Anatomy & Physiology Study Guide: Brain, Skull, Vertebrae, and Muscles

Brain

Major Regions and Structures

The brain is the central organ of the nervous system, responsible for processing sensory information, controlling motor functions, and regulating behavior and cognition. It is divided into several lobes and specialized areas.

• Frontal lobe: Involved in reasoning, planning, movement, and problem-solving.

• Temporal lobe: Responsible for auditory processing and memory.

• Occipital lobe: Main center for visual processing.

• Parietal lobe: Processes sensory information such as touch, temperature, and pain.

• Precentral gyrus: Primary motor cortex, controls voluntary movements.

• Postcentral gyrus: Primary somatosensory cortex, receives sensory input.

• Central sulcus: Separates frontal and parietal lobes.

• Longitudinal fissure: Divides the two cerebral hemispheres.

• Lateral sulcus (Sylvian fissure): Separates temporal lobe from frontal and parietal lobes.

• Broca's area: Controls speech production.

• Wernicke's area: Involved in language comprehension.

• Corpus callosum: Connects left and right cerebral hemispheres.

• Thalamus: Relay station for sensory and motor signals.

• Hypothalamus: Regulates homeostasis, hormone release, and autonomic functions.

• Pineal gland: Secretes melatonin, regulates circadian rhythms.

• Pituitary gland: Master endocrine gland, controls other glands.

• Midbrain, Pons, Medulla (oblongata): Components of the brainstem, control vital functions.

• Lateral ventricle, Third ventricle, Fourth ventricle: Cavities containing cerebrospinal fluid (CSF).

• Cerebral aqueduct: Connects third and fourth ventricles.

All 12 cranial nerves of brainstem: Identification and basic function are essential for understanding sensory and motor pathways.

Spinal Cord

Major Structures

The spinal cord is a long, thin, tubular structure that connects the brain to the peripheral nervous system and transmits neural signals.

• Conus medullaris: Tapered end of the spinal cord.

• Cauda equina: Bundle of spinal nerves below the conus medullaris.

• Filum terminale: Fibrous extension anchoring the spinal cord.

• Pia mater, Dura mater: Protective membranes (meninges) surrounding the spinal cord.

• Spinal fluid space/Central canal: Contains cerebrospinal fluid.

Bones of the Skull

Major Bones and Features

The skull protects the brain and forms the structure of the face. It consists of several bones and features important for anatomical orientation.

• Frontal bone

• Parietal bone

• Occipital bone

• Temporal bone

• Sphenoid bone

• Ethmoid bone

• Crista galli

• Lacrimal bone

• Palatine bone

• Mandible: Lower jaw, includes body, ramus, condyle, coronoid process.

Major Openings of the Skull

Openings in the skull allow passage of nerves and blood vessels.

• Superior orbital fissure

• Inferior orbital fissure

• Optic canal

• Foramen rotundum

• Foramen ovale

• Foramen canal

• Internal acoustic (auditory) meatus

• External acoustic (auditory) meatus

• Jugular foramen

• Foramen magnum

Vertebrae

Structure and Classification

Vertebrae are the bones forming the vertebral column (spine), providing support and protection for the spinal cord.

• Body: Main weight-bearing portion.

• Lamina, Pedicle: Form the vertebral arch.

• Spinous process: Posterior projection for muscle attachment.

• Transverse process: Lateral projections for muscle and ligament attachment.

• Vertebral foramen: Canal for spinal cord.

• Superior/inferior vertebral notch: Form intervertebral foramina for spinal nerves.

• Articular processes (facet): Form joints between vertebrae.

• Atlas (C1): Supports the skull, allows nodding motion.

• Axis (C2): Has the dens (odontoid process), allows rotation.

• Cervical vertebrae (C1-C7): Neck region.

• Thoracic vertebrae (T1-T12): Upper back, attach to ribs.

• Lumbar vertebrae (L1-L5): Lower back, largest vertebrae.

• Sacrum, Coccyx: Base of spine.

Eye

Major Structures

The eye is the organ of vision, composed of several layers and structures that focus and process light.

• Cornea: Transparent front layer, refracts light.

• Sclera: White outer layer, provides protection.

• Iris: Colored part, controls pupil size.

• Pupil: Opening for light entry.

• Lens: Focuses light onto retina.

• Ciliary body: Produces aqueous humor, controls lens shape.

• Retina: Contains photoreceptors (rods and cones).

• Optic nerve: Transmits visual information to brain.

• Extraocular muscles: Control eye movement (superior/inferior/lateral/medial rectus, superior/inferior oblique).

Ear

Major Structures

The ear is responsible for hearing and balance, consisting of external, middle, and inner parts.

• Auricle (pinna): External part, collects sound.

• Lobule: Lower part of auricle.

• External acoustic meatus: Ear canal.

• Tympanic membrane: Eardrum, vibrates with sound.

• Malleus, Incus, Stapes: Middle ear ossicles, transmit vibrations.

• Auditory (Eustachian) tube: Equalizes pressure.

• Semicircular canals: Balance organs.

• Cochlea: Spiral-shaped, contains sensory cells for hearing.

• Utricle, Saccule: Detect linear acceleration and head position.

Muscles of the Head

Major Muscles

Muscles of the head are involved in facial expression, mastication, and eye movement.

• Stylohyoid

• Occipitofrontalis

• Orbicularis oculi

• Orbicularis oris

• Zygomaticus

• Sphenoid

• Masseter

• Temporalis

Muscles Acting on Neck, Trunk, and Scapula

Major Muscles

These muscles are responsible for movement and stabilization of the neck, trunk, and shoulder region.

• Sternocleidomastoid: Rotates and flexes the neck.

• Trapezius: Moves scapula and supports arm.

• Rhomboid major: Retracts scapula.

• Rhomboid minor: Retracts scapula.

• Iliocostalis, Longissimus, Spinalis: Erector spinae muscles, extend vertebral column.

• Quadratus lumborum: Flexes spine laterally.

• External intercostal, Internal intercostal: Muscles of respiration.

• Diaphragm: Main muscle of inspiration.

• External oblique, Internal oblique, Transversus abdominis, Rectus abdominis: Abdominal wall muscles, support trunk and aid in movement.

Skull Sutures

Major Sutures

Sutures are immovable joints between skull bones.

• Sagittal

• Coronal

• Lambdoid

• Squamous

Summary Table: Major Skull Openings and Their Functions

Opening	Location	Main Function
Foramen magnum	Occipital bone	Passage for spinal cord
Optic canal	Sphenoid bone	Passage for optic nerve
Jugular foramen	Between temporal and occipital bones	Passage for jugular vein and cranial nerves
Internal acoustic meatus	Temporal bone	Passage for facial and vestibulocochlear nerves
Superior orbital fissure	Sphenoid bone	Passage for oculomotor, trochlear, abducens, and ophthalmic nerves

Additional info:

• Some terms and structures were expanded for clarity and completeness.

• Functions of muscles and bones were inferred based on standard anatomical knowledge.