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SKULL & ORBIT see handouts ORBITAL REGION Fronto-Zygomatic suture – over outer canthus, palpate w/finger tips Superior Orbital Notch – located in sup. orbital rim, (highest point of curve. Supercilliary Ridge – palpated bilaterally @ the most medial aspect of the orbit. Glabella – located on frontal bone. Flattened midline area between (2) ridges, differs from one subject to another. Nasion – ½” below glabella Nasolacrimal Canal – inner cantus of eye, located by pressing lightly when eye is closed. Anterior Nasal Spine – “False Spine” @ acanthion,. Zygomatic Arch – palpate don lateral aspect of head.

SKULL SKULL & ORBIT SKULL REGION Mastoid Process – push auricle of ear forward and palpate. Pre-auricular point – on root of Zygomatic arch, verified by feeling faint pulse of the superficial temporal artery over that bone. Head of mandible – palpate by pushing tragus up w/ moving jaw from side to side.

SKULL SKULL & ORBIT SKULL REGION MASTOID PROCESS

SKULL SKULL & ORBIT LINES AND POINTS OML (radiographic) IOML (Reids) EAM GML Auricular line - @ rt. angles to IOML through EAM Interpupilary Line AML GAL Inion – (EOP) unmistakably found Lambda – 3”in. above inion (meeting of lamboid and Sagittal suture) Inner cantus Outer cantus

SKULL SKULL & ORBIT VESSELS: 1. Common carotid artery – behind anterior border of sternomastoid muscle. Runs from SC.jt to level of upper border of thyroid cartilage. (c-4) it divides into internal and external carotids.

SKULL SKULL & ORBIT VESSELS: 2. External carotid artery – after bifurcation @tragus divides into maxillary and superficial temporal arteries.

SKULL SKULL & ORBIT VESSELS: 3.Maxillary artery – feeds maxilla and facial bones.

SKULL SKULL & ORBIT VESSELS: 4. Superficial temporal – feeds the scalp. (ant. & post. brain

SKULL SKULL & ORBIT VESSELS: 5.Internal carotid artery – runs upward entering skull through carotid canal in temporal bone. Supplies the ant. 2/3 of the brain with blood. It eventually unites w/the opposite int. car. & vertebral art. via the Circle of Willis & basilar art. @ the base of the brain.

SKULL The circle of Willis (also called the cerebral arterial circle or arterial circle of Willis) is a circle of arteries that supply blood to the brain. It is named after Thomas Willis (1621-1673), an English physician.[1]

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SKULL 6. Vertebral artery – runs up back of neck through the vertebral foramina in the transverse processes. (C-1 – C-6)

SKULL Venous Sinuses of the skull: are channels between the two layers of the dura matter (outer) Dura Matter Venous Sinuses

SKULL Venous Sinuses: Blood Drains,→ 1. SSS (Superior Sagittal Sinus) runs from glabella to inion. → 2. Transverse Sinus - @ inion it travels lat. to a pt. opp. the base of the mastoid process.→ 3. Jugular foramen – where blood leaves skull and transverse sinus becomes internal jugular vein►►►► empties into subclavian vein….

SKULL FIVE LOBES OF THE BRAIN 1. Frontal – ant. above orbits & nasal cavities, lower border is ½” above fronto-zygomatic suture.

SKULL FIVE LOBES OF THE BRAIN 2. Temporal – lower border corresponds approx. to the upper border of Zygoma.

SKULL FIVE LOBES OF THE BRAIN 3. Occipital – continuation of temporal lobe runs above Zygomatic arch down to the EOP.

SKULL FIVE LOBES OF THE BRAIN 4. Parietal – lies in posterior cranial fossa below level of inion.

SKULL FIVE LOBES OF THE BRAIN 5. Insula – lies behind occipital bone “5th Lobe”

SKULL FIVE LOBES OF THE BRAIN

MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain SKULL MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain 1. Longitudinal Fissure – divide the cerebrum into (2) hemispheres. Separation is complete ant/post., however, the hemispheres are connected by a band of white fibers in the center called the Corpus Callousum. The long. Fissure also contains Falx Cerebri which is an extension of the dura matter. Corpus Callousum Falx Cerebri Longitudinal Fissure

MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain SKULL MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain 2. Transverse Fissure – separates the cerebrum from the cerebellum

MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain SKULL MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain 3. Central Fissure *Rolando Fissure – separates frontal & parietal lobes.

MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain SKULL MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain 4. Lateral Fissure *Sylvian Fissure – separates frontal & parietal lobes above & temporal below

MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain SKULL MAJOR FISSURES OF THE BRAIN Fissures divide the lobes of the brain 5. Parietal/Occipital Fissure– separates parietal lobes & occipital lobe

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SKULL ANATOMY Cerebrum: * largest and most prominent part of the human brain * governs all higher mental processes * stimulates sensation, controls motor activities. * center for reason, intellect, memory, language, and consciousness. * Has (2) hemispheres and is separated by a longitudinal fissure.

SKULL ANATOMY Midbrain/Mesencephalon: * smallest aspect of brainstem * extends from the Pons to the diencephalon * rests on sphenoid bone * involved in hearing and visual reflexes

SKULL ANATOMY Diencephalon: * located between the cerebrum & mesencephalon * consists of several structures and is near the 3rd ventricle. * houses the thalamus and hypothalamus glands

SKULL ANATOMY Layers of material before the brain: Skull Periostem Dura mater Subdural space Arachnoid Subarachniod (vessels lie here) Pia mater The brain

SKULL ANATOMY Gray Matter: Groups of cell bodies and their dendrites on surface of brain called – Cortex deep within the brain – Nuclei

SKULL ANATOMY White Matter: Bundles of axons and their myelin sheaths sheets Forms the conduction pathways of nerve tracts which propagate messages from one area of gray mater to the next

SKULL ANATOMY Meningies: Covering of the brain into (3) layers, A. pia matter- inner – (attached to brain) B. arachnoid – middle C. duramater – outer – (spinal cord)

SKULL ANATOMY Meningies: pia matter- inner – (attached to brain)

Arachnoid cyst; sonogram SKULL ANATOMY Meningies: arachnoid - middle Arachnoid cyst; sonogram

SKULL ANATOMY Meningies: duramatter – outer – (spinal cord)

SKULL ANATOMY Brainstem: includes, Medulla Pons Midbrain

SKULL Brainstem: Medulla Oblongata ANATOMY Most inferior portion of the brain stem Continuous w/spinal cord Contains vital centers that regulate; Heartbeat, respiration and blood pressure

SKULL ANATOMY Brainstem: Pons Bridge Lies just above medulla and is cont. with it Connective link for various aspects of the brain Relays info. Between cerebrum and cerebellum

SKULL ANATOMY Brainstem: Midbrain -smallest aspect of brainstem -extends from the Pons to the diencephalon -rests on sphenoid bone - involved in hearing and visual reflexes

SKULL ANATOMY Ventricles: Fluid filled cavities within the brain where CSF flows. CSF flows from the lateral ventricle to the 3rd ventricle, through the cerebral aqueduct to the 4th ventricle then into the subarachnoid space.

Ventricles: Various Imaging Modalities SKULL Ventricles: Various Imaging Modalities

CSF (Cerebral Spinal Fluid) SKULL CSF (Cerebral Spinal Fluid) -Baths the brain and spinal cord -Provides a protective cushion -Formed in the Choroid Plexus -Contains H2O,electrocytes, and proteins

SKULL Choroid Plexus Specialized structure in the ventricles Produces CSF Start as tiny blood ves. within the 3rd vent. & lat. vent.’s

SKULL Cerebellum Second largest aspect of the brain Responsible for smooth coordinated movement The cerebellum (Latin: "little brain") is a region of the brain that plays an important role in the integration of sensory perception and motor control.

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SKULL THIRD VENTRICLE - Lies in middle of forebrain - Superior to the Sella Turcica

SKULL Fourth Ventricle Lies in the hindbrain The fourth ventricle has a characteristic diamond shape in cross-sections of the human brain. It is located within the pons or in the upper part of the medulla.

SKULL Lateral Ventricle’s One in each hemisphere of the cerebrum separated by the corpus callosum Communicate with each other The lateral ventricles are part of the ventricular system of the brain. Classified as part of the telencephalon, they are the largest of the ventricles. corpus callosum

Lateral Ventricle Communications (4) SKULL Lateral Ventricle Communications (4) 1. Foramen of Monro (Interventricular) – connects lateral ventricle to upper part of third ventricle. SEE HANDOUT…

Lateral Ventricle Communications (4) SKULL Lateral Ventricle Communications (4) 2. Foramen of MAGENDIE – extends from midline of roof of the 4th ventricle to the subarachnoid space. The median aperture of the brain (or foramen of Magendie) is an opening in the hollow nerve tube, connecting the fourth ventricle of the brain with the subarachnoid space. SEE HANDOUT…

Lateral Ventricle Communications (4) SKULL Lateral Ventricle Communications (4) 3. Foramen of LUSCHKA – extends from the roof of the lateral recesses of the 4th ventricle to the subarachnoid space. SEE HANDOUT…

Lateral Ventricle Communications (4) SKULL Lateral Ventricle Communications (4) 4. Aqueduct of Sylvius (cerebral) – connects posterior portion of 3rd ventricle to the 4th ventricle. SEE HANDOUT…

SKULL Old CSF Is disposed of through osmosis through the arachnoid villi on the top of the brain and filters into the bloodstream. Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient.

SKULL Falx Cerebri The falx cerebri, so named from its sickle-like form, is a strong, arched fold of dura mater which descends vertically in the longitudinal fissure between the cerebral hemispheres. It is also attached to the occipital bone.

SKULL GLANDS The pituitary gland, or hypophysis, Located in st. Endocrine gland Master gland, secretions stimulate other endocrine glands Stimulates growth The pituitary gland, or hypophysis,

SKULL GLANDS Endocrine glands are glands that secrete their product (hormones) directly into the blood rather than through a duct. This group contains the glands of the Endocrine system. The main Endocrine glands include the pituitary gland, the pancreas, the gonads, the thyroid gland and the adrenal glands. Other organs which are not so well known for their endocrine activity include the stomach, which produces such hormones as ghrelin.

SKULL GLANDS 2. Thalmus -Influences mood -Between cerebrum and midbrain -Rely station The Thalamus The thalamus is the way-station of the brain's networks. It has three circuits running through its walnut sized core.

SKULL GLANDS 3. Pineal Gland -Endocrine gland that influences the onset of puberty -Calcifies over later in life -Located in body of thalamus

SKULL STRUCTURES Caudate Nucleus -located in the center of all white matter Center of cerebrum Island of gray matter Basal-ganglia (posture) The basal ganglia (or basal nuclei) are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. Mammalian basal ganglia are associated with a variety of functions: motor control, cognition, emotions and learning.

SKULL STRUCTURES Corpus Callosum -vast nerve tracts Allow communication between the (2) hemispheres The corpus callosum is a structure of the mammalian brain in the longitudinal fissure that connects the left and right cerebral hemispheres. It is the largest white matter structure in the brain, consisting of 200-250 million contralateral axonal projections. It is a wide, flat bundle of axons beneath the cortex. Much of the inter-hemispheric communication in the brain is conducted across the corpus callosum.

SKULL STRUCTURES Peduncles -white matter that allows communication between different aspects of the brain. In anatomy, a cerebral peduncle is a band of neurons, resembling a stalk, which connect varied parts of the brain

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SKULL ANATOMY Cranium (8) Bones Occipital (1) Temporal (2) -surround and protect the brain Occipital (1) Temporal (2) Sphenoid (1) Ethmoid (1) Parietal (2) Frontal (1)

SKULL ANATOMY Cranium (8) Bones Occipital (1) -Forms inferiorposterior portion of the cranium -Foramen magnum -Prominent bump, EOP, Inion

SKULL ANATOMY Temporal (2) -Contain many complex structures -Forms both sides of the base of the cranium. -Ant.- Zygomatic Arches, -Petrous pyramids -TMJ, EAM, IAM -Hearing, balance, equilibrium -Jugular foramina & Carotid canals

SKULL ANATOMY Sphenoid (1) -Butterfly shaped bone -(3) Major parts; a. body, b. lesser wings, c. greater wings -Body contains the ST, houses the pituitary gland(hypophysis)

SKULL ANATOMY Ethmoid (1) -Smallest of cranial fossa bones -Cube shaped, divides into (4) parts; 1. Horizontal portion (cribriform plate)(horizontal plate) contains olfactory nerves, Crista galli which anchors the brain to the anterior cranial fossa. 2. Vertical portion (perpendicular plate) – forms bony nasal septum 3&4. two lateral masses (labyrinths), thin walls containing Ethmoid air cells. Also contain middle and superior nasal conchae (turbinate's)

SKULL ANATOMY Ethmoid

SKULL ANATOMY Parietal (2) -2 sides form most of the cranium -Superior aspect (vertex) each side is somewhat square in shape and have a concave internal surface.

SKULL ANATOMY Frontal (1) Vertical portion: -Squamous (forehead), anterior vault -Frontal sinuses -glabella Horizontal Portion -Forms roof of ea. Orbit (orbital plate)

SKULL ANATOMY FACIAL BONES (14) Nasal (2) Lacrimal (2) Maxilla (2) Zygoma (2) Palantine (2) Inferior Nasal Conche (2) Vomer (1) Mandible (1)

SKULL ANATOMY FACIAL BONES (14) Nasal (2) The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.

SKULL ANATOMY FACIAL BONES (14) Lacrimal (2) The lacrimal bone, the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders.

SKULL ANATOMY FACIAL BONES (14) Maxilla (2) The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible, which is also a fusion of two halves at the mental symphysis

SKULL ANATOMY FACIAL BONES (14) Zygoma (2) The zygomatic bone (malar bone) is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It forms part of the orbit and is commonly referred to as the cheekbone

SKULL ANATOMY FACIAL BONES (14) Palantine (2) The palatine bone is a bone in the palate (Latin palatum; unrelated to palatium 'palace', from which other senses of palatine derive

SKULL ANATOMY FACIAL BONES (14) Inferior nasal conchae (2) The inferior nasal concha (Inferior Turbinated Bone) is one of the turbinates in the nose. It extends horizontally along the lateral wall of the nasal cavity [Fig. 1] and consists of a lamina of spongy bone, curled upon itself like a scroll.

SKULL ANATOMY FACIAL BONES (14) Volmer (1) The Vomer (from Latin vomer, -ĕris, "ploughshare") is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and touches the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones

SKULL ANATOMY FACIAL BONES (14) Mandible (1) The mandible (from Latin mandibūla, "jawbone") or inferior maxillary bone is, together with the maxilla, the largest and strongest bone of the face [citation needed]. It forms the lower jaw and holds the lower teeth in place.

SKULL ANATOMY ORBITS (2) In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. It can also mean the skin which surrounds the eye of a bird. In the adult human, the volume of the orbit is 30 ml, of which the eye occupies 6.5 ml. [1]

SKULL ANATOMY ORBITS -Cone shaped structure -Surrounds and protects the eyeball (Oculus Bulbous) -Created by the junction of the sphenoid, frontal and Ethmoid bone of the cranium -Also created by the junction of the Lacrimal, palatine, maxillary and Zygoma bones of the face.

SKULL ANATOMY ORBITS (3) OPENINGS Superior Orbital Fissure Inferior Orbital Fissure Optic Canal

SKULL SUTURES Squamous Suture- on the side of the cranium, joins temporal and parietal bone. Coronal Suture – runs transversely across the top of the cranium and is the articulation between thefrontal and parietal bones.

SKULL SUTURES 3. Sagittal Suture – articulation between parietal bone and MSP. 4. Lambdoidal Suture – posterior in cranium and joins the occipital and parietal bones.

CEREBRAL VASCULAR SYSTEM SKULL CEREBRAL VASCULAR SYSTEM -Thin and weak, have no valves. Allows blood to flow in either direction, this is a problem because it may create a route for blood-borne-pathogens to pass from the body to the brain and the brain to the body…. The blood-brain barrier (BBB) is a membranic structure that acts primarily to protect the brain from chemicals in the blood, while still allowing essential metabolic function. It is composed of endothelial cells, which are packed very tightly in brain capillaries. This higher density restricts passage of substances from the bloodstream much more than endothelial cells in capillaries elsewhere in the body. Astrocyte cell projections called astrocytic feet (also known as "glial limitans") surround the endothelial cells of the BBB, providing biochemical support to those cells. The BBB is distinct from the similar blood-cerebrospinal fluid barrier, a function of the choroidal cells of the choroid plexus.

VENOUS DRAINAGE (3) SEGEMENTS (Sinuses) SKULL VENOUS DRAINAGE (3) SEGEMENTS (Sinuses) Cerebral – drains superficial and deep inner-lying veins (drains into the dural). Dural – receives blood from the cerebral veins. (drains into the internal jugular segment). Internal Jugular Segment- begins with the sigmoid sinus. (drains out into jugular foramen).

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12 Cranial Nerves MR FACE CORONAL Numbered from anterior to posterior, according to their attachment to the brain…All have specific functions; touch, smell, sight, hearing, etc….. Cranial nerves are nerves that emerge directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized. The nerves from the third onward arise from the brain stem.

Olfactory Nerve (CN1) – “Smell” (18-20) small nerve bundles. Optic Nerve (CN2) – “Sight” arise from optic retina. Oculomotor Nerve (CN3) – “moves eye” emerges from midbrain. Trochlear Nerve (CN4) – “muscle” controls sup. orbital muscle. Trigeminal Nerve (CN5) – “sensory” (3) divisions, ophthalmic, maxillary and mandibular. Abducens Nerve (CN6) – “motor impulses” lat. movement of eye. Facial Nerve (CN7) – “taste” facial nerves and 2/3 of the tongue. Vestibulocochlear Nerve (CN8) – “sound” picks up sounds & interrupts. Glossopharyngeal Nerve (CN9) – “motor” impulses, monitors blood. VagusNerve (CN10) – “stimulates” pharynx, larynx, thoracic & abdomen viscera. Accessory Nerve (CN11) - “stimulates” pharynx, palatine & larynx. Hypoglossal Nerve (CN12) -“muscle” muscle of tongue.