Anatomy/Neuroanatomy/Physiology Flashcards
Respiration
- breathing (inhalation and exhalation)
- the exchange of gas between an organism and its environment
- supplies energy for speech
Inhalation
- draws air into the lungs
- brings oxygen to blood
- when lungs expand, the pressure within the lungs is reduced and air moves into the lungs to equalize pressure in and outside of the lungs
Process of inhalation
- chest and lungs expand
- diaphragm lowers
- air flows in through the nose and mouth
- air goes down pharynx and between open VFs
- air continues downward through trachea and bronchial tubes
- air reaches lungs
Exhalation
- helps get rid of mixed air and gases that result from respiratory metabolism
- caused by muscle contraction to reduce the volume of the chest cavity
- creates positive pressure within the lungs
- speech occurs during exhalation
Framework of respiration
- lungs
- bronchi
- trachea
- spinal column
- sternum
- rib cage
Lungs
- soft, spongy, porous, elastic, pink structures located in the thoracic cavity where the exchange of gas in respiration takes place
- right lung is shorter, broader, and bigger
Bronchi
- tubes composed of cartilaginous rings that extend from the lungs upward to the trachea
- subdivide into bronchioles (become progressively less cartilaginous and more muscular)
- communicate with the alveolar ducts that open into tiny air sacs in the lungs
Trachea
- a tube formed by ~20 cartilaginous rings (incomplete in back where connected to esophagus) connected to the cricoid cartilage and the larynx
- functions as a passageway for air
Spinal Column
consists of 32-33 individual vertebrae divided into 5 segments
5 segments of spinal column
- 7 cervical
- 12 thoracic (attached to ribs)
- 5 lumbar
- 5 sacral
- 3-4 coccygeal (form coccyx)
Sternum
breastbone; made up of 3 parts (manubrium, body/corpus, xiphoid process)
Rib cage
composed of 12 pairs of ribs, sternum, and 12 thoracic vertebrae
Muscles of respiration
- thoracic muscles of inspiration
- abdominal muscles of expiration
Thoracic muscles of inspiration
- Diaphragm
- External intercostal muscles
- Serratus posterior superior
- Levator costarum brevis
- Levator costarum longis
- Sternoclediomastoid
- Trapezius
- Pectoralis major
- Pectoralis minor
- Serratus anterior
- Levator scapulae
- Rhomboideus major
- Rhomboideus minor
- Internal intercostal
- Innermost intercostal
- Transversus thoracis
Diaphragm
- primary muscle of inspiration
- thick, dome-shaped muscle that separates the abdomen and thorax (innervates C3-C5)
External intercostal muscles
- primary muscle of inspiration
- 11 pairs of muscles between the ribs that raise the ribs up and out to increase diameter of the thoracic cavity for inhalation (innervates T2-T11)
Internal intercostal
- primary muscle of inspiration
- depresses ribs 1-11 (innervates T2-T11)
Abdominal muscles of expiration
- Latissimus dorsi
- Rectus abdominis
- Transversus abdominis
- Internal oblique abdominis
- Quadratis lumborum
Larynx
- the voice box and home of the VFs
- musculo-cartilaginous structure that lies at the top of the trachea
- valving mechanism
- serves as protection for the trachea while swallowing
- aids cough reflex
- closes VFs to build subglottic pressure
Laryngeal structures
- Hyoid bone
- Epiglottis
- Thyroid cartilage
- Cricoid cartilage
- Arytenoid cartilages
- Corniculate cartilages
- Cuneiform cartilages
Hyoid bone
- superior boundary of the phonatory system
- serves as a point of attachment for many tongue muscles
- made up of corpus and 2 greater cornua and 2 lesser cornua
- doesn’t articulate with bones
Epiglottis
- protective, leaf-like piece of cartilage
- drops to cover the larynx during swallowing
Thyroid cartilage
- largest cartilage
- protects the larynx
- formed by two plates fused at midline (thyroid notch)
Cricoid cartilage
- completely surrounds the trachea
- often seen as the uppermost tracheal ring
Arytenoid cartilages
-small, pyramid shaped cartilages connected to the cricoid cartilage through the cricoarytenoid joint, which permits sliding and circular movements
Corniculate cartilages
- small, cone-shaped cartilages that sit on the apex of the arytenoids
- assist in reducing laryngeal opening when a person is swallowing
Cuneiform cartilages
- stiffen/tense the aryepiglottic folds
- located under the mucous membrane covering the aryepiglottic folds
Laryngeal muscles
- intrinsic
- extrinsic
Purpose of intrinsic laryngeal muscles
- primarily responsible for controlling sound production
- major functions include opening/closing/tensing/relaxing VFs
- both attachments are within the larynx
Posterior cricoarytenoid
- abducts VFs
- innervates CN X (vagus)
- recurrent laryngeal nerve branch
Lateral cricoarynteoid
- adducts VFs
- increases medial compression
- innervates CN X (vagus)
- recurrent laryngeal nerve branch
Transverse arytenoid
- adducts VFs
- innervates CN X (vagus)
- recurrent laryngeal nerve branch
Oblique arytenoid
- pulls apex of arytenoids in medial direction
- innervates CN X (vagus)
- recurrent laryngeal nerve branch
Thyroarytenoid
- tenses VFs
- the internal thyroarytenoid (vocalis muscle/VFs) is the primary portion of the thyroarytenoid muscle, which vibrates and produces sound
- innervates CN X (vagus)
- recurrent laryngeal nerve branch
Cricothyroid
- lengthens and tenses VFs
- made up of pars recta and pars oblique
- innervates CN X (vagus)
- external branch of the superior laryngeal nerve branch
Intrinsic laryngeal muscles
- Posterior cricoarytenoid
- Lateral cricoarytenoid
- Transverse arytenoid
- Oblique arytenoid
- Thyroarytenoid
- Cricothyroid
Purpose of Extrinsic laryngeal muscles
- elavates or depresses larynx
- support larynx and fix its position by elevating or depressing the laryngeal structure
- only one attachment is within the larynx
Extrinsic laryngeal muscles (elevators)
- *suprahyoid muscles
- Digastric
- Geniohyoid
- Mylohyoid
- Stylohyoid
- Hyoglossus
- Genioglossus
Digastric
innervates CN V (trigeminal) and CN VII (facial)
Geniohyoid
innervates CN XII (hypoglossal) and C1
Mylohyoid
innervates CN V (trigeminal)
Stylohyoid
innervates CN VII (facial)
Hyoglossus
innervates CN XII (hypoglossal)
Genioglossus
innervates CN XII (hypoglossal)
Extrinsic laryngeal muscles (depressors)
- *infrahyoid muscles
- Thyrohyoid
- Omohyoid
- Sternothyroid
- Sternohyoid
Thyrohyoid
innervates CN XII (hypoglossal) and C1
Omohyoid
innervates C1-C3
Sternothyroid
innervates C1-C3
Sternohyoid
innervates C1-C3
Vocal folds
- vibrate to produce sound
- composed of epithelium (outer), lamina propria (middle), and vocalis muscle (inner)
Aryepiglottic folds
- separate the laryngeal vestibule from the pharynx and help preserve the airway
- composed of a ring of connective tissue and muscle extending from the tips of the arytenoids to the larynx
False VFs
- vibrate only at very low fundamental frequencies and usually not during typical phonation
- compress during activities of coughing and lifting heavy items
Myoelastic-Aerodynamic Theory
the VFs vibrate because of the forces of pressure of air and the elasticity of the VFs
Process of Myoelastic-Aerodynamic Theory
- air flows out of lungs and is temporarily stopped by closed VFs
- increase in subglottic pressure
- blows VFs apart
- VFs sent into vibration
- air moves with increase velocity through glottal opening
- pressure between edges of VFs decreases
- VFs sucked back together
Bernoulli Effect
- caused by the increased speed of air passing between the VFs
- the sucking motion of the VFs toward one another
Process of Bernoulli Effect
- air flows out of lungs and is temporarily stopped by closed VFs
- increase in subglottic pressure
- blows VFs apart
- VFs sent into vibration
- cycle of opening and closing VFs
- repeated more than 100x/sec during vocalization
Mucosal Wave Action
- critical to vibration of VFs
- may be impacted by abnormal growths
Process of Mucosal Wave Action
- the cover and the transition over the vocalis muscle slide and produce a wave
- wave travels across the superior surface of the VF
- wave dissipates before reaching inner surface of thyroid cartilage
Cortical areas
- primary motor cortex
- Broca’s area
- somatosensory cortex
- supplementary motor cortex
Cerebellum
- regulates motor movement
- key to the coordination of laryngeal muscles for phonation and the effective functioning of other speech systems
Cranial Nerves involved with vocal mechanism
- CN VII (facial); innervates posterior belly of digastric muscle
- CN X (vagus); innervates larynx
Primary branches of Vagus Nerve
- superior laryngeal nerve
- recurrent laryngeal nerve
Superior laryngeal nerve
- internal branch provides all sensory information to the larynx
- external branch supplies motor innervation solely to the cricothyroid muscle
Recurrent laryngeal nerve
- supplies all motor innervation to the interaryenoid, posterior cricoarytenoid, thyroarytenoid, and lateral cricoarytenoid
- supplies all sensory information below the VFs
Resonation
- modification of laryngeal tone by selective dampening or enhancement of specific frequencies
- primary resonators include pharynx, nasal cavity, and oral cavity
Pharynx
- throat
- part of the upper airway, located superiorly and posteriorly to the larynx
- size and shape of the pharynx are modified by the position of the tongue (forward vs. back) and vertical position of the larynx (high vs. low)
Nasal cavity
produces nasals by relaxation and lowering of soft palate/velum, which couples the nasal and oral cavities
Velum
- raising and retracting of velum during productions of sounds helps make contact with posterior pharyngeal wall and separates the oral and nasal cavity
- elevated and retracted for production of all other oral sounds in English
Oral cavity
primary resonating structure for English sounds (besides nasals)
Source-Filter Theory
- depicts the vocal tract as a series of linked tubes (pharnx, nasal cavity, oral cavity) providing the variable resonating cavity to produce speech
- energy from vibrating VFs (source) is modified by the resonance characteristics of the vocal tract (filter)
- changes in the configuration and shape determine the sound
Articulation
- the movement of speech structures to produce speech sounds
- primary articulatory structures include the pharynx, soft palate, hard palate, mandible, teeth, tongue, lips, and cheeks
Segments of Pharynx
- laryngopharynx
- oropharynx
- nasopharynx
Laryngopharynx
begins immediately superior to the larynx and ends at base of tongue
Oropharynx
extends up to the soft palate
Nasopharynx
ends where the two nasal cavities begin
Muscles of the pharynx
- Salpingopharyngeus
- Stylopharyngeus
- Superior pharyngeal constrictor
- Middle pharyngeal constrictor
- Inferior pharyngeal constrictor, cricopharyngeus
- Inferior pharyngeal constrictor, thyropharyngeus
Salpingopharyngeus
- elevates lateral pharyngeal wall
- innervates CN X (vagus) and CN XI (accessory)
Stylopharyngeus
- elevates and opens pharynx
- innervates CN IX (glossopharyngeal)
Superior pharyngeal constrictor
- constricts pharynx diameter
- pulls pharyngeal wall forward
- innervates CN X (vagus) and CN XI (accessory)
Middle pharyngeal constrictor
- narrows diameter of pharynx
- innervates CN X (vagus) and CN XI (accessory)
Inferior pharyngeal constrictor, cricopharyngeus
- constricts superior orifice of esophagus
- innervates CN X (vagus) and CN XI (accessory)
Inferior pharyngeal constrictor, thyropharyngeus
- reduced diameter of lower pharynx
- innervates CN X (vagus) and CN XI (accessory)
Soft palate
- velum
- flexible muscular structure at the juncture of the oropharynx and the nasopharynx
- can be elevated or depressed
Muscles of soft palate
- Levator veli palatini
- Tensor veli palatini
- Platoglossus
- Palatopharyngeus
Levator veli palatini
- primary elevator of the velum
- innervates CN X (vagus) and CN XI (accessory)
Tensor veli palatini
- tenses velum
- dilates Eustachian tube
- innervates CN V (trigeminal)
Platoglossus
- elevates and depresses velum
- CN X (vagus) and CN XI (accessory)
Palatopharyngeus
- narrows pharyngeal cavity
- lowers velum
- elevates larynx
- innervates CN X (vagus) and CN XI (accessory)
Uvula
small, cone-shaped structure at the tip of the velum
Velopharyngeal closure
occurs when soft palate is raised and retracted and the muscles of the pharynx move inward to meet the muscles of the soft palate, causing a sphincter-like action and nasal port closure
Hard palate
- bony, hard palate that serves as the roof of the mouth and the floor of the nose
- part of the maxillae + maxillary bones
Parts of maxillary bones
- premaxilla
- palatine process
- alveolar process
Premaxilla
front portion housing the four upper front teeth (incisors)
Palatine process
- consists of two pieces of bone that grow and fuse at midline in utero
- failure of fusion = cleft palate
Alveolar process
outer edges of maxillary bone housing the molar, bicuspid, and cuspid teeth
Mandible
- lower jaw
- houses the lower teeth and forms the floor of the mouth
- formed by fusion of two bones, but considered to be one bone in adults
- alveolar arch is the part of the mandible that houses the teeth
- mandible is attached to the temporal bone of the skull by the temporomandibular joint
- muscles of the mandible open and close the mouth and aid in chewing food and can be categorized as elevators or depressors
Muscles of mandible (elevators)
- masseter
- temporalis
- medial (internal) pterygoid
- lateral (external) pterygoid
- innervates CN V (trigeminal)
Muscles of mandible (depressors)
- anterior belly of digastric (CN V - trigeminal)
- posterior belly of digastric (CN VII - facial)
- geniogyoid (CN VII - facial)
- mylohyoid (CN V - trigeminal)
Teeth
- lower dental arch is part of mandible
- upper dental arch is part of maxillary bone
- primary function is mastication, but also help produce speech sounds
- babies have 20 temporary teeth
- adults have 32 teeth (8 incisors, 4 canine, 8 premolar, and 12 molar)
Tongue
important in eating and speech production
Parts of tongue
- tip
- blade
- dorsum
- root
- lingual frenulum
Intrinsic muscles of tongue
- superior longitudinal muscle
- inferior longitudinal muscle
- transverse muscles
- vertical muscles
Extrinsic muscles of tongue
- genioglossus
- styloglossus
- hyoglossus
- chondroglossus
- palatoglossus
Lips
primary muscle is orbicularis oris
Cheeks
primary muscle is buccinator
Facial muscles
- mentalis
- platysma
- risorius
- buccinator
- depressor labii inferioris
- depressor anguli oris
- zygomatic minor
- zygomatic major
- orbicularis oris inferioris and superioris
- levator anguli oris
- levator labii superioris
- levator labii superioris alaeque nasi
Glial cells/Neurologia
- cells of the CNS
- do not transmit nerve impulses
- mainly support and protect the nerve cells
Schwann Cells
cells of the PNS
Satellite Cells
cells of the PNS
Neurons
- most important type of nerve cells
- receive, process, and transmit information
- made up of nerve fibers and soma/cell body
Nucleus
- core of soma
- covered in membrane
Dendrites
- short fibers extending from soma
- receive neural impulses from axons of other cells and transmit impulses to cell body
Axons
- long fibers extending from soma
- wrapped in myelin sheath (facilitates impulse transfer)
- have terminal/end buttons at the tip that make contact/sit close to the dendrites of other neurons
- send out impulses generated within the neuron
Nervous system
an organization of nerves according to specific spatial, structural, and functional principles
Synapses
- junctures between neurons where communication takes place
- consists of the terminal button of one neuron, the receptive site of another neuron, and the synaptic cleft/space between the two neurons
Neural transmission
a chemical process of information exchange at the level of the synapse
Neurotransmitter
- a chemical contained within the terminal buttons that helps make contact between two cells by diffusing itself across the synaptic cleft
- becomes bound to receptors in the postsynaptic membrane
- may cause the inhibition/excitation of the next neuron
- dopamine and acetylcholine are the two most important neurotransmitters in the motor system
Sensory/Afferent neurons
cranial nerves that carry sensory impulses from the peripheral sense organs toward the brain
Motor/Efferent Neurons
- cranial nerves that transmit impulses away from CNS
- cause glandular secretions/muscular contractions
Interneurons
- most common type of neuron in the nervous system
- links neurons with other neurons
- plays an important role in controlling movement
Peripheral Nervous System (PNS)
- a collection of nerves outside the skull and spinal column that carry sensory impulses originating in the peripheral sense organs to the brain, and motor impulses originating in the brain to the glands and muscles of the body
- contains 3 types of nerves (cranial, spinal, and autonomic)
Cranial nerves
- emerge from the brainstem and are attached to the base of the brain
- 12 pairs
- part of the lower motor system
- receive much of their innervations from the corticobulbar tract of the pyramidal system
- exit through the holes in the base of the skull at different levels of the brainstem and top portion of the spinal cord
- numbered for vertical order of which they exit the skull
Acronym for cranial nerves + sensory/motor
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Olfactory, Optic, Oculometer, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal
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Cranial nerves associated with speech, language, and hearing
CN V, VII, VIII, IX, X, XI, XII
Trigeminal Nerve (CN V)
- sensory fibers: ophthalmic branch, maxillary branch, mandibular branch
- motor fibers: jaw muscles
Ophthalmic branch
sensory branches to nose, eyes, and forehead
Maxillary branch
sensory branches to upper lip, maxilla, upper cheek area, upper teeth, maxillary sinus and palate
Mandibular branch
sensory branches to mandible, lower teeth, lower lip, tongue, part of the cheek, and part of external ear
Damage to Trigeminal Nerve
- inability to close mouth
- difficulty chewing
- trigeminal neuroglia
Facial Nerve (CN VII)
- sensory fibers: taste sensation on anterior 2/3 of tongue
- motor fibers: innervate muscles important to facial expression and speech
Damage to Facial Nerve
mask-like appearance with minimum to no facial expression
Vestibulocochlear Nerve (CN VIII)
- vestibular branch
- acoustic branch
Vestibular branch
primarily responsible for maintenance of equilibrium/balance
Acoustic branch
transmits sensory information from the cochlea of the inner ear to primary auditory cortex in brain (where it is interpreted)
Damage to Vestibulocochlear Nerve
- hearing loss
- balance difficulties
Glossopharyngeal Nerve (CN IX)
- sensory: processing taste sensation from posterior 1/3 of tongue and providing general sensation for tympanic cavity, ear canal, Eustachian tube, faucial pillars, tonsils, soft palate, and pharynx
- motor: innervate stylopharyngus and upper pharyngeal constrictor muscles
Damage to Glossopharyngeal Nerve
- difficulty swallowing
- unilateral loss of the gag reflex
- loss of taste/sensation from posterior 1/3 of tongue
Vagus Nerve (CN X)
- sensory: convey information from digestive system, heart, trachea, pharynx, and lungs
- motor: supply digestive system, heart, and lungs
- recurrent laryngeal nerve
- pharyngeal branch
Recurrent Laryngeal Nerve
- regulates intrinsic muscles of larynx (excluding cricothyroid)
- damage may result in total/partial paralysis of VFs
Pharyngeal Branch
supplies pharyngeal constrictors and all the muscles of the velum (excluding tensor tympani)
Damage to Vagus Nerve
- difficulty swallowing
- paralysis of the velum
- voice problems
Accessory Nerve (CN XI)
- supplies the trapezius and sternocleidomastoid muscles, which assist in head and shoulder movements
- cranial fibers innervate the uvula and levator veli palatini muscles of the soft palate
Damage to Accessory Nerve
- neck weakness
- paralysis of sternoclediomastoid
- inability to turn head
- inability to shrug shoulders or raise arm above shoulder level
Hypoglossal Nerve (CN XII)
- runs under tongue
- supplies three extrinsic tongue muscles (styloglossus, hyloglossus, and genioglossus)
- supplies all intrinsic muscles of the tongue
Damage to Hypoglossal Nerve
- tongue paralysis
- diminished intelligibility
- swallowing problems
Purpose of Spinal Nerves
- controls various bodily activities
- can be motor, sensory, or mixed
- transmit information from CNS to the muscles and carry sensory information from peripheral receptors to the CNS
- 31 pairs attached to spinal cord through two roots
- pairs divided into segments named for the region of the spinal cord to which they are attached
Spinal Nerves
- 8 pairs of cervical spinal nerves (C1-C8)
- 12 pairs of thoracic spinal nerves (T1-T12)
- 5 pairs of lumbar spinal nerves (L1-L5)
- 5 pairs of sacral spinal nerves (S1-S5)
- 1 pair of coccygeal spinal nerves (Co1)
Spinal Cord structures
- conus medullaris
- cauda medullaris
- filum terminale
Conus medullaris
where spinal cords ends at the L1 vertebra level
Cauda medullaris
lowermost nerves
Filum terminale
where there are no spinal cord segments
Autonomic Nervous System
- generally viewed as part of PNS
- controls and regulates internal environment of our bodies with two branches that supply the body’s smooth muscles and various glands that secrete hormones
- does not have a direct effect on speech, language, or hearing
Sympathetic Nervous System
- mobilizes the body for “fight or flight” situations
- activation accelerates the heart rate, dilates the pupils, raises blood pressure and increases blood flow to the peripheral body structures causing a feeling of arousal
- people who stutter may experience increased dysfluency with activation of the sympathetic nervous system
Parasympathetic Nervous System
- brings body back to state of relaxation
- lowers blood pressure
- slows heart rate
- increases activity within stomach and generally relaxes the body, causing a more relaxed and calm feeling
Central Nervous System (CNS)
- acts as motor command center for planning, originating, and carrying out transmission of messages
- composed of spinal cord and brain
- enclosed within vertebral column and cranial structure
- key structures of brain include brainstem, reticular activating system, diencephalon, basal ganglia, cerebellum, and cerebrum
- other key structures include pyramidal and extrapyramidal systems, connecting fibers within brain, cerebral ventricles, protective layers of brain, and structures that provide cerebral blood supply
Brain
- acts as central station that coordinates activity, integrates information and issues commands
- most important structure in the body for language, speech, and hearing
Brainstem
- oldest part of brain
- connects spinal cord and brain via diencephalon
- serves as bridge between cerebellum and all other CNS structures
Internal makeup of brainstem
- longitudinal fiber tracts
- cranial nerve nuclei
- reticular formation
Key structures of brainstem
- midbrain
- pons
- medulla
Midbrain
- narrow structure that connects brainstem and cerebellum
- substantia nigra runs the vertical length of the midbrain and controls many motor and sensory functions
- postural reflexes
- visual reflexes
- eye movements
- head movements
Pons
- round, bulging structure that bridges the two halves of the cerebellum
- connects cerebellum and various cerebral structures through the inferior and middle peduncles
- transmits information relative to movement from the cerebral hemispheres to the cerebellum
- contains many descending motor fibers and is involved with balance and hearing
- houses the nuclei for trigeminal and facial nerves
- important for speech production
Medulla
- contains fibers that originate in the cerebellum and cerebrum and move downward to form the spinal cord
- includes several centers that control vital, automatic bodily functions (breathing, digestion, heart rate, and blood pressure)
- houses cranial nerve nuclei for CN VIII, IX, X, XI, and XII
- contains nerve fibers that carry commands from the motor center of the brain to various muscles contralaterally
- important for speech production
Reticular Activating System
- a structure within the midbrain, brainstem, and upper portion of the spinal cord
- integrates motor impulses flowing out of the brain with sensory impulses flowing into it
- plays a role in the execution of motor activity
- primary mechanism of attention and consciousness
Diencephalon
- located above midbrain and between brainstem and cerebral hemispheres
- composed of third ventricle, thalamus, and hypothalamus
Third ventricle
tall and narrow space filled with cerebrospinal fluid
Thalamus
- largest structure in diencephalon that regulates sensory information to the brain and relays sensory impulses to various portions of the cerebral cortex
- critical for maintenance of consciousness and alertness
Hypothalamus
helps integrate the actions of the autonomic nervous system and controls emotions
Basal ganglia
- structures primarily composed of gray matter that are found deep within the brain
- highly complex system of neural pathways that have connections with many subcortical and cortical areas that receive input from the frontal lobe and relay information back to the higher centers of the brain via the thalamus
- composed of corpus striatum
- part of extrapyramidal system
Damage to basal ganglia
- unusual body postures
- dysarthria
- changes in body tone
- involuntary/uncontrolled movements
Cerebellum
- consists of two hemispheres
- primary fiber bundles serve as connections between brainstem and cerebellum
- afferent fibers mediate sensorimotor information to the cerebellum
- efferent fibers transmit information from cerebellum to the brainstem
- receives neural impulses from other brain centers and helps coordinate and regulate those impulses
- regulates equilibrium, body posture, and coordinates fine motor movements
Damage to cerebellum
- neurological disorder
- abnormal gait
- disturbed balance
- ataxic dysarthria
- other communication disorders
Cerebrum
- complex structure of intricate neural connections with gray cells on top
- includes topmost portion of brain and arranged in 6 layers
- gyri: ridges
- sulcus: shallow valleys
- fissures: deeper valleys
- longitudinal fissure
- Fissure of Rolando/central sulcus
- Sylvian fissure/lateral cerebral fissure
Longitudinal fissure
divides left and right hemispheres
Fissure of Rolando/central sulcus
divides anterior and posterior half of the brain
Sylvian fissure/lateral cerebral fissure
starts at the inferior portion of the frontal lobe and moves laterally and upward
Frontal lobe
- anterior portion of cerebrum
- attributes to function of deliberate plans and intentions that dictate a person’s conscious behavior
- contains critical areas for speech production (primary motor cortex, supplementary motor cortex, and Broca’s area)
Primary motor cortex
- located on the precentral gyrus
- contralaterally controls voluntary movement of skeletal muscles through the pyramidal system and modified by the extrapyramidal system
Supplementary motor cortex
- involved in motor planning of speech
- plays secondary role in regulating muscle movements
Broca’s area
- controls lip, tongue, jaw, and laryngeal movements
- highly involved in speech production
Parietal lobe
- located on upper sides of cerebrum
- primary somatic sensory area
- integrates somesthetic sensations (pain, pressure, temperature, and touch)
- contains postcentral gyrus, supramarginal gyrus, and angular gyrus
Postcentral gyrus
- sensory cortex/sensory strip
- primary sensory area that integrates and controls somesthetic sensory impulses
Supramarginal gyrus
- critical for speech and language
- damage may result in conduction aphasia and agraphia
Angular gyrus
- critical for speech and language
- damage may result in difficulties in writing, reading, naming, and transcortical sensory aphasia
Occipital lobe
- located behind parietal lobe
- primary visual cortex
Temporal lobe
- makes up lower 1/3 of cerebrum
- composed of 3 major gyri (superior/upper temporal gyrus, middle temporal gyrus, inferior/lower temporal gyrus)
- includes Heschl’s gyri and Wernicke’s area
Heschl’s gyri
- critical for speech and hearing
- composed of primary auditory cortex and auditory association cortex
- primary auditory cortex receives sound stimuli from the acoustic nerve bilaterally
- auditory association area synthesizes the information to be recognized as whole units
Wernicke’s area
- critical to the comprehension of written and spoken language
- damage may result in fluent but meaningless speech and difficulties with comprehension
Pyramidal system
- direct motor activation pathway that is primarily responsible for facilitating (fine) voluntary muscle movement
- composed of corticospinal tract and corticobulbar tract
Corticospinal tract
- has nerve fibers that descend from the motor cortex of each hemisphere and continue to course vertically through the midbrain and pons to communicate with spinal nerve at different levels
- exits the vertebrae foramina through the spinal column to innervate the muscles of the trunk and limbs contralaterally
Corticobulbar tract
- critical to speech production
- control all voluntary movements of the speech muscles
- originate in the motor cortex and course downward along the corticospinal tract and terminate in the brainstem
- innervate muscles of the larynx, pharynx, soft palate, tongue, face, and lips
Lower motor neurons
- motor neurons in the spinal and cranial nerves
- part of the peripheral nervous system
- activity eventually results in muscular movement
Upper motor neurons
- motor fibers within central nervous system
- descending motor fibers
- include pathways of pyramidal and extrapyramidal systems
Extrapyramidal system
- transmits impulses that control the postural support needed by fine motor movements
- composed of different subcortical nuclei
- indirect activation system
- activity begins in cerebral cortex and ultimately influences lower motor neurons
- helps maintain pressure, tone, and regulate movements resulting from lower motor neuron activity
Damage to extrapyramidal system
motor disturbances (involuntary movement disorders)
Connecting fibers to the brain
- keeps information flowing throughout the brain
- projection fibers
- association fibers
- commissural fibers
Projection fibers
- create connections between the cortex and subcortical structures
- originate primarily in the premotor and primary motor areas in the frontal lobe
- form upper motor neuron system of the pyramidal tract (direct activation pathway for voluntary motor movements)
- afferent projection fibers
- efferent projection fibers
Afferent projection fibers
relay sensory information from peripheral sense organs to the brain
Efferent projection fibers
relay motor commands to the glands and muscles
Association fibers
- connect areas within a hemisphere to maintain communication
- arcuate fasiculus
Arcuate fasiculus
most important bundle of superior longitudinal fibers that connects Broca’s and Wernicke’s area
Commissural fibers
- interhemispheric connectors
- corpus callosum is most important and connects the two hemispheres
Cerebral ventricles
- a system of cavities deep within the brain filled with cerebrospinal fluid, which is produced by the choroid plexus and circulates throughout the nervous system to nourish neural tissues, remove waste, cushion the brain and regulate intracranial pressure
- 2 lateral ventricles
- third ventricle
- fourth ventricle
Protective layer of spinal cord
vertebral column
Protective layers of brain
- skin
- skull
- meninges (dura mater, arachnoid, and pia mater)
Dura mater
thick, tough, outermost membrane that adheres to the skull and arachnoid
Arachnoid
- semitransparent, thin and delicate, web-like, vascular, middle layer
- cerebrospinal fluid fills subarachnoid space
Pia mater
delicate, thin, transparent membrane that adheres to the brain
Cerebral blood supply
- brain requires 25% of body’s oxygen and 20% of its’ blood supply
- lack of blood supply to brain can cause damage within 4-6 minutes
- 4 major structures (aorta, vertebral arteries, carotid arteries, and Circle of Willis)
Aorta
main artery of the heart that carries blood from the left ventricle to the rest of the body
Vertebral arteries (right and left)
- emerge from two subclavian arteries that supply blood to the upper extremities
- as they branch up, merge to form the basilar artery, which then divides again into two posterior cerebral arteries which supply the temporal and occipital lobes
- other arteries supply the inner ear, cerebellum, and pons
Carotid arteries (right and left)
- enter the neck and branch to an internal and external artery and enter the brain
- include exterior, middle, internal, and anterior
External carotid artery
-moves toward face and branches into smaller arteries to supply the muscles of the mouth, nose, forehead and face
Internal carotid artery
major supplier of blood to the brain
Middle carotid artery
-supples the cortex/frontal lobe (motor and sensory functions and language, speech, and hearing functions
Anterior carotid artery
supplies parietal and frontal lobes, corpus callosum, and basal ganglia
Circle of Willis
- formed at base of brain where two carotid and two vertebral arteries join and anterior and posterior communicating arteries
- provides a common blood supply to various cerebral branches
