Vertebral Anatomy and Functions Quiz

Structural Anatomy - Week 1

• Course objectives depend on self-directed learning.
• Students need to be accountable for their progress.
• Essential steps for success: review the course outline, buy the textbook, and read the assigned readings.
• Actively participate in class, take thorough notes that are testable, and ask questions.
• Allocate at least 4 hours per week to the course.

Bone Formations

• Protuberance: A bump, projection, or eminence on a bone.
• Fossa: A shallow depression in a bone.
• Foramen: An opening or hole in a bone.
• Border: An edge of a bone.
• Process: A point at the end of a bone.
• Condyle: A rounded articular protrusion at the end of a bone.
• Epicondyle: A protrusion above a condyle on a long bone.
• Angle: A corner, point or apex of a bone.
• Line: A ridge or raised straight surface on a bone.
• Symphyis: A fibrocartilaginous fusion between two bones.
• Ramus: An arm or branch of a bone.
• Plate: A flat surface of a bone.
• Tuberocity: A large rounded prominence of a bone where muscles attach.
• Tubercle: A small rounded prominence of a bone where muscles attach.
• Trochanter: A large protrusion where muscles attach.
• Groove: A long, narrow depression in a bone.
• Crest: A ridge along the surface of a bone.

Structure and Components of the Spine

• Primary or kyphotic curves form in utero.
• Thoracic region is one of the primary spinal curves.
• Sacral region is one of the primary spinal curves.
• Cervical curve develops in infants as they hold their heads up.
• Lumbar curve develops as toddlers learn to walk upright.
• Spinal curves adapt to accommodate various organs.
• Regions of the spine are described by characteristics of the individual vertebrae.

General Structure of Vertebrae

• Anterior vertebral body is the weight-bearing portion.
• Its cylindrical shape and compact bone increases in size from T4 down, as it strengthens to manage increased weight-bearing responsibilities.
• Vertebral arches form a tunnel called the vertebral canal as the vertebrae are stacked.
• Pedicles are part of the vertebral arch extending posteriorly from the body.

Special Vertebrae

• C1 (Atlas): A ring-shaped bone that supports the skull.
• It has no spinous process or vertebral body. It has anterior and posterior arches with tubercles. It has lateral masses.
• C2 (Axis): The strongest cervical vertebra, has a dens (odontoid process).
• This process extends superiorly from the vertebral body and acts as a pivot point for C1 and the skull’s rotation.

Structure of Individual Vertebrae

• Cervical vertebrae are small, rectangular, and broad.
• Thoracic vertebrae are heart-shaped, with costal demi-facets for rib articulations. The first 10 ribs articulate this way. T eleventh and twelfth ribs only have one costal demifacet.
• Lumbar vertebrae are large, kidney-shaped, and have progressively wider vertebral bodies as they move downward.

Sacrum

• Large triangular bone at the base of the spine.
• Concave posteriorly.
• Formed by the fusion of sacral vertebrae (S1-S5).
• Fusion occurs between the age of 18-30.
• Located between the two wings (ilium) of the pelvis.

Intervertebral Discs (IVDs)

• Fibrocartilage plates joining adjacent vertebrae.
• Match the shape of the vertebral bodies.
• Act as shock absorbers.
• Their shape slightly changes to accommodate spinal motion.
• Between all adjacent vertebrae, except for C1-C2 (these are synovial joints).
• They strongly bind the vertebrae together.
• Thinnest in the thoracic region, thickest in the lumbar region
• Thick in the lordotic areas (anteriorly), thin in the kyphotic area (posteriorly).
• Discs are essential for weight-bearing.
• Their strength contributes to resisting fracture in the spine but discs can be susceptible to damage from shearing and rotatory forces. This is usually seen as the 'lift and twist injury'.

Structure of Intervertebral Discs

• Annulus fibrosus is an outer collar/ring of fibrocartilage lamellae organized concentrically.
• Fiber direction in adjacent layers is at right angles to each other which provides flexibility/strength/support.
• Superficial fibres are attached to the peripheral collar of compact bone.
• Deeper fibres are attached to the margins of the central disc of hyaline cartilage.
• These hyaline cartilaginous plates make up the superior and interior surfaces of the vertebral bodies.

Facet Joints

• Paired joints connecting adjacent vertebral arches.
• Plane/gliding synovial joints.
• Articular surfaces include Superior articular facets of the inferior vertebrae and Inferior articular facets of the superior vertebrae.
• No intrinsic ligaments specifically for facet joints.
• Support comes from joint capsules and accessory ligaments of the spine.
• Movements vary according to spinal region
• C-spine facets are horizontally oriented.
• Facilitate flexion and extension; rotation must occur with lateral bending.
• T-spine facets are vertical.
• Facilitate slight rotation; flexion and extension.
• L-spine facets are vertical.
• Restrict rotation; allow flexion, extension and lateral bending.

Accessory Ligaments of the Spine

• Anterior Longitudinal Ligament: Runs along the anterior aspect of all vertebral bodies. Attaches to occiput to sacrum.
• Posterior Longitudinal Ligament: Runs within the posterior aspect of the vertebral bodies. Goes from C2 to the sacrum.
• Ligamentum Flavum: Short repeating fibres that attach to adjacent laminae. Constructed mostly of elastin.
• Yellow colour
• Interspinous Ligament: Short fibres between adjacent spinous processes (throughout entire spine, but not obvious in thoracic region due to T-spine spinous processes overlapping).
• Intertransverse Ligament: Short fibres between the transverse processes. Throughout the entire spine.
• Supraspinous Ligament: Extensive (S1-C7), and attaches to the tips of the spinous processes.
• Nuchal Ligament: Attaches to tips of cervical spinous processes.
• Acts as a septum between muscles on either side.

Bone Structures of the Thorax

• Sternum
• Composed of Manubrium, Body, Xiphoid Process.
• Articulations with ribs 1-7 (via costal cartilages)
• Clavicle
• Elongated, S-shaped bone.
• Acromial and sternal extremities
• Conoid and trapezoid tubercles
• Ribs
• True, False, and Floating ribs
• Costal cartilages (connect ribs to sternum)
• Articulation with thoracic vertebrae

Apertures of the Thorax

• Thoracic Inlet: Kidney-shaped opening at the top of the thorax.
• Borders: T1 vertebral body, manubrium, and first pair of ribs and costal cartilages.
• Structures: Trachea, esophagus, brachiocephalic trunk, left subclavian artery, veins, pleura (of apex of the lung) travel through the inlet.
• Thoracic Outlet: Large, inferior opening at the base of the thorax.
• Borders: T12 vertebral body, xiphisternal joint, and the inferior costal margin.
• Structures: Esophagus, vagus nerve, abdominal aorta, inferior vena cava pass through the outlet.

Contents in the Thorax

• The thorax is a cavity which encompasses important respiratory, cardio-vascular, nervous, digestive and lymphatic structures.
• Lungs, bronchi, trachea, esophagus, pleura, part of the liver and spleen are found within the thorax, along with the heart, aorta, vena cava and lymphatic trunks.

Spinal Cord

• 18 inches long, 1/2 inch wide.
• Located between vertebrae L1 and L2
• Symmetrical bilaterally.

Nervous System

• Spinal nerves (e.g., cervical plexus, brachial plexus, lumbar plexus, sacral plexus) connect the spinal cord to different areas of the body.
• The spinal cord is made up of cervical, thoracic, lumbar and sacral nerves.

Cranial Bones

• Neurocranium: 8 bones (frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid, 1 ethmoid).
• Viscerocranium: 15 irregular bones (2 lacrimal, 2 nasal, 2 maxilla, 2 zygomatic, 2 palatine, 2 inferior nasal concha, 1 mandible, 1 vomer, 1 ethmoid).

Spinal Meninges

• Dura mater
• Subdural space
• Arachnoid mater
• Subarachnoid space
• Pia mater

For Next Week

• Plan your studies
• Review the spinal meninges
• Begin studying the muscles of the back (see next slide for specifics).

Back Muscles

• Diagrams depict specific back muscles like: longissimus capitis, splenius capitis, serratus posterior superior, splenius cervicis, iliocostalis, longissimus, spinalis (Erector spinae (cut)), semispinalis capitis, semispinalis thoracis, external intercostals, and quadratus lumborum.