Pages: 460-473
Blood supply of the brain
The blood supply of the
brain comes mainly from the
great cerebral circle which
lies ventral to hypothalamus.
-
-
-This
(formerly known as circle of Willis)
circle is supplied from:
-
Paired internal carotid artery
-
Basilar artery
-
Direct continuation of ventral spinal
artery (reinforced by anastomosis
with vertebral artery).
Venous drainage

The cranial sinuses enclosed within
Dura mater are divided into dorsal and
ventral system (limited communication)

The dorsal sinus collect blood from
dorsal part of the brain it includes:
 Dorsal sagittal sinus (within falx cerebri)
 Transverse sinuses within tentorium erebelli
Venous drainage
- The ventral or basilar system drains:
- The ventral part of the brain
- Receives major flow from veins that enter the
orbit after draining much of the face, including
the nasal cavity.
Cranial Nerves
•
Twelve pairs:
– 2 attach to forebrain
(Telen- & Diencephalon)
– 10 attach to
brainstem
(Midbrain, Pons, Medulla oblongata)
•
Names relate to
appearance or function
The 12 Pairs of Cranial Nerves
I - Olfactory Nerves - Sensory - sense of Smell [cribriform
plate] (neuron cell bodies located within olfactory epithelium
on the ethmoidal labyrinth.
II = Optic N. — Vision
[optic foramen]
cell bodies are in the retina (actually the "nerve" is a CNS tract
enveloped by meninges)
III - Oculomotor Nerves
[orbital fissure]
-Mixed nerve (motor & sensory)
- Primary motor: Innervates four of the extrinsic eye
muscles (dorsal, medial, & ventral rectus; ventral oblique)
(ciliary body {accommodation} & iris {constrict pupil}
The 12 Pairs of Cranial Nerves
IV - Trochlear Nerves
[orbital fissure]
-Mixed nerves, innervates an extrinsic eye muscle
- Dorsal oblique m
V - Trigeminal Nerves - Provides sensory innervation to
the face and motor innervation to chewing muscles
1- Ophthalmic n.: orbit; cornea; eyelids; & skin medial to eye
[orbital
fissure]
2- Maxillary n.: both lids laterally; upper jaw, teeth, lips;
nose & nasal cavity
[round f. & alar canal]
3- Mandibular n.: lower jaw, teeth, tongue; temporal region skin;
innervates muscles of mastication
[oval foramen]
VI -Abducens Nerve
[orbital fissure]
- Mixed nerve, Abducts the eyeball (Lateral rectus m. ), 3rd
eyelid & retractor bulbi m.
The 12 Pairs of Cranial Nerves
VII = Facial N.
[stylomastoid f.]
(Mixed)
-Facial expression (ears, eye lids, nose, & lips)
-Nasal glands, lacrimal gland, the two ventral
Salivary glands (sublingual & mandibular)
-Taste buds of rostral two-thirds of tongue

VIII - Vestibulocochlear Nerves
[internal acoustic meatus]
 -Sensory nerve of hearing and equilibrium
organ found within petrous part of temporal
bone:
The 12 Pairs of Cranial Nerves
IX - Glossopharyngeal Nerves
[jugular foramen]
- Mixed nerves, innervates structures of the tongue
and pharynx
-Taste; Pharyngeal sensation; Saliva
-taste buds at caudal 1/3rd of tongue
-parotid & zygomatic salivary glands
- Sensory receptors in pharynx, middle ear, and carotid sinus
& carotid body
The 12 Pairs of Cranial Nerves
X = Vagus N.
[jugular foramen]
-mm. of larynx, pharynx & esophagus (voice; cough;
swallow)
-Thoracic & abdominal viscera
(receptors in viscera and in the larynx, also pharynx
-Taste in region of pharynx
- Skin of external auditory meatus
XI = Accessory N.
[jugular foramen]
— Neck mm. [cleidocervicalis; cleidomastoideus;
omotransversarius; trapezius]
The 12 Pairs of Cranial Nerves
XII = Hypoglossal N.
[hypoglossal foramen]
— Tongue mm
- styloglossus, hyoglossus, genioglossus & intrinsic
musculature)
- contributes to innervations of sternohyoid &
sternothryroid mm.]