Exam 2- Nerves

Cutaneous Innervation Via Cervical Plexus

Skin is innervated by C2, C3, C4 VPR

Lesser occipital nerve (C2), Great auricular nerve (C2, C3), Transverse cervical nerve (C2, C3), supraclavicular nerve (C3, C4)

Emerge at Erb’s Point

Lesser Occipital Nerve (C2)

Cervical Plexus

Follows posterior border of SCM to reach mastoid process and behind the ear

Great Auricular Nerve (C2, C3)

Cervical Plexus

Large

Courses vertically on SCM towards angle of mandible and parotid region

Transverse Cervical Nerve (C2, C3)

Crosses SCM horizontally towards the anterior

triangle of the neck

Supraclavicular nerves (C3, C4)

Crosses the clavicle towards the inferior

posterior triangle and upper chest and thorax

Brachial Plexus branches in posterior triangle

Dorsal scapular nerve (C5). Nerve to subclavius (C5-C6), suprascapular nerve (C5-C6), Long thoracic nerve (C5-C7)

Dorsal Scapular Nerve

Pierces lateral side of middle scalene

Long thoracic nerve

Pierces lateral side of middle scalene

Vagus Nerve (CN X)

Courses inside carotid sheath, anterior to subclavian artery, medial to phrenic

Right vagus nerve gives off right recurrent laryngeal nerve at right subclavian artery

Left vagus nerve gives off left recurrent laryngeal nerve

Gives off superior laryngeal n. branch

▪ Internal laryngeal n. – branch of

sup. laryngeal n. that travels w/

superior laryngeal a.

▪ External laryngeal n. – branch of

sup. laryngeal n. that travels w/

superior thyroid a.

▪ Gives off recurrent laryngeal n. branch

that ascends between trachea &

esophagus

Phrenic Nerve

Formation: VPR C3-C5

Course: Descends on anterior surface of anterior

scalene m., lateral to ascending cervical a.

Enters superior thoracic aperture

Courses along pericardium to the diaphragm

Function: Motor innervation to diaphragm, sensory innervation from parietal peritoneum in right upper quadrant of abdomen

Ansa Cervicalis

Somatic motor innervation to infrahyoid muscles

Formed from C1-C3 VPRs

Loop shape

Superficial to internal jugular v

Two components: Descendens hypoglossi, descendens cervicalis

Descendens Hypoglossi

Superior root, Formed from C1 VPR Fibers running with hypoglossal n (CN XII)

Supplies superior belly of omohyoid, upper parts of sternohyoid and sternothyroid

Descendens Cervicalis

Inferior root, Formed from C2 and C3 VPR fibers

Supplies inferior belly of omohyoid, lower parts of sternohyoid and sternothyroid

Trigeminal n (CN V)

Branches into V1, V2, V3

Ophthalmic, maxillary, and mandibular nerves

Sensory nerve of the face

Inferior Alveolar Nerve

Branch of CN V3

Gives off nerve to mylohyoid

Nerve to Mylohyoid

Innervates mylohyoid and anterior belly of digastric

Facial Nerve (CN VII)

Trunk innervates stylohyoid and posterior

Belly of digastric mm

Glossopharyngeal Nerve (CN IX)

Conveys visceral sensory innervation

from carotid sinus (baroreceptors) and

carotid body (chemoreceptors), which

are both located at bifurcation of

common carotid a.

Accessory Nerve (CN XI)

Innervates SCM and Trapezius

Hypoglossal Nerve (CN XII)

- Crosses superficial to carotid arteries

▪ Helps deliver C1 VPR fibers to ansa

cervicalis, thyrohyoid, and geniohyoid mm.

▪ Passes deep to mylohyoid to innervate

tongue muscles

ANS in Anterior Triangle

Superior cervical ganglion: source of internal and external carotid nerves

Middle Cervical: may be absent

Inferior cervical ganglion: may fuse with first thoracic ganglion to form stellate ganglion

Sympathetic Trunk

Receives preganglionic sympathetic axons

that all:

• Originate at T1-L2 spinal cord levels

• Enter trunk via white rami in thorax

• Fibers ascend to cervical region

Source of postganglionic sympathetic axons

that either:

• Exit via gray rami into cervical spinal nerves

• Supply thoracic viscera via cardiac nerves

• Travel to head & neck via periarterial plexuses

Ophthalmic N, CN V1

Exits cranial cavity via the superior orbital fissure

→ Moves through orbit to reach the upper face

→ Terminal branches of V1 on the face:

→External nasal

→Supratrochlear

→Infratrochlear

→Supraorbital

→Lacrimal

Maxillary Nerve, CN V2

Exits cranial cavity via foramen rotundum

→ Moves through the pterygopalatine fossa

→ Terminal branches of V2 on the face

→Zygomatic-facial n.

→Zygomatico-temporal n.

→Infraorbital n.

Mandibular Nerve, CN V3

Exits cranial cavity via foramen ovale

→ Courses through infratemporal fossa (motor + sensory)

→ Terminal branches of V3 on the face

→Auriculotemporal n.

→Buccal n.

→Mental n.

CN V3 has BOTH motor & sensory fibers

→ CN V1 and CN V2 are entirely sensory

→ CN V starts in the middle cranial fossa

→ It moves through foramen ovale to the

infratemporal fossa

→ Divides into 3 portions:

→ Main trunk

→ Anterior division

→ Posterior division

Cilary Ganglion

→ Inside the orbit along the lateral side of CN II

→ Receives CN III (pre-gg para); some branches ride CN V1

→ Target: pupillary constrictor muscle

Pterygopalatine Ganglion

→ Housed in the pterygopalatine fossa in the deep midface

→ Receives CN VII’s greater petrosal nerve (pre-gg para)

→ ANS fibers travel with CN V2 branches

→ Target: glandular mucosa of the nasal & oral cavities

Otic Ganglion

Supported by CN V3 just inferior to foramen ovale

→ Receives CN IX’s lesser petrosal nerve (pre-gg para)

→ ANS fibers travel with CN V3’s auriculotemporal nerve

→ Target: parotid gland

- Parasympathetic ganglion containing

postganglionic neurons which receive

the preganglionic fibers from the

glossopharyngeal nerve (CN IX) via its

lesser petrosal nerve branch

Submandiublar Ganglion

Supported by CN V3’s lingual nerve near back of mouth

→ Receives CN VII’s chorda tympani nerve (pre-gg para)

→ Target: submandibular and sublingual glands

Parasympathetics travel with…

Trigeminal Branches

Sympathetics Travel With…

Arteries

Branches of Mandibular Nerve

Main trunk, anterior division, posterior division

Main Trunk CN V3

Meningeal branch: sensory to meninges, travels with middle meningeal artery

Nerve to medial pterygoid: motor to medial pterygoid

Anterior Division of CN V3

Masseteric nerve

→ Motor to masseter m.

→ Sensory to TMJ

Deep temporal nerves

→ Motor to temporalis m.

Nerve to lateral pterygoid

→ Motor to lateral pterygoid

Buccal nerve

→ Sensory to skin of cheek and nearby

gums

Posterior Division of CN V

Auriculotemporal nerve, lingual, inferior alveolar nerve

Auriculotemporal Nerve

Sensory to TMJ, skin near ear

→ Surrounds middle meningeal a.

→ Carries postganglionic

parasympathetic fibers from otic

ganglion to parotid gland

Lingual Nerve

Sensory to ant. 2/3 tongue

→ Carries chorda tympani n. to the

submandibular gg. and glands,

and ant. 2/3 tongue (taste)

Inferior Alveolar Nerve

Sensory to mandible teeth & skin

→ Enters mandibular foramen after

giving off n. to mylohyoid

→ Ends as mental n. on the chin

Chorda tympani Nerve

From the facial n. (CN VII)

→ Carries preganglionic

parasympathetic fibers to

the submandibular

ganglion

→ Carries taste fibers from

the anterior two-thirds of

the tongue

→ Leaves the skull through the

petrotympanic fissure

→ Travels with the lingual

nerve of CN V3