Skull & Intracranial cavity

22 April 2010

Cranial Meninges

· Dura

– Same tough layer that covers spinal cord

– Has a tight adherence to the skull, particularly at the sutures

– Carries meningeal arteries

· Arachnoid

– Lines the inner surface of dura

– Subarachnoid space filled with cerebrospinal fluid

· Pia

– Covers surface and supports blood vessels

Netter, 2003 pl. 95; Netter, 2006 pl. 100

Deep to the dura...

· Subarachnoid space

· Cerebral veins on surface drain into venous sinuses in the dura

· Pia mater

Netter, 2003 pl. 96; Netter, pl. 102

The Venous sinus system of the skull is the course of venous drainage of the brain. Sinuses are enclosed within the dura.

· Cavernous sinus

· Sup. Petrosal sinus

· Transverse sinus

· Sigmoid sinus

· Jugular foramen

· Straight sinus

· Sup. Sagittal sinus

· Confluence of sinuses

Netter, 2003 pl. 98; Netter, 2006 pl. 104

Projections of the dura in the sagittal and horizontal planes separate parts of the brain.

· Falx cerebri

· Tentorium cerebelli - A sheet of dura that forms a floor that supports the occipital

lobes of the cerebrum and forms a roof for the posterior cranial fossa.

· Superior sagittal sinus this & other sinuses all drain into jugular vein

Netter, 2003 pl. 9, 97; Netter, 2006 pl. 11, 103

Cerebrospinal Fluid

· Choroid plexus

· 3rd ventricle

· Cerebral aqueduct

· 4th ventricle

· Lateral & median apertures

· Subarachnoid space cranial & spinal

· Arachnoid granulations

Martini Fig 15.6, see Netter 2003 pl. 103; Netter, 2006 pl. 109

Cranial Fossae & Landmarks

· Anterior, Middle & Posterior Cranial Fossae

– Crista galli

– Sphenoidal ridge

– Anterior clinoid pr.

– Sella turcica

– Posterior clinoid pr.

– Clivus

– Groove for middle meningeal a. & v.

– Petrous ridge

– Groove for sigmoid sinus

– Groove for transverse sinus

Netter, 2003 pl. 9; Netter, 2006 pl. 11

Foramina of the intracranial fossa

Cribiform plate (Olfactory)

Optic canal (Optic)

Superior Orbital Fissure

(Occulomotor, Trochlear,

Ophthalmic(V1), Abducens,)

F. Rotundum (Maxillary (V2))

F. Ovale (Mandibular (V3))

F. Lacerum

Internal Acoustic Meatus

(Facial, Vestibulocochlear)

Jugular F. (Glossopharyngeal,

Vagus, Accessory)

Hypoglossal Canal (Hypoglossal)

Foramen magnum

Netter, 2003 pl. 9; Netter, 2006 pl. 11

Features of the Ventral view of skull

Foramen ovale

Foramen lacerum

Foramen spinosum

Carotid canal

External auditory meatus

Styloid process

Stylomastoid foramen

Mastoid process

Jugular foramen

Occipital condyle

Netter, 2003 pl. 8; Netter, 2006 pl. 10

Parts of brain with respect to cranial nerves

Cerebral hemispheres

Midbrain

Pons

Cerebellum

Medulla

Netter 2003, pls. 100, 108; Netter, 2006 pl. 106, 114

Tentorial Incisure

Special Senses

· Special somatic afferent -- optic n, vewstibulocochlear n.

· Special Visceral afferent -- olfactory n., sense of taste from branches of facial and glossopharyngeal nn

CN V - Trigeminal nerve

· Semilunar ganglion

– V1 - Ophthalmic br.

– V2 - Maxillary br.

– V3 - Mandibular br.

Netter, 2003 pl. 116; Netter, 2006 pl. 122

Course of Facial nerve

· Internal acoustic meatus

· Facial canal

· Petrotympanic fissure

· Genicular ganglion

· Facial prominence of facial nerve

Netter, 2003 pl. 117; Netter, 2006 pl. 123

Blood Supply to Brain

· Anterior Cerebral aa.

– Anterior Communicating Br.

· Internal Carotid

– Middle Cerebral aa.

– Posterior Communicating Br.

· Posterior Cerebral

· Basilar a.

· Vertebral a.

Netter, 2003 pl. 130, 132, 133; Netter, 2006 pl. 136, 139, 140, .

Neurovascular relationships of the cavernous sinus

· Optic chiasm

· Hypophysis

· Internal carotid a.

· CN III

· CN IV

· CN VI

· CN V₁

· CN V₂

· Sphenoidal sinus

Netter, 2003 pl. 98; Netter, 2006 pl. 104