Gross Anatomy 2 - Lecture Exam 1

Anatomy

The study of the structural organization of the body

Gross Anatomy

The study of those structures visible to the naked eye

Prone

When the body lies face downward

Supine

When the body lies face upward

Median Plane

A vertical plane which passes through the midline of the body, dividing it into symmetrical R/L halves

Sagittal Plane

Any vertical plane which passes through the body, either within or parallel to the median plane

Midsagittal Plane

Synonymous with median plane

Parasagittal Plane

Any vertical plane which passes through the body parallel to but not within the median plane.

Coronal Plane

Any vertical plane which passes through the bod at right angles to the median plane, dividing the body into anterior and posterior parts

Horizontal Plane

Any pane which passes through the body, at right angles, to both the median and coronal planes, dividing the body into upper and lower parts.

Parietal

Relating to the lining of a cavity (refers to membranes)

*Pretty close*

Visceral

Relating to the covering of an organ (refer to membranes)

\
*Very close*

Motor innervation to the muscles of facial expression

Via branches of the Facial Nerve (CN VII)

\
Off the 2nd pharyngeal arch

Bell’s Palsy

1/2 of face paralyzed

\
Facial Nerve Paralysis (CN VII)

\
Facial Canal Inflammed

\
Paralysis of all pharyngeal arch muscles - canal compresses nerve.

Sensory innervation to the face is via what?

branches of the Trigeminal nerve (C.N. V)

\
Importance of neurological testing for this.

\
Trigeminal nerve divides into 2 major branches before emerging onto the face.

3 Primary Divisions of Trigeminal (CN V)

Ophthalmic Nerve - Distributing primarily to the face and scalp

\
Maxillary Nerve - Distributing primarily to the cheek and the area lateral to the orbit

\
Mandibular Nerve - Distributing primarily to the chin and temporal region

\
*These three further divide*

5 Branches of the Ophthalmic Nerve

Supraorbital Nerve - Biggest, covers scalp

Supratrochlear Nerve - Medial to above “pulley”

External Nasal Nerve - Outside of nose

Infratrochlear Nerve - Below “pulley” bit of eye to nose

Lacrimal Nerve - Lacrimal aparatus of eye (above eye)

Maxillary Nerve

Sygomatocotemporal Nerve

Zygomaticofacial Nerve - Small

Infraorbital Nerve - Large “N” (out of infraorbital foramen)

\- Most frequently injured with blows to the face (boxing)

Mandibular Nerve

Distributed to chin and temporal region

\
Auriculotemporal Nerve - Entire temporal region (longest)

Buccal Nerve - Cheek

Mental Nerve - Mental foramen (mental = chin)

Trigeminal Neuralgia (Tic Douloureux)

*Unhappy tick/wince from pain*

\
A condition characterized by sudden attacks and sever pain occuring in an area of sensory distribution of the Trigeminal Nerve (CNV)

Often due to touch (or wind)

Occurs MC in the maxillary division

Second MC in mandibular division

Least common in ophthalmic division

Cause = unknown

Spinal trigeminal nucleus extends down to the CA and is involved with pain reception from face (cervical adjustments might help)

The sensory innervation of the posterior aspect of the neck and scalp is from what?

The posterior (dorsal) primary rami of cervical nerves 2 to 4.

Greater Occipital Nerve (Posterior Primary Rami of C2)

\
Divides into 3 categories:


1. Greater Occipital Nerve (Posterior Primary Ramus of C3) - supplies the occipital region
2. Third Occipital Nerve (Posterior Primary Ramus of C3) - Supplies the upper part of the back of the neck
3. Posterior Primary Ramus of C4 - Supplies the lower part of the back of the neck (where it fuses with the trap)

\

Note -

C1 has no posterior root carrying sensory fibers. It is strictly motor nerve.

Usually no sensory function

The sensory innervation of the anterior and lateral aspect of the neck is from what?

The Anterior (Ventral) Primary Rami of Cervical nerves 2 to 4

\
Sensory Branches of the Cervical Plexus (Ant. Ramus)


1. Lesser Occipital Nerve (C2) - Supplies the lateral part of the occipital region, posterior to the ear (behind)
2. Great Auricular Nerve (C2, C3) - Supplies the angle of the mandible, and the area inferior to the ear. It accompanies the external jugular vein. (area immediately below it)
3. Transverse Cervical Nerve (C2, C3) - Supplies the anterior surface of the neck (and throat)

Sensory Nerves Image

*See Image*

Cervical Plexus

Supraclavicular Nerve (C3, C4)

Supplies the lateral surface of the neck, there are 3 subdivisions of this nerve


1. Medial Supraclavicular Nerve
2. Intermediate Supraclavicular Nerve
3. Lateral Supraclavicular Nerve

\

Motor Branches of the Cervical Plexus

In addition to the sensory nerves the Cervical Plexus also carries motor fibers tot he infrahyoid (strap) muscles. These motor fibers arise from a loop called the ansa cervicalis

Parts of the Ansa Cervicalis

1. Superior Root - From C1 or C1 and C2.


1. This portion descends from the hypoglossal nerve to join the inferior root (C2/C3)
2. Inferior Root - From C2 and C3


1. This portion descends from cervical nerve branches to join the superior root.

What muscles do the two roots that unite and form the ansa cervicalis supply?

Sternohyoid

Sternothyroid

Omohyoid

Where does the thyrohyoid muscle receive its innervation from?

Exclusively from C1 fibers through the hypoglossal nerve.

The Phrenic Nerve

Considered part of the Cervical Plexus

\- Originates from C3, C4, C5

*C3, 4, 5 keep the diaphragm alive*

\
It is a *motor* to the diaphragm and *sensory* to some of the membranes of the thorax and abdomen.

\
Found in the back, lying on the anterior surface of the anterior scalene muscle. It runs vertically down the muscle and into the thorax.

Platysma

Most superficial Muscle

\
N - Cervical branch of facial nerve (CN VII)

F - Depresses the mandible and draws down the corner of the mouth (frowning)

Sternocleidomastoid

N - Accessory Nerve (CN XI)

F - Chief flexor of the head

Torticollis (Wryneck)

Pathological contraction of the sternocleidomastoid

\
Head tilted forward and face turned away from the affected side

\
Types:

\- Congenital torticollis: results from fibrous tissue tumor which develops at or shortly before birth.

\- Muscular torticollis: due to birth injury

\- Spasmodic torticollis: occurs in adults and is due to abdominal tonicity (abnormal). Often responds well with chiropractic care.

Trapezius

N - Accessory Nerve (CN XI) and C3 and C4 from the cervical plexus

F - The upper portion elevates, the middle portion reacts, the lower portion depresses scapula.

*Functions in scapulohumeral rhythmn*

\
Many patients have problems with upper trap due to technology.

Veins

External Jugular Vein - 2nd largest in neck

\
The external jugular vein drains the face and scalp and also contains a large amount of cerebral blood.

\
It is formed immediately below the parotid gland by the union of two things:


1. Retromendibular Vein
2. Posterior Auricular Vein - Behind Ear

\
It runs downward and backward along the lateral surface of the SCM and empties into the subclavian vein.

\
The tributaries of the external jugular vein include the:


1. Retromandibular Vein
2. Posterior Auricular Vein
3. Posterior External Jugular Vein
4. Anterior Jugular Vein
5. Transverse Cervical Vein
6. Suprascapular Vein

\
While this is the most common arrangement for the tributaries of the external jugular, many variations occur.

Prominent External Jugular Vein

When venous pressure is normal, the external jugular vein is invisible, or nearly so, topographically.

*If super skinny may see some of it, should not be any bulging*

\
In congestive heart failure or obstruction of the supra vena cava, it becomes very prominent throughout its length.

\
*Exception*

Opera singers and bag pipe players develop prominent external jugular veins due to intrathoracic pressure during singing and playing.

Lymph Nodes

Superficial cervical lymph nodes are found along the external jugular vein, superficial to the SCM

Triangles of the Neck

When viewed laterally, the neck is divided into 2 major triangles by the SCM

\
The anterior triangle lies in front of the SCM. The posterior triangle lies behind it.

Posterior Triangle

SCM, Trap, Clavicle

\
The boundaries of the posterior triangle are as follows:


1. Anterior boundary - the posterior border of SCM
2. Posterior boundary - the anterior border of trapezius
3. Inferior boundary - the superior border of the middle third of the clavicle.

*The important visceral structures of the neck are found in the anterior triangle. The posterior triangle will not be discusses in detail*

Anterior Triangle

The boundaries of the anterior triangles are as follows:


1. Superior boundary - the inferior border of the mandible
2. Anterior boundary - the anterior midline
3. Posterior boundary - the anterior border of SCM

\
The apex of the anterior triangle lies inferiorly, at the jugular notch

\
The roof of the anterior triangle is formed by the investing layer of the deep cervical fascia, and the superficial cervical fascia, and the platysma.

\
Subdivisions of the Anterior Triangle


1. Submental Triangle - below chin
2. Submandibular (digastric triangle
3. Carotid Triangle
4. Muscular Triangle

\
\

Submental Triangle

Below chin

\
Only one of the anterior triangle subdivisions which is *unpaired*

\
Boundaries:

The L/R anterior bellies of digastric and the body of the hyoid bone

\
Floor:

The mylohyoid muscle

\
Contents:

Minor veins and lymph nodes

Submandibular (Digastric) Triangle

Boundaries:

The inferior border of the mandible, the anterior belly of digastric, and the posterior belly of digastric

\
Floor:

The hylohyoid and hyoglossus muscles.

\
Contents:

The submandibular (2nd largest gland) gland, the internal carotid artery, facial artery, internal jugular vein, glossopharyngeal nerve (CN IX), and the vagus nerve (CN X)

\
*Clinical Note*

When palpating and adjusting, many neurovascular and vital structures here!

Carotid Triangle

Common carotid artery bifurcates here into internal and external carotid arteries.

\
Boundaries:

The posterior belly of digastric, the superior belly of omohyoid, and the anterior border of sternocleidomastoid.

\
Floor:

Portions of the thyrohyoid, hyoglossus, and inferior and middle constrictor muscles (swallowing muscles)

\
Contents:

Parts of the common and internal carotid arteries, the external carotid artery and 3 of its branches


1. Superior thyroid artery
2. Lingual artery
3. Facial artery

Corresponding tributaries of the internal jugular vein

Muscular Triangle

Meet at throat - midline

\
Boundaries:

The superior belly of omohyoid, anterior midline of the neck, and the ant border of the SCM

\
Floor:

Posterior layer of pretracheal fascia

\
Contents:

Strenohyoid and sternothyroid muscles, thyroid glands, brachea, and eophagus.

Hyoid Bone

*Forensic application - broken during strangulation*

\
The hyoid bone is located between the mandible and larynx, and serves as a point of attachment for many muscles.

\
It does not articulate with any other bone.

\
Parts:


1. Body
2. Greater Horn
3. Lesser Horn

\

Infrahyoid Muscles

The infrahyoid muscles are 4 ribbon-like muscles which attach to the hyoid bone. They function primarily to move the hyoid bone and larynx.

\
Muscles Include:


1. Omohyoid
2. Sternohyoid
3. Sternothyroid
4. Thyrohyoid

\
\

Omohyoid

N - Ansa cervicalis (C1, C2, C3)

F - Depresses the hyoid bone and larynx

Sternohyoid

N - Ansa cervicalis (C1, C2, C3)

F - Depresses the hyoid bone and larynx

Sternothyroid

Fan shaped deep to sternomyoid

\
N - Ansa cervicalis (C1, C2, C3)

F - Depresses the larynx

Thyrohyoid

N - C1 though hypoglossal nerve

F - Depresses the hyoid bone

Overview

*See image*

Why all the muscles to depress the hyoid bone and larynx?

Pull downward

\
Swallowing → most complex of all visceral functions

*most important*

Larynx up and down

Speaking (speech) → not primary muscles of speech

*secondary muscle*

Respiration (breathing) → minor function

If the hyoid is fixed (by infrahyoid muscles) digastric depresses mandible

*not much force required to open mouth*

Cervical Fascia

Fascia is dense, sheet-like layer of connective tissue

\
Surrounds and supports both the superficial cervical fascia and the deep cervical fascia.

Deep cervical fascia is further subdivided into 4 parts

\

1. Superficial Cervical Fascia - outer layer indicated on diaphragm


1. A thin layer of connective tissue which encloses the platysma muscle and contains cutaneous nerves, superficial veins, and lymph nodes.
2. Deep cervical fascia


1. Investing layer (of the deep cervical fascia)


1. This layer lies deep to the superficial cervical fascia and splits to enclose the SCM and Traps
2. Pretracheal Fascia


1. This layer encloses the thyroid gland, trachea, and esophagus
3. Prevertebral Fascia


1. This layer encloses the vertebral column and the deep muscles of the back.
4. Carotid Sheath *paired*


1. This layer is a cylinder of fascia which extends from the base of the skull to the root of the neck

Cervical Fascia Contains Some Structures

1. Common carotid artery
2. Internal carotid artery
3. Internal jugular vein
4. Vagus nerve
5. Deep cervical lymph nodes

\
The external carotid artery exits the sheath before giving off its branches in the neck.

Function and Clinical Significance of Fascial Layers

Function:

Provide slippery surface to decrease friction during…

\- Gross movements of the head/neck

\- Swallowing

\-- Adhesions between layers can cause neck pain

\-- May be treated with myofacial release

\
Clinical significance:

\- Serve as channel for infections

*pretracheal fascia may allow an infection to spread from head/neck to mediastimun directly*

\- Cancer involving the deep cervical lymph nodes can compress internal jugular veins

Superior Thoracic Aperture (Thoracic Inlet)

The superior thoracic aperture is the opening through which structures of the neck pass into the thorax

\
The boundaries of the superior thoracic aperture include the:


1. First thoracic vertebra
2. First ribs and their cartilages
3. Manubrium of sternum

\
Kidney shaped

\
Major structures that pass through the aperture:


1. Arteries


1. Brachiocephalic Trunk
2. Left Common Carotid Artery
3. Left subclavian Artery
4. Internal Thoracic Artery
2. Veins


1. Brachiocephalic vein (only on R)
3. Nerves


1. Phrenic Nerve
2. Vagus Nerve
3. Recurrent Laryngeal Nerve
4. Sympathetic Trunk
4. Viscera


1. Trachea
2. Esophagus
3. Cervical Pleura
4. Apex of Lung
5. Thymus

Potential for Lung Collapse with Neck Injury

The cervical pleura and the apex of the lung pass through the superior thoracic aperature immediatly posterior to the origin of the SCM

\
A broken 1st rib/penetrating around of the neck may cause lung collapse (atelectasis)

\- Can cut lung/pleura

\- Subclavian artery/vein

Thymus

Involutes (shrinks) after puberty

Result is decreased immune function with age

\- Elderly struggle with immune function.

\
Thymus is part of the immune system, produces T-lymphocytes. T cells will mature in thymus throughout life.

\
Usually composed of 2 irregular lobes, lies primarily behind the manubrium and body of sternum

\
Extensions into the neck and around the front and sides of the trachea are common.

\
Thymus lies inferior to the thyroid gland

Sternohyoid and sternothyroid muscles lie anteriorl to the thymus and thyroid gland

\
Blood Supply: Internal thoracic artery

N - Stellate Ganglion of Sympathetic Trunk and Vagus

Thyroid Gland

Endocrine gland (releases into blood)

Produces thyroxine and calcitonin

\
It lies at the level of cervical vertebrae 5 through thoracic vertebrae 1

\
It is generally either H or U shaped and consists of 3 parts:


1. Left Lobe
2. Right Lobe
3. Isthmus (connects R/L lobes)

\
Anatomical Variations:

\- Approximately 50% of thyroid glands also have a pyramidal lobe, which extends upward from the isthmus as a finger or glandular tissue

\- Another common variation found associated with the thyroid gland is the levator glandulae thyroideae muscle, which connects the isthmus of the thyroid gland with the hyoid bone.

Blood Supply to the Thyroid Gland

Highly vascular due to endocrine function

\
Arteries:


1. Superior thyroid artery - from external carotid artery
2. Inferior thyroid artery - from the thyrocervical trunk

\
**Anatomical Variations**

Thyroid Ima Artery - An inconstant branch to the thyroid gland, from the brachiocephalic trunk (in about 10% of individuals)

*Can be punctures during tracheotomy!*

\
Veins:


1. Superior thyroid vein - to the internal jugular vein
2. Middle thyroid vein - to the internal jugular vein
3. Inferior thyroid vein - to the brachiocephalic vein

\
\

Innervation to the Thyroid

Innervation from the superior, middle, and inferior cervical sympathetic ganglia

Goiter

Abnormal enlargement of the thyroid gland that produces swelling in the anterior neck

\
Size can vary (could be softball sized)

\
Endemic Goiter:

\- Due to dietary deficiency of iodine (necessary to produce thyroxine)

\-Gland size increases to increase output hormone largely inactive

\- Causes hypothyroidism (S: cold, weight gain, tired, decreased metabolic rate)

\- Common to a region → now its rare due to things like iodized salt.

\
Exophthalmic Goiter:

\- Due to autoimmune disease

\- Thyroid stimulating immunoglobulins bind to receptor site, cause overactivity of gland

\- Hormone is active (plenty of iodine)

\- Hyperthyroidism (Grave’s disease) - S/S: Skinny, eating lots, sweaty, hot a lot, fast metabolism, tachycardia, bulging eyes due to fat deposits behind eyes.

Note on Recurrent Laryngeal Nerve

Branches off vagus within thorax, then travels up into the neck to supply motor innervation to all but one of the laryngeal muscles.

\
In neck → Lies first on the posterior surface of the thyroid lobe, then deep to the lobe.

\
Controls muscle of speech and airway

\
\

Parathyroid Gland

Endocrine glands which are involved in calcium homeostasis

\
*Essential to life*

\
Small ovoid bodies located on the posterior surface of the thyroid gland. Usually 4 parathyroid glands, though the number varies from two to six.

\
Blood Supply:


1. Inferior thyroid artery
2. Superior thyroid artery

\
N - From inferior or middle cervical sympathetic ganglia

Factors contributing to the difficulty of thyroid surgery…

1. Presence of parathyroid glands
2. Vascularity (lots of blood supply)
3. never (recurrent laryngeal nerve) - paralysis of this nerve could suffocate a person.

Trachea

Primarily a thoracic structure

\
“windpipe” - begins at the larynx at the level of cervical vertebra 6 within the thorax - splits into L/R main bronchi

\
Walls are supported by a series of incomplete cartilaginous rings, which are open posteriorly.

*C-shaped cartilage allows for rigidity/shape to stay during contraction*

\
The posterior gap is spanned by the *trachialis muscle*

Opening in rings allows expansion of esophagus during swallowing.

\
Blood Supply - Inferior Thyroid Artery

N - Recurrent Laryngeal Nerve

Esophagus

Muscular tube which connects the pharynx to the stomach

\
Begins in the neck at the level of cervical vertebra 6 and lies posterior to the trachea

\

Carotid Arteries

main arteries of the head and neck are the L/R common carotid arteries

\
Common carotid artery ascends within the carotid sheath to the carotid triangle where it splits into 2 braches:


1. Internal carotid artery - Internal carotid artery has no branches in the neck. Enters the skill through the carotid canal (in temporal bone) to supply blood to the brain, no branches.
2. External carotid artery - Supply everything on inside of head. The external carotid artery is the main source of blood to structures of the neck, face, and scalp. (structures external to the skull)

\

What are the 8 branches of the external carotid artery?

**S**ave **A** **L**ady **F**alling **O**ut **O**f **A** **P**lane **S**uperman

\
Superior thyroid artery

Ascending pharyngeal artery

Lingual artery

Facial artery

Occipital artery

Posterior auricular artery

Superficial temporal artery

Maxillary Artery

\
*The superficial temporal artery and maxillary artery represent the terminal branches of the external carotid*

Carotid Sinus

Slight dilation of the internal carotid artery where it joins the common carotid. It is a barorecptor (blood pressure sensor)

\
N - Glossopharyngeal Nerve (CN IX)

Carotid Body

Small reddish-brown mass located within or deep to the bifurcation of the common carotid artery. Chemoreceptor which detects changes in the chemical makeup of blood within the carotid.

\
N - The carotid sinus branch of the Glossopharyngeal nerve (CNIX)

Internal Jugular Vein

Never visible topographically

\
Largest vein of neck

\
Begins at jugular foramen as the direct continuation of the sigmoid sinus

\
Drains into the brachiocephalic vein

Superior Jugular Bulb

Dilation of the internal jugular vein at its origin below the jugular foramen.

Tributaries of the Internal Jugular Vein

FLIPS/M

\

1. **I**nferior Petrosal Sinus
2. **P**haryngeal Veins
3. **F**acia Vein
4. **L**ingual Vein
5. **S**uperior Thyroid Vein
6. **M**iddle Thyroid Vein

\

Inferior Jugular Bulb

The dilation of the internal jugular vein near its termination into the brachiocephalic vein

Glossopharyngeal Nerve

Mixed motor and sensory

\
The glossopharyngeal nerve (CN IX) emerges from the medulla oblongata and passes through the jugular foramen.

Branches:


1. Tympanic Nerve - Sensory to the tympanic cavity and secretomotor to the parotid gland (senses pain in otis media)
2. Branch to the Carotid Sinus - Sensory to both the carotid sinus and carotid body
3. Pharyngeal Branch - This branch unites with branches from the vagus and sympathetic trunk to form the pharyngeal plexus. Pharyngeal branch of the glossopharyngeal nerve is sensory to the pharynx.


1. Senses pain in acute pharyngitis
2. Afferent limb of the gag reflex (CN IX)
4. Branch to the Stylopharyngeus - Motor to the stylopharyngeus muscle
5. Tonsillar Branch - Sensory tot he mucous membrane over the tonsil and to the soft palate.


1. Senses pain in tonsils
6. Lingual Branch - Supplies taste and general sensation to the posterior third of the tongue.

\
\

Vagus Nerve (CN X)

The vagus nerve is the longest cranial nerve, with an extensive distribution in the head, neck, thorax, and abdomen.

\
Vagus means “wanderer”

\
It emerges from the medulla oblongata and exits the skull through the jugular foramen, along with the glossopharyngeal and accessory nerves.

\
2 Ganglia in the neck:


1. Superior (jugular) ganglion: located in the jugular foramen
2. Inferior (nodose) ganglion: bigger, can look like a lymph node

\
Branches of the Vagus in the head and neck:


1. Meningeal branch


1. Arises from the superior ganglion.
2. Supplies the dura mater with sensory innervation
3. Cervicogenic headache association
2. Auricular Branch


1. Arises from the superior ganglion
2. Sensory to the auricle, floor of external auditory meatus, and tympanic membrane
3. Pharyngeal Branch


1. Efferent (motor) limb of gag reflex
2. Arises from the inferior (motor) ganglion
3. Chief motor nerve to the muscles of the pharynx and soft palate
4. Most fibers originate from accessory nerve (CN XI), then joins with vagus
5. Pharyngeal plexus is motor to all the muscles of the pharynx except for stylopharyngeus (innervated by the glossopharyngeal nerve), and to all of the muscles of the soft palate except for tensor veli palatini (innervated by trigeminal nerve)
4. Superficial Laryngeal Nerve


1. Divides into two
2. Superior laryngeal nerves arise from the inferior ganglion, then divides into two:


1. Internal Laryngeal Nerve: Sensory to the mucous membrane of the larynx superior to true vocal cords
2. External Laryngeal Nerve: Motor to the cricothyroid and inferior constrictor muscles
5. Recurrent Laryngeal Nerve


1. Most important
2. Arises from the vagus within the thorax and then ascends back into the beck.
3. Ascends in groove between the trachea and esophagus and is closely applied to the posterior surface of the thyroid gland
4. Dives deep into membrane of larynx
5. Sensory to the mucous membrane of larynx, below true vocal folds and trachea.
6. Motor to all of the muscles of the larynx, except for cricothyroid.

Clinical consequences of damage to the recurrent laryngeal nerve

Unilateral damage →

Respiratory stress, hoarseness (partial aphonia), partial flaccid paralysis.

\
Bilateral damage →

Complete aphonia, may result in suffocation.

\
Causes:

\- Cutting it (surgery) by accident

\- Trauma during thyroid surgery (difficult to operate)

\- Goiter or thyroid tumor (as expand, nerve compressed/damaged

\- The nerve comes off the vagus in the thorax (there are things in the thorax)

\- - Lung tumor

\-- Part of apex of lung is in the neck

\-- Aortic aneurysms

Accessory nerve (CN XI)

Formed by the union of 2 parts:


1. Cranial Part - originates from the medulla oblongata (short one)


1. Joins vagus just above the inferior vagal ganglion.
2. Supplies the vagus with moor fibers that travel to..


1. Pharyngeal branch of the vagus - to the muscles of the pharynx and soft palate
2. Recurrent Laryngeal Nerve - to the muscles of the larynx
2. Spinal Part - originates from sides of the spinal cord


1. Both ascends though the foramen magnum and joins the cranial part for a short distance.
2. Both parts exit through the jugular foramen
3. Motor to the SCM and traps (2 largest mm of neck)

Hypoglossal Nerve (CN XII)

Motor nerve to the tongue

\
Originates from the MO and exits the skull through the **Hypoglossal Canal**

\
Loops downward and forward, deep to the posterior belly and intermediate tendon of digastric.

\
\*Some of the fibers carried by the hypoglossal are proper to the nerve itself, while others originate from cervical spinal nerves and merely “hitch a ride” with the hypoglossal.

\
Branches:


1. Meningeal Branches


1. Supply the dura mater - cervicogenic headache
2. Superior Root of the Ansa Cervicalis


1. Superior root of ansa cervicalis consists maily of C1 fibers, and unites with the inferior root (from C2/3) to form the ansa cervicalis, which is motor to the infrahyoid muscles (sternohyoid, sternothyroid, omohyoid)
3. Nerves to Thyrohyoid and Geniohyoid


1. These branches of the hypoglossal also consist of C1 fibers. They are motor to the Thyrohyoid and Geniohyoid muscles
4. Lingual Branches


1. From medula
2. Motor to the extrinsic and intrinsic muscles of the tongue.

Cervical Part of the Sympathetic Trunk

*Sympathetic fibers from cervical ganglia also supplies the heart - fight/flight survival mechanism.*

\
The cervical part of the sympathetic trunk begins at the base of the skull and is continuous with the thoracic part of the trunk.

Preganglionic Sympathetic Fibers

Supply structures of the head and neck, originating from T1 to T3

\
Travel up the trunk to one of several cervical ganglia, where they synapse.

\
Post ganglionic fibers distribute from the ganglia to the blood vessels, smooth muscle and glands of the head and neck.

\

Cervical Sympathetic Ganglia

1. Superior Cervical Ganglion


1. Supplies structures in the head
2. lies at the level of C1-3 immediately below the base of the skull
3. Branches from this include:


1. Internal Carotid Nerve - large, goes with internal carotid artery into skull.
2. Superior Cervical Cardiac Nerve - From superior cervical ganglia to cardiac plexus
3. Branches to the Pharyngeal Plexus - Motor: Vagus, symp: from sympathetic trunk
2. Middle Cervical Ganglion


1. Middle cervical ganglion lies at the level of C6
2. Branch:


1. Middle Cervical Cardiac Nerve (to cardiac plexus)
3. Vertebral Ganglion (C7)


1. Variable and is often fused with either the middle or inferior cervical ganglion
2. Lies at C7 level
3. Gives off branches to the plexus along the vertebral artery (not always there)
4. Cervicothoracic (Stellate) Ganglion


1. Star like
2. C7-T1
3. Formed by fusion of the inferior cervical ganglion to the first thoracic ganglion
4. Posterior to the vertebral artery and anterior to the TVP of C7 and neck of 1st rib.
5. Branch:


1. Inferior Cervical Cardiac Nerve (to the cardiac plexus)

Ansa Subclavia

Nerve bundle with loops anterior to the subclavian artery, connecting the vertebral ganglion to the cervicothoracic ganglion

\
*part of sympathetic trunk*

Osteology of Mandible

Largest, sturdiest facial bone

\
Parts:

\- Body: Large, horizontal part of the mandible

\- Alveolar Process: Upper border of the body, containing the tooth sockets (alveoli)

\- Ramus: Vertically ascending part of the mandible

\- Angle: At posterior terminus of the body

\- Condylar Process: Articulates with the temporal bone to form the temporomandibular joint

\- Coronoid Process: Area of attachment for muscles of mastication (no articulation)

Features of the internal (lingual) surface of the mandible

\- Superior Mental Spine: Origin of the Genioglossus muscle

\- Inferior Mental Spine: Origin of the Geniohyoid muscle

\- Digastric Fossa: Origin of the anterior belly of digastric

\- Mylohyoid Line: Origin of the Mylohyoid muscle

\- Sublingual Fossa: Location of the sublingual gland

\- Submandibular Fossa: Location of part of the submandibular gland

Digastric Muscle

N →

Posterior Belly: Cervical branch of the Facial Nerve (CN VII)

Anterior Belly: Nerve to Mylohyoid (CN V)

\
A →

Elevates the Hyoid Bone and depresses the Mandible when Hyoid is flexed.

Mylohyoid Muscle

N →

Nerve to Mylohyoid (CNV)

\
A →

Elevates Hyoid Bone and floor of the mouth

Geniohyoid Muscle

N →

C1 fibers through Hypoglossal

\
A →

Elevates Hyoid bone and tongue

Genioglossus Muscle

Largest tongue muscle

\
N →

Hypoglossal Nerve (all but one)

\
A →

Draws tongue forward, protrudes tip of tongue (sticks tongue out)

Hyoglossus Muscle

N →

Hypoglossal Nerve (CN XII)

\
A →

Draws tongue downward

Floor of mouth saying “Ahhh”

\
*A small portion of hypglossus may take origin from the lesser horn of the hyoid bone. This muscle slip is called the chondroglossus.*

Styloglossus Muscle

N →

Hypoglossal Nerve (CN XII)

\
A →

Draws tongue upward and backward

Pulls tongue back into mouth

Stylohyoid Muscle

N →

Facial Nerve and post. belly of digastric

\
A →

Elevates hyoid bone and tongue

\
*Pierced by the inferior tendon of the digastric muscle*

Submandibular Gland

One of the three large, paired salivary glands

\
Wraps around the posterior border of the mylohyoid

\
Consists of 2 parts:


1. Superficial Part - large, lies within the submandibular triangle and the submandibular fossa
2. Deep Part - small, lies superior to the hylohyoid muscle.


1. Submandibular duct is 5cm long, opens into the oral cavity on *sublingual caruncle*, located lateral to the frenulum of the tongue.

\
Innervation - Parasympathetic fibers from the facial nerve (CN VII) via the submandibular ganglion.

Sublingual Gland

The sublingual gland is the smallest of the 3 major salivary glands

\
Lies superior to the mylohyoid muscle, in the sublingual fossa (shallow)

\
Empties into the floor of the mouth by 12 short ducts, locates along th sublingual fold.

\
N →

Parasympathetic fibers from the facial nerve (CN VII) via the submandibular ganglion

*Lingual Nerve* - crosses under submandibular duct on its way to the tongue!

\

Nerves associated with the mandible:

\

Lingual, glossopharyngeal, hypoglossal

Blood vessels associated with the mandible

Lingual artery & vein

\
Facial artery & vein

Lymph nodes of the mandible

Submandibular and submental lymph nodes

Functions of the Nasal Cavity

1. To provide an airway
2. Olfaction
3. Warming and moistening of inspired air
4. Cleaning of inspired air (goblet cells, mucous secretions)