Anatomy Test 1

Anatomy vs. Physiology 

• Anatomy: study of structure 

• Physiology: study of function

Directional Terms

• Superior/rostral: towards head

• Inferior/caudal: towards feet

• Anterior/ventral: front

• Posterior/dorsal: back

Laterality

• Bilateral: both sides

• Unilateral: one side

• Ipsilateral: same side

• Contralateral: opposite side

Central nervous system 

• Brain and spinal cord

• Receives refines, and makes sense of info 

• Sends commands to muscles, glands, and organs 

Peripheral nervous system

• Cranial and spinal nerves

• Somatic NS (voluntary)

• Autonomic NS (involuntary)

  • Sympathetic (fight or flight)

  • Parasympathetic (grow and reset)

Gray matter

• Cerebral cortex and deep clusters within brain 

• Inner layer of spinal cord 

• Interneurons and cell bodies of sensory and motor neurons

• Processes and interprets info 

White matter

• Deep-ish within brain 

• Outer layer of spinal cord 

• Nerves in PNS

• Tracts in the CNS 

• Myelinated axons of sensory and motor neurons 

• Transmits info 

Olfactory nerve

1. sensory/afferent

• Sense of smell

• Close relationship to taste, eating, and swallowing 

• Damage can affect taste perception

• Origin: cerebral hemisphere 

Optic nerve

2. sensory/afferent

• Relays info from retinas to the occipital lobes 

• All sensory info from the left side of each eye is processed in the right occipital lobe and vice versa

• Origin: thalamus 

Oculomotor

3. motor/efferent 

• Controls movement of eye

• Pupil contraction

• Eyelid opening and closing

• Origin: midbrain

Trochlear nerve

4. motor/efferent 

• Moves eyes down and out (abducts)

• Origin: midbrain

Trigeminal nerve

5. both

• Sensory: controls sensation of touch on face

• Motor: innervates muscles for chewing

• Origin: pons

  • Ophthalmic branch (S): sensation of forehead, upper face, and scalp

  • Maxillary branch (S): sensation of upper teeth, upper lip, cheek, nasal cavities, and sides of face

  • Mandibular (B): sensation of lower teeth, lower gums, bottom lip, temperature and texture of food; innervates muscles for chewing 

Abducens nerve

6. motor/efferent 

• Innervates muscles that abduct eye 

• Damage can cause diplopia (double vision)

• Origin: pons

Facial nerve

7. both 

• Sensory: senses taste on anterior ⅔ of tongue

• Motor: innervates muscles of face

• Origin: pons

  • Temporal branch (M): moves forehead muscles

  • Zygomatic branch (M): allows for forceful eye closure

  • Buccal branch (M): moves nostrils, upper lip, corner of mouth, spontaneous eye blinks

  • Mandibular branch (B): moves lower lip, senses taste on anterior ⅔ of tongue

Vestibulocochlear nerve

8. sensory/afferent 

• “Auditory nerve”

• Senses sound via the cochlea

• Senses balance and movement signals via the vestibular system

• Origin: pons & medulla 

Glossopharyngeal nerve

9. both 

• Sensory: senses taste on posterior ⅓ of tongue

• Motor: innervates superior muscles of pharynx (swallowing) and the parotid gland (saliva production)

• Origin: medulla

  • Tympanic branch (B): innervates production of saliva; sensation of mucus in middle ear and eustachian tube

  • Pharyngeal branch (B): moves superior muscles of pharynx; sensation of mucus in pharynx 

  • Motor branch (M): elevates and widens pharynx

  • Tonsillar & lingual branch (B): innervates back of tongue, tonsils, and soft palate; senses taste on back ⅓ of tongue 

Vagus nerve

10. both

• Sensory: inferior larynx 

• Motor: innervates inferior pharynx and inferior larynx

• Origin: medulla

  • Pharyngeal plexus (M): innervates muscles of inferior pharynx and velum (swallowing and non-nasal phonemes)

  • Superior laryngeal nerve (B): sensation of inferior larynx; innervates cricothyroid muscle (tensing vocal folds)

  • Recurrent laryngeal nerve (M): innervates intrinsic muscles of larynx

Accessory nerve

11. motor/efferent 

• Spinal component innervates trapezius and sternocleidomastoid 

• Cranial component shares functions with the vagus nerve like innervating the velum and uvula 

Hypoglossal nerve

12. motor/efferent 

• Innervates all intrinsic (fine motor) and most extrinsic (gross motor) muscles of the tongue 

Types of neurons

• Sensory neuron: transmits sensory info from receptory cells to the spinal cord or brain

• Motor neuron: transmits impulses of motor movement from the brain or spinal cord to muscles and glands 

• Interneuron: conjoins neurons within the same brain region, helping with processing and interpreting info over short distances 

Glial cells

• CNS:

  • Astrocytes: provide structural support, synaptic waste disposal, and their end feet layer helps establish the blood-brain barrier

  • Oligodendrocytes: produces myelin, has multiple “tentacles”

  • Microglia: clears waste, damaged, neurons, and pathogens

• PNS:

  • Schwann cells: produces myelin, creates “burrito” layer

Dura mater

• The protective, thick, fibrous outer layer that enwraps the brain and spinal cord

• Protects the CNS from injury

Arachnoid mater

• Web like middle layer 

• Contains cerebrospinal fluid and millions of blood vessels 

• Cushions the brain and spinal cord and allows for the circulation of CSF

Pia mater

• Very thin and delicate layer that adheres directly to the surface of the brain and spinal cord

• Nourishes nervous tissue through blood vessels

Ventricular system

• An interconnected series of fluid-filled cavities that make and circulate cerebrospinal fluid

• The lateral ventricles hold the most CSF and contain the choroid plexus - the tissue that produces the most CSF

• Allows the skull to “float” and have protective cushioning

• Provides waste removal during sleep

• CSF flow: Lateral Ventricles → Foramen of Monro → Third Ventricle → Fourth Ventricle → Subarachnoid Space

Left hemisphere

• Zone of language

• Broca’s area: expressive language

• Wernicke’s area: auditory interpreting 

• Arcuate fasciculus: white matter pathway connecting Broca and Wernike area, enables repetition of words and phrases

• Angular gyrus: reception of visual language (sign, reading)

Right hemisphere

• Nonlinguistic aspects of communication (emotion, figurative language)

• Macrostructure processing - how details fit together

• Visuospatial processing

• Attention 

• Non-speech sounds

• Facial recognition 

Corpus callosum

• Largest white matter pathway deep within the longitudinal fissure 

• Connects the right and left hemisphere for communication and coordinated processing 

Frontal lobe

Prefrontal cortex

• Higher-level cognition

• Decision making

• Problem solving

• Impulse control 

Primary motor cortex 

• Controls voluntary muscle movements across the opposite side of the body
  
  

Broca’s Area

• Responsible for speech production, articulation, and organizing the grammatical structure of Words

Parietal lobe

• Receiving and processing somatosensation (touch, pain, spacial info)
  
  

Primary sensory cortex

• Receives somatosensation contralaterally

Temporal lobe

• Receiving and processing sound and memory

Wernicke’s area

• Auditory language comprehension 

Primary auditory cortex

• Receives afferent auditory signals

• Left side processes speech sounds and sends to Wernicke’s area 

• Right side processes non-speech sounds

Hippocampus

• Converts short-term memory to long-termmemory 

Occipital lobe

• Responsible for visual processing 

Primary visual cortex

• Left occipital lobe receives the right visual field of each eye, and vice versa

• Damage can lead to cortical blindness (true vision loss)

Visual association cortex

• Processes and interprets what’s being seen

• Damage can lead to visual agnosia (inability to perceive)

Insula

• Responsible for interoception (monitoring internal bodily states)

• Supports autonomic regulation

• Contributes to emotional awareness and the motor planning of speech 

Aphasias

Broca Aphasia 

• Nonfluent (relatively few words)

• Knows meaning, but can’t express well

Wernike Aphasia

• Fluent

• Poor comprehension (sounds like nonsense)

Conduction Aphasia

• Understands language 

• Can’t repeat accurately 

Brainstem

• Responsible for life-giving functions

• One of the oldest parts of the brain

• Most somatosensory and motor pathways pass through the brainstem

Midbrain

• Contains the cerebral peduncles 

• Contains the substantial nigra, which produces dopamine (related to Parkinson’s)

• Helps control eye movements, vision, and hearing

Pons

• Acts as a bridge connecting the cerebellum and the rest of the brain

• Helps coordinate balance and facial movements

Medulla Oblongata 

• Houses the respiratory center (vegetative respiration)

• Swallowing pattern generator

• Also controls vital functions like heartbeat and blood pressure 

• Pyramidal decussation: Motor neuron fibers from the primary motor cortex cross to the opposite side of the body within the medulla, creating contralateral innervation 

Lesions

 

• Lesion above the medulla → damage on the side of the body contralateral to the lesion  

• Lesion below pyramidal decussation → damage on the side of the body ipsilateral to the lesion 

Hemiparesis

A unilateral weakness of the body

Hemiplegia

Unilateral paralysis of the body

Reticular activating system

• A number of nuclei in the brainstem collectively known as the reticular activating system (RAS)

• Works to regulate the level of wakefulness or arousal, including the sleep/wake cycle

• Also contributes to autonomic functions, like blood pressure and respiration 

Brainstem reflexes

• A reflex is a motor response generated automatically in response to incoming stimuli, without waiting for the cerebrum to decide

• Gag reflex: occurs when parts of the posterior oral cavity or posterior pharyngeal wall are touched, causing contraction of the pharynx and closure of the airway to prevent aspiration

• Vestibulo-Ocular Reflex: causes the muscles of the eyes to contract and move in the direction opposite of changes in head position detected at the semicircular canals (focusing on a popsicle stick)

Cerebellum 

• “The little brain” 

• Monitors and refines movement

• Three lobes: anterior, posterior, flocculonodular 

• Left and right hemispheres, connected by the vermis

• Gray matter on outer layer, white matter inner layer

Peduncles

• Connects the cerebellum to the CNS at the pons via three paired peduncles

  • Middle: receives rough motor plans from contralateral cerebrum 

  • Inferior: receives somatosensory info about body position for integration into movement plans 

  • Superior: sends refined motor plans onward to the thalamus then cerebrum 

• By comparing intended movement to incoming somatosensation, the cerebellum monitors and refines movement

Ataxic dysarthria

A lack of vocal motor control due to damage in the cerebellum

Thalamus

• Acts as a relay station and sensory filter

• All sensory pathways (except olfaction) pass through the thalamus before going to the cerebrum 

• Pathways branch out to the different lobes depending on the sensory info 

• Receives refined motor plans from the cerebellum then relays them to the primary motor cortex 

Basal ganglia

• Four major structures: putamen, globus pallidus, subthalamic nucleus, and substantia nigra

• Facilitates desired voluntary movement and inhibits unwanted involuntary movement 

• Damage is related to Parkinson’s and Huntington’s disease

Limbic system

Deeply involved in regulating emotions and behaviors like feeding, mating, motivation, and emotional learning

• Hypothalamus

• Amygdala

• Mamillary bodies

Hypothalamus

• Regulates autonomic functions (heart rate, blood pressure, hunger, thirst, sexual arousal) via control of the pituitary gland

Amygdala

• Deep within each temporal lobe  

• Generates negative emotions like aggression, fear, anger, and anxiety 

• Involved in emotional memory and fear conditioning  

• A hyperactive amygdala can contribute to anxiety disorders 

Mamillary bodies

• Small bodies of nuclei in the front of the thalamus, connected to the hippocampi 

• Involved in spatial and episodic memory  

• Damage can produce anterograde amnesia

Spinal cord

• Houses major afferent/sensory and efferent/motor pathways transmitting impulses between the brain and the PNS

• Narrows near its inferior end at the conus medullaris, then splits into loose strands of spinal nerves — the cauda equina

• Generates spinal reflexes

Anoxia

• Extreme lack of oxygen

• Damages the hippocampus and cerebellum first, often causing memory deficits and ataxic dysarthria

  
  

Hypoxia

Less extreme lack of oxygen

Hypercapnia

Carbon dioxide poisoning

Breathing is usually…

• …under autonomic control, but can be placed under volitional (voluntary) control for a short period  

  • Speech breathing is volitionally controlled  

  • Speech is an overlaid function, so if homeostasis is disrupted, speech will stop until things go back to normal (if you talk too long, you’ll pass out)

Visceral thorax

• The major organs and soft tissues of the thorax 

• Contains the heart, lungs, respiratory passages, and associated connective tissue and muscles

Upper respiratory tract

• Nasal cavity

• Oral cavity

• Pharynx

• Larynx

Nasal cavity

• Lined with mucosal membrane behind the nares (in the nostrils), which is responsible for warming and filtering inspired air

Oral cavity

• Where food enters the body

• Vital for articulation

• Anterior boundary: lips

• Posterior boundary: palatoglossal arch

• Superior boundary: soft and hard palates

• Inferior boundary: mandible 

• Lateral boundary: cheeks 

Pharynx

• Link for air to move from the nasal and oral cavities inferiorly to larynx

• Link for food to move from the oral cavity inferiorly to esophagus

• Contracts during swallowing to avoid choking 

• Contains 3 loose sections 

Larynx

• Made of the epiglottis, vocal folds, and the glottis

• Uses a protective valve mechanism to prevent food, liquid, and saliva from entering the lungs

• Autonomic cough and voluntary throat clearing abilities 

• Phonation 

• Valsalva maneuver: a breathing technique that forces air against a closed airway to increase pressure inside the chest, good for increased stability and ear pressure equalization

Trachea

• The major passage for air between larynx and lungs

• Open tube with ~20 horseshoe shaped cartilages

• Fibrous membrane and smooth muscle between cartilage rings holds the structure together

• Goblet cells produce mucus to trap particles inside the trachea, and cilia sweep mucus up the trachea to remove them 

Bronchial tree

• Primary (left and right) bronchi serve as airways to the lungs

• Secondary bronchi subdivide from the primary bronchi to serve the individual lobes of the lungs

• Tertiary bronchi serve the individual segments of each lobe of each lung

• Terminal respiratory bronchioles supply air to the alveoli for gas exchange

Alveoli

• Terminal respiratory bronchioles open into the alveolar ducts

• The alveolar ducts transport air directly into the alveolar sac

• The alveolar sacs are chambers off which the individual alveoli are formed

• Alevoil are wrapped in capillaries, which allows for gas exchange with the bloodstream

Lungs

• The right lung is larger

  • It’s shorter but wider, losing some space to the liver

  • 3 lobes: superior, middle, and inferior

• The left lung is smaller 

  • Shares the left side of the thorax with the mediastinum (heart cavity)

  • 2 lobes: superior and inferior