Unit 1 Exam

Question 1

Which spinal regions innervate the dermatomes of the umbilicus region?

Answer 1

T10

Question 2

What spinal nerve segments make the cervical plexus?

Answer 2

C1-C5

The phrenic nerve is important from this plexus as it innervates the thoracic diaphragm.

Question 3

Which spinal regions innervate the dermatomes of the base of the neck and shoulders?

Answer 3

C3 and C4

Question 4

What spinal nerve segments make the brachial plexus?

Answer 4

C5-T1

Question 5

Specify the spinal nerves that do not contribute to a spinal nerve plexus.

Answer 5

Thoracic Nerves (T2-T12) do not contribute to nerve plexuses but rather instead innervate the ribs.

Question 6

Where are the PRE and POST ganglionic cell bodies found in the PARASYMPATHETIC branch of the ANS?

Answer 6

Parasympathetic preganglionic cell bodies (Craniosacral): in the brainstem and the sacral region. The preganglionic neurons can travel the routes of the sympathetic chain but will not synapse in the sympathetic chain (CN 3,7,9,10 are parasympathetic friends)

Postganglionic neurons are usually embedded within the visceral organ walls with its respective ganglia (Like CN-X).

Postganglionic neurons within the head. COPS (Ciliary, Otic, Pterygopalatine ganglion, sublingual/submandibular)

Question 7

Which spinal region innervate the dermatomes of the nipple regions?

Answer 7

T4

Question 8

Distinguish the anatomical locations of paravertebral and prevertebral sympathetic post-ganglia.

Answer 8

Paravertebral post-ganglia found on the sides of the vertebral column.
Prevertebral post-ganglia found on top of the abdominal aorta.

Question 9

What spinal nerve segments make the sacral plexus?

Answer 9

L4-S4

Question 10

Which spinal region innervate the dermatomes of of the xiphoid process?

Answer 10

T6

Question 11

Which spinal regions innervate the dermatomes of the inguinal region?

Answer 11

L1

Question 12

Where are the PRE and POST ganglionic cell bodies found in the SYMPATHETIC branch of the ANS?

Answer 12

Sympathetic preganglionic cell bodies: of the CNS within the grey matter (nuclei) of the lateral horns at the T1-L3 levels (thoracolumbar division).

Post-ganglionic cell bodies found at the Paravertebral ganglia (sympathetic chain) and the Pre-vertebral ganglia (pre-aortic ganglia).

Question 13

What spinal nerve segments make the lumbar plexus?

Answer 13

L1-L4

Question 14

Specify the locations of the preganglionic parasympathetic neuron cell bodies whose fibers travel in the Vagus nerve (X) and in the pelvic splanchnic nerves.

Answer 14

Nuclei grey matter of the brainstem and nuclei in sacral regions within grey matter of the spinal cord of S2-S4 (Cranial-Sacral Outflow).

Question 15

Specify the locations of the preganglionic parasympathetic neuron cell bodies whose fibers travel in the vagus nerve and in the pelvic splanchnic nerves

Answer 15

Nuclei grey matter of the brainstem (Vagus nerve X) and nuclei in sacral regions (Pelvic splanchnic) within grey matter of the spinal cord of S2-S4.

Question 16

Define craniosynostosis and explain its effect on subsequent cranial growth; predict the shape of the neurocranium when the sagittal or coronal suture is involved.

Answer 16

Craniosynostosis is when the cranial sutures are pre-maturely fused. This will cause abnormal head shape and growth.

When the sagittal suture is infused, it limits the skull width and grows anteriorly and posteriorly making it long and narrow.

When the coronal suture is involved, it will result in a short and wide appearance.

Question 17

Specify the spinal cord segments that contain the preganglionic sympathetic neurons involved in the innervation of head and neck structures along with the postganglionic cell bodies.

Answer 17

Sympathetic innervation to structures in the head and neck begins with preganglionic sympathetic neurons located in the T1-T4 regions of the spinal cord that synapse to the inferior, middle, or superior cervical ganglia.

Superior: C1-C4
Middle: C5-C6
Inferior (stellate ganglion): C7-C8

Question 18

Explain how the POSTganglionic sympathetic fibers destined to innervate structures in the head and neck travel to reach their target organs

Answer 18

Reach head and neck structures by either traveling with branches of the cervical spinal nerves, or by traveling along the surfaces of blood vessels.

Question 19

List the four cranial ganglia that house postganglionic parasympathetic neuronal cell bodies. (COPS)

Answer 19

• Ciliary ganglion for the preganglionic parasympathetic fibers of the oculomotor nerve (CN III) synapse in the ciliary.
• Pterygopalatine ganglion for the preganglionic parasympathetic fibers within the greater petrosal branch of facial nerve (CN VII) to innervate the LACRIMAL GLANDS.
• Submandibular ganglia for the preganglionic parasympathetic fibers of the chorda tympani branch of the facial nerve (CN VII) to innervate SUBMANDIBULAR AND SUBLINGUAL SALIVARY GLANDS.
• Otic ganglion for the preganglionic parasympathetic fibers of the glossopharyngeal nerve (CN IX) to innervate the PARTOID SALIVARY GLANDS.

Question 20

Specify the innervation of the muscles of facial expression; describe the functions of the following clinically significant muscles of facial expression: orbicularis oculi, orbicularis oris, buccinator, occipitofrontalis.

Answer 20

All muscles of facial expression are innervated by the motor portion of the facial nerve, one of the three primary branches of the facial nerve (CN VII) - Exit the stylomastoid foramen.

Orbicularis oculi: this sphincter of the eyelid functions to close the eyelids (as in blinking) and in doing so spreads lacrimal fluid (tears) over the cornea of the eye, preventing its desiccation.

Orbicularis oris: this sphincter of the mouth seals the lips & prevents drooling.

Buccinator: this muscle forms the skeleton of the cheek, this muscle assists in keeping masticated food between the occluding upper and lower teeth during chewing.

Occipitofrontalis (epicranius): Moves the scalp and eyebrows.

Question 21

List the common symptoms of facial nerve palsy and identify some of the common causes of this condition.

Answer 21

Facial nerve palsy is caused by damage to the facial nerve and or the damage to the parotid gland since the nerves course through the gland. Symptom can include the inability to smile, relaxation or loss of normal creases and furrows of the face, drooling, food collecting in the cheek, and a dry cornea due to absence of blinking.

Question 22

List the five layers of the scalp. SCALP ACRONYM

Answer 22

1. Skin
2. Dense Connective Tissue
3. Aponeurotic Layer
4. Loose connective tissue “Danger Zone” in scalp lacerations
5. Pericranium (periosteum) of the skull

Question 23

Specify the location of the danger zone of the scalp and discuss its significance with respect to the spread of scalp infections.

Answer 23

Damage aponeurotic layer can expose the loose connective tissue underneath (Danger zone) which can allow foreign pathogens, materials, blood, etc. into the epidural space via the EMISSARY VEINS.

Question 24

List the three layers of the deep cervical fascia and the compartments of the neck each defines.

Answer 24

Investing musculofascial layer

Pre-visceral fascia (pre-tracheal fascia)

Pre-vertebral fascia

Question 25

List the structures contained within the carotid sheath.

Answer 25

Carotid sheath contains internal Juglar veins, Vagus nerve, cervical lymph nodes, and the carotid artery

Question 26

Specify the two muscles invested by the investing layer of deep cervical fascia and contained within the musculofascial compartment of the neck.

Answer 26

The trapezius and the sternocleidomastoid (SCM)

Question 27

Specify the innervation of the sternocleidomastoid and trapezius muscles; describe the actions of the sternocleidomastoid muscle when acting both unilaterally and bilaterally.

Answer 27

SCM and trap muscles innervated by spinal accessory nerve (CN XI)
Bilateral action of the SCM involves flexion of the neck.
Unilateral action of the SCM involves lateral flexion of the neck and rotates the head and bring ear to the IPSILATERAL shoulder.

Question 28

Distinguish the functions of the carotid sinus and carotid body.

Answer 28

Carotid Sinus: dilated region of the artery is a baroreceptor that senses changes in arterial blood pressure (Innervated by the CN-IX).

The carotid body is a chemoreceptor that monitors the level of oxygen in the blood.

Question 29

Specify where in the neck the spinal accessory nerve is vulnerable to injury and describe the functional deficits expected in such an injury.

Answer 29

Posterior triangle it nears the carotid sheath and the deep cervical chain of lymph nodes and is susceptible to injury in deep cervical lymph node biopsies. Injury here results in shoulder dysfunction because of loss of function of trapezius. Assess CN XI by asking patient to shrug their shoulders

Question 30

Specify the arterial supply and venous drainage of the thyroid gland. Explain the clinical significance of a thyroid ima artery and inferior thyroid veins.

Answer 30

Inferior pole of each thyroid gland is supplied by the inferior thyroid artery of thyrocervical trunk (branch of subclavian artery), superior pole is supplied by the superior thyroid artery (external carotid artery)

Superior, middle (both to internal jugular vein), and inferior (to brachiocephalic) thyroid veins drain the thyroid gland

Inferior thyroid and thyroid ima artery is around the midline area of the trachea and tracheostomy is done around this area putting these vessels at risk for bleeding.

Question 31

Relate the locations of the greater and lesser supraclavicular fossae of the neck to the sternocleidomastoid muscle; specify the structures that can be accessed in each fossa.

Answer 31

Lesser supraclavicular fossa - space between the sternal and clavicular heads of the SCM, superior to the clavicle. Internal jugular vein can be assessed by needle or a catheter

Greater supraclavicular fossa - posterior the clavicular head of the SCM and superior to the clavicle, subclavian artery can be palpated as well as the supraclavicular lymph nodes

Question 32

Specify the two major groups of lymph nodes that drain head & neck structures

Answer 32

Cervical nodes and the peri-cranial nodes

Question 33

Specify the tissues drained by the tonsillar, submandibular, and submental lymph nodes and indicate where each is located in the neck.

Answer 33

Tonsillar - lymph from the palatine tonsil (behind the ramus of the mandiable)

Submandibular - lymph from the throat (below the middle mandibular body)

Submental - lymph from the mouth (below the mental foramen)

Question 34

Specify functional modalities specific to each of the twelve cranial nerves

Answer 34

Pure Sensory: CN I, II , VIII

Pure Motor: CN III, IV, VI, XI, XII

Mixed: CN V, VII, IX, X

Question 35

3. List the four cranial nerves that transmit autonomic (preganglionic parasympathetic) nerve fibers from the brainstem; specify the smooth muscles and glands innervated by each

Answer 35

• Vagus nerve (CN-X) innervates visceral organs of the thoracic and abdominal cavities
• Oculomotor nerve (CN-III) innervates the ciliary muscles of the eye and sphincter pupillary muscles of the iris, synapse on ciliary ganglion
• Facial Nerve (VII)

chorda tympani carries taste sensation for anterior 2⁄3 of tongue and innervates
submandibular and sublingual salivary glands, synapses on submandibular gland.

Greater petrosal nerve innervates lacrimal gland and mucus producing glands in the nose and palate and synapses on the pterygopalatine ganglion

• Glossopharyngeal nerve (IX) - innervate parotid gland, synapse on otic ganglion

Question 36

What is the name of the V1 branch and its functions?

Answer 36

(Ophthalmic) Sensory division, sensory info from eye, anterosuperior aspect of the nose and upper face, anterior scalp, ethmoidal, frontal, sphenoid paranasal sinuses.

Question 37

What is the name of the V2 branch and its functions?

Answer 37

(Maxilliay) Sensory division, sensory info to the posteroinferior nose, Midface, palate and upper jaw, maxillary dentition, maxillary paranasal sinus.

Question 38

What is the name of the V3 branch and its functions?

Answer 38

(Mandibular) Sensory division include: auricotemporal nerve, lingual nerve, ANTERIOR 2/3 tongue and inferior alveolar nerve/mental nerve.

Motor division include: muscles of mastication like the temporalis, massester, medial and lateral pterygoid.

Motor also includes the tensor tympani muscle that attach to malleus.

Question 39

Specify the functional modalities specific to each of the following primary branches of CN VII: Motor branch, Chorda tympani and Greater petrosal.

Answer 39

Motor branch: Innervates muscles of facial expression (passes through the PAROTID gland). This includes orbicularis ori, oculi, buccinator, and occipitofrontalis.

Chorda Tympani: carries pre-ganglionic parasympathetic fibers for synapse on the salivary glands, and taste sensations on anterior 2/3 of the tongue.

Greater Petrosol Nerve: Carries pre-ganglionic parasympathetic fibers that synapse on the ganglion of the lacrimal glands, and mucus producing glands in the nose.

Question 40

List the three layers of the eye and specify the components of the outer and middle layers

Answer 40

Sclera Outer layer, avascular

Choroid, ciliary body (secrete aqueous humor for the posterior and anterior chamber) and iris (sphincter and dilator pupillae) make the middle layer which is vascular.

Retina will make the inner layer containing rods and cones (The macula lutea or the fovea has highest concentration of cones)

Question 41

Specify the functions of the ciliary process and aqueous humor of the eye; explain the significance of the canal of Schlemm in glaucoma

Answer 41

The ciliary process produce the aqueous humor for both anterior and posterior chambers. The canal of Schlemm is where the aqueous humor is drained but glaucoma results in the failure of the draining causing increased intraocular pressure resulting in glaucoma.

Question 42

Explain the role of the ciliary muscle of the eye in accommodation; specify the division of the autonomic nervous system that innervates the ciliary muscle.

Answer 42

The ciliary muscle adjust the shape of the lens allowing for focusing which is called accommodation. Innervated by parasympathetic component of oculomotor nerve (CN III).

Question 43

List the two muscles of the iris and explain their actions; specify the division of the autonomic nervous system responsible for innervating each

Answer 43

sphincter pupillae muscle – constrict the iris to let less light in. The sphincter muscle is innervated by parasympathetic neurons of the autonomic nervous system (CN-III)

dilator pupillae muscle – expands the iris to let more light in. The dilator muscle is innervated by the sympathetic neurons of the autonomic nervous system. (T1-T4).

Question 44

List and describe the symptoms of Horner’s syndrome and specify its etiology.

Answer 44

Loss of sympathetic input to the head,

Results in loss of function of the superior tarsal muscle and slight drooping (ptosis) of the upper eyelid, constricted pupil (miosis) due to loss of function of the dilator pupillae, and an absence of sweating (anhydrosis).

Question 45

Define papilledema and explain its anatomical basis.

Answer 45

Compromised blood flow to the retina due to increased CSF pressure which results in swelling of the retina of the optic disc and compromising the optic nerve.

Question 46

Describe the functions of the following features of the eyelids: conjunctiva, tarsal glands, orbicularis oculi, levator palpebrae superioris, superior tarsal muscle.

Answer 46

Conjunctiva: Lines the inner surface of the eyelid to provide protection and lubrication. Palpebral on the inner upper eyelid and bulbar on the inferior inner eyelid.

Tarsal glands: secrete lipids that prevent lacrimal fluids from spilling out of the open eye.

Orbicularis oculi: Closes the eye of the palpebral part and the orbital part. Figure 8.81

Levator palpebrae superioris: raise or elevate the upper eyelid

Superior tarsal muscle: Its function is to assist in elevating the upper eyelid

Question 47

Describe the corneal reflex and specify its afferent (sensory) and efferent (motor) limbs

Answer 47

Blinking reaction caused by motor innervation of orbicularis oculi (CN VII) and sensory innervation by CN V1

Cornea is touched lightly using a wisp of cotton, which should stimulate blinking in both eyelids. The afferent limb of this reflex is CN V1 (ophthalmic), and the efferent limb is the facial nerve (CN VII).

Question 48

Describe the significance of the orbital septum of the eyelid as it relates to the confinement and spread of infections.

Answer 48

The orbital septum separates the skin, connective tissue, and muscular layers of the eyelids, which are continuous with these same layers in the face, from the orbit proper and forms a “barrier” that prevents facial infections from spreading into the orbit, and vice versa.

Question 49

Relate the dural venous sinuses to dural folds

Answer 49

Dural folds are locations of dural venous sinuses – endothelium-lined channels that receive venous blood from the brain and transmit it through and out of the cranial cavity. All sinuses drain into the internal jugular vein.

Question 50

Specify the principal routes of venous blood flow through the dural venous sinuses.

Answer 50

Valveless structures, so blood will flow in either direction. most of the blood will exit through internal jugular veins. Some go to Baston’s Plexus in the epidural space. Valveless sinuses and veins within the cranial cavity contribute to infections

Question 51

List the three types of veins that drain to dural venous sinuses.

Answer 51

Cerebral veins, Diploid veins and Emissary veins.

Question 52

Explain the significance of the basilar plexus and occipital sinuses in the metastasis of cancer to the vertebrae and brain.

Answer 52

Occipital sinus is a midline sinus in the falx cerebelli. This and the basilar plexus communicate with the Batson’s plexus through the foramen magnum. Because these areas are valveless and blood runs in any direction, tumor cells may spread to vertebrae and the brain through Batson’s plexus and the sinuses.

Question 53

Discuss the significance of the middle meningeal artery with respect to calvarial fractures and epidural (extradural) hemorrhage.

Answer 53

Strong blows to the side of the head in the region of pterion can easily fracture the thin bone at that site and tear the underlying middle meningeal artery. In these injuries blood accumulates in the epidural potential space between the bone of the skull and the outer layer of the dura

Question 54

Explain the significance of bridging veins and dural venous sinuses to subdural (dural border) hematomas.

Answer 54

Referred to as “bridging veins” because they must “bridge” the subarachnoid space to gain access to and open into the dural venous sinuses. SUBDURAL hematoma is the accumulation of blood between the dura and arachnoid due to tears of the bridging veins that drain blood from the brain to the dural venous sinuses; such tears often occur when the brain makes a sudden and substantial “move” or “shift” within the cranial cavity as a result of a strong blow to the head

Question 55

Specify the vessels that pass through the following cranial openings: foramen spinosum, jugular foramen, and carotid canal.

Answer 55

Foramen spinosum - middle meningeal artery (from the maxillary branch)

Jugular foramen - internal jugular vein

Carotid canal - internal carotid artery

Question 56

Explain the anatomical basis of blowout fractures of the orbit and identify the soft tissue structures at risk of injury.

Answer 56

Maxillary and ethmoid sinus for blowout fractures. This can damage the inferior rectus.

Question 57

Specify the structures that pass through each of the following foramina or canals: inferior orbital fissure, supraorbital foramen/notch, superior orbital fissure, optic canal.

Answer 57

Inferior orbital fissure - infraorbital nerves of CN V2 and petrous branch of the facial nerve (CN VII).

Supraorbital foramen - supraorbital nerve of CN V1

Superior orbital fissure - CN V1, III, IV, VI, and superior ophthalmic vein

Optic canal - ophthalmic artery and CN II

Question 58

Distinguish the structures embedded in the dural wall of the cavernous sinus from those that pass centrally through the sinus.

Answer 58

Embedded in the dural wall are CN III, IV, and V1 as well as a short portion of the V2. All the rest of the superior orbital fissure nerves pass through the cavernous sinus as well as the internal carotid artery.

Abducens (CN VI) travels most medially.

Question 59

Specify the bony articulations of the temporomandibular joint and list the movements allowed at this joint.

Answer 59

The synovial joint articulation occurs between the condyle head of mandible and the mandibular fossa (glenoid fossa, articular fossa) of the temporal bone. FIBROCARTILAGE on articular surface.

Upper capsule allows PROTRUSION and RETRACTION.
Lower capsule allows DEPRESSION and ELEVATION.

Question 60

List the four muscles of mastication; specify their action(s) at the temporomandibular joint and their innervation.

Answer 60

• Temporalis: Retract the mandible
• Masseter: Elevate the mandible
• Medial Pterygoid: Elevate the mandible
• Lateral Pterygoid: Protrusion of the mandible but also assist in depression as well where gravity does most of the work.

All 4 muscles innervated by the CN-V3 and they work together by acting on the TMJ to produce movement of the mandible.

Question 61

Specify the branches of the maxillary and mandibular nerves that innervate the upper and lower dentition.

Answer 61

Mandibular (V3) division of the inferior alveolar nerve will innervate the lower dentitions.
Maxillary (V2) division of the anterior, middle, and posterior superior alveolar will innervate the upper dentitions.

Question 62

5. Distinguish the functions of the following cranial nerves in the oral cavity and tongue, and in chewing: V2, V3, motor branch of VII, chorda tympani of VII, IX, X, XII.

Answer 62

V2: Maxillary; branches into anterior, middle, posterior superior alveolar branches to innervate teeth in upper jaw ; general sensory for palate

V3→Mandibular → Anterior 2⁄3 sensory of tongue through lingual n.; innervates muscles of mastication

Motor branch of VII→ buccinator (keep food in center of mouth to allow proper chewing)

chorda tympani of VII→ TASTE and SENSATION for anterior 2⁄3 tongue.

IX→ posterior 1⁄3 taste and general sensory of tongue.

X→ Motor to soft palate and PALATOGLOSSUS muscle.

XII→ Motor function of all of tongue.

Question 63

Specify how the glossopharyngeal (CN XI) and vagus (CN X) nerves are assessed clinically; specify afferent and efferent limbs of the gag reflex.

Answer 63

Clinicians use the gag reflex to assess the status of the glossopharyngeal nerve (CN IX). The afferent limb of this reflex is the glossopharyngeal nerve; the efferent limb of this reflex is the Vagus nerve (CN X), which innervates the palatoglossus and palatopharyngeal muscles.

Question 64

Specify the location within the neck and the clinical significance of the retropharyngeal space

Answer 64

Infections that originate in the mouth, nose and throat can break through the buccopharyngeal fascia and enter the retropharyngeal space, where they can then lead to airway obstruction and/or spread to the mediastinum. This space is avascular so antibiotics will not work and need surgical intervention.

Question 65

Explain the anatomical basis of tooth pain secondary to maxillary sinus infections

Answer 65

The root of the teeth is separated from the maxillary sinus by a thin cortex of bone which can be eroded when a sinus infection is present and cause tooth pain.

Question 66

Specify where the following structures open into the nasal cavity: anterior, middle, and posterior ethmoidal air cells (Ethmoid sinus), frontal sinus, sphenoid sinus, maxillary sinus, nasolacrimal duct.

Answer 66

• Sphenoid sinus: Sphenoethmoidal recess.
• Anterior Ethmoidal air cells: Semilunar hiatus
• Middle ethmoidal air cells: Ethmoidal bulla
• Frontal sinus: Semilunar hiatus
• Maxillary sinus: Semilunar hiatus
• Posterior ethmoidal air cells: sphenoethmodial recess.
• Nasolacrimal duct: Inferior meatus

Question 67

Distinguish the locations of arterial plexuses in the nasal cavities that are prone to epistaxis and specify the arteries involved in each; explain the anatomical basis of the management of a posterior nosebleed.

Answer 67

90% of nosebleed occur in the Kiesselbach’s area which is an anastomosis arterial branches of the facial, maxilliary, and opthalamic.

The posterior nosebleeds are managed with nasal packing posterior to the middle turbinate.

Question 68

Specify the routes by which infections of the nasal cavities can spread to other locations

Answer 68

Infections of the nasal cavities may spread to the cranial fossa via cribriform foramina.

Infections of the nasal cavities may spread posteriorly to the middle ear via the auditory tube.

Infections may also spread to the conjunctiva through the nasolacrimal duct. (Pinkeye appearance alongside URI symptoms in patients!)

Question 69

List the lymphatic tissues that form “Waldeyer’s Ring” and specify their locations

Answer 69

lingual tonsil: embedded within the mucosa of the pharyngeal part of the tongue.

pharyngeal tonsil: embedded within the mucosa of the roof of the nasopharynx.

palatine tonsils (right and left): located within the tonsillar fossae of the oropharynx

Question 70

7. Specify the cranial nerves that transmit general sensory information and pain from the following regions of the upper respiratory tract: nasal cavity walls and paranasal sinuses, opening of the auditory tube, oropharynx, and tonsillar fossae

Answer 70

Nasal cavity walls and Paranasal sinuses: Ophthalmic CN-V1 and the maxillary CN-V2.

Opening of the auditory tube (Eustachian tube): CN-IX

Oropharynx and Tonsillar fossae: Receive their sensory innervation from branches of the glossopharyngeal nerve (CN IX).

Question 71

List the three subdivisions of the ear and describe the function of each.

Answer 71

External ear: Conduct sound
Middle ear: Conduct sound
Inner ear: Transduce the sound

Question 72

Specify the functions of the stapedius and tensor tympani muscles in hearing and specify their motor innervation of each.

Answer 72

Stapedius: Reduce the vibrations of the stapes during loud noises to prevent sensory damage to the inner ear. Innervated by motor portion of CN-VII.

Tensor tympani: Function to tighten the tympanic membrane innervated by V3 and also to prevent ear damage.

Question 73

Describe the function of the auditory tube (pharyngotympanic tube; Eustachian tube).

Answer 73

The primary function of the Eustachian tube is to equalize air pressure between the atmosphere and the middle ear by allowing air to enter and leave the tympanic cavity through the nasopharynx.

Question 74

6. Distinguish the functions of CNs V3, motor branch of VII, VIII, IX and X in the ear.

Answer 74

Sensory innervation of the skin of the auricle, external acoustic meatus and external surface of the tympanic membrane is via several nerves including branches of cranial nerves V, VII and X.

Sensory innervation of mucous membranes that line the tympanic cavity is done by CN IX.

Tensor tympani (V3) branch that is involved in tightening the tympanic membrane and stapedius muscle innervated by CN VII work together to dampen the noise.

CN VIII (Vestibulocochlear nerve): Provides vestibular nerve and cochlear nerve to provide functions of balance (equilibrium) and hearing for transmission to the brain.

Question 75

Distinguish the functions of the following nerves in the larynx: superior laryngeal nerve (internal and external branches), recurrent laryngeal nerve. All from CN-X

Answer 75

Superior laryngeal nerve

• Internal Branches - Provides sensory innervation to the mucosa of the Larynx above the level of the Vocal Ligaments (and to the “root” of the Tongue as well). Initiates the COUGH REFLEX.
• External Branches - Provides motor innervation to the cricothyroid muscle and the upper Esophageal Sphincter of the Pharynx. Injury causes an inability to make explosive sounds due to paralysis of the Cricothyroid muscle.

Recurrent laryngeal nerve → Innervates all intrinsic laryngeal muscles except cricothyroid muscle. INJURY to a recurrent laryngeal nerve will significantly impact the movements of one vocal ligament, resulting in hoarseness of the voice.

Question 76

Specify the anatomical locations where the internal laryngeal nerve and the left and right recurrent laryngeal nerves are susceptible to injury; specify the symptoms expected with injury of each.

Answer 76

Internal laryngeal nerve and recurrent nerve is susceptible at the piriform recess area when sharp objects swallowed.

Recurrent nerve is ALSO susceptible to injury during thyroidectomy due to location. Both will have loss of cough reflex → also see hoarseness of voice in recurrent because recurrent inn vocal cords.

Question 77

What nerves and or vessels go through the cribriform foramen?

Answer 77

CN-I, olfactory nerve

Question 78

What nerves and or vessels go through the optic Canal?

Answer 78

CN-II, Optic Nerve and ophthalmic artery

Question 79

What nerves and or vessels go through the superior orbital fissure?

Answer 79

CN-III, CN-IV, CN-VI, CN-V1, and superior ophthalmic vein.

Question 80

What nerves and or vessels go through the internal acoustic meatus?

Answer 80

CN-VII, and CN-VIII

Question 81

What nerves and or vessels go through the foramen rotundum?

Answer 81

CN-V2

Question 82

What nerves and or vessels go through the foramen spinosum?

Answer 82

Middle meningeal artery, a branch of the maxillary artery.

Question 83

What nerves and or vessels go through the foramen ovale?

Answer 83

CN-V3

Question 84

What nerves and or vessels go through the jugular foramen?

Answer 84

CN-IX, CN-X, CN-XI, and internal julgar vein.

Question 85

What nerves and or vessels go through the stylomastoid foramen?

Answer 85

CN-VII

Question 86

What nerves and or vessels go through the hypoglossal canal?

Answer 86

CN-XII

Question 87

What nerves and or vessels go through the foramen magnum

Answer 87

Vertebral arteries, spinal cord