ANAT 5010 - unit 9

superior: lower border of the mandible

inferior: anterior - jugular/suprasternal notch, sternoclavicular joint, clavicle, and acromion process; posterior - CV7

sagittal plane divides the left and right sides

what are the boundaries of the neck?

sternocleidomastoid

what divides the neck into anterior and posterior triangles?

anterior: superior border of manubrium

lateral: rib1

posterior: body of TV1

what makes the border of the root of the neck?

- subclavian vessels and immediate branches/tributaries, common carotid artery, and internal jugular vein

- phrenic, vagus and recurrent laryngeal nerves, the sympathetic chain

- trachea, esophagus, thyroid and para-thyroid glands, thoracic duct, and right lymphatic duct

- apex of the lungs

what are the contents in the root of the neck?

- anterior: posterior border of the SCM

- posterior: anterior border of the trapezius

- inferior: clavicle

what makes up the border of the posterior triangle of the neck?

omohyoid

what divides the posterior triangle into sub-triangles?

investing layer of deep cervical fascia (attaches to borders of trapezius and SCM, superior nuchal line, and clavicle)

what makes up the roof of the posterior triangle?

prevertebral layer of deep cervical fascia

the carper on a floor of muscles that include the splenius capitis and cervicis, levator scapulae, posterior scalene, middle scalene, anterior scalene; continues to axilla as axillary sheath

superficial cervical fascia

encircles the neck; contains fat, cutaneous nerves, and the platysma

investing layer of deep cervical fascia

surrounds the trapezius and sternocleidomastoid muscles; forms the roof of both anterior and posterior triangles

visceral DCF (pretracheal)

surrounds viscera of the neck: pharynx and esophagus, larynx and trachea, and thyroid and parathyroid glands

middle/muscular DCF (pretracheal)

surrounds and contains the infrahyoid strap muscles in the anterior neck

carotid sheath

surrounds and contains the carotid vessels, internal jugular vein, vagus nerve, and deep cervical lymph nodes; ansa cervicalis on anterolateral aspect of carotid sheath

superior mediastinum

pretracheal layers of DCF continue inferiorly to reach the - in the thorax

origin: manubrium and sternal end of the clavicle

insertion: mastoid process

what is the origin and insertion of the sternocleidomastoid?

action: rotates head to the opposite side unilaterally, flexes the neck bilaterally, accessory muscle of respiration

innervation: spinal accessory nerve (motor) and C2 and C3 VPR (sensory)

what is the action and innervation of the sternocleidomastoid?

platysma muscle

found in the superficial fascia of the anterolateral neck; runs superficial to the EJV and visible cutaneous nerves; spans fascia over clavicle to inferior mandible

action: tense neck skin and depress angle of the mouth

innervation: cervical branch of facial nerve (CN V||)

what is the action and innervation of the platysma?

origin: upper border of scapula just medial to the scapular notch

insertion: hyoid bone

what is the origin and insertion of the omohyoid muscle?

inferior belly: in the posterior triangle; separates the occipital and omoclavicular/subclavian sub-triangles

superior belly: in the anterior triangle

where are the two bellies of the omohyoid located?

ansa cervicalis (C1-3 VPR)

what is the innervation of the omohyoid muscle?

anterior scalene

what is the key landmark in the posterior triangle?

origin: transverse process of CV3-6

insertion: scalene tubercle of rib 1

what is the origin and insertion of the anterior scalene?

action: flex neck and assist forced inhalation bilaterally; lateral flexion unilaterally

innervation: cervical VPRs

what is the action and innervation of the anterior scalene?

- prevertebral fascia

- subclavian vein

- phrenic nerve

- ascending cervical artery

- transverse cervical artery

- suprascapular artery

- omohyoid muscle

what is superficial and anterior to the anterior scalene muscle?

- subclavian artery

- roots of VPR forming the brachial plexus

what is between the anterior and middle scalene muscles?

origin: transverse processes of CV2-7

insertion: rib 1 posterior to the groove for the subclavian artery

what is the origin and insertion of the middle scalene?

action: flex neck and assist forced inhalation bilaterally; lateral flexion unilaterally

innervation: C3-C7 VPR

what is the action and innervation of the middle scalene?

origin: transverse processes of CV4-6

insertion: second rib

what is the origin and insertion of the posterior scalene?

action: flex neck and assist forced inhalation bilaterally; lateral flexion unilaterally

innervation: C5-C7 VPR branches

what is the action and innervation of the posterior scalene?

- 1st rib

- anterior scalene

- middle scalene

what are the borders of the interscalene triangle?

roots of the brachial plexus and the 3rd part of the subclavian artery

what is in the interscalene triangle?

Erb's point

nerve point on the neck

lesser occipital nerve (C2)

follows posterior border of SCM to reach the mastoid process and behind the eat

great auricular nerve (C2-3)

large; courses vertically on SCM towards the angle of the mandible and parotid region

transverse cervical nerve (C2-3)

crosses SCM horizontally towards the anterior triangle of the neck

suprascapular nerves (C3-4)

crosses the clavicle towards the inferior posterior triangle and upper chest and thorax

dorsal scapular nerve and long thoracic nerve

pierces the lateral side of the middle scalene

inside the carotid sheath, anterior to subclavian artery, and medial to phrenic enrve

where is the vagus nerve located as it passes from the neck to the thorax?

right: right recurrent laryngeal nerve at the right subclavian artery

left: left recurrent laryngeal nerve at the arch of the aorta

what do the right and left vagus nerves give off?

descends on the anterior surface of the anterior scalene (lateral to the ascending cervical artery), enters superior thoracic aperture, courses along pericardium to the diaphragm

what path does the phrenic nerve take as it passes from the neck to the thorax?

- motor innervation to the diaphragm (severance paralyzes the ipsilateral hemidiaphragm)

- sensory innervation from the parietal peritoneum in the right upper quadrant of the abdomen (irritation causes referred pain to the shoulder)

what is the function of the phrenic nerve?

- passes between the anterior and middle scalenes

- ends at the lateral border of the first rib (where it changes to axillary artery)

where are the subclavian arteries located?

anterior scalene

what divides the subclavian artery into three parts?

- vertebral artery: enters the transverse foramen of CV6; ascends to supply the brain and brainstem

- internal thoracic artery: descends posterior to the sternal end of the clavicle into the thorax

- thyrocervical trunk: extends superiorly from the subclavian; splits into the inferior thyroid artery, transverse cervical artery, and suprascapular artery

what branches off the first part of the subclavian artery?

costocervical trunk (from posterior aspect of the vessel; deep to the anterior scalene)

- branches into the deep cervical artery (supplies deep muscles on back of neck) and the highest intercostal artery (supplies the first two intercostal spaces)

what branches off the second part of the subclavian artery?

dorsal scapular artery (weaves between the superior and middle trunks of the brachial plexus)

what branches off the third part of the subclavian artery?

external jugular vein

formed by union of the retromandibular and posterior auricular veins; runs vertically superficial to the SCM; drains into the subclavian vein

internal jugular vein

begins at jugular foramen on skull; runs laterally within the carotid sheath; ends by joining the subclavian vein to form the brachiocephalic vein

subclavian vein

begins at lateral border of first rib; passes anterior to the anterior scalene muscle; joins the internal jugular vein to from the brachiocephalic vein

internal jugular vein and subclavian veins

what makes the venous angle?

right lymphatic duct

drains the R upper limb and shoulder, R upper thorax, and R head/neck

thoracic duct

drains everything that the right lymphatic duct doesn't

trachea

first tracheal cartilage at ~CV7 level; 6-8 tracheal rings palpable in the neck; isthmus of thyroid gland covers rings 2-3

esophagus

begins at the pharyngoesophageal junction at CV6; passes posterior to the trachea

cervical pleura and lung apex

apex of lungs and cervical pleura extend above rib 1 into the posterior triangle; at risk during central line placement or supraclavicular surgery