Download 18._master-main_vessles,last4cranial_Ns2010-10

Common Carotid Artery :
Origin : Rt.C.C.arise from
brachiocephalic artery behind
sternoclavicular j., left C.C. arise from
arch of aorta in sup.mediastinum.
Termination : 2 terminal branches
, external & internal carotid arteries at
the upper border of thyroid cartilage
(opposite C4 vertebra).
At point of bifurcation, it presents a
carotid sinus and carotid body behind,
,they are innervated by glossopharyngeal N. , the sinus acts as pressoreceptor(regulate blood pressure in
cerebral arteries), but the body acts as
a chemo-receptor (regulate respiration).
Common Carotid Artery :
Origin : Rt.C.C.arise from
brachiocephalic artery behind
sternoclavicular j., left C.C. arise from
arch of aorta in sup.mediastinum.
Termination : 2 terminal branches
, external & internal carotid arteries at
the upper border of thyroid cartilage
(opposite C4 vertebra).
At point of bifurcation, it presents a
carotid sinus and carotid body behind,
,they are innervated by glossopharyngeal N. , the sinus acts as pressoreceptor(regulate blood pressure in
cerebral arteries), but the body acts as
a chemo-receptor (regulate respiration).
Common Carotid Artery :
It is embedded within the carotid
sheath with internal j.v. + vagus N.
Relations :
Anterolaterally : skin, fascia,
sternomastoid, sternothyroid,
sternohyoid & sup.belly of omohyoid.
Posteriorly :
transverse processes of lower 4 cervical
vertebrae + prevertebral Ms.
(longus colli & longus capitis) +
sympathetic trunk.
Medially : larynx, pharynx, trachea,
esophagus & lobe of thyroid gland.
Laterally : internal J.V. + vagus
nerve.
External Carotid Artery :
It supplies structres in neck, face,,
scalp ,tounge & maxilla.
Origin : at superior border of
thyroid cartilage (at C4 vertebra),
its pulsation can be felt.
It terminates in parotid gland
behind neck of mandible by
dividing into superficial temporal &
maxillary arteries.
It lies at its beginning medial to
Int.C.artery, then backward then
laterally.
External Carotid Artery :
Relations :
Antero-laterally (superficial
relation) :
1-skin, fascia.
2-it is crossed by hypoglossal N.,
stylohyoid + post.belly of digastric,
Medially (deep relation) :
1-internal C. artery (above).
2-pharynx.
3- Stylopgaryngeus muscle , glossopharyngeal N. & pharyngeal
branch of vagus.
(structures between int.& ext.
arteries)
Branches of External Carotid Artery :
Superior thyroid artery.
Ascending pharyngeal artery.
Lingual artery.
Facial artery.
Occipital artery.
Posterior auricular artery.
Superficial temporal artery.
Maxillary artery.
Branches of External Carotid Artery :
Superior thyroid artery :
-it gives off a branch to sternomastoid & superior laryngeal artery ,
which pierces thyrohyoid membrane
with int. laryngeal N.
Ascending pharyngeal artery.
Lingual artery :
-arise opposite the greater horn of
hyoid bone ,to enter
submand.region and supply tongue.
-it is crossed by hypoglossal N.
Branches of External Carotid Artery :
Facial artery :
-it arises from ext.C.artery just above the
greater cornu of hyoid bone. It has a wavy
course.
-it ascends deep to and grooved post. part
of submand.gland, then between gland and
body of mandible to pierce deep fascia at
base of mandible to enter face.
Occipital artery :
-It supplies back of scalp.
Posterior auricular artery :
-arises at the level of upper border of
post.belly of digastric to supply auricle.
Terminal branches : inside
substance of parotid gland behind neck of
mandible, it terminates into Superficial
temporal + Maxillary arteries.
Internal Carotid Artery :
It arises at the upper border of
thyroid cartilage (C4 vertebra).
It lies in the carotid sheath.
It enters the cranial cavity through
the carotid canal.
It supplies the brain, eye, forehead,
& nose
It has no branches in the neck.
Atherosclerosis in the neck…. visual
defect due to insufficient blood flow
through central artery of retina.
Insufficient blood flow in middle
cerebral artey… motor & sensory loss.
Internal Carotid Artery :
Relations :
Anterolaterally (superficial) :
-Skin &fascia.
-Ant.border of sternomastoid.
-Post.belly of digastric.
Above the digastric :
-Stylohyoid, stylopharyngeus,
styloglossus + glossopharyngeal N.,
pharyngeal branch of vagus,
parotid gland, & external carotid
artery (above).
Posteriorly : sympathetic trunk,
upper 3 cervical vertebrae.
Medially : pharynx.
Laterally : internal j.v. + vagusN.
Subclavian artery :
Origin : right from brachiocephalic behind sterno-clavicular
joint., left from arch of aorta in
sup.mediastinum.
Course : in the root of neck, it
is divided into 3 parts by scalenus
anterior.
-1st part extends from its origin to
medial border of scalenus ant.
-2nd part lies posterior to this Ms.
-3rd part extends from lat.border
of scalenus ant. to outer border of
1st rib,where it becomes axillary Ar
1st part of Subclavian artery :
•Relations :
Anteriorly :
-common carotid , vagus,
symp.trunk (ansa subclavia),
int.j.v. & left phrenic N.
Posteriorly : apex of lung &
pleura, Rt.recurrent laryngealN
Branches :
1-vertebral artery..
2-thyrocervical trunk.
3-internal thoracic(mammary)
artery.
Scalenus Anterior & Phrenic nerve :
Note, the roots of phrenic N. lie laterally to scalenus anterior,
but phrenic N. lies anterior to scalenus anterior.
1-Vertebral Artery :
Course :
-it passes in front of T.process of
7th C.V. to ascend through
foramina in transverse processes
of upper 6 cervical vertebrae.
-it emerges from T.process of
atlas to pass behind its lateral
mass,then pierces dura mater
medially to enter vertebral canal
and enter skull via foramen
magnum to supply brain.
Relations :
-Anteriorly : C.C.artery and
crossed by thoracic duct.
Posteriorly :T.procees of 7thc.v. &
stellate ganglion.
Branches : spinal & muscular.
2-Thyro-cervical trunk :
It gives off 3 branches :
1-inferior thyroid artery : ascends
along med.border of scalenus ant.
to level of cricoid cartilage (C6V.)
to reach post. border of thyroid gl.
2-superficial cervical &
3- suprascapular arteries : they
pass across scalenus anterior to
enter post. triangle of the neck.
3-Internal thoracic artery :
Arises from lower border of 1st
part of subclavian artery.
Enters thorax behind 1st costal
cartilage.
2nd part of subclavian :
Relations :
Anteriorly : scalenus ant.
Posteriorly : cervical pleura & apex
of lung.
Branches : one branch…..
Costo-cervical trunk : from its
back. It gives off :
1-sup.intercostal artery : gives rise
to 1st & 2nd post. Intercostal arteries.
2-deep cervical artery : to muscles
of back of neck.
3rd part of subclavian :
Extends from lateral margin of
scalenus ant. to the outer border
of 1st rib ,where it becomes
axillary artery.
It lies in post.triangle of neck.
Subclavian vein :
It begins at outer border of 1st rib
as a continuation of axillary
vein.
At medial border of scalenus ant.,
it joins int.j.v. to form
brachiocephalic vein.
It lies in lower anterior corner of
post.triangle of neck , posterior &
close to undersurface of medial
1/3 of clavicle, so it is a safe site
of catheterization ( infraclavicular approach).
Its tributaries : Ext.J.V
Internal jugular vein :
Course :
It receives blood from brain, face
& neck .
It begins at jugular foramen as a
continuation of sigmoid sinus.
It descends through the neck in
the carotid sheath.
It unites with subclavian vein to
form brachio-cephalic vein.
Tributaries of Internal jugular vein :
Inferior petrosal sinus : drains
cavernus sinus, leaves skull via jugular
foramen to join int.j.v.at its sup.bulb.
Pharyngeal veins.
Lingual vein.
Facial vein : leaves face superficially
over submandibular gl. It joins
ant.division of retromandibular v. to
join the internal j.v.
Sup.thyroid vein : leaves sup.pole of
thyroid into int.j.v.
Middle thyroid vein : leaves lobe of
thyroid gl. to drain into int.J.V.
Venous drainage of thyroid gland
External jugular vein :
It lies in superficial fascia deep to
platysma, lying on sterno-mastoid.
Just above the clavicle, it peirces
deep fascia to drain into subclavian
vein.
Structures superficial to
sternocleidomastoid are :
skin, platysma, external j.v., great
auricular N., transverse cervical N.
& investing layer of deep cervical
fascia.
Internal j.v. catheterization :
Int.j.v. descends through neck
from a point halfway between tip
of mastoid process & angle of jaw
to sternoclavicular joint.
In posterior approach,, the
neddle & catheter are introduced
into vein 2 fingers above clavicle at
post. border of sternomastoid
In anterior approach,, the
neddle & catheter are inserted into
vein at the apex of triangle formed
by sternal & clavicular heads of
sternomastoid muscle.
LAST 4 CRANIAL NERVES
Glossopharyngeal Nerve
Origin : Medulla Oblongata of Brain.
It has motor, sensory & parasymp.Fs.
Course & relations :
-It has 2 sensory ganglia (sup.& inf.) in the
jugular foramen
-It leaves skull through jugular foramen to
descend in the upper neck within carotid
sheath.
-It leaves carotid sheath to pass between
internal & external C. Ar.
-It winds around stylopharyngeus Ms. between
Sup. & middle constrictors of pharynx into the
back of tongue deep to hyoglossus.
-it terminates by dividing into terminal
branches supplying m.m.of pharynx, tonsils,
soft palate & post.1/3 of tongue
Branches of Glossopharyngeal N.
Tympanic branch : arises from inf. ganglion, it
has parasymp. secreto-motor to parotid gland
via auriculotemporal nerve.
Carotid branch : sensory to carotid sinus &
carotid body .
Muscular : motor to Stylopharyngeus.
Pharyngeal branches (sensory) :
to
form the sensory part of pharyngeal plexus to
supply m.m. of pharynx, tonsils, & soft palate.
Lingual terminal branches : for general & taste
sensation of post.1/3 of tongue.
Applied anatomy: pain of tonsilitis may be
referred to middle ear through glossopharyngeal
nerve because the nerve supplies both structures
VAGUS NERVE
Vagus Nerve
Origin : It emerges from
Medulla.O. to leave the skull
with 9th & 11th Ns. through
jugular F.
It has motor, sensory &
parasympathetic Fs.
Course :
It has 2 sensory ganglia ,
superior within j.F. & inferior
just below j.F.
At inf. ganglion, cranial root of
accessory N. joins vagus N. and
distributed in its pharyngeal &
recurrent laryngeal branches.
Vagus nerve :
It descends in the upper part of
neck within carotid sheath, firstly
between int.j.v.& int.c.Ar., then
between Int. j.v. & C.C.Ar.
At the root of neck, it lies in front of
to 1st part of subclavian Ar. It passes
through thorax and pierces
diaphragm at esophageal opening to
end in abdomen.
It innervates heart,/ respiratory
passages, / G.I.T.( pharynx- left
colic flexure), liver & pancreas.
Branches of Vagus nerve :
From superior ganglion :
1-meningeal branch. to dura of posterior
cranial fossa
2-auricular br. for ext. acoustic meatus. From
inferior ganglion :
3Pharyngeal br. : to form Motor part of
pharyngeal plexus, to supply all Ms.of
pharynx except Stylopharyngeus
(by glossopharyngeal N.), + all Ms.of soft
palate except tensor veli palatini
(by mandibular division of trigeminal).
4-Superior laryngeal N. ,it divides into : aInternal laryngeal N., pierces thyrohyoid
membrane with sup. laryngeal artery, to
supply sensory F. to m.m. of upper part of
larynx above vocal fold.
b-External laryngeal N., to supply
Cricothyroid ms.
Branches of Vagus nerve :
5- cardiac branches : parasymp.,
to end in cardiac plexus in the
thorax.
6- Right recurrent laryngeal N. :
it hooks behind 1st Subclavian artery
to ascend in groove bet. trachea &
esoph. to supply all Ms.of larynx
(motor) except Cricothyroid , +
m.m. of larynx (sensory), below
vocal folds.
7- left R.L.N. : it hooks around
arch of aorta , behind ligamentum
arteriosum, then ascends into neck in
groove bet. trachea & esoph….as
Rt.R.L.N.
Testing the Integrity of Vagus nerve :
Depends on testing the function of
branches to pharynx, soft palate, & larynx.
Pharyngeal reflex or gag-reflex may be
tested by touching lateral wall of pharynx
with spatula causing the patient to gag due
to contraction of pharyngeal Ms.
Innervation of soft palate can be tested
by saying ‘ah’, normally soft palate rises and
uvula moves backward in the middle.
Lesion of innervation of larynx may
reveal in horseness or absence of voice, and
laryngoscopic examination may reveal
paralysis of abductor muscles of larynx.
ACCESSORY NERVE
Accessory nerve
It is purely motor N., formed by
union of cranial & spinal roots.
Cranial root arises from
Medulla.O.
Spinal root arises from upper 5
or 6 cervical segments of spinal
cord, It enters skull through the
foramen magnum to join the
cranial root within the cranial
cavity.
Distribution of Accessory N.
Both roots form the united trunk
that emerges from jugular F.
Branches of Accessory nerve :
Cranial root separates from
spinal root to join vagus at its
inferior ganglion to distribute
through its pharyngeal & laryngeal
branches to supply Ms. of soft
palate & pharynx (via pharyngeal
plexus) and to Ms. of larynx (via
R.L.N, except cricothyroid).
Spinal root pierces deep surface
Distribution of Accessory N.
of Sternomastoid to supply it , then
emerges from posterior border of
sternomastoid and crosses post.
triangle, lying on the levator
scapulae, finally passes deep to
trapezius to supply it.
Testing the Integrity of Accessory nerve :
Accessory N. supplies
sternomastoid & trapezius Ms. by
its spinal root.
Aske the patient to rotate head to
one side against resistance causing
contraction of sternomastoid of
opposite side.
Aske the patient to shrug the
shoulders causing action of
trapezius, to compare the power on
the 2 sides.
Distribution of Accessory N.
Pharyngeal plexus of nerves
It lies on the outer wall of pharynx, mostly on the midlle
constrictor.
It is formed of pharyngeal branches of glossopharyngeal N.
(sensory part) + of vagus N. including fibres of cranial root of
accessory (motor part) + of superior cervical sympathetic ganglion
(sympathetic part), to supply pharynx & soft palate.
Hypoglossal Nerve
Origin : Arises from Medulla.O.
to leave skull via hypoglossal canal
.
It is purely motor N. to the
tongue.
Course :
In its upper part, it is joined by a
branch from cervical plexus
(C1N.) to supply thyrohyoid &
geniohyoid.
Distribution of Hypoglossal N.
 later it leaves hypoglossal N. as
descending branch of hypoglossal
N.
Hypoglossal Nerve
 It descends with the vagus N.
between int.j.v. & int.C.artey, then
crosses in front of internal &
external carotid arteries.
 Then it crosses in front of
lingual artery to enter
submandibular region.
Branches of Hypoglossal Nerve :
Meningeal branch.
 N.to Thyrohyoid & Geniohyoid
(via C1).
Descending branch of hypoglossal
C1 leaves hypoglossal N. in front of
carotid sheath to join the descending
cervical N.(C2,3) of cervical plexus to
form a loop of Ansa cervicalis.
Ansa cervicalis loop supplies
omohyoid, sternohyoid &
sternothyroid Ms.
Distribution of Hypoglossal N.
Muscular branches : to all Ms.of
tongue, Except palatoglossus,
(supplied by pharyngeal plexus)
Hypoglossal N. lesion
Ask the patient to protrude
his tongue :
A, Rt.&Lt. genioglossus muscle
contract together.
B, tip of tongue is protuded
anteriorly in the middle line.
C, lesion of hypoglossal N. on
Rt. Side leads to atrophy &
wrinkling of the tongue on the
same side of lesion.
D, when asking patient to
protrude the tongue, the tip
deviates to side of the lesion.
Cervical Plexus :
Formation :
It is formed by union of
anterior rami of upper 4
cervical nerves, which form
loops that lie in front of levator
scapulae & scalenus medius.
It lies behind prevertebral layer
of deep cervical fascia , int. J.V.
,carotid sheath & Sternomastoid.
Branches of Cervical Plexus :
Cutaneous : lesser occipital (C2),
great auricular (C2,3), transverse
cutaneous (C2,3)& supraclavicular
nerves (C3,4), which enter post.triangle.
Muscular to 1-prevertebral Ms.,
2-sternomastoid (proprioceptiveC2,3),
3-(C3,4) to supply :
-diaphragm (phrenic N.)
-Trapezius & levator scapulae.
4- C2,3 - inferior root of Ansa
cervicalis it unites with superior root of
Ansa cervicalis (C1) to form loop of
Ansa cervicalis to supply infrahyoid
Ms. : omohyoid, sternohyoid &
sternothyroid.
Branches of Cervical Plexus :
Communicating branches :
- C1 fibres join hypoglossal N.
- Grey rami communicantes :
from superior cervical
sympathetic ganglion to
C1,2,3,4
Formation & Branches of Ansa Cervicalis
Cervical part of Symp.Trunk :
It extends from base of skull , to
the neck of 1st rib, where it becomes
the thoracic part.
It lies in front of cervical transverse
processes, longus capitis & longus
colli Ms., behind carotid sheath
medial to vagus N.& vertebral artery.
 It has 3 ganglia., superior, middle &
inferior (cervico-thoracic or stellate
ganglion).
Cervical part of Sympathetic Trunk
Anterior relations :
carotid sheath.
Posterior relations :
1-Cervical transverse processes.
2-Longus capitis & longus colli
(prevertebral muscles).
Lateral relations :
1-vagus N.
2-vertebral artery…
(except inferior or stellate
ganglion,which lies behind
vertebral artery).
Superior Cervical Symp. Ganglion
It is the largest ganglion, lies at the
level of C2,3 vertebrae.
Branches :
1-Internal carotid nerve : it
accompanies the int.c.Ar. into carotid
canal ,where it divides into branches to
form internal carotid plexus.
2-Gray rami communicates to the
upper 4 anterior rami of cervical
nerves 3-External carotid nerve : it
divides into branches to form
symp.plexus around ext.C.artery & its
branches.
4-Cranial N.branches :
which join 9th ,10th , & 12th cranial
Superior Cervical Symp. Ganglion
5-Pharyngeal branches : which unite
with the pharyngeal branches of
glossopharyngeal(9) & vagus(10)
nerves to form the pharyngeal plexus.
6-Superior cardiac branch : which
ends in cardiac plexus in thorax.
Middle Cervical Symp.Ganglion :
It lies at level of cricoid cartilage
(opposite 6th C.V.).
Branches :
1-Gray rami communicates to
anterior rami of 5th & 6th cervical
nerves.
2-Thyroid branches : which pass
along inferior thyroid artery to form
plexus to supply thyroid gland.
3-Middle cardiac branch : which
ends in cardiac plexus in thorax.
4-Ansa suclavia : it forms a loop
around 1st part of subclavian artery
(in front, then behind artery) to join
inferior cervical symp. ganglion.
Inferior Cervical Symp.Ganglion
(cevicothoracic or stellate ganglion) :
Usually, It is fused with 1st thoracic
ganglion to form stellate ganglion.
It lies in interval between transverse
process of 7th C.v. & neck of 1st rib,
behind vertebral artery.
Branches :
1-Gray rami communicates to
anterior rami of 7th & 8th cervical Ns.
2-Arterial branches to subclavian &
vertebral arteries to form plexuses.
3-Inferior cardiac branch to join
the cardiac plexus in the thorax.
Horner’s Syndrome :
It includes :
•
1-constriction of pupil (myosis), due to lesion of dilator pupillae
supplied by sympathetic Fs., which pass in the long ciliary N.
2-ptosis (droping of upper eyelid), due to paralysis of smooth
part of levator palpebrae superioris supplied by symp.fibres
from superior cervical symp. ganglion.
3-Enophthalmos (depression of eyeball into the orbital cavity),
due to paralysis of symp.Fs. of internal carotid symp. plexus.
Causes:Lesionofthesympatheticnervesupplytotheorbit.
•
1- lesion of cervical part of spinal cord.
2- Traumatic injury to cervical part of symp.trunk.
3- pressure on stellate ganglion by cervical rib or cancer.
Cervical rib :
The transverse process of 7th
cervical vertebra may be
abnormally elongated or it may be
separated to form a cervical rib.
It can causes pressure on
symp.trunk, ( stellate ganglion),
(in interval between cervical rib &
neck of 1st rib).
 lower trunk of brachial plexus, &
subclavian artery cross over
cervical rib instead of 1st rib.
Cutaneous branches of Cervical Plexus :
Lesser occipital N.(C2) :
it passes along post.border of
sternocleidomastoid.
-it pierces deep fascia to supply :
skin of neck & skin of lateral
part of back of head
Great auricular N.(C2,3)
-it passes upwards, forwards,
superficial to sternomastoid with
external j.v.
-it pierces deep fascia and divides into
anterior & post. branches to supply :
skin of face covering parotid gland, skin
over angle of mandible (ant.branch) &
skin covering mastoid process, and of
lower part of auricle (post.branch).
Cutaneous branches of Cervical Plexus :
Transverse cervical
cutaneous Ns. (C2,3) :
-it passes forwards superficial to
sternomastoid, and pierces deep fascia.
-it divides into upper & lower branches,
to supply : skin of antero-lateral surface
of neck.
Supraclavicular Ns.(C3,4) :
-it arises as a single trunk which divides
into, medial, intermediate & lateral
supraclavicular nerves.
-they descend in post. triangle to pierce
deep fascia above clavicle to supply :
skin of lower part of neck, medial &
intermediate branches supply skin of
front of chest down to level of 2nd rib
(sternal angle), lateral branches supply
skin of shoulder over upper ½ of
Scalenus Anterior :
It is important landmark in the root of
neck
Origin : transverse processes of 3rd ,4th , 5th
& 6th cervical vertebrae.
Insertion : scalene tubercle on inner
border of 1st rib & a ridge on upper surface
of 1st rib.
N.Supply : anterior rami of 4th ,5th ,& 6th
cervical nerves.
Action :
1-elevation of 1st rib (during deep
inspiration).
2when acting from below, it laterally flexes &
rotates cervical part of vertebral column.
Relations of Scalenus Anterior :
Anteriorly :
1-prevertebral layer of deep cervical
fascia.
2-phrenic nerve, deep to this fascia
3-superficial cervical &
suprascapular arteries.
4-internal j.v. & subclavian v.
Posteriorly :
1-subclavian artery (2nd part).
2-brachial plexus.
3-scalenus medius.
4-cervical pleura.
Note, the phrenic N. deep to prevertebral layer of deep cervical
fascia,+ internal jugular vein + transverse cervical artery are the
anterior relations to scalenus anterior.
Note, scalenus medius + brachial plexus are the posterior relations
to scalenus anterior.
Relations of Scalenus Anterior :
Medially :
1-vertebral artery & vein.
2-inferior thyroid artery & thyrocervical trunk.
3-sympathetic trunk & thoracic
duct on left side.
Laterally :
1- brachial plexus.
2- subclavian artery (3rd part).
3- roots of phrenic N.
Scalenus Anterior & Phrenic nerve :
Note, the roots of phrenic N. lie laterally to scalenus anterior,
but phrenic N. lies anterior to scalenus anterior.
The right phrenic N. enters thorax in front of scalenus anterior
but the left phrenic enters thorax in front of left subclavian artery.
Phrenic Nerve
Origin : from cervical 3,4,5 nerves.
It is the only motor nerve supply to
diaphragm.
It has also sensory fibres for diaphragm +
pleura & peritoneum covering upper & lower
surfaces of central part of diaphragm.
The right phrenic enters thorax in front of
scalenus anterior, but the left one enters
thorax in front of subclavian artery.
Anterior relations : prevertebral layer
of deep cervical fascia, internal jugular vein ,
superficial cervical & suprascapular arteries,
and thoracic duct + beginning of
brachiocephalic vein on the left..
Posterior relations : scalenus anterior,
subclavian artery & cervical dome of pleura.
Scalenus Medius :
Origin : transverse process of
atlas & next 5 cervical vertebrae.
Or (from transverse .processes of
all cervical vertebrae).
Insertion : upper surface of 1st
rib behind groove for subclavian
artery.
N.supply : anterior (ventral)
rami of all cervical nerves.
Action : (as scalenus anterior)
1-it assists in elevating 1st rib.
2-it laterally flexes & rotates
cervical part of vertebral column.
Scalenus Posterior :
It may be absent or blended
with scalenus medius.
Origin : transverse processes
of lower cervical vertebrae.
Insertion : outer surface of
2nd rib.
N.supply : anterior rami of
lower cervical nerves.
Action :
1-elevation of 2nd rib.
2-lateral flexion & rotation of
cervical vertebral column, when
active from below.