Lesson 4 (Nerves and Blood Vessels of the Spinal Column and Thorax).pptx

Lesson 4
NERVES AND BLOOD VESSELS

Introduction
 The thoracic region of the body showcases the
remarkable complexity of human physiology.
Nerves, blood vessels, and arteries in this
critical region enable sensation and allow
blood to flow throughout the entire body.

What to expect:
 Nerves
a detailed explanation on each spinal region location,
function and movement. (e.g. Cervical Spinal Nerves
C1-C8’s individual purposes)
 Blood Vessels
 A portioned illustration/explanation on different parts
of the trunk ( abdomen and neck)

 Cervical spinal nerves, also called cervical nerves,
provide functional control and sensation to different
parts of the body based on the spinal level where they
branch out from the spinal cord.
 Note: innervations can vary from person to person..

Cervical Nerves Function (C1-C3)
 C1, C2, and C3 (the first three cervical nerves) help
control the head and neck, including movements
forward, backward, and to the sides.1 The C2
dermatome handles sensation for the upper part of the
head, and the C3 dermatome covers the side of the face
and back of the head.2 (C1 does not have a
dermatome.)

Cervical Nerves Function (C4)
 C4 helps control upward shoulder movements.1 C4
(along with C3 and C5) also helps power the
diaphragm—the sheet of muscle that stretches to the
bottom of the rib cage for breathing.1 The C4
dermatome covers parts of the neck, shoulders, and
upper part of arms.

 C5 helps control the deltoids (which form the rounded
contours of the shoulders) and the biceps (which allow
bending of the elbow and rotation of the forearm).1
The C5 dermatome covers the outer part of the upper
arm down to about the elbow.
 C6 helps control the wrist extensors (muscles that
control wrist extension) and also provides some
innervations to the biceps.1,3 The C6 dermatome
covers the thumb side of the hand and forearm.

 C7 helps control the triceps (the large muscle on the
back of the arm that straightens the elbow) and wrist
extensor muscles.1,3 The C7 dermatome goes down the
back of the arm and into the middle finger.

 C8 helps control the hands, such as finger flexion
(handgrip).1,3 The C8 dermatome covers the pinky
side of the hand and forearm.

Thoracic Spine
 The thoracic spine has 12 nerve roots (T1 to T12) on
each side of the spine that branch from the spinal
cord and control motor and sensory signals mostly
for the upper back, chest, and abdomen.

Thoracic Nerves’ Function (T1-T12)
 The thoracic spine (highlighted) spans the upper and
mid-back. It includes twelve vertebrae named T1
through T12

Thoracic Nerves Path
 Each thoracic spinal nerve is named for the vertebra
above it. For example, the T3 nerve root runs between
the T3 vertebra and T4 vertebra. There are 12 thoracic
spinal nerve root pairs (two at each thoracic vertebral
level), starting at vertebral level T1-T2 and going down
to T12-L1.
 Each thoracic nerve root exits the spinal canal through
a bony hole, called an intervertebral foramen. This
bony hole is formed by two adjacent vertebrae, and its
size and shape can slightly shift as the vertebrae move.

Thoracic Nerves Path
 After branching from the spinal cord and traveling through
the foramen, a thoracic nerve root branches into two
different nerve bundles that feed into the nerves at the
front (ventral ramus) and back (dorsal ramus) of the body.
At the T1 through T11 levels, the ventral ramus eventually
becomes an intercostal nerve that travels along the same
path as the ribs (specifically between the innermost and
internal intercostal muscles that connect adjacent ribs). At
T12, the ventral ramus becomes a subcostal nerve that
travels beneath the twelfth rib. At T1 through T12, the
dorsal ramus goes into the back muscles and also provides
sensation to the skin.

Thoracic Nerves Function (T1-T5)
T1 and T2 (top two thoracic nerves)
feed into nerves that go into the top of
the chest as well as into the arm and
hand.
T3, T4, and T5 feed into the chest wall
and aid in breathing.

Thoracic Nerves Function (T6-T12)
 T6, T7, and T8 can feed into the chest
and/or down into the abdomen.
 T9, T10, T11, and T12 can feed into the
abdomen and/or lower in the back.

Lumbar Spinal Nerves
 The lumbar plexus is a network of nerve fibres that
supplies the skin and musculature of the lower limb. It
is located in the lumbar region, within the substance
of the psoas major muscle and anterior to the
transverse processes of the lumbar vertebrae.

 The plexus is formed by the anterior rami (divisions)
of the lumbar spinal nerves L1, L2, L3 and L4. It also
receives contributions from thoracic spinal nerve 12. In
this article, we shall look at the anatomy of the lumbar
plexus – its formation and major branches.

Note:
On the following slides, we’ll tackle
about the intersecting path of the
lumbar nerves (from the roots to the
muscle then back to the roots again.)

Lumbar Spinal Nerves
 The spinal nerves L1 – L4 form the basis of the lumbar
plexus. At each vertebral level, paired spinal nerves
leave the spinal cord via the intervertebral foramina of
the vertebral column. Each nerve then divides into
anterior and posterior nerve fibres.

 The lumbar plexus begins as the anterior fibres of the
spinal nerves L1, L2, L3, and L4.

Take this picture as reference on the following
explanation regarding Lumbar Nerves:

Lumbar Spinal Nerves (Path)
 Iliohypogastric Nerve
-The iliohypogastric nerve is the first major
branch of the lumbar plexus. It runs to the iliac crest,
across the quadratus lumborum muscle of the
posterior abdominal wall. It then perforates the
transversus abdominis, and divides into its terminal
branches.

Lumbar Nerves Function (L1-L5)
 Roots: L1 (with contributions from T12).

 Motor Functions: Innervates the internal oblique and
transversus abdominis.

 Sensory Functions: Innervates the posterolateral gluteal
skin in the pubic region.
------ (Tip: an easy way to remember that the IlioHypogastric
comes before the IlioInguinal is that H comes before I in
the alphabet!)

 Genitofemoral Nerve
-After leaving the psoas major muscle, the
genitofemoral nerve quickly divides into a genital
branch, and a femoral branch.

 Roots: L1, L2.

 Motor Functions: The genital branch innervates the
cremasteric muscle.

 Sensory Functions: The genital branch innervates the
skin of the anterior scrotum (in males) or the skin over
mons pubis and labia majora (in females). The femoral
branch innervates the skin on the upper anterior
thigh.

 Lateral Cutaneous Nerve of the Thigh
-This nerve has a purely sensory function. It
enters the thigh at the lateral aspect of the inguinal
ligament, where it provides cutaneous innervation to
the skin there

 Roots: L2, L3
 Motor Functions: None.
 Sensory Functions: Innervates the anterior and lateral
thigh down to the level of the knee.

 Obturator Nerve
 The obturator nerve is a major peripheral nerve of the lower
limb.
 The obturator nerve is formed from the lumbar plexus. It
receives fibres from the anterior divisions of L2, L3 and L4.
 After its formation, the obturator nerve descends through the
fibres of the psoas major and emerges from its medial border.
It then travels posteriorly to the common iliac arteries and
laterally along the pelvic wall – towards the obturator foramen
of the pelvis.

 Roots: L2, L3, L4.
 Motor Functions: Innervates the muscles: obturator
externus, pectineus, adductor longus, adductor brevis,
adductor magnus, gracilis.
 Sensory Functions: Innervates the skin over the medial
thigh.

 Femoral Nerve
 The femoral nerve is one of the major
peripheral nerves of the lower limb.
 The femoral nerve is the largest branch of
the lumbar plexus. It is derived from the
anterior rami of nerve roots L2, L3 and
L4.

 After arising from the lumbar plexus, the
femoral nerve travels inferiorly through the
psoas major muscle of the posterior
abdominal wall. It supplies branches to the
iliacus and pectineus muscles prior to
entering the thigh.

The femoral nerve then passes
underneath the inguinal ligament to
enter the femoral triangle. Within this
triangle, the nerve is located lateral to
the femoral vessels (unlike the nerve,
the femoral artery and vein are
enclosed within the femoral sheath).

 Nerve roots: L2-L4
 Motor functions: Innervates the anterior thigh muscles
that flex the hip joint (pectineus, iliacus, sartorius)
and extend the knee (quadriceps femoris: rectus
femoris, vastus lateralis, vastus medialis and vastus
intermedius),
 Sensory functions: Supplies cutaneous branches to the
anteromedial thigh (anterior cutaneous branches of
the femoral nerve) and the medial side of the leg and
foot (saphenous nerve).

 Roots: L2, L3, L4.
 Motor Functions: Innervates the muscles: Illiacus,
pectineus, sartorius, all the muscles of quadriceps
femoris.
 Sensory Functions: Innervates the skin on the anterior
thigh and the medial leg.

Sacral Nerves
 Sacral Spine Diagram
 The sacral spine (sacrum) is located below
the lumbar spine and above the tailbone,
which is known as the coccyx. Five bones
that are fused together make up the triangle-
-shaped sacrum, and these bones are
numbered S-1 to S-5.

Sacral Nerves Function
 S1 nerves affect the hips and the groin area.
 S2 nerves affect the backs of the thighs.
 S3 nerves affect the medial buttock area.
 S4 nerves affect the perineal

Other important nerves in the
thoracic region:
 Vagus nerves: These cranial nerves travel in the carotid
sheath with the internal jugular vein and common carotid
arteries before moving into the thorax.
 Phrenic nerves: These nerves arise from the 3rd, 4th, and
5th cervical nerves and descend into the thorax to
innervate the diaphragm.
 Cervical portion of the sympathetic trunks: These trunks
are located to the front and sides of the cervical vertebrae.
They contain the superior, middle, and inferior cervical
sympathetic ganglia.

Order of topic:
Neck
Abdomen

Main arteries in the root of the neck:
 Brachiocephalic trunk: This artery branches off the arch
of the aorta just behind the manubrium. It moves to the
right and divides into the right common carotid and
right subclavian arteries.
 Right and left subclavian arteries: The right subclavian
branches off the brachiocephalic trunk, and the left
subclavian starts from the arch of the aorta.

Right and left subclavian artery
branches:
 The vertebral artery runs through the foramina
of the transverse processes of the first six
cervical vertebrae.
 The internal thoracic artery runs into the
thorax.
 The costocervical trunk gives rise to superior
intercostal and deep cervical arteries.

Right and left subclavian artery
branches:
 The thyrocervical trunk has several (3)branches:
1. the suprascapular artery, which supplies blood to the muscles
on the back of the scapula, and the cervicodorsal trunk,
which branches off into the dorsal scapular and superficial
cervical arteries (sometimes the dorsal scapular artery
branches off the subclavian artery).
2. The dorsal scapular artery supplies the levator scapulae
3. rhomboid muscles of the upper back. The inferior thyroid
artery also stems from the thyrocervical trunk. It supplies
blood to the thyroid and parathyroid glands and the larynx,
plus it sends blood to muscles of the neck.

Veins
accompany the arteries in the root of
the neck. They return blood to the
heart from the head.

Veins (Neck)
 External jugular vein: This vein drains blood from
the scalp and face and empties into the subclavian
vein lateral to the internal jugular vein.
 Anterior jugular vein: This vein drains blood from
superficial submandibular veins and drains to the
external jugular vein or the subclavian vein.

Veins (Neck)
 Left and right anterior jugular veins: These two veins
join to form the jugular venous arch.
 Subclavian vein: This vein begins near the 1st rib and
joins the internal jugular vein in the anterior cervical
triangle where it forms the brachiocephalic vein. This
area is called the venous angle.

Abdominal and Pelvic Cavities
 As the abdomen and pelvis contain the majority of
internal organs, these regions need to be supplied by
an extensive network of arteries and veins. That being
said, all arterial blood delivered to this region comes
via branches of the abdominal aorta, and all venous
blood eventually finds its way back to inferior vena
cava (IVC).

Abdominal aorta (Aorta
abdominalis)
 The abdominal aorta is a continuation of the thoracic aorta,
once it has traversed the aortic hiatus of the diaphragm. As it
supplies just about everything in the abdomen and pelvis, it is
a large caliber artery, and is as wide as a garden hose (~25mm)
and gives numerous branches.

 The course of the abdominal aorta is quite simple. After
passing through the aortic hiatus (T12), it descends slightly to
the left of the lumbar vertebrae, with the inferior vena cava
being just right to it.

VISCERAL BRANCHES OF ABDOMINAL AORTA

Abdominal aorta branches
Visceral: celiac trunk, superior
mesenteric artery, middle suprarenal
arteries, renal arteries, gonadal arteries,
inferior mesenteric artery
Parietal: inferior phrenic artery, lumbar
arteries, median sacral artery
Terminal: common iliac arteries

Venous Drainage (Abdomen)
 The venous drainage follows a similar pattern:
 Superior epigastric vein, a tributary to the internal
thoracic vein
 Inferior epigastric and deep circumflex iliac veins, the
tributaries to the external iliac vein
 Superficial circumflex iliac and superficial epigastric
veins, the tributaries to the femoral and greater
saphenous veins
 10th and 11th intercostal veins and the subcostal vein
 Lumbar veins, tributaries to the inferior vena cava

Stomach
 The stomach is supplied by the branches of the
celiac trunk, which include the right and left
gastric, right and left gastro-omental, short gastric
and posterior gastric arteries. Venous blood is
conveyed by the right, left and short gastric,
prepyloric, right and left gastro-omental veins.
They all empty into the system of the hepatic
portal vein.

The Intestines
 The intestines have very rich blood supply. Put simply,
they are supplied and drained by the branches of three
primary vessels: the celiac, superior and inferior
mesenteric vessels.

A closer look to the intestines:
 Small Intestine
 The duodenum is supplied by the superior and inferior
pancreaticoduodenal arteries, which are the branches of the
gastroduodenal and superior mesenteric arteries,
respectively. Venous drainage occurs via the prepyloric,
superior pancreaticoduodenal and inferior
pancreaticoduodenal veins, which are and drained by the
superior mesenteric and hepatic portal vein.
 The jejunum and ileum are supplied by the jejunal and ileal
arteries, and drained by their venous counterparts, the
jejunal and ileal veins (tributaries of the superior
mesenteric vein).

 Large Intestine
 The cecum is supplied by the ileocolic artery, and drained
by the ileocolic vein.
 The ascending colon is supplied by the ileocolic and right
colic arteries (both branches of the superior mesenteric
artery), and is drained by their venous counterparts, the
ileocolic and right colic veins.
 The transverse colon is supplied by the middle colic artery
(proximal ⅔) and left colic artery (distal ⅓). It is drained
their venous equivalents which empty into the superior
mesenteric and inferior mesenteric veins, respectively.

 Large Intestine
 The descending and sigmoid colon are supplied by
the left colic and sigmoid arteries, which are
branches of the inferior mesenteric artery. Venous
blood is drained via veins of the same name which
empty into the inferior mesenteric vein drains.
 The rectum and anal canal recieve arterial blood
from the superior, middle and inferior rectal
arteries. The venous blood is conveyed through the
superior, middle and inferior rectal veins.

Liver and gallbladder
 The tissue of the liver is supplied by the hepatic
artery, which is a branch of the celiac trunk.
Interestingly, the blood delivered by the hepatic
artery only represents one quarter of the total
blood volume received by the liver. The other three
quarters of the blood delivered to the liver come
from the hepatic portal vein. Venous blood is
drained by the hepatic veins, which empty into the
inferior vena cava.

Pancreas
 The pancreas is supplied by the pancreatic branches of
the splenic, gastroduodenal and superior mesenteric
arteries (SMA).
 The splenic artery gives off several pancreatic branches
which supply the body and tail of the pancreas. The
gastroduodenal artery gives off the superior
pancreaticoduodenal artery, whereas the superior
mesenteric artery provides the inferior
pancreaticoduodenal artery; these deliver arterial blood
to the head of the pancreas. The pancreas is drained by
the pancreatic and pancreaticoduodenal veins, which
empty into the splenic, superior mesenteric and hepatic
portal veins.

Kidneys
Kidneys are supplied by the renal
arteries, which are bilateral branches of
the abdominal aorta. The kidneys are
drained by the renal veins, which are
tributaries to the inferior vena cava.

INFERIOR VENA CAVA
 The inferior vena cava (IVC) is the headmaster of the
veins department. It collects all the blood from the
abdomen, pelvis and lower limbs and carries it to the
right atrium of the heart. The IVC is formed by
merging of the left and right common iliac veins at the
L5 vertebral level, just in front of the aortic
bifurcation.

INFERIOR VENA CAVA
 The inferior vena cava then ascends to the right of the
abdominal aorta along the vertebral column, receiving
blood from numerous tributaries, and eventually
passing through the caval foramen of the diaphragm.
Notice that the veins draining the organs of
gastrointestinal tract do not empty into the inferior
vena cava. This is important to remember! Continue
reading below to find out more about their venous
drainage.

VEINS OF HEPACTIC PORTAL SYSTEM

Hepatic Portal Vein (Vena
portae hepatis)
 The hepatic portal vein is a vein that receives all the venous blood from the
stomach, small and large intestines, pancreas and spleen.
 It arises at the confluence of the superior mesenteric and splenic veins, just
posterior to the neck of the pancreas. It passes through the porta hepatis
together with the hepatic artery and bile duct as it enters the liver. Once
processed and detoxified through the liver, the venous blood delivered by the
hepatic portal vein leaves the liver via the hepatic veins, which empty into the
inferior vena cava.
 When there is an obstruction of the portal system e.g. due to cirrhosis of the
liver, blood can be shunted away from the liver to systemic veins through
portosystemic anastomoses.
 These occur between vessels which feed into the portal vein and nearby
systemic veins e.g. splenic vein to left renal vein. This helps to reduce portal
venous pressure during portal hypertension.
 Although this is useful for a short period of time, bypassing the liver may be
dangerous, as that means foregoing the detoxification process.

THE CAVA-CAVAL ANASTOMOSES
ANTERIOR
ABDOMINAL
WALL

Reproductive organs
Reproductive organs in both sexes are
supplied by branches of the gonadal
(testicular or ovarian) and internal iliac
vessels.

Blood supply of the male pelvis:
 Concerning the blood supply of the male pelvis, here are
the must-know facts:
 The ductus deferens (formerly known as the vas deferens)
is supplied by the superior vesical artery and drained by
the testicular vein.
 Seminal glands are supplied by the inferior vesical and
middle rectal arteries, and drained by the middle rectal
veins.
 The prostate is supplied by the inferior vesical, internal
pudendal and middle rectal arteries. It is drained by the
prostatic venous plexus which empties into the internal
iliac vein.

Blood supply of the male pelvis:
 The testes are supplied by the testicular arteries, and
drained by the pampiniform venous plexus. Testicular
veins emerge from the plexus, with the right testicular
vein emptying into the IVC, and the left into the left renal
vein.
 The penis is supplied by the branches of internal and
external pudendal arteries, while it is drained by the deep
dorsal vein of the penis, a tributary to the internal
pudendal vein.

Blood supply of the female pelvis:
Several facts to remember about the female
pelvis blood supply:
 The ovaries are supplied by the ovarian
arteries, and drained by the pampiniform
venous plexus which empties into the
ovarian vein. Note that the right ovarian vein
empties to the IVC, whereas the left empties
into the left renal vein.

Blood supply of the female pelvis:
 The uterus is supplied by the uterine arteries
and drained by the uterine veins.
 The vagina is supplied by the uterine, vaginal
and internal pudendal arteries. It is drained
by the vaginal venous plexus.

Source:
NERVES…
 https://www.dummies.com/education/science/anatomy/the-nerves-
and-blood-vessels-in-the-thoracic-region/
 https://www.slideshare.net/mobile/Rabab90/nerves-vessels-of-
thoracic-wall
 https://www.slideshare.net/mobile/hermizan84/spinal-nerve
 https://www.spine-health.com/conditions/spine-anatomy/cervical-
spinal-nerves
 https://www.spine-health.com/conditions/upper-back-pain/thoracic-
spinal-nerves
 https://teachmeanatomy.info/lower-limb/nerves/lumbar-plexus/

Source:
BLOOD VESSELS
 https://www.dummies.com/education/science/anatomy/nerves-and-
blood-vessels-in-the-root-of-the-neck/

Lesson 4 (Nerves and Blood Vessels of the Spinal Column and Thorax).pptx

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