Download NECK AND MEDIASTINUM

Neck and Mediastinum
OBJECTIVES:
- Identify the triangles of the neck and the location
of lymph nodes within the neck.
- Identify the following structures within the neck:
carotid artery, jugular vein, larynx, strap muscles,
thyroid, sternocleidomastoid muscle, clavicle,
sternal notch, esophagus, recurrent laryngeal
nerve, vagus nerve and phrenic nerve.
- Describe the limitations of the mediastinum.
- List the organs found in the mediastinum.
Christopher Ramnanan, Ph.D.
[email protected]
Skeleton of neck
Styloid and
Mastoid
processes
of the skull*
Mandible
Hyoid Bone
Manubrium
Clavicle
7 Cervical
Vertebra
C-spine architecture (thin
body, thick IV discs, etc.)
designed for mobility and
flexibility
FYI: In this patient’s case, they used
bone from hip, titanium pins, and
wires to reattach head to neck
-Initially: lost all motor and sensory
capability below the shoulders;
required ventilator
Proc Natl Acad Sci U S A. 2002 Dec
24;99(26):17066-71.
-5 Years after Accident: regained
some sensation, limited motor ability,
and limited ability to breath on his
own
Skeleton of neck: Landmarks
C1 lines up with palate;
C1/C2 can be assessed
‘open-mouth’ view
Epiglottis
Hyoid Bone
Thyrohyoid
membrane
C3
C4/C5
C6
Thyroid Cartilage (
Cricothyroid
membrane
Cricoid Cartilage
Trachea
Neck Musculature
Notes
Because the C-spine is built for mobility, we require extensive musculature
that both facilitates motion and increases stability. Cervical region also
features extensive ligamentous support.
Some of these features have been covered previously (scalenes, longus
colli, longus capitis, ligaments), not amongst today’s objectives
Today’s objectives: Sternocleidomastoid (SCM), strap muscles
(infrahyoid muscles)
Neck Muscles: The SCM
Notes
-Innervated by CN XI
-Serves as important boundary dividing posterior vs. anterior cervical
triangle
-Aids in ID of cervical plexus cut. nerves (FYI), internal jugular vein, and
external jugular vein
Neck Muscles: The Strap Muscles
Infrahyoid muscles
Serve to steady or
depress the hyoid bone,
larynx
Generally: innervated
by ansa cervicalis (C1C3)*
Omohyoid
Ant. and Post.
Digastric M.
Thyrohyoid*
Sternothyroid
Sternohyoid
Note
-These muscles faciliate dynamic movements in speaking, swallowing
-Appreciate relationship to larynx, trachea, and thyroid gland
Note the digastric muscle (suprahyoid group; used as landmark for
anterior neck triangles)
Thyroid Gland
Typically 2 lobes connected by isthmus;
variable pyramidal lobe; gland is proximal to
nerves of the larynx that are at risk during
thyroidectomy
Typically two bilateral arteries:
-Superior thyroid a from ECA
-Inferior thyroid a from thyrocervical trunk
Variable, uncommon midline supply:
Thyroid ima a can supply gland from inferior
aspect
Three bilateral veins:
Superior thyroid v from IJV
Middle thyroid v from IJV
Inferior thyroid v from brachiocephalic v
Nerves of the Cervical Region (Lateral View)
Spinal Accessory N. (CN XI) Dives
into deep surface of Trapezius, also
innervates SCM
Vagus N. (CN X):
Runs with IJV and
CCA in Carotid
Sheath
Phrenic N. (C3-C5):
Descends on surface of
Anterior Scalene
Ansa Cervicalis (C1-C3):
Loop of Nerve that supplies
Strap Muscles; Embedded
on Surface of Carotid Sheath
Roots of Brachial
Plexus (C5-T1):
Emerge b/w anterior
and middle scalene
Nerves of the Cervical Region (Anterior View)
Cutaneous Nerves of the Cervical Plexus (ex. Transverse Cervical N,
Supraclavicular N; names are FYI): emerge superficially posterior to the SCM
Left and Right Recurrent Laryngeal N. (branches of CN X): recur in proximity to
trachea and thyroid gland; note asymmetry
Sympathetic Trunk (“Beads on String”): deep, paravertebral location
Common Carotid Artery
Bifurcation ~C4 Level into
Internal (Brain) and External
(Neck, Scalp, Face) Carotid
Arteries
Carotid sinus detects pressure
Carotid body detects blood
oxygenation (O2, C02, pH)
Of the 8 ECA branches, note today:
-Superior thyroid a.
-Facial a.
-Superficial temporal a.
Veins of the Head and Neck
Internal Jugular Vein (IJV)
-Principle vein of the brain, face,
neck, and scalp
-Runs in carotid sheath (w/CN X
and common carotid a.)
External Jugular Vein
-Assists IJV in draining face,
neck, and scalp
-Superficial to SCM muscle
Anterior Jugular Vein
-Variably present; aids in drainage
of thyroid gland
Cervical Lymphatic Drainage
Generally: Superficial (drains skin) and deep (viscera) lymphatic drainage follows
superficial and deep venous drainage; many different classification patterns for
deep venous drainage
Ex. American Academy of Otolaryngology–Head and Neck Surgery
Arch Otolaryngol Head Neck Surg. 2002;128(7):751-758
FYI: http://emedicine.medscape.com/article/849834-overview#a4
(Level I)
Submandibular
Submental
Oral Cavity,
Tongue, Lip
Cancer
(Level VI)
Anterior Triangle
Group
Thyroid, Laryngeal
Cancer
(Level V) Posterior Triangle
(Level II) Upper Jugular
(Level III) Middle Jugular
(Level IV) Lower Jugular
Levels II-V: Cancer of deep
structures (Oral Cavity, Nasal
Cavity, Pharynx)
Common Examples of Drainage Patterns
Anterior Triangle
Boundaries:
Mandible
SCM
Median line of neck
The Anterior Triangle is
subdivided by omohyoid
and digastric muscles:
Posterior Triangle
Boundaries:
SCM
Trapezius
Clavicle
Carotid ∆
Posterior digastric
SCM
Superior omohyoid
Submandibular ∆
Mandible
Anterior digastric
Posterior digastric
Submental ∆
(unpaired ∆)
Bilateral anterior
digastrics
Hyoid bone
Muscular ∆
Superior omohyoid
SCM
Median line
Posterior ∆
Key structures:
CN XI
External Jugular Vein
Roots of the brachial plexus (not
shown here)
Cutaneous nerves of the cervical
plexus (names are FYI):
Lesser Occipital n.
Great auricular n.
Transverse Cervical n.
Supraclavicular n.
Motor nerves of the cervical
plexus (not shown here):
Ansa Cervicalis
Phrenic Nerve
Let’s go to school and party
Posterior ∆
Key structures:
EJV (not shown here)
1)CN XI
2) Roots of brachial plexus
FYI: Cut. Nerves of the
cervical plexus
3) Lesser Occipital n.
4) Great auricular n.
(Transverse cervical and
supraclavicular not
shown here)
3
4
5
1
6
5) Ansa Cervicalis
6) Phrenic Nerve
2
Carotid ∆
Key structures
-Common carotid artery
and its bifurcation;
several branches of the
External Carotid A.
-IJV
-Vagus nerve
-Ansa cervicalis
Submandibular ∆
“Digastric ∆”
Key structures
-Submandibular gland
-CN XII Hypoglossal
Nerve (Motor to tongue
muscles)
-Facial artery/vein
Submental ∆
Muscular ∆
Key structures
Key structures
Superficial:
Infrahyoid or
“Strap” muscles
Deep:
Thryoid gland, Larynx
Submental lymph nodes
Mylohyoid (note median
raphe)
The Mediastinum
Mediastinum: ‘standing in the middle’, central compartment of thoracic cavity
Sup. Boundary:
Superior Thoracic Aperture
(1st rib, T1 body, manubrium)
Sternal
Angle
Transverse
thoracic plane
T4/T5
IV Disc
Inferior Boundary:
Diaphragm
Superior Mediastinum: Many structures (see later slide)
Anterior Mediastinum: Thymus (prominent in children), some lymph nodes
Middle Mediastinum: Heart, phrenic nerves, pericardiacophrenic a/v
Posterior Mediastinum: Many structures (see later slides)
Thoracic Outlet Syndrome in the News,
affecting Fantasy Hockey Lineups Everywhere!
L and R
Brachiocephalic V.
Superior Mediastinum
Left Recurrent
Laryngeal N
Vagus N
Phrenic N
SVC
(Upper
Part)
Aortic Arch
and its
branches:
‘B’ ‘C’
‘S’ Sympathetic
Trunk
Esophagus
Trachea
Thoracic
Duct (not
shown)
Posterior Mediastinum: Arteries and Veins
Thoracic Aorta:
Intercostal a, bronchial
a., esophageal a.
Azygos Venous
System:
Azygos V and Arch of
the Azygos on R,
Hemi-and Accessory
Azygos on L
Intercostal v.,
Bronchial v.,
Esophageal v.
Note: Esophagus
courses from the
superior mediastinum
to the posterior
mediastinum
Posterior Mediastinum: Nerves and Lymphatics
Vagus Nerves (PS to
organ nervous
plexuses)
Sympathetic Trunk
(Sympathetic supply for
whole body; feeds
organ nervous plexuses
via splanchnic nerves)
Intercostal Nerves
(somatic motor and
sensory)
Thoracic Duct lymph
from lower body, back
body wall, abdominal
viscera  drains to left
venous angle in
superior mediastinum
The Mediastinum, Lateral Views (Lungs Removed)
ID:
-Trachea
-Esophagus
-BCS br. of aorta
-Phrenic Nerve
-Vagus Nerve
-Arch of the
Azygos Vein
-Sympathetic
Trunk
-Greater
Splanchnic Nerve
Note: Relationship of Vagus and Phrenic
Nerves to Root of the Lungs
Left Lateral
Right Lateral
Subcut. cervical
fascia
Investing layer
(SCM/Traps)
Fascial layers of neck (FYI
today; revisit in Unit II)
Buccopharyngeal
fascia
Pretracheal
Layer
(Muscular)
(Visceral)
Prevertebral
Layer
(C-spine
muscles)
Carotid
Sheath
(CCA, IJV,
Vagus)
The deep cervical fascia forms cleavage planes that
1) limits spread of infection
2) Invests/support structures (can be manipulated); and
3) Conveys the ability for structures to slide/glide across one another
LAB CHECKLIST – NECK AND MEDIASTINUM
NB: Items italicized are conceptual, those denoted with a * are FYI
BONES
-
Styloid process*
Mastoid process*
Mandible
Hyoid bone
Manubrium
Sternal angle (of Louis)
Clavicle
Cervical vertebra
1st rib
T1 body
-
NECK STRUCTURES
Epiglottis
Thyrohyoid membrane
Thyroid cartilage
Cricothyroid membrane
Cricoid cartilage
Trachea
Carotid triangle
Submandibular triangle
Submental triangle
Muscular triangle
Posterior triangle
Thyroid gland
Larynx
Fascial layers of neck*
-
-
-
ARTERIAL SUPPLY
Superior thyroid a.
Inferior thyroid a.
Thyroid ima
Arch of aorta and its derivatives
Thoracic aorta
- Intercostal a.
- Bronchial a.
- Esophageal a.
Common carotid artery
Internal carotid a.
External carotid a.
- Superficial temporal a.
- Facial a.
- Superior thyroid a.
VENOUS DRAINAGE
External jugular v.
Internal jugular v.
Anterior jugular v.
Superior thyroid v.
Middle thyroid v.
Inferior thyroid v.
Facial vein
Left and right branchiocephalic vein
Superior vena cava
Azygos v.
Arch of the Azygos
Bronchial v.
Esophageal v.
INNERVATION
- Cervical plexus cutaneous nerves*
- Transverse cervical n.*
- Supraclavicular n.*
- Lesser occipital n.*
- Great auricular n.*
- Ansa cervicalis (C1-C3)
- Vagus n. (CN X)
- Phrenic n.
- Roots of brachial plexus (C5-T1)
- Spinal accessory n. (CN XI)
- Hypoglossal n. (CN XII)
- Left and Right recurrent laryngeal n.
- Sympathetic trunk
- Intercostal n.
- Greater splanchnic n.
MUSCLES
- Sternocleidomastoid (SCM)
- Infrahyoid muscles
- Omohyoid
- Sternohyoid
- Thyrohyoid
- Sternothyroid
- Anterior and posterior digastric muscles
- Mylohyoid
LYMPHATICS
- General drainage (superficial vs. deep) of cervical
structures