Cranial Cavity Lab

Anterior Cranial Fossa

• Cribriform plate (ethmoid bone): Houses olfactory nerves (CN I) from the nasal cavity to olfactory bulbs.

• Lesser wings (sphenoid bone).

• Crista galli (ethmoid bone): Vertical projection where the falx cerebri (a dural fold) attaches.

Middle Cranial Fossa

• Body of sphenoid bone.

• Greater wings (sphenoid).

• Squamous and petrous parts (temporal bone): Hosts inner ear structures.

• Optic canals: Transmit optic nerves (CN II) and ophthalmic artery.

• Superior orbital fissures: Passage for CN III (oculomotor), CN IV (trochlear), CN V1 (ophthalmic branch), CN VI (abducens), and superior ophthalmic vein.

• Foramina:

  • Foramen rotundum: Maxillary nerve (CN V2).

  • Foramen ovale: Mandibular nerve (CN V3).

  • Foramen spinosum: Middle meningeal artery and vein.

  • Foramen lacerum: Filled with cartilage in life.

• Sella turcica: Holds the pituitary gland in its hypophysial fossa.

• Grooves for middle meningeal arteries: Impressions from the middle meningeal arteries supplying meninges.

Posterior Cranial Fossa

• Clivus: Supports the brainstem.

• Foramen magnum: Spinal cord, vertebral arteries, and spinal part of CN XI pass through.

• Hypoglossal canals: Transmit hypoglossal nerves (CN XII) for tongue muscle innervation.

• Jugular foramina: Contains internal jugular vein, CN IX (glossopharyngeal), CN X (vagus), CN XI (accessory).

• Internal acoustic meatuses: Passage for Facial (CN VII) and vestibulocochlear (CN VIII) nerves.

• Grooves for superior petrosal, transverse, and sigmoid sinuses: Impressions for venous sinuses draining blood from the brain.

Scalp and Meninges

Scalp Layers

• Skin: Protective covering with hair follicles and glands.

• Dense connective tissue: Contains dense connective tissue, providing structure.

• Aponeurosis: Tendinous layer connecting frontalis and occipitalis muscles, allowing scalp movement.

• Loose connective tissue: Provides mobility for the scalp over the skull.

• Periosteum: Dense covering over skull bones.

Meninges

• Dura mater: Tough outer layer protecting the brain.

• Arachnoid mater: Web-like middle layer containing cerebrospinal fluid (CSF) in the subarachnoid space.

• Pia mater: Delicate inner layer covering the brain's surface.

Spaces

• Epidural space: Potential space between dura and skull.

• Subdural space: Between dura and arachnoid mater, with small blood vessels.

• Subarachnoid space: Contains CSF, cushioning the brain.

Other Meningeal Features

• Arachnoid granulations: Allow CSF drainage into the venous system via dural sinuses.

• Dural venous sinuses: Drain blood from the brain (e.g., superior/inferior sagittal sinus, transverse sinus).

  • Contains structures such as CN III, IV, V1, V2, VI in the cavernous sinus.

• Dural folds:

  • Falx cerebri: Separates cerebral hemispheres.

  • Tentorium cerebelli: Separates cerebrum from cerebellum.

  • Falx cerebelli: Separates cerebellar hemispheres.

  • Tentorial notch: Opening for brainstem passage.

Brain Arteries

• Vertebral arteries: Supply posterior brain.

• Basilar artery: Supplies brainstem and cerebellum.

• Internal carotid arteries: Supply anterior and middle brain regions.

• Cerebral arteries:

  • Anterior cerebral artery: Supplies medial frontal lobes.

  • Middle cerebral artery: Supplies lateral brain surfaces.

  • Posterior cerebral artery: Supplies occipital lobes.

  • Superior cerebellar artery: Supplies upper cerebellum.

• Communicating arteries: Connect circle of Willis for collateral circulation.

Other Structures in the Neck and Face

Emissary Veins

• Connect internal skull veins (dural venous sinuses) to external veins, assisting blood drainage from the brain.

Diploe

• Layer of spongy bone between inner and outer cortical bone layers in the skull.

Orbit Lab Bones

• Lacrimal bone: Medial wall of the orbit.

• Nasolacrimal canal: Carries tears from lacrimal sac to nasal cavity.

• Ethmoid bone (lamina papyracea): Medial wall.

• Zygomatic bone: Lateral wall of the orbit.

• Sphenoid bones: Greater wing (lateral wall) and lesser wing (posterior wall/roof).

• Frontal bone (orbital plate): Roof of the orbit.

• Maxilla: Floor and medial wall of the orbit.

• Foramina and canals: Pathways for nerves and vessels, including optic canal and superior orbital fissure.

Structures of the Living Eye and Lacrimal Apparatus

• Cornea: Focus light.

• Sclera: The eye's protective outer layer.

• Iris: Controls pupil size.

• Conjunctiva: Lubricates the eye.

• Lacrimal structures: Facilitate tear production.

Nerves of the Orbit

• Ophthalmic nerve (CN V1): Sensation to forehead, scalp, upper eyelid.

• Frontal nerve: Splits into:

  • Supraorbital nerve: Supplies forehead sensation.

  • Supratrochlear nerve: Medial forehead sensation.

• Lacrimal nerve: Innervates the lacrimal gland and conjunctiva.

• Nasociliary nerve: Sensation to eye and nasal cavity.

Extraocular Muscles

• Superior rectus: Elevates and adducts the eye.

• Inferior rectus: Depresses and adducts the eye.

• Medial rectus: Adducts the eye.

• Lateral rectus: Abducts the eye.

• Superior oblique: Depresses and abducts the eye.

• Inferior oblique: Elevates and abducts the eye.

• Levator palpebrae superioris: Elevates upper eyelid.

Neck Lab Osteology

• Clavicle, Sternum: Support thoracic structure.

• Mastoid process: Attachment for sternocleidomastoid (SCM).

• Hyoid: Aids in tongue movement and swallowing.

• Triangular areas:

  • Posterior triangle: Contains CN XI, external jugular vein.

  • Anterior triangle: Major blood vessels and cranial nerves.

Muscles

• SCM: Rotates and flexes the neck.

• Trapezius: Elevates and retracts the scapula.

• Platysma: Tenses neck skin.

• Infrahyoid muscles: Depression of hyoid during swallowing.

Nerves

• Spinal accessory nerve (CN XI): Innervates SCM and trapezius.

• Phrenic nerve: Innervates diaphragm.

Vessels

• Internal and external jugular veins: Drain blood from brain and surface cranium.

• Subclavian veins: Drain upper extremities into brachiocephalic veins.

Vascular Supply of the Neck

• Aortic arch: Main arterial source.

• Carotid arteries: Internal supplying brain, external supplying face.

• Vertebral artery: Supplies brainstem and posterior brain.

Nerves of the Neck

• Vagus nerve (CN X): Functions in larynx, pharynx, parasympathetic processes.

• Hypoglossal nerve (CN XII): Controls tongue muscles.

Fascia

• Deep cervical fascia: Surrounds neck structures.

• Carotid sheath: Encloses carotid artery and internal jugular vein.

Face Lab Components

• Parotid region: Contains the parotid gland, critical for saliva production.

• Facial nerve branches: Innervate facial expression muscles.

Muscles of Facial Expression

• Temporalis: Elevates mandible for chewing.

• Zygomatic nerves: Innervate muscles of facial expressions.

• Buccal nerves: Innervate buccinator and expression-related muscles.

Vessels

• External carotid artery: Supplies blood to face, neck, and scalp.

• Facial artery and vein: Supply and drain blood from the face.

Nerves

• Trigeminal nerve (CN V): Sensory innervation through three divisions (V1, V2, V3).

External Ear Anatomy

• Auricle (Pinna): Collects sound waves.

• External Acoustic Meatus: Leads to TM; transmits sound waves.