Transcript The Head & Neck

The Neck
Head & Neck Unit – Lecture 11
‫ حيدر جليل األعسم‬.‫د‬
The Neck
It is the region of the body that lies between lower borders of the mandible
(superiorly) and suprasternal notch and upper border of clavicle (inferiorly).
Posteriorly, the neck extends from the superior nuchal line to intervertebral
disc between C7 & T1 vertebrae.
Compartments of the Neck:
1.Visceral compartment: is anterior and
contains parts of digestive system (pharynx &
esophagus) and respiratory systems (larynx
& trachea), and several endocrine glands;
2.Vertebral compartment: is posterior and
contains cervical vertebrae covered
posteriorly by a large mass of extensor
muscles and anteriorly a smaller group of
flexor muscles.
3.Two Vascular compartments which are
lateral and contain the vertically running
carotid arteries, internal jugular veins, vagus
nerve, and deep cervical lymph nodes.
Sternocleidomastoid Muscle
It is the Key Muscle of the Neck It divides the neck into anterior and posterior
triangles. Its anterior border covers carotid arteries, internal jugular vein, and
deep cervical lymph nodes; it also overlaps thyroid gland. It is covered
superficially by skin, fascia, platysma muscle and external jugular vein. Deep
surface of posterior border is related to cervical plexus of nerves, phrenic
nerve, and upper part of brachial plexus.
Origin: Manubrium sterni (sternal head)
and medial third of clavicle (clavicular head)
Insertion: Mastoid process of temporal
bone and occipital bone
Action: Two muscles acting together flex
neck draw head forward; one muscle
rotates face to opposite side.
Nerve Supply: Spinal part of accessory
nerve and anterior rami of C2 & C3.
Neck Superficial structures
1. Skin of the Neck: Natural cleavage lines are horizontal around the neck
2. Superficial Cervical Fascia: thin layer enclosing other structures of the neck
platysma muscle, cutaneous nerves, superficial veins & superficial lymph nodes
3. Platysma is a thin muscular sheet embedded in superficial fascia.
4. Deep Cervical Fascia: It is deep to
superficial layer and is condensed in certain
areas to form well-defined fibrous sheets.
5. Cutaneous Nerves of the neck:
Posterior rami of cervical nerves C2 to C5.
Anterior rami of cervical nerves C2 to C4.
6. Superficial Veins of the neck:
A. External Jugular Vein
B. Anterior Jugular Veins
7. Superficial Lymph Nodes: lie along
external jugular vein superficial to
sternocleidomastoid muscle.
Cutaneous Nerves of the neck
Posterior rami of cervical: C2 to C5
supply skin overlying back of the neck and
back of the scalp as high as the vertex.
Greater occipital nerve:
is a branch of the posterior ramus of
the 2nd cervical nerve.
Anterior rami of cervical:
Nerves C2 to C4: supply front & sides of
neck & form cervical plexus from which
different branches emerges around the
posterior border of sternocleidomastoid:
1. Lesser occipital nerve (C2)
2. Great auricular nerve (C2 & C3)
3. Transverse cutaneous nerve (C2 & C3)
4. Supraclavicular nerves (C3 & C4)
Superficial Veins of the neck
External Jugular Vein
It begins behind angle of mandible by union
of posterior auricular vein & posterior
division of Retromandibular vein.
It descends obliquely across
sternocleidomastoid and just above clavicle,
pierces deep fascia and drains into
Subclavian vein.
Anterior Jugular Veins:
begin just below chin (by union of several
small veins) and runs downword close to
the midline. The two sides united by a
transverse trunk (jugular arch) just above
suprasternal notch. The vein then turns
sharply laterally and passes deep to
sternocleidomastoid muscle to drain into
external jugular vein.
Muscular Triangles of the Neck
Sternocleidomastoid divides the neck into:
Anterior Triangle:
bounded above by body of mandible,
posteriorly by anterior border of
sternocleidomastoid, and anteriorly by
midline. The Superficial neck muscles in
anterior triangle of neck are divided into
suprahyoid & infrahyoid muscles. Anterior
triangle is further subdivided by superficial
muscles into carotid, submandibular,
submental & muscular triangle.
Posterior Triangle: is bounded posteriorly
by trapezius muscle, anteriorly by
posterior border of sternocleidomastoid &
inferiorly by middle 1/3 of clavicle.
Posterior triangle is further subdivided by
inferior belly of omohyoid into a large
occipital triangle above & a small
supraclavicular triangle below.
Suprahyoid Muscles
They are 4 suprahyoid muscles in submental and
submandibular triangles. They pass from hyoid bone
to skull or mandible and raise the hyoid.
1. Stylohyoid: arises from base of styloid process and
passes anteroinferiorly to attach to lateral area of the
body of hyoid bone. During swallowing it pulls hyoid
bone posterosuperiorly and is innervated by facial n.
2. Digastric: has two bellies connected by a tendon,
which attaches to the body of hyoid bone:
Posterior belly arises from mastoid notch on medial
side of mastoid process of temporal bone;
Anterior belly arises from digastric fossa on lower
inside of mandible.
Action: When mandible is fixed, it raises hyoid bone;
and when hyoid bone is fixed, it lowers the mandible.
Innervation: posterior belly by the facial nerve,
whereas anterior belly is by trigeminal nerve.
3. Mylohyoid: Floor of the mouth
4. Geniohyoid: Floor of the mouth
Infrahyoid Muscles
They are 4 infrahyoid muscles in the muscular triangles. Because of their
appearance, they are sometimes referred to as the 'strap muscles'.
1. Sternohyoid: is a long, thin muscle originating from
posterior aspect of sternoclavicular joint and adjacent
manubrium and inserted onto body of hyoid bone. It
depresses the hyoid & innervated by ansa cervicalis.
3. Omohyoid: is lateral to sternohyoid muscle and
consists of two bellies with an intermediate tendon
that is attached to clavicle by fascial sling. It depresses
and fixes hyoid bone. It is innervated by the ansa
cervicalis.
Inferior belly: begins on superior border of scapula,
medial to suprascapular notch, and passes forward
and upward across the posterior triangle ending at
the intermediate tendon;
Superior belly: begins at intermediate tendon &
attached to body of hyoid.
Infrahyoid Muscles
They are 4 infrahyoid muscles in the muscular triangles. Because of their
appearance, they are sometimes referred to as the 'strap muscles'.
3. Thyrohyoid:
It is deep to superior parts of omohyoid and
sternohyoid. Originating at oblique line on lamina
of thyroid cartilage it passes upwards to insert into
greater horn and adjacent aspect of body of hyoid.
It depresses hyoid, but when hyoid is fixed it raises
the larynx. It is innervated by C1 fibers through
hypoglossal nerve.
4. Sternothyroid:
It lies beneath sternohyoid, and in continuity with
thyrohyoid. It arises from posterior surface of the
manubrium of sternum and passes upwards to
attach to oblique line on lamina of thyroid
cartilage. Sternohyoid muscle draws the larynx
(thyroid cartilage) downward and is innervated by
ansa cervicalis.
Subdivisions of Anterior Triangle
Subdivision
Submental
triangle
(unpaired)
Submandibul
ar triangle
(paired)
Carotid
triangle
(paired)
Muscular
triangle
(paired)
Boundaries
Anterior belly of digastric
laterally; body of hyoid bone
inferiorly & midline.
Lower border of mandible
superiorly; anterior and
posterior bellies of digastric
inferiorly
Posterior belly of digastric
superiorly; superior belly of
omohyoid anteroiferiorly;
anterior border of sternocleidomastoid posteriorly
Hyoid superiorly, midline of
neck medially; superior belly
of omohyoid & anterior
border of sternocleidomastoid
laterally
Contents
Submental lymph nodes; tributaries forming
anterior jugular vein
Submandibular gland; submandibular lymph
nodes; hypoglossal nerve; mylohyoid nerve;
facial artery and vein
Common facial vein; cervical branch of facial
nerve; common carotid artery; external &
internal carotid arteries; superior thyroid;
ascending pharyngeal; lingual, facial & occipital
arteries; internal jugular vein; vagus , accessory
& hypoglossal nerves; superior & inferior roots
of ansa cervicalis; transverse cervical nerve
Sternohyoid, omohyoid, sternohyoid, and
thyrohyoid muscles; thyroid and parathyroid
glands; pharynx
Carotid System
Common carotid arteries:
Right common carotid: from brachiocephalic trunk
- right sternoclavicular joint. (neck only?)
Left common carotid: direct branch of aortic arch left sternoclavicular joint. (thorax & neck)
Both arteries ascend through neck lateral to
Trachea & esophagus and behind anterior border
of sternocleidomastoid (within a fascial
compartment (Carotid Sheath). its course is closely
related to internal jugular vein & vagus nerve. Near
superior edge of thyroid cartilage, it divides into
external & internal carotid arteries.
Relations of the Common Carotid Artery
Anterolaterally: Skin, Fascia, Sternocleidomastoid, Sternohyoid,
Sternothyroid & Superior Belly of Omohyoid.
Posteriorly: Transverse processes of lower four cervical vertebrae,
Prevertebral muscles & sympathetic trunk.
Medially: Larynx, Pharynx and below trachea & esophagus. The lobe of the
thyroid gland also lies medially.
Laterally: Internal jugular vein & posterolaterally the vagus nerve.
Carotid System
Carotid Sinus:
It is dilation at bifurcation of common
carotid artery and beginning of internal
carotid artery. It contains receptors that
monitor changes in blood pressure (paroreceptor) and are innervated by a branch of
the glossopharyngeal nerve. A rise in blood
pressure causes slowing of heart rate and
vasodilatation of arterioles.
Carotid Body:
It is a small structure that contains
accumulation of chemical receptors and
lies posterior to bifurcation of common
carotid artery. It is sensitive to high CO2 &
low O2 contents in blood. It causes a rise in
blood pressure & heart rate & an increase
in respiratory movements.
Internal
Carotid
Arteries
It is a terminal branch of common carotid artery
& supplies brain, eye, forehead &part of nose.
It ascends in neck within carotid sheath (with
internal jugular vein & vagus nerve). It passes
deep to parotid salivary gland. Internal carotid
artery gives off no branches in the neck.
Relations of Internal Carotid Artery in Neck:
Anterolaterally: Below digastric: skin, fascia,
anterior border of sternocleidomastoid and
hypoglossal nerve. Above digastric: stylohyoid,
stylopharyngeus, glossopharyngeal nerve,
pharyngeal branch of vagus nerve, parotid gland
and external carotid artery.
Posteriorly: Sympathetic trunk, Longus Capitis &
Transverse processes of upper 3 cervical
vertebrae.
Medially: Pharyngeal wall & Superior laryngeal
nerve.
Laterally: Internal jugular vein & Vagus nerve.
External Carotid Arteries
It is 2nd terminal branch of common carotid
artery. It supplies structures in neck, face, scalp,
tongue & maxilla. It terminates in substance of
parotid gland behind neck of mandible by
dividing into superficial temporal & maxillary aa.
its pulsations can be felt near its origin.
Relations of the External Carotid Artery:
Anterolaterally:
Lower level: Ant. border of sternocleidomastoid.
Above this level: crossed by hypoglossal nerve,
posterior belly of digastric muscle & stylohyoid.
Within parotid gland: crossed by facial nerve.
Posteriorly: Internal jugular vein lies first lateral
& then posterior to it.
Medially: pharynx & internal carotid artery.
Structures passing between external & internal
carotid arteries. glossopharyngeal nerve,
pharyngeal branch of vagus & Stylopharyngeus.
Internal Jugular Vein
It is continuation of sigmoid sinus receiving blood from brain, face & neck & it
descends within carotid sheath initially posterior to ICA & then passes lateral to it
& remain lateral to common carotid artery with vagus nerve posterior to it
&partially between the 2 vessels. It joins subclavian vein behind
medial end of clavicle to form brachiocephalic vein. Its
course is closely related to deep cervical lymph nodes.
It has dilatation at its upper end (superior bulb) & near
its termination (inferior bulb).
Relations of the Internal Jugular Vein
Anterolaterally: Skin, fascia, sternocleidomastoid & parotid.
Its lower part is covered by sternothyroid, sternohyoid &
omohyoid muscles. Higher up, it is crossed by stylohyoid,
posterior belly of digastric & spinal part of accessory nerve.
Posteriorly: Transverse processes of cervical vertebrae,
levator scapulae, scalenus medius, scalenus anterior,
cervical plexus, phrenic nerve, thyrocervical trunk,
vertebral vein & first part of subclavian artery.
Medially: Above: internal carotid artery and 9th, 10th, 11th, and 12th cranial
nerves. Below: common carotid artery and vagus nerve.
Nerves of Anterior Triangle of Neck
These include:
Cranial nerves : facial, glossopharyngeal, vagus, accessory, and hypoglossal nerves
Peripheral nerves: Transverse cervical n. & upper & lower roots of ansa cervicalis.
1.Glossopharyngeal nerve [IX]: It descends between
internal carotid artery & internal jugular vein, then
passes between internal & external carotid arteries,
and curves around lateral border of stylopharyngeus
muscle. At this point, it continues in an anterior
direction, deep to hyoglossus muscle and reaches
base of tongue & palatine tonsil.
2. Hypoglossal nerve [XII]:
It is medial to internal jugular vein & internal carotid
artery immediately outside skull and then it passes
outward between internal jugular vein & internal
carotid artery . It supplies tongue but does not give
off any branches as it passes through anterior triangle
of the neck.
Nerves of Anterior Triangle of Neck
These include:
Cranial nerves : facial, glossopharyngeal, vagus, accessory, and hypoglossal nerves
Peripheral nerves: Transverse cervical n. & upper & lower roots of ansa cervicalis.
3. Transverse cervical nerve:
It is a branch of cervical plexus arising from anterior rami of cervical nerves C2- C3.
It emerges from beneath posterior border of sternocleidomastoid (middle of the
muscle).
4. Accessory nerve [XI]:
It emerges between internal jugular vein
& internal carotid artery. It passes then
lateral to internal jugular vein to
Disappear beneath anterior border of
sternocleidomastoid. Accessory nerve
gives off no branches through the anterior
triangle of the neck.
Nerves of Anterior Triangle of Neck
5. Vagus nerve [X]:
It is enclosed in carotid sheath behind internal jugular vein & internal carotid and
common carotid arteries. Branches of vagus nerve include motor pharyngeal
branch, carotid body branch, superior laryngeal nerve & possibly a cardiac branch.
6. Ansa cervicalis:
It is a loop of nerve fibers from cervical nerves
C1-C3 that innervate muscles of anterior triangle.
It begins as branches from cervical nerve C1
joining hypoglossal nerve, then some of
cervical nerve fibers leave it again and
descend between internal jugular vein and
internal carotid first, and then common
carotid arteries. These nerve fibers forms
Superior Root of Ansa Cervicalis:
innervate superior belly of omohyoid and
upper parts of sternohyoid & sternothyroid muscles.
Inferior root of ansa cervicalis: is a nerve from C2 & C3.
It innervate inferior belly of omohyoid, and lower
parts of sternohyoid and sternothyroid.
The Thyroid Gland
One of the contents of Anterior
Triangle
Thyroid Gland
It is one of the endocrine glands and
consists of right and left lobes connected
by a narrow isthmus. It is a vascular organ
surrounded by a sheath derived from
pretracheal layer of deep fascia. The sheath
attaches gland to Larynx & Trachea. Each
lobe is pear shaped, with its apex being
directed upward as far as oblique line on
lamina of thyroid cartilage; its base is at
level of 4th or 5th tracheal ring.
Isthmus extends across the midline in front
of 2nd, 3rd & 4th tracheal rings with
sometimes a Pyramidal Lobe projecting
upward. A fibrous or muscular band
frequently connects pyramidal lobe to
hyoid bone; if it is muscular, it is called
Levator glandulae thyroideae.
Thyroid Gland
Relations of the Lobes
Anterolaterally: Sternothyroid, Sup. belly of
omohyoid, Sternohyoid & sternocleidomastoid.
Posterolaterally: Carotid sheath (common
carotid artery), internal jugular vein & vagus.
Medially:Larynx, Trachea, Pharynx &Esophagus
Associated with these, are cricothyroid muscle
and its nerve supply External laryngeal nerve.
Finally, in a groove between esophagus &
trachea is recurrent laryngeal nerve.
Rounded posterior border of each lobe is
related posteriorly to Superior and Inferior
Parathyroid Glands and anastomosis between
superior and inferior thyroid arteries.
Relations of the Isthmus
Anteriorly: Sternothyroid, sternohyoid, anterior
jugular veins, fascia & skin.
Posteriorly: 2nd, 3rd and 4th rings of trachea.
Arterial Supply of Thyroid Gland
1. Superior thyroid artery: a branch of
external carotid artery that descends to
upper pole of each lobe, accompanied
by external laryngeal nerve.
2. Inferior thyroid artery: a branch of
thyrocervical trunk that ascends behind
the gland to level of cricoid cartilage. It
then turns medially and downward to
reach posterior border of the gland.
The recurrent laryngeal nerve crosses
either in front of or behind the artery,
or it may pass between its branches.
3. Thyroidea ima: sometimes present
and arise from brachiocephalic artery
or arch of aorta. It ascends in front of
trachea to isthmus.
Thyroid Gland
Venous drainage of thyroid gland:
Superior and Middle thyroid veins:
drain into internal jugular vein.
Inferior thyroid veins: anastomose with
one another and drain into left
brachiocephalic vein in the thorax.
Lymph Drainage of thyroid gland:
It drains mainly laterally into deep
cervical lymph nodes. A few lymph
vessels descend to paratracheal nodes.
Nerve Supply of thyroid gland:
Superior, middle, and inferior cervical
sympathetic ganglia
Parathyroid Glands
They are 4 endocrine glands with ovoid shape
(6 mm long max.) closely related to posterior
border of thyroid gland & lying within its
fascial capsule.
Superior parathyroid glands are more
constant in position & lie at level of middle of
posterior border of thyroid.
Inferior parathyroid glands usually lie close to
inferior poles of thyroid gland. Blood Supply
of Parathyroid glands:
Arterial supply: superior & inferior thyroid aa.
Venous drainage: into superior, middle and
inferior thyroid veins.
Lymph Drainage: Deep cervical & paratracheal
lymph nodes
Nerve Supply: Superior or middle cervical
sympathetic ganglia.
Functions of the Parathyroid Glands: produce parathyroid hormone
Posterior Triangle of Neck
Posterior Triangle of the neck
Posterior triangle of the neck is on lateral
aspect of the neck in direct continuity with
upper limb.
Boundaries:
Anteriorly: Sternocleidomastoid post. edge
Posteriorly: by anterior edge of trapezius.
Inferiorly (base): middle third of clavicle;
Superiorly (apex): is occipital bone (post.
to mastoid process between attachments
of trapezius & sternocleidomastoid.
Roof: investing layer of cervical fascia
Floor: consist of (from superior to inferior)
splenius capitis, levator scapulae, and
posterior, middle & anterior scalene
muscles covered by prevertebral layer of
cervical fascia.
Contents of posterior triangle
Vessels:
1.External jugular vein
2.Subclavian artery & its branches
3.Subclavian vein
4.Transverse cervical & suprascapular aa.
Nerves:
1. Accessary nerve.
2. Branches of Cervical Plexus.
3. Components of brachial plexus.
Accessory nerve: (in posterior triangle)
It cross anterior triangle till reaching superior
border of sternocleidomastoid muscle, then
passes either deep to or through it to enter
posterior triangle. It crosses posterior triangle in
an oblique downward direction within investing
layer of cervical fascia till reaching anterior
border of trapezius muscle to supply it.
Report
Cervical Plexus:
- Roots (origins)
- Branches
- Distribution of branches & their destination
- References
2012 - 12 – 16 ‫موعد التسليم االحد‬
End of the Lecture
GOOD LUCK