maxillary sinus is the ...?

LARGEST paranasal sinus and is situated between the orbit and the alveolar process of the maxilla, which contains the maxillary teeth.


The skull consists of the ...?

Cranium and the facial skeleton.


The maxillary sinus has poor gravitational drainage because ...?

The ostium of the sinus is situated on the superior part of the medial wall of the sinus.


The mucosa of the nasal cavity is innervated by the ...?

1. Olfactory (I).
2. Branches of the ophthalmic (V1).
3. Maxillary V2.


The cell bodies of bipolar olfactory neurons are ...?

Scattered in the olfactory mucosa and are NOT collected together in a sensory ganglion.


The olfactory nerve consists of ...?

Numerous fascicles of central process of olfactory neurons that pass superiorly through the cribriform plate of the ethmoid and into the anterior cranial fossa.


The central processes of olfactory neurons synapse in the ...?

Olfactory bulb in the floor of the anterior cranial fossa.


Primary olfactory neurons are continuously replaced. The life span of these cells ranges from ...?

30-120 days in mammals.


A lesion to the olfactory nerve fibers may ...?

1. Alter --> hyposmia.
2. Distort --> Dysosmia.
3. Lost --> Anosmia.


Olfactory deficits may be caused by ...?

A fracture of the cribriform plate, which damages the primary olfactory neurons.


A fracture of the cribriform plate may also tear ...?

The meninges of the olfactory bulb and result in CSF rhinorrhea, a discharge of CSF from the nostrils.


Branches of the V1 innervate a ...?

Small part of the lateral nasal wall.


Branches of the V2 supply most of ...?

The lateral nasal wall and septum.


The mucous glands of the nasal cavity are innervated by ...?

Preganglionic PNS in the facial nerve and by postganglionic PNS axons from the pterygopalatine ganglion.


Which arteries supply the nasal cavity?

1. Maxillary.
2. Ophthalmic.
3. Facial.


Branches of the arteries that supply the nasal cavity contribute to ...?

Kiesselbach's plexus on the anterior part of the nasal septum, which helps regulate the thermal environment of inspired air.


The pterygopalatine fossa is a space at a "crossroad" of the skull:

Laterally --> With the infratemporal fossa, medially with the nasal cavity.
Anteriorly --> With the orbit.
Inferiorly --> With the oral cavity.
Posteriorly --> With middle cranial fossa and the base of the skull.


The pterygopalatine fossa contains the ...?

Pterygopalatine ganglion and preganglionic and postganglionic PNS axons associated with it.


Pterygopalatine ganglion - The preganglionic PNS axons course in ...?

The greater petrosal nerve - Branch of VII.


Pterygopalatine ganglion - Postganglionic PNS axons supply ...?

Mucous glands of the nasal cavity, oral cavity, nasopharynx, and the lacrimal gland.


What opens into the pterygopalatine fossa?

1. 2 Fissures (pterygomaxillary and inferior orbital).
2. 2 Foramina (rotundum, sphenopalatine).
3. 2 Major canals (pterygoid, palatine).
--> Open into the pterygopalatine fossa.
--> These openings transmit branches of the maxillary artery, maxillary nerve, and facial nerve into or out of the fossa.


Branches of the maxillary artery that traverse the fossa supply the ...?

1. Nasal cavity.
2. Hard and soft palate.
3. Nasopharynx.
4. Maxillary teeth and face.


All 3 divisions of the trigeminal nerve also carry ...?

Proprioceptive fibers.
--> The cell bodies of the proprioceptive neurons are found INSIDE THE CNS, not in the trigeminal ganglion - These neurons innervate sensory receptors in skeletal muscles innervated by cranial nerves.


The maxillary division V2 - Course:

Traverses the foramen rotundum --> Becomes the maxillary nerve in the pterygopalatine fossa --> Gives rise to 3 main branches:
1. Zygomatic.
2. Infraorbital.
3. Pterygopalatine.


The pterygopalatine nerves pass through the pterygopalatine ganglion (without synapsing) and become ...?

Renamed as they emerge from the ganglion as the greater and lesser palatine nerves, nasopalatine nerve, posterior lateral nasal nerve, and pharyngeal nerve.


The pterygoid canal contains the ...?

Nerve of the pterygoid canal.


The nerve of the pterygoid canal is formed by the ...?

Deep petrosal nerve and the greater petrosal nerve, which join in the foramen lacerum.


The greater petrosal nerve is a ...?

Mixed branch of the facial nerve that carries preganglionic PNS axons that synapse in the pterygopalatine ganglion and taste fibers from the palate.


The deep petrosal nerve is a branch of ...?

The periarterial plexus on the internal carotid artery that carries postganglionic SNS axons from the superior cervical ganglion.


The optic canal + the superior orbital fissure transmit structures into and out of the orbit:

Optic canal --> Optic nerve and optic artery.
S.O.F. --> III, IV, V1, VI + superior ophthalmic vein.


The eyeball mainly consists of 3 concentric layers:

1. The sclera.
2. The choroid.
3. The retina.


Anteriorly, the eyeball contains the ...?

Cornea and the lens, which are the transparent refractive media of the eye.


The lens lies posterior to the ...?

Cornea and is separated from it by the iris and the pupil.


The lens is held in place by the fibers of the ...?

Suspensory ligament.


Changes in the tension of the suspensory ligament alter the ...?

Refractive power of the lens by allowing its anterior and posterior surfaces to increase or decrease their curvature.


Relaxation of the suspensory ligament results in ...?

Incr. curvature of the lens.


The orbit contains 4 smooth muscles:

1. Superior tarsal muscle --> The smooth muscle of the levator palpebrae superioris, which elevates the upper eyelid.
2. The dilator pupillae and the constrictor pupillae --> Anterior aspect of the eyeball in the iris and act to alter the diameter of the pupil.
3. The ciliary muscle is in the ciliary body.


In the accomodation reflex, or the near response, the ciliary muscle ...?

Contracts and the lens becomes thicker, and there is constriction of the pupils and convergence.


Convergence results from ...?

Simultaneous contraction of both medial rectus muscles.


ALL OF THE MUSCLES used in the near response are innervated by ...?

PNS or skeletal motor fibers in the CN III nerve.


The lacrimal gland is located in the ...?

Upper lateral corner of the orbit.


The lacrimal gland is innervated by the ...?

Preganglionic PNS fibers in CN VII + postganglionic PNS axons from the pterygopalatine ganglion.


All of the myelin of axons of the optic nerve are formed by ...?

Oligodendrocytes --> Affected in MS.


Anopsia of the R/L eye - Cause?

Optic neuritis - In MS or in occlusion of central artery of retina.


R/L nasal hemianopsia - Cause:

Aneurysm of internal carotid artery.


Bitemporal heteronymous hemianopsia - Cause of lesion:

Craniopharyngioma/ pituitary adenoma.