Meninges, CSF Meninges, CSF and Blood and Blood

Supply of the Supply of the Head and NeckHead and Neck

Ruhaizan, Diyana, Fatimah, Fadhila, Marshitah, Marzura, Sakinah

Meninges Meninges (singular Meninx)(singular Meninx)

• Def: are 3 membranous envelopes; Dura mater, Arachnoid and Pia Mater - surrounding brain and spinal cord

• Functions:1. Protecting the brain and spinal cord from

mechanical injury2. Providing B.S. to skull & hemispheres3. Providing a space for the flow of CSF

MeningesMeningesDura mater-most superior-toughest &

inflexible-”Tough mother”

(latin name)Arachnoid -middle layer-Spider web-like

of B.S.Pia mater-innermost layer-”tender mother”

(latin name)

PRODUCTION OF CSFPRODUCTION OF CSF• CSF is a clear fluid produced by dialysis of blood in

the choroid plexus.• Further production also comes from the ependymal

cell linings and vessels within the pia mater.• Edendymal cell production of CSF is via ultrafiltration

of blood plasma and active transport across the ependymal cells.

• Of the total CSF production, 35% is produced within the third ventricle of the brain, 23% via the fourth ventricle and 42% from general ependymal cell filtration.

FUNCTION OF CSFFUNCTION OF CSF• Cerebrospinal fluid (CSF) surrounds the brain as well as the

central canal of the spinal cord.• It helps cushion the central nervous system (CNS), acting in a

similar manner to a shock absorber. • It also acts as a chemical buffer providing immunological

protection and a transport system for waste products and nutrients.

FUNCTION OF CSFFUNCTION OF CSF• The CSF also provides buoyancy to the soft neural tissues

which effectively allows the neural tissue to "float" in the CSF prevents the brain tissue from becoming deformed under its own weight.

• It acts as a diffusion medium for the transport of neurotransmitters and neuroendocrine substances.

FLOW OF CSFFLOW OF CSFCSF

(from choroid plexus)

Interventricular Foramina

3rd Ventricle(located in

diechephalon)

4th Ventricle(located in hindbrain)

Subarachnoid Space

Cerebromedullary cistern

Circulate over the cerebral hemisphere

Flows down the length of spinal cord in the subarachnoid

space

Dura & Arachnoid Meninges

Drained into venous sinuses

(through arachnoid granulation in dorsal

sagittal sinus)

Hydrostatic

pressure

Central canal of spinal cord

Through cerebral aqueduct

MAJOR MAJOR ARTERIES ARTERIES SUPPLYINSUPPLYIN

G G HEAD AND HEAD AND

NECKNECK

Arteries supplying Head & Arteries supplying Head &

NeckNeck

The major arteries supplying head and neck derived from :

1. Common carotidi. internal carotid arteryii. External carotid artery

2. Subclavian arteries3. Vertebral artery

(branched from 1st part of subclavian a.)

Common Carotid ArteryCommon Carotid Artery

• CCA runs upwards to the sup. border of thyroid cartilage at C3

• Bifurcates into external and internal carotid a.

Blood supply- Arteries

I The external carotid artery provides the major blood

supply for the face and mouth.

• The two major terminal branches of the external carotid

artery are the maxillary and the facial arteries.

Blood supply- Arteries

Blood supply- Arteries i. The maxillary artery is the large of the two terminal branches of the external carotid artery.

• It arises behind the angle of the mandible and supplies the deep structures of the face.

Blood supply- ArteriesMajor branches of the maxillary artery:

1. Infraorbital artery2. Posterior superior alveolar artery3. Inferior alveolar artery

1

2

3

Blood supply- Arteries

1. Infraorbital artery gives branches to anterior and middle superior alveolar

arteries. Their distribution to the maxillary incisors and cuspid teeth and to

the maxillary sinuses.

2. Posterior superior alveolar artery. Its distribution is to the maxillary molar

and premolar teeth and gingiva.

3. Inferior alveolar artery. It descends close to the medial surface of the

mandibular ramus to the mandibular foramen. Before entering the foramen, it

gives off the mylohyoid branch which supplies tissues in the floor of the

mouth.

Blood supply- Arteries

ii. The facial

artery is the other major

branch of the external

carotid artery.

• It enters the face at the

inferior border of the

mandible. It passes forward

and upward across the

cheek towards the angle of

the mouth.

• It continues upward

along the side of the nose

and ends at the medial

canthus (inner corner) of

the eye.

Blood supply- Arteriesiii. The lingual artery also is a branch of the external carotid artery.

• Its distribution is along the surface of the tongue.

Internal Carotid Internal Carotid ArteryArtery

• There are no branches of ICA in the neck; passes superiorly in the neck within carotid sheath anterior to transverse process of upper cervical vertebrae and enters skull thru carotid canal

• At its root, ICA has a dilatation area a.k.a carotid sinus

• Inside skull, gives off to

opthalmic a. (supplies optic nerve,

eye, orbit an scalp)

Arterial supply of the Arterial supply of the brainbrain

• Normally divided into anterior and posterior cerebral circulation

• Two main pair of artery supplying cerebral artery and cerebrum:

i. Int carotid a.ii. Vertebral a.

Venous Drainage of the Head Venous Drainage of the Head

and Neckand Neck• The veins of the head and neck collect

deoxygenated blood and return it to the heart. • Anatomically, the venous drainage can be divided

into three parts:o Venous drainage of the brain and meninges: Supplied by the dural

venous sinuseso Venous drainage of the scalp and face: Drained

by veins synonymous with the arteries of the face and scalp. These drain into the internal and external jugular veins.

o Venous drainage of the neck: Carried out by the anterior jugular veins.

External Jugular External Jugular VeinVein

• The external jugular vein and its tributaries supply the majority of the external face.

• It is formed by the union of two veins:o Posterior auricular vein - drains the area of scalp superior and

posterior to the outer ear.o Retromandibular vein (anterior branch) – itself formed by the

maxillary and superficial temporal veins, which drain the face.

Anterior Jugular Anterior Jugular VeinsVeins

• The anterior jugular veins vary from person to person.

• They are paired veins, which drain the anterior aspect of the neck.

• Often they will communicate via a jugular venous arch.

• The anterior jugular veins descend down the midline of the neck, emptying into the subclavian vein.

Internal Jugular Internal Jugular VeinVein

• The internal jugular vein (IJV) begins in the cranial cavity, as a continuation of the sigmoid sinus

• The initial part of the IJV is dilated, and is known as the superior bulb. 

• The vein exits the skull via the jugular foramen.

• In the neck, the internal jugular vein descends within the carotid sheath, deep to the sternocleidomastoid, and lateral to the common carotid artery.

• At the bottom of the neck, posteriorly to the sternal end of the clavicle, the IVJ combines with the subclavian vein to form the brachiocephalic vein.

• Immediately before its termination, the inferior end of internal jugular vein dilates, to form the inferior bulb of the IJV. 

Dural Venous Dural Venous SinusesSinuses

• The dural venous sinuses are spaces between the periosteal and meningeal layers of dura mater, which are lined by endothelial cells.

• They collect venous blood from the veins that drain the brain and bony skull, and ultimately drain into the internal jugular vein.