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SKULLSKULL & ORBIT see handouts

ORBITAL REGIONFronto-Zygomatic suture – over outer canthus, palpate w/finger tipsSuperior 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 glabellaNasolacrimal 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.

SKULLSKULL & 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.

SKULLSKULL & ORBIT

SKULL REGION

MASTOID PROCESS

SKULLSKULL & ORBIT

LINES AND POINTS

OML (radiographic)IOML (Reids)EAMGMLAuricular line - @ rt. angles to IOML through EAMInterpupilary LineAMLGALInion – (EOP) unmistakably foundLambda – 3”in. above inion (meeting of lamboid and Sagittal suture)Inner cantusOuter cantus

SKULLSKULL & 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.

SKULLSKULL & ORBIT

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

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

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VESSELS:

4. Superficial temporal – feeds the scalp. (ant. & post. brain

SKULLSKULL & ORBITVESSELS:

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.

SKULLThe 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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SKULL6. Vertebral artery – runs up back of neck through the vertebral foramina in the transverse processes. (C-1 – C-6)

SKULLVenous Sinuses of the skull: are channels between the two layers of the dura matter (outer)

Venous Sinuses Dura Matter

SKULLVenous 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….

SKULLFIVE LOBES OF THE BRAIN

1. Frontal – ant. above orbits & nasal cavities, lower border is ½” above fronto-zygomatic suture.

SKULLFIVE LOBES OF THE BRAIN

2. Temporal – lower border corresponds approx. to the upper border of Zygoma.

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3. Occipital – continuation of temporal lobe runs above Zygomatic arch down to the EOP.

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4. Parietal – lies in posterior cranial fossa below level of inion.

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5. Insula – lies behind occipital bone “5th Lobe”

SKULLFIVE LOBES OF THE BRAIN

SKULLMAJOR FISSURES OF THE BRAIN

Fissures divide the lobes of the brain1. 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.

Longitudinal Fissure Corpus Callousum Falx Cerebri

SKULLMAJOR FISSURES OF THE BRAIN

Fissures divide the lobes of the brain

2. Transverse Fissure – separates the cerebrum from the cerebellum

SKULLMAJOR FISSURES OF THE BRAIN

Fissures divide the lobes of the brain

3. Central Fissure *Rolando Fissure – separates frontal & parietal lobes.

SKULLMAJOR FISSURES OF THE BRAIN

Fissures divide the lobes of the brain

4. Lateral Fissure *Sylvian Fissure – separates frontal & parietal lobes above & temporal below

SKULLMAJOR FISSURES OF THE BRAIN

Fissures divide the lobes of the brain

5. Parietal/Occipital Fissure– separates parietal lobes & occipital lobe

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SKULLANATOMY

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.

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

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

SKULLANATOMYLayers of material

before the brain:

A. SkullB. PeriostemC. Dura materD. Subdural spaceE. ArachnoidF. Subarachniod (vessels lie here)G. Pia materH. The brain

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

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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

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

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

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Meningies:- arachnoid - middle

Arachnoid cyst; sonogram

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Meningies:- duramatter – outer – (spinal cord)

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Brainstem: includes,-Medulla

-Pons-Midbrain

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

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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

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Brainstem: Midbrain

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

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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.

SKULLVentricles: Various Imaging

Modalities

SKULLCSF (Cerebral Spinal Fluid)

-Baths the brain and spinal cord-Provides a protective cushion-Formed in the Choroid Plexus-Contains H2O,electrocytes, and proteins

SKULLChoroid Plexus

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

SKULLCerebellum

-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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SKULLTHIRD VENTRICLE

- Lies in middle of forebrain- Superior to the Sella Turcica

SKULLFourth 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.

SKULLLateral 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

SKULLLateral Ventricle

Communications (4)1. Foramen of Monro (Interventricular) – connects lateral ventricle to upper part of third ventricle.

SEE HANDOUT…

SKULLLateral Ventricle

Communications (4)2. Foramen of MAGENDIE – extends from midline of roof of the 4th ventricle to the subarachnoid space.

SEE HANDOUT…

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.

SKULLLateral 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…

SKULLLateral Ventricle

Communications (4)4. Aqueduct of Sylvius (cerebral) – connects posterior portion of 3rd ventricle to the 4th ventricle.

SEE HANDOUT…

SKULLOld 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.

SKULLFalx 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.

SKULLGLANDS

1. Pituitary Gland:

-Located in st.-Endocrine gland-Master gland, secretions stimulate-other endocrine glands-Stimulates growth

The pituitary gland, or hypophysis,

SKULLGLANDS

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.

SKULLGLANDS

2. Thalmus

-Influences mood-Between cerebrum and midbrain-Rely station

The ThalamusThe thalamus is the way-station of the brain's networks. It has three circuits running through its walnut sized core.

SKULLGLANDS

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

SKULLSTRUCTURES

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.

SKULLSTRUCTURES

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.

SKULLSTRUCTURES

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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SKULLANATOMY

Cranium (8) Bones

-surround and protect the brainOccipital (1)Temporal (2)Sphenoid (1)Ethmoid (1)Parietal (2)Frontal (1)

SKULLANATOMYCranium (8) Bones

Occipital (1)-Forms inferiorposterior portion of the cranium-Foramen magnum-Prominent bump, EOP, Inion

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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

SKULLANATOMY

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)

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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)

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Ethmoid

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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.

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Frontal (1)

Vertical portion:-Squamous (forehead), anterior vault-Frontal sinuses-glabella

Horizontal Portion-Forms roof of ea. Orbit (orbital plate)

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

SKULLANATOMY

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.

SKULLANATOMY

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.

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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

SKULLANATOMY

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

SKULLANATOMY

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

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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.

SKULLANATOMY

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

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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.

SKULLANATOMY

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]

SKULLANATOMYORBITS

-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.

SKULLANATOMY

ORBITS (3) OPENINGS

1. Superior Orbital Fissure2. Inferior Orbital Fissure3. Optic Canal

SKULLSUTURES

1. Squamous Suture- on the side of the cranium, joins temporal and parietal bone.

2. Coronal Suture – runs transversely across the top of the cranium and is the articulation between thefrontal and parietal bones.

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3. Sagittal Suture – articulation between parietal bone and MSP.

4. Lambdoidal Suture – posterior in cranium and joins the occipital and parietal bones.

SKULLCEREBRAL 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.

SKULLVENOUS DRAINAGE (3) SEGEMENTS

(Sinuses)

1. Cerebral – drains superficial and deep inner-lying veins (drains into the dural).

2. Dural – receives blood from the cerebral veins. (drains into the internal jugular segment).

3. Internal Jugular Segment- begins with the sigmoid sinus. (drains out into jugular foramen).

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12 Cranial Nerves

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.