Neck MTL

What is contained within the carotid sheath?

"I see 10 CCs in the IV" I See (IC) = Internal Carotid Artery 10 (CN 10) = Vagus Nerve CC = Common Carotid Artery IV = Internal Jugular Vein AND Deep Cervical Lymph Nodes! **Receives fascial contributions from all 3 layers of the deep cervical fascia

What does the muscular triangle contain?

1. Platysma muscle 2. Facial artery and vein 3. Anterior and communicating jugular veins 4. Hyoid bone 5. Thyroid cartilage 6. Thyrohyoid membrane 7. Cricoid cartilage 8. Cricothyroid membrane/ligament 9. Thyroid gland 10. Infrahyoid muscles (sternohyoid, omohyoid, sternothyroid, thyrohyoid)

Besides the muscles in the suboccipital triangle, what other 2 muscles does the suboccipital nerve (C1) innervate?

1. Rectus capitis posterior minor 2. Semispinalis capitis

What are the 4 sub triangles contained within the anterior triangle of the neck?

1. Submandibular 2. Submental 3. Carotid 4. Muscular

What does the investing layer of the deep cervical fascia contain?

2 muscles = SCM, Traps 2 glands = submandibular, parotid

What is the site that is often used to access the IVJ (internal jugular vein) during central line placement of catheterization of the heart?

A depression located between the sternal and clavicular heads of the SCM, just superior and lateral to the sternal extremity of the clavicle

What are the borders of the SUPERFICIAL posterior triangle of the neck?

Anterior = Posterior border of SCM Posterior = Anterior border of Trapezius Inferior = Middle 3rd of clavicle Roof = Investing layer of deep cervical fascia Floor = Prevertebral layer of deep cervical fascia (covering splenius capitis, elevator scapulae, scalenes)

Thyrocervical trunk

Arises from the first part of the Subclavian Artery Gives off 3 branches... 1. Suprascapular artery --> supra and infraspinatus muscles 2. Transverse cervical artery --> traps, levator scapulae, rhomboids 3. Inferior thyroid artery --> thyroid gland

Lesser Occipital Nerve (C2)

Ascends from puncture nervosa along the posterior border of the SCM Provides cutaneous innervation to the scalp posterior and superior to the auricle of the ear

Great Auricular Nerve (C2, C3)

Ascends on the external surface of SCM parallel to EJV Provides cutaneous innervation to skin inferior to the auricle and to parotid gland

Axillary sheath

At the base of the neck where the prevertebral layer of fascia is drawn out laterally by the nerve roots C5-T1 that form the brachial plexus

Splenius Capitis Muscle

Attachements Medial = Ligamentum nuchae, spinous processes T1-T6 Lateral = Mastoid process and superior nuchal line Innervation Dorsal rami of mid-cervical spinal nerves Actions Unilateral = Laterally flex and rotate head to SAME side Bilateral = extend head

Inferior Oblique Muscle

Attachements Medial = spinous process C2 Lateral = transverse process of C1 Innervation Suboccipital Nerve - C1 Actions Strong rotator of C1 and head to same side

Sternohyoid Muscle

Attachements Superior = Body of hyoid bone adjacent to midline Inferior = Manubrium of sternum and medial end of clavicle Innervation Ansa Cervicalis (C1-C3) Actions Depress the hyoid bone during swallowing and vocalization

Omohyoid Muscle

Attachements Superior = Hyoid bone lateral to sternohyoid Inferior = Superior border of scapula medial to scapular notch Innervation Ansa Cervicalis (C1-C3) Actions Depress and retract hyoid bone

Thyrohyoid Muscle

Attachements Superior = Inferior border of hyoid body/greater horn Inferior = Oblique line of thyroid cartilage Innervation C1 via hypoglossal nerve Actions Depress hyoid bone / elevate thyroid cartilage (larynx)

Sternothyroid Muscle

Attachements Superior = Oblique line of thyroid cartilage Inferior = Manubrium of sternum Innervation Ansa Cervicalis (C1-C3) Actions Depress thyroid cartilage and larynx

Middle Scalene Muscle

Attachements Superior = Transverse process of C1 to C6 Inferior = External surface of 1st rib, posterior to groove for subclavian artery Innervation Ventral rami of C3-C8 Actions Flex neck laterally, elevate 1st rib during inspiration

Levator Scapulae Muscle

Attachements Superior = Transverse process of C1-C4 Inferior = Superior boded of scapula Innervation Dorsal scapular nerve (C4, C5) and C3, C4 Actions Elevate scapula, inferior rotation of scapula

Anterior Scalene Muscle

Attachements Superior = Transverse process of C3/C4 to C6 Inferior = Scalene tubercle of 1st rib Innervation Ventral rami of C4-C6 Actions Flex neck laterally, elevate 1st rib during inspiration

Posterior Scalene Muscle

Attachements Superior = Transverse process of C4 to C6 Inferior = External surface of 2nd rib Innervation Ventral rami of C6-C8 Actions Flex neck laterally, elevate 2nd rib during inspiration

Platysma muscle

Attachements Superior = inferior border of mandible and fascia Inferior = fascia over superior part of pec major and deltoid muscles Innervation Cervical branch of Facial Nerve (CN VII) Actions Tighten skin on neck; grimace

Rectus Capitus Posterior Major Muscle

Attachements Superior = inferior nuchal line Inferior = spinous process C2 Innervation Suboccipital Nerve - C1 Actions Unilateral = rotate head to same side Bilateral = extend head

Superior Oblique Muscle

Attachements Superior = lateral occipital bone btw superior and inferior nuchal lines Inferior = transverse process of C1 Innervation Suboccipital Nerve - C1 Actions Unilateral = laterally bend the head Bilateral = extend the head

Sternocleidomastoid Muscle (SCM)

Attachements Superior = mastoid process, lateral 1/2 superior nuchal line Inferior = Manubrium of sternum and medial 1/3rd clavicle Innervation Accessory Nerve (CN XI), branches of C2, C3 Actions Unilateral = Turn head to opposite side, laterally flex head to same side Bilateral = extend head, flex cervical vertebrae, accessory muscle of respiration

Rectus Capitus Posterior Minor Muscle

Attachements Superior = medial aspect of inferior nuchal line Inferior = posterior tubercle of C1 Innervation Suboccipital Nerve - C1 Actions Extend head

Suboccipital Triangle - Borders and Contents

Borders: Roof = Semispinalis capitis muscle Medial border = Rectus capitis posterior major muscle Lateral border = Superior oblique muscle Inferior border = Inferior oblique muscle Floor = Posterior arch of C1 Contents: Suboccipital nerve (C1) Vertebral artery

Occipital Artery

Branch of external carotid artery One branch = to SCM One branch = descending that anastomoses with other arteries, continues to supply the scalp on the back o the head

Phrenic Nerve

C3-C5 Motor innervation to diaphragm Sensory innervation to pericardium, medicinal pleura, diaphragmatic peritoneum On anterior surface of Anterior Scalene

Brachial Plexus

C5-C8, T1 Innervate upper limb Pass between Anterior Scalene and Middle Scalene WITH Subclavian Artery!

Accessory Nerve (CN XI)

Cranial root Motor axons from medulla oblongata Do NOT exit skull - join adjacent vagus nerve Spinal root Axons from C1-C5 Exit skull via jugular foramen Innervate SCM and Trapezius muscles

By puncturing what structure, can you access the airway?

Cricothyroid membrane / ligament (Blue in pic) Stretches between thyroid cartilage and cricoid cartilage

Subclavian vein

Drains mainly veins of upper limb and EJV Medially joins the IJV to form the brachiocephalic vein

Suprascapular vein

Drains muscles around the scapula

Supraclavicular Nerve (C3, C4)

Emerge together from posterior border of SCM, then divide into medial, intermediate, lateral branches Supplies skin along clavicle and over shoulder

External Jugular Vein

Formed by union of Posterior Auricular Vein and Retromandibular Vein Drains smaller vessels of scalp and face into Subclavian Vein

Characteristics of Axis (C2)

Has body with dens, bifid spinous process Dens articulates with C1 to form synovial pivot joint Superior articular facets lie anteromedial to transverse processes and articulate with C1 inferior articular facets via gliding synovial joints

Venous air embolism

If EJV is cut close to where it pierces the roof of the posterior triangle, its lumen will be held open by the investing layer of facia Negative pressure in the thoracic cavity will suck air into the vein, which causes a venous air embolism Then, air is drawn into the right side of the heart, creating a bubbly foam that hinders blood flow Patient presents with churning noise in thorax, cyanosis (blue discoloration), dyspnea (shortness of breath). If pressure is applied to severed EJV, air can not enter heart and symptoms can be prevented until vein is sutured.

Characteristics of typical cervical vertebrae - C3-C7

Large triangular vertebral foramen Transverse processes have foramen (transverse foramen) = for vertebral artery and vein Short bifid spinous processes (EXCEPT C7 = vertebra prominens = very long)

Thyroid Cartilage

Largest, most superior cartilage in neck Formed by 2 plates that fuse in midline to create "laryngeal prominence" Open posteriorly (NOT ring) Superior = thyrohyoid membrane Inferior = Cricothyroid joint

Alar fascia

Layer that lies between the pretracheal and prevertebral layers Subdivides the retropharyngeal space Attaches to the carotid sheaths on each side

Greater Occipital Nerve (C2)

Loops around inferior border of inferior oblique muscles and runs posterior to suboccipital triangle Pierces semispinalis wapitis and trapezius muscles Innervates posterior aspect of scalp

What does the muscular portion of the pretracheal layer of the deep cervical fascia contain? What about the visceral portion?

Muscular portion = infra hyoid muscles Visceral portion = thyroid gland, trachea, esophagus **Posteriorly is continuous with the buccopharyngeal fascia of pharynx

Carotid tubercle

On C6 The large anterior tubercle of transverse process The common carotid artery can be compressed against it and the vertebral body to control bleeding

Vertebral Artery

Passes transversely between C1 and occipital bone in deep part of suboccipital triangle to enter foramen magnum Branch of subclavian artery Ascends from the root of the neck to the foramen magnum via the transverse foramina of cervical vertebrae (except C7) Main source of blood for brain

What is the consequence of the supraclavicular nerves and the phrenic nerves having a common segmental origin at C3 and C4?

Referred pain to the shoulder from pleuritis/ abdominal inflammations that irritate branches of the phrenic nerve occurs via the supraclavicular nerves

Cricoid Cartilage

Ring with a broad posterior lamina and narrow band anteriorly Complete ring of cartilage, very strong Attached to thyroid (superior) via median cricothyroid membrane/ligament Inferior = cricotracheal ligament that attaches cricoid cartilage to 1st tracheal ring

Characteristics of Atlas (C1)

Ring-like bone, NO spinous processes or vertebral body Posterior arch has groove for vertebral artery on superior surface Horizontal superior articular facets articulate with occipital condyles of skull C1 articulates with C2 via dens and 2 lateral inferior articular facets

Transverse Cervical Nerve (C2, C3)

Runs transversely across the SCM toward midline of neck Provides cutaneous innervation to skin of anterior triangle of neck

What are the contents of the DEEP posterior triangle of the neck?

Same borders as the superficial posterior triangle Contents: 1. Splenius capitis 2. Levator scapulae 3. Scalenes (anterior, middle, posterior) 4. Brachial plexus 5. Phrenic nerve 6. Thryrocervical trunk = suprascapular artery, transverse cervical artery, inferior thyroid artery) 7. Subclavian vein 8. Suprascapular vein

Superficial vs. Deep Cervical Fascia

Superficial Cervical Fascia Loose fatty later between dermis of skin and investing layer of deep cervical fascia Contains cutaneous nerves, blood vessels, lymphatics, platysma muscle Deep Cervical Fascia 3 layers = investing, pretracheal, prevertebral Membranous fascia that forms compartments and separate muscle layers and neurovascular structures

What are the boundaries for the anterior triangle of the neck?

Superior/Base: Inferior border of Mandible Posterior: Anterior border of SCM Anterior: Midline of Neck Apex: Jugular notch of Manubrium Roof: Infesting layer of deep cervical fascia, covered by platysma muscle and superficial cervical fascia Floor: Pharynx, Larynx, Thyroid gland

What will happen if one Accessory Nerve is damaged?

The head at rest will be turned toward the damaged side

Hyoid Bone

U-shaped bone at level of C3 vertebra No bony articulations - very mobile Consists of body, greater and lesser horns (cornua)

What does the prevertebral layer of the deep cervical fascia contain?

Vertebral column and associated muscles = longs colli, longs wapitis, splenius, longissmus, semispinalis, scalene muscles Inferiorly will blend with anterior longitudinal and supraspinous ligaments

Under what conditions can the EJV become dilated and prominent on the neck?

When venous pressure is chronically elevated, during congestive heart failure