Anatomy & Physiology: Study Guide to the Brain, Skull, Vertebrae, and Associated Structures

Brain

Major Regions and Structures

The brain is the central organ of the nervous system, responsible for processing sensory information, regulating bodily functions, and enabling cognition and emotion. It is divided into several lobes and contains numerous specialized structures.

• Frontal lobe: Involved in voluntary movement, decision-making, and problem-solving.

• Temporal lobe: Processes auditory information and is important for memory.

• Occipital lobe: Primary center for visual processing.

• Parietal lobe: Integrates sensory information from various parts of the body.

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

• Postcentral gyrus: Primary somatosensory cortex, processes tactile information.

• Central sulcus: Separates the frontal and parietal lobes.

• Longitudinal fissure: Divides the two cerebral hemispheres.

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

• Broca's area: Involved in speech production.

• Wernicke's area: Involved in language comprehension.

• Corpus callosum: Large bundle of nerve fibers connecting the two hemispheres.

• Thalamus: Relay station for sensory and motor signals.

• Hypothalamus: Regulates homeostasis, including temperature, hunger, and hormone release.

• Pineal gland: Produces melatonin, regulates sleep cycles.

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

• Midbrain, Pons, Medulla (oblongata): Components of the brainstem, control vital functions such as breathing and heart rate.

• Lateral and Third ventricles: 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 the main pathway for information connecting the brain and peripheral nervous system.

• 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 (CSF).

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 notable features.

• Frontal bone

• Parietal bone

• Occipital bone

• Temporal bone

• Sphenoid

• Ethmoid

• Crista galli

• Lacrimal

• Palatine

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

Sutures: Immovable joints between skull bones, including sagittal, coronal, lambdoid, and squamous sutures.

Zygomatic arch: Cheekbone structure formed by the zygomatic and temporal bones.

Vertebrae

Structure and Classification

The vertebral column supports the body and protects the spinal cord. It is composed of individual vertebrae with distinct features.

• Body: Main weight-bearing portion.

• Lamina, Pedicle: Parts of the vertebral arch.

• Spinous process, Transverse process: Projections for muscle attachment.

• Vertebral foramen: Opening for the spinal cord.

• Intervertebral notch/foramen: Passage for spinal nerves.

• Articular processes (superior/inferior): Form joints between vertebrae.

• Cervical vertebrae (C1-C7): Includes Atlas (C1) and Axis (C2, with dens/odontoid process).

• Thoracic vertebrae (T1-T12): Articulate with ribs.

• Lumbar vertebrae (L1-L5): Largest vertebrae, support lower back.

• Sacrum and Coccyx: Fused vertebrae at the base of the spine.

Major Openings of the Skull

Foramina and Canals

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

• Superior/inferior orbital fissure

• Optic canal

• Foramen ovale/rotundum/spinosum/magnum

• Internal/external acoustic (auditory) meatus

• Jugular foramen

Eye

Major Structures

The eye is the organ of vision, composed of several layers and specialized structures.

• Cornea, Sclera: Outer protective layers.

• Iris, Pupil: Control light entry.

• Lens: Focuses light on the retina.

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

• Retina: Contains photoreceptors for vision.

• Choroid: Vascular layer supplying the retina.

• Optic nerve: Transmits visual information to the brain.

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

Ear

Major Structures

The ear is responsible for hearing and balance, divided into external, middle, and inner regions.

• Auricle (pinna): External ear structure.

• Lobule: Earlobe.

• External acoustic meatus: Ear canal.

• Tympanic membrane: Eardrum.

• Ossicles: Malleus, incus, stapes (transmit sound vibrations).

• Semicircular canals, utricle, saccule, cochlea: Inner ear structures for balance and hearing.

Muscles of the Head

Major Muscles

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

• Stylohyoid

• Occipitofrontalis

• Orbicularis oculi/oris

• Zygomaticus

Muscles Acting on Neck, Trunk, and Scapula

Major Muscles

These muscles are responsible for movements of the head, neck, trunk, and upper limb.

• Sternocleidomastoid

• Trapezius

• Rhomboid major

• Rhomboid minor

• Iliocostalis, Longissimus, Spinalis: Components of the erector spinae group.

• Quadratus lumborum

• External/internal intercostal

• Diaphragm: Main muscle of respiration.

• External/internal oblique, transversus abdominis, rectus abdominis: Abdominal wall muscles.

Table: Classification of Vertebrae

The following table summarizes the main types of vertebrae and their distinguishing features:

Type	Number	Key Features
Cervical	7 (C1-C7)	Small body, transverse foramina, Atlas (C1) and Axis (C2) specialized
Thoracic	12 (T1-T12)	Articulate with ribs, long spinous process
Lumbar	5 (L1-L5)	Large body, short spinous process
Sacral	5 (fused)	Forms sacrum, articulates with pelvis
Coccygeal	3-5 (fused)	Forms coccyx (tailbone)

Additional info:

• For cranial nerves, students should be able to identify each nerve and describe its primary function (e.g., olfactory nerve for smell, optic nerve for vision, etc.).

• Muscles of the head and neck are often tested for their origin, insertion, action, and innervation.

• Openings of the skull are clinically important as they transmit nerves and vessels; for example, the foramen magnum transmits the spinal cord.