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

• Functions:1. Protecting the brain and

spinal cord from mechanical injury

2. Providing blood supply to skull & hemispheres

3. 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

blood supplyPia mater-innermost layer-”tender mother”

(latin name)

Production of CSFProduction of CSF

• Cerebrospinal Fliud (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.

Production of CSFProduction of CSF• 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.

• 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.

Function of CSFFunction of CSF

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

SUPPLYING SUPPLYING HEAD AND HEAD AND

NECKNECK

Arteries supplying Arteries supplying Head & NeckHead & Neck

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

The external carotid artery: provides the major blood supply for the face and mouth.

• The two major terminal branches of the external carotid artery:

the maxillary arteries

facial arteries

Blood supply- Arteries

• 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- Arteries

Major 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 canine 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

• 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- Arteries

• The lingual artery also is a branch of the external carotid artery.

Its distribution is along the surface of the tongue.

Blood supply- Arteries

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 through 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. Internal carotid arteryii. Vertebral artery

Venous Drainage of Venous Drainage of the Head and Neckthe Head and 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:1. Venous drainage of the brain and meninges:

Supplied by the dural venous sinuses2. 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.

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

External Jugular VeinExternal Jugular Vein• 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.

External Jugular VeinExternal Jugular Vein

Anterior Jugular VeinsAnterior Jugular Veins• 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.

Anterior Jugular VeinsAnterior Jugular Veins

Internal Jugular VeinInternal Jugular Vein• 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. 

Internal Jugular VeinInternal Jugular Vein

Internal Jugular VeinInternal Jugular Vein

Dural Venous SinusesDural Venous Sinuses• 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.

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