Anatomy Final Review PDF

Anatomy: Study of the structure of body parts Physiology: Study of the function of body parts The anatomical position is characterized by body erect, thumbs pointing laterally,and arms to the side. Transverse (horizontal) plane: Divides body horizontally (90°to vertical plane) into superior and i...

Anatomy: Study of the structure of body parts Physiology: Study of the function of body parts The anatomical position is characterized by body erect, thumbs pointing laterally,and arms to the side. Transverse (horizontal) plane: Divides body horizontally (90°to vertical plane) into superior and inferior parts (top and bottom). Produces a cross section Frontal Plane(coronal): Divide the body into anterior and posterior sections (vertically). Sagittarius Plane: Divide the body into left and right sections(vertically). Maintenance of homeostasis in the human body is accomplished mostly through negative feedback loops. Nervous system that has three overlapping functions are represented by sensory input, integration, and motor output. Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will be to sensory (afferent) division of the nervous system Cranial bones almost entirely surround the brain and protects it. The relationship between cranial bones is that its superficial to the brain. 1. Olfactory 2. Optic 3. Oculomotor 4. Trochlear 5. Trigeminal 6. Abducens 7. Facial 8. Vestibulocochlear 9. Glossopharyngeal 10. Vagus 11. Accessory 12. Hypoglossal The somatic nervous system is activated when a person extends their arm. The primary motor cortex is located in the frontal lobe, anterior to the central sulcus. The ventricles, within the central nervous system are continuous(all connected) and filled with cerebral spinal fluid. Functions of cerebral spinal fluids are nourishment of the brain, reduce brain weight, and protect from outside impacts. The corpus callosum is made up of commissural fibers and is also the large commissure that connects the right and left sides of the brain. Flexure lines: Dermal folds at or near joints. Skins inability to slide easily for joint movement causes deep creases. Collagen fibers running parallel to the skin surface; incisions parallel to these lines heal more readily is what causes cleavage(tension) lines in the reticular layer of the dermis. Lymphatic: picks up and cleans excess fluid from tissue Endocrine: controls body with chemical molecules(hormones). Endocrine gland stimulus humoral, hormonal and neural Integumentary System has two layers which are epidermis and dermis. Skin structure from superficial to deep is epidermis, dermis, and subcutaneous(hypodermis). Cells that's are found in epidermis and serve specific roles in protection and pigmentation are squamous cells, melanocytes(skin color), and dendritic cells. The skin constitutes three main types of barriers that help protect the skin are chemical, physical and biological. Sweat, sebrum, and acid mantle contribute to the skins chemical barrier. Squamous cells of the stratum corneum that are flat, dead and kerantinized describe the physical barriers of the skin. Keratinocytes, Melanocytes, Dendritic cells, and Tactile cells are the four main cell types found in the epidermis. The order of the epidermis layers from deepest layer is Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum, Stratum corneum. Stratum corneum: The layer of the epidermis where the cells are considered protective but nonviable. Stratum spinosum: The layer of the epidermis that is several layers thick and contains pre-keratin. Stratum basale: The layer that contains the mitotic viable cells of the epidermis. Stratum granulosum: The layer of the epidermis that contains one to five layers of flattened cells and deteriorating organelles. A needle would pierce the epidermal layers of the forearm by first piercing corneum, granulosum, spinosum, basale. Two layers of the dermis are the papillary and reticular. Reticular layer responsible for tension lines in skin Sudoriferous (sweat) glands are categorized as two distinct types that are eccrine and apocrine. The primary function of eccrine sweat glands is to regulate body temperature through sweat found in palms, soles and forehead. The primary function of apocrine sweat glands is the secretion of sweat that contributes to body odor when broken down by bacteria. The primary function of sebaceous glands is to produce oil(sebum) that lubricates skin and hair. The frontal bone is anterior to the occipital bone. The carpals are distal to the humerus. The tibia is proximal to the metatarsal. The heart is posterior to the sternum. Osteoclast: Breaks down bone. Osteocytes: reside in lacunae, maintain bone. Osteoblast: Builds up bone. Osteoprogenitor: Develop into Osteoblasts. Agonist: Primary muscle involved in the action. Muscle that is primarily responsible for bringing about a particular movement Fixator: Gives the primary muscle a stable base to act. Muscle that stabilizes the origin of another muscle Synergist: Assists the primary muscle in action. Muscle that aids another by promoting the same movement Antagonist: Opposes the primary muscle involved in movements. Muscle that opposes and reverses the action of another muscle Hemoglobin in red blood cells with lower levels of melanin give fair skin its pinkish hue. Carotene is a yellow to orange pigment that accumulates in the stratum corneum and hypodermis. Cyanosis has low oxygenation of hemoglobin Pallor: Anemia, low blood pressure, fear, or anger Erythema: Fever, hypertension, inflammation, or allergy Jaundice: Liver disorders(yellow) Bruises (ecchymoses or hematomas): Clotted blood beneath the skin Brown or black "necklace" pigmentation: Insulin resistance and elevated blood glucose levels. Can also be seen in people who are diabetic. Pale/pink; Low blood iron Skin cancer basal cells carcinoma(least malignant as it's in stratum basale cells slowly invading dermis and hypodermis), squamous cells carcinoma(can metastasize, involves keratinocytes of stratum spinous), and melanoma which in the cancer of melanocytes; most dangerous because it's highly metastatic and resists chemotherapy. Hypodermis is the tissue layer in subcutaneous is deep to skin. The reason the hypodermis acts as a shock absorber is that the major part of its makeup is fat, which serves as an effective shock absorber. Cell division would be most common among he basale layer of the epidermis. Joint stability factors are muscle tension/tone, articulating surface and reinforcing ligaments. Three main structural classifications of joints are fibrous, cartilaginous, and synovial. Sub-types for fibrous joints are gomphoses(holds tooth in socket and are peg and socket joint), satures(joints of skull lines), and syndesmoses(ankle and wrist sprains) Synchondroses, and Symphyses are two types of cartilaginous joints. Six types of synovial joints are Hinge, Pivot, Saddle, Ball-and-socket, Condyloid, and Gliding. Gliding occurs in plane joints, when one flat bone surface moves over the flat surface of a similarly flat bone and its very common in the intercarpal joints. Plane: Intercarpal joints Hinge: Elbow joints Presence of a synovial cavity, articular cartilage, synovial membrane, and ligaments are characteristics of hinge joint. Saddle: Carpometacarpal joint of thumb A ball and socket joint produces multiaxial movement and its in hip joint. Main functional classifications of joints are Synarthroses(immovable), Amphiarthroses(slightly movable). Diarthroses(freely movable) Tendon: connects muscle to bone Ligaments: connects two bones and holds a joint together. Connective tissue sacs lined with a synovial membrane and laid that act as a cushion in places where friction develops. Cartilage: Shock absorber that lines joints and provides cushioning (e.g., hyaline cartilage). Synchondroses and symphyses are examples of catilagenous. Labrum: Ring of cartilage or soft tissue surrounding joints to provide stability and cushioning (e.g., shoulder, hip) Sulci are depressions while gyri are ridges in the cerebrum(cerebral hemisphere and it's a executive site). Abduction: Movement along the frontal plane, away from the midline Adduction: Movement along the frontal plane, toward the midline. Dorsiflexion: Bending foot toward shin; Plantar flexion: Pointing toes downward Most of the bones in our body develop in-utero (fetal development) through a process called Endochondral Ossification. Intramembranous ossification begins within fibrous connective tissue membrane formed by mesenchymal cells(forms frontal, parietal, occipital, temporal, and clavicle bones). Appositional is a type of bone growth continues throughout the life span. Metabolism, one of the 8 requirements for life, refers to all the chemical reactions that occur in the body, including Catabolism (aka the breakdown of molecules) and Anabolism (aka the synthesis of molecules). During growth and development, bone growth in length occurs through a process called longitudinal growth. This process occurs at the epiphesial plate. Four main characteristics shared by all muscles are Excitability, Contractility, Extensibility, and Elasticity. Three types of muscle tissue are skeletal, smooth, and cardiac. Myofibrils, Sarcoplasmic reticulum, and t tubules are modified organelles found in skeletal muscle. Skeletal and cardiac muscles have striations. Medullary cavity is the hallow part of Yellow bone marrow. Osteons are pillar like structures units of compact bone. When stimulated by calcium (Ca²⁺), troponin and tropomyosin in muscle contraction move exposing binding sites on actin for myosin attachment. function of the sarcoplasmic reticulum (SR) in muscle cells is to store and release calcium ions to regulate muscle contraction. Four step of cross bridge cycle is Cross Bridge Formation, Working Stroke, Cross Bridge Detachment, and then Cocking of Myosin Head. Is the neuromuscular junction the synaptic vesicles in the axon terminals store acetylcholine, which is released into the synaptic cleft to stimulate muscle contraction. Muscle sheaths from external to internal are Epimysium, Perimysium, Endomysium. Endomysium: surrounds an individual muscle cell Sesamoid bones in knee(Patella) Short is carpals The connective tissue that surrounds an individual muscle cell is called epimysium. Insertion: Attachment to movable bone; Origin: Attachment to immovable or less movable bone. The clavicle can be classified as appendicular bone. First step of fracture repair is hematoma formations, second step is fibrocartilaginous callus formation, third step is boney callus formation, and fourth step is bone remodeling. Most of the bones in our body develop in utero through a process called intramembranous ossification. Atlas: the bone that articulates with the occipital condyles, and in the vertebra allows the head to nod yes in the atlas. Cervical Vertebrae: These bones are the smallest and lightest vertebrae. Lumber region in the vertebral column that receives the most stress by bearing most of the weight of the body. Femur, tibia, and talus are bones that have weight bearing. Rickets bone disease results in bowed legs in children and can be caused by Vitamin D deficiency or insufficient dietary calcium. Thumb -saddle joint -biaxial -diarthrosis Shoulder -ball and socket -multiaxial -diarthrosis (freely movable) Elbow -hinge -uniaxial -diathrosis Skull -sutures -synarthrosis (immovable) -nonaxial Pubic symphysis -cartiliginous -amphiarthroisi (little movement) SENSORY RECEPTORS Respond to stimuli with graded potentials that trigger nerve impulses Interpretation of stimulus occurs in the brain Types: Mechanoreceptors -- touch, pressure, stretch (MUSCLE SPINDLES) Thermoreceptors -- temp and are also exteroceptors Photoreceptors -- light Chemoreceptors -- chemicals Nociceptors -- pain Ventral root is only motor (voluntary movement) Dorsal root is only sensory Ventral ramus and Dorsal ramus are mixed sensory and motor. SIGNAL TRANSMISSION between a 2 neuron chain 1. Action potential arrives at the axon terminal of the presynaptic neuron. 2.Voltage gated Calcium channels open and calcium enters the axon terminal. 3.Synaptic vesicles release neurotransmitters. 4.Neurotransmitters bind to receptors on the post synaptic neuron. 5.Ligand gated ion channels are opened, and cell depolarization occurs. 6.Neurotransmitters are removed by reuptakes or diffusion. SPINAL REFLEX PATHWA (ARC) 1\. Receptor: site of stimulus 2. Sensory Neuron: transmits impulse to CNS 3. Integration Center: within CNS (spinal cord or brain) 4. Motor Neuron: sends impulse to effector organ 5. Effector: muscle fiber responds to stimulus with contraction Action Potential: Sends information allowing neurons to communicate Electrical signal occurring in axon of neuron Travels down axon, triggering voltage gated channels (Na2+ and K+) MUSCLE FIBER/CELL Made up of myofibrils that form a sarcomere (functional unit) membrane Myofibrils = Actin and Myosin Sarcoplasmic Reticulum Stores Ca 2+ Sarcolemma = cell Relaxation = ATP binding to myosin causing it to detach from actin + Ca2+ released back into SR Sarcomere is the contraction unit for skeletal muscle. Skeletal muscle contraction: 1. Electrical signal travel along sarcolemma, then the signal travel into t-tubules where they enter the triad, in the triad calcium is released from the sarcoplasmic reticulum, calcium then combines with tropic/tropomyosin complex, active sites in the actin are exposed, myosin globular heads combine with actin, cross bridges are formed and power stroke occur, myofilaments slide over each other, and ATP combines with myosin and cross bridges between actin and myosin is broken. Irregular bones: Coccyx, sacrum, sphenoid, hyoid, and vertebra. Sacrum: This bone shapes the posterior wall of the pelvis Coccyx: The fused rudimentary tailbone. Cranial nerves travel to portions of the head and neck. The vagus travels to the abdominal and thoracic cavities. Hip flexion occurs in the Sagittal plane. Muscle Striations are typically in skeletal muscle. Smooth Muscle is characterized by filaments that attach to dense bodies within the cell, lack of troponin, and no sarcomeres. Unitary smooth muscle is able to transmit electrical signals (action potential) to a neighboring smooth muscle cell sarcolemma through gap junctions. Smooth muscle is organized into longitudinal and circular layers around hollow organs. Sliding filament model of contraction involves actin and myosin sliding over each other and partly overlapping. Muscle contraction that generates force but no change in muscle length is termed isometric contraction. If Muscle was stretched to the point where thick and thin filaments no longer overlapped no muscle tension could be generated. Extensor Carpi Longus thin muscle located on the posterior, superficial surface of the forearm. sarcomere contracts and thin filaments move over thick filaments you would expect to see I-bands to appear smaller. I-band contains actin filaments, but not myosin filaments. I-band and H-zone increases in size. A-band and M-line don't change size. Both actin and myosin are found in the A-band. A sarcomere is the distance between two Z-disc. The thicker filaments are the Myosin filaments. Smooth muscle contraction has Calmodulin,dense bodies, Autonomic Nervous system, and increase in intracellular calcium will result in contraction. The site of calcium binding site differs from skeletal muscle contraction. Skeletal muscle contraction has t-tubules, Neuromuscular junction, and Fast forceful contractions. Both skeletal and smooth muscle contractions have Actin and Myosin binding. Excitation Contraction Coupling in order: Electrical signal travels along the sarcolemma and down the t-tube; calcium is released from sarcoplasmic reticulum; calcium combines with troponin/tropomyosin complex; active sites on the actin are exposed; cross bridge are formed and power stoke occur; myofilaments slide over each other. Inversion, eversion, dorsiflexion and plantar flexion are special movements of the ankle joint. If muscle insertion is on the lateral side of a joint its most likely involved in extension. A joint is where two or more bones meet. In a motor neuron, the axon terminal releases Acetylcholine(Ach), a neurotransmitter, into the synaptic cleft, the space between the axon terminal and muscle sarcolemma. Acetylcholine is a neurotransmitter released at motor end plates by the axon terminals. It's also a excitatory neurotransmitters secreted by motor neurons innervating skeletal muscle The diffuse junction in smooth muscle is analogous/similar to the neuromuscular at skeletal muscle. The calcium needed for skeletal muscle contraction is released from the Sarcoplasmic Reticulum, and in smooth muscle calcium is mainly from extracellular sources/intracellular fluid. When a WHOLE muscle contracts, the insertion of a muscle is moved toward the origin. Cheeks hurt from smiling so much which is the action and feeling caused by masseter. Neck strain from stressing is zygomaticus. Crossed extensor reflex is a polysynaptic reflex involving both sides of the body and is demonstrated when a person steps on a sharp object. Binding of neurotransmitter to the muscarinic receptor would decrease heart rate. The target organ receives dual innervation is Small intestine. Saltatory is a type of conduction that occurs in myelinated axons as its only possible by the myelin sheath. Brain is separated into left and right hemisphere by longitudinal fissure. When membrane changes charge, voltage gated channels can either open or close. Raynaud's is an ANS condition/disease that results in pale then cyanotic skin in the fingers and/or toes from exposure to cold. The relative refractory period is the phase during an action potential when a larger stimulus would be required to trigger another action potential. An exceptionally strong stimulus can trigger a response. Absolute refractory period: The neuron cannot respond to a second stimulus, no matter how strong. Depolarization: The interior of the cell becomes less negative due to an influx of sodium ions. Voltage-gated Na+ channels open. Repolarization: The specific period during which potassium ions diffuse out of the neuron due to a change in membrane permeability. Na+ channels are inactivating, and voltage-gated K+ channels open. Hyperpolarization: Some K+ channels remain open, and Na+ channels rest. Action potential: Also called a nerve impulse transmitted by axons. Threshold stimulus: Any stimulus at or above this level will result in action potential. Ependymal cells are a type of neuroglial cell that lines the ventricles of the brain. In the patellar tendon reflex, the sensory neuron from the muscle spindle receptor synapses in the spinal cord with a motor neuron to the quadriceps and a(n) inhibitory interneuron that inhibits the motor neuron to the hamstrings. Rectus femoris, vastus medialis and vastus lateralis is part of the quadriceps. Nerves that make and release acetylcholine are classified as cholinergic nerves while those that make and release norepinephrine and epinephrine are classified as adrenergic nerves. Autonomic dysreflexia is a disorder of the Autonomic Nervous System seen in individuals with spinal cord injuries that results in a life-threatening increase in blood pressure Sympathetic and parasympathetic divisions have antagonistic effects on most organs as they are automatic with two neuron path. They also contain unmyelinated neurons. Sympathetic division has short preganglionic and long postganglionic fibers; parasympathetic has long preganglionic and short postganglionic fibers. Somatic has one neuron path, and Ach in the primary neurotransmitter as well as in the Parasympathetic. Sympathetic has EPI released from adrenal gland. The \"fight or flight\" division of the autonomic nervous system is the sympathetic division. Dynamic antagonism or dual innervation refers to the influence of both sympathetic and parasympathetic nervous system on an effector tissue. 1. Sympathetic : Short preganglionic, long postganglionic fibers.target 1 of 7 2. Sympathetic : Collateral ganglia.target 2 of 7 3. Parasympathetic : Known to be active during rest and digest responses.target 3 of 7 4. Parasympathetic : Decreases heart rate.target 4 of 7 5. Parasympathetic : Maintenance functions.target 5 of 7 6. Parasympathetic : Stimulates ciliary muscles of the eye, which makes the lens bulge for close vision.target 6 of 7 Postganglionic neurons(dendrites & cell bodies), Adrenal medulla and sarcolemma of skeletal muscle cells at neuromuscular junction is where nicotinic receptors are found. Pituitary gland (hypophysis): The size and shape of a pea; produces hormones that stimulate other endocrine glands. Adrenal medulla: Is part of the sympathetic nervous system. Pancreas: Produces hormones that regulate glucose levels in the body. Parathyroid glands: Primary regulators of blood calcium levels. Thyroid gland: Produces the body\'s major metabolic hormones. The Hypothalamus: Controls autonomic responses and visceral command center. Primary control central integration in APN is hypothalamus. Cerebellum is the area of the brain that mainly functions in the control of balance, and processes input from many sensory receptors to provide coordinated movements. Vital center for the control of heart rate, respiration, and blood pressure are located in the medulla oblongata. The continual state of partial constriction of the blood vessels is referred to as sympathetic tone. Collections of nerve cell bodies outside the central nervous system, where synapses are located, are called ganglia. Central nervous system has two regions that are diencephalon and brain stem. Diencephalon includes epithalamus, hypothalamus, and thalamus (Gateway to the cerebrum). Brain stream includes medulla oblongata, midbrain, and pons. It also produces automatic behaviors necessary for survival. Axial and appredicukar Cell aids bone remodeling osteoblast Effector 9 abdominal pelvic region most likely to include appendix is right inguinal region. Abdominal muscle from superficial to deep is external oblique, internal oblique, rectus abdominis and then transverse abdominis. Sebaceous gland is glands secrete sebum, an oily like substance. Two body system that refer to ways of communication between tissues endocrine and nervous system. Know modes and glads. Division of nervous system. parathyroid hormone increases osteoclast activity to release more calcium ions into the bloodstream. Calcium ions is the final chemical messenger and \"trigger\" for muscle contraction. It binds to troponin. Activates synaptic vesicles in axon terminals to fuse with plasma membrane of axon terminal. The interior surface of a neuron\'s plasma membrane at resting membrane potential will have a negative charge and contains less sodium than outside of the cell. Acetylcholine: A neurotransmitter released at motor end plates by the axon terminals. Sodium ions:It diffuses across the cell membrane resulting in depolarization. Neuromuscular junction: Where the axon of a motor neuron connects with the muscle fibers. Acetylcholinesterase Periosteum Epiphyseal plate Posterior and dorsal Primary way of regulating body is negative feedback Transmits action potential along muscle sarcolemma is excitation contraction coupling Glenohumeral joint (shoulders) and knee are in Synovial structure has diarthrosis. Pituitary gland¡¡ Surround muscle fascicle is perimysium Smooth muscle myofilaments similar to zodiac in skeletal muscle ips dense bodies Hormones can be composed of either amino acid and be water soluble or cholesterol(steroid) liquid soluble. Amino acid-based hormones they require a receptor in the plasma membrane. Bone is what regulate calcium in our system Molecules are secreted into the extracellular fluid(blood) and circulate around the body are hormones. Nervous system communicate with action potential Type of cartilage that protects two bones from directly touching where they articulate is articulate cartilage(hyaline). Articular cartilage found at the ends of the long bones serves to provide a smooth surface at the ends of synovial joints. Sarcoplasmic reticular in skeletal muscle Thick myofilaments is myosin dark Aband Sarcomere Eccentric isotonic contraction isotonic contraction, the muscle changes in length and moves the \"load\". Major gland that regulates sleep wake cycles is pineal gland Skeletal muscle consciously controlled Broca is a motor speech area scientific for speech and Werkin for comprehension Adrenergic and cholinergic muscadine receptors on target organs are both is g-protein(involves a 2^nd^ messenger, causes widespread metabolic change, responses are complex, slow and often prolonged). G-Proteins coupled receptors and only excitatory are cholinergic muscarinic receptor, adrenergic a1 and b2. Cholinergic nicotinic is not part of g-protein coupled receptors. Hair cells within structure convert sound waves into electrical nervous signals is the cochlea. Two subtypes of cholinergic receptors is nicotinic and muscarinic. Nocotinic is always excitatory Voltage gated channels Rods central located Cones more poeohirally Nerve plexus innervates flexor and extensor muscle surrounding the carpals in the brachial plexus. Lumbar plexus: The obturator and femoral nerves branch from this plexus. Brachial plexus: Striking the \"funny bone\" (ulnar nerve) may cause injury to a nerve of this plexus. Trauma to a nerve of this plexus may cause wrist drop. Sacral plexus: A fall or improper administration of an injection to the buttocks may injure a nerve of this plexus. Cervical plexus: The phrenic nerve branches from this plexus. Oligodendrocytes surround and insulate axons in CNS these surround axon in PNS are Schwann cells. After axonal injury, regeneration in peripheral nerves is guided by Schwann cells. The Trigeminal nerve is composed of the ophthalmic, maxillary, and mandibular branches. A patient suffering from the inability to distinguish various types of odors. This patient may have damaged their olfactory nerve. Vagus nerve primary contributes autonomic nervous system to parasympathetic nervous system. Patient having trouble balancing when standing may indicate damage/trauma to vestibulocochlear nerve. A physician can determine the approximate location of a spinal injury simply by testing areas of the skin for numbness/lack of sensation.These skin areas referred to dermatomes. Adrenal gland specialized postgangliad neuron in ANS of the SNS branch. Steps of the pathway of sound waves involved with 'hearing": 1. Sound travels from the auricle to the auditory canal. 2.Tympanic membrane vibrates. 3.Ossicles transmit sound waves to the oval windows. 4.Hair cells deflect and depolarize. The tympanic membrane is located at the terminus of the external acoustic canal. The frequency of a sound wave determines pitch, while the amplitude of a sound wave determines loudness. Retina: The sensory layer of the eye. The inner layer (retina) contains both the pigmented layer and the neural layer. The fibrous layer includes the tough sclera (the \"white\" of the eye) as well as the transparent cornea. Lens: The structure most responsible for focusing light rays that enter the eye. Aqueous humor: Helps maintain the intraocular pressure; located in the anterior part of the eye. Fovea centralis: Area of greatest visual acuity. Difficult to discriminate the color of an object at night because at night, the amount of light entering the eye is insufficient to stimulate the cone cells but is sufficient to stimulate the rod cells. Main function of the rods in the eye is vision in dim light There are three layers of neurons in the retina. The axons of which of these neuron layers form the optic nerves are ganglion cells. Receptors for hearing are located in the cochlea. Tom is a 45-year-old male that has lost his ability to hear high frequency sounds. The most likely explanation for this would be damage to the hair cells near the oval window in the cochlear duct. The spiral organ (organ of Corti) sorts waves by frequency. Higher frequencies are detected nearer to the oval window, while lower frequencies are detected further down the basilar membrane. Iris structure regulates the amount of light passing to the visual receptors of the eye. The cone cells are photoreceptor cells that require brighter light. By differentiating input from three different types of cones, the brain can differentiate color and high resolution. The stapes is attached to the oval window, a thin membrane that separates the middle ear and the internal ear. The function of the ossicles is to transmit the vibratory motion of the eardrum to the oval window. In sequence, the tympanic membrane vibrations are transferred to the malleus, then the incus, and finally the stapes. As the stapes vibrates, it moves the oval window, which in turn sets the fluids of the internal ear into motion, eventually exciting the hearing receptors.