Vertebral Column Anatomy

Vertebral Column

• 33 bones, 24 separate, 9 fuse (sacrum & coccyx)
• Approximately 70cm long in an adult of average height
• 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 3-4 coccygeal
• Functions: weight-bearing, anchor for muscles & ligaments, protection of spinal cord
• Normal curvatures: cervical and lumbar are concave, thoracic and sacral are convex

Supporting Elements of Vertebral Column

• Ligaments: strap-like, support the column of bones to stay upright; major are anterior & posterior longitudinal ligaments
• Intervertebral discs: cushioning between bony vertebral bodies; shock absorbers; 25% length of the vertebral column
  • Nucleus pulposus: acts like a rubber ball within the disc, providing elasticity and compressibility
  • Annulus fibrosus: holds together successive vertebrae & resists tension in the spine

A Typical Vertebra

• Gets larger as you descend the column
• Weight-bearing body + vertebral arch
• Vertebral arch: 2 pedicles + 2 laminae
• Arch + body enclose a vertebral foramen
• Pedicles: have notches on superior & inferior surfaces → intervertebral foramina
• 7 processes from each vertebral arch:
  • Spinous process: muscle attachment
  • Transverse processes (2): muscle attachment
  • Paired superior & inferior articular processes: link vertebrae above & below

Cervical Vertebrae

• 7 total, #1 & 2 have unusual structures and no intervertebral disc
• #3-7 are considered typical:
  • Body is oval, broader side-to-side than front-to-back
  • Spinous process is short and spilt at the end
  • Vertebral foramen is large -Each transverse process contains a transverse foramen for passage of the vertebral artery to the brain

Atlas (Cervical Vertebra #1)

• No body or spinous process
• Posterior & anterior neural arches
• Superior articular facets articulate with occipital condyles allowing the head to nod “yes”

Axis (Cervical Vertebra #2)

• Similar to C3-C7, except for dens or odontoid process which allows the head to rotate “no”
• Dens is the “missing” body of the atlas

Thoracic Vertebrae

• 12 total, all have ribs attached
• Increase in size from the first to the last
• Features:
  • Body is roughly heart-shaped and bears facets for ribs
  • Vertebral foramen is circular
  • Spinous process is long and points down
  • Transverse processes have facets for articulation with tubercles of ribs

Lumbar Vertebrae

• Lower back, major weight-bearing function
• Bodies are kidney-shaped and increase in size from top to bottom
• Features:
  • Pedicles & laminae are shorter & thicker than those of other vertebrae
  • Spinous processes are flat & short
  • Vertebral foramen is triangular
  • Inferior & superior facets are unique - curved

Sacral Vertebrae

• Starts as 5 separate vertebrae, fuse in adolescents = sacrum
• Articulates with 5th lumbar and laterally with hip bones (sacroiliac joint)
• Note: sacral promontory, transverse lines and sacral foramina
• Note: median sacral crest, sacral canal and sacral hiatus

Coccygeal Vertebrae

• Tailbone = 3 or 4 fused coccygeal vertebrae
• Attachment area for some pelvic ligaments, but otherwise useless

Bony Thorax

• Thoracic vertebrae + ribs + costal cartilages + sternum
• Protective cage around heart, lungs & major blood vessels
• Supports shoulder girdle & upper limbs
• Provides area of muscle attachment for back, chest & shoulders

Sternum

• Anterior midline of thorax
• Fusion of 3 bones: Manubrium, body & xiphoid process
• Manubrium articulates with clavicles via clavicular notches and with the first pair of ribs
• Body has notches for articulation with the 2nd to 7th ribs
• Xiphoid process is the attachment of some abdominal muscles

Ribs

• 12 per side, all attach to the vertebral column at the back
• Curve inferior-anteriorly
• 7 true ribs attach directly to the sternum
• False ribs: Ribs 8-10 attach indirectly to the sternum via costal cartilage and rib 7
• Floating ribs: ribs 11 & 12 are not attached anteriorly
• Features of a typical rib: shaft, head, neck, tubercle
• Note: the costal groove, 2 facets on the head (one articulates with the same-numbered vertebra and the other with the superior vertebra), tubercle articulates with the same-numbered thoracic vertebrae

Appendicular Skeleton

• Pectoral girdle: clavicles & scapulae
• Pelvic girdle: hip bones (coxal bones) plus upper & lower limbs

Pectoral Girdle

• Clavicle: S-shaped, slightly curved, acts as a brace to push the arms laterally
• Scapulae: thin, triangular flat bones, dorsally, between ribs 2 & 7
• Note: superior, medial & lateral borders, spine, acromion, coracoid process

Upper Limb

• 30 separate bones: arm, forearm, wrist and hand

Humerus

• Longest bone of the upper limb, the only bone of the "arm"
• Articulates with the scapula proximally, radius + ulna distally
• Note: head, anatomical neck, greater tubercle, lesser tubercle, intertubercular sulcus, surgical neck
• Note: 2 condyles + 2 epicondyles
  • Trochlea: articulates with ulna
  • Capitulum: articulates with radius
  • Ulnar nerve runs behind the medial epicondyle

Forearm

• 2 parallel long bones: radius & ulna
• Articulates with humerus & wrist bones, also articulate with each other proximally and distally
  • Interosseous membrane is a strong fibrous sheet between the radius & ulna
• Ulna (elbow joint): slightly longer than radius, olecranon & coronoid process, radial notch on coronoid process, styloid process
• Radius (wrist joint): head at proximal end, distal end is the wider end
  • Distal end: medial ulnar notch & lateral styloid process

Hand

• 27 bones total: carpus, metacarpus & phalanges

Carpus (wrist)

• 8 carpal bones - only scaphoid & lunate articulate with radius
• “So Long To Pittsburgh” (scaphoid, lunate, triquetrum, pisiform)
• “Time To Call Home” (trapezium, trapezoid, capitate, hamate)
• “Sally Left The Party To Take Cathy Home”

Metacarpus

• 5 long bones, distal ends are knuckles
• Numbered 1-5 from the thumb to the little finger

Phalanges

• 3/finger & 2/thumb = miniature long bones
• Numbered 1-5 from thumb to little finger
• Proximal, middle & distal except for thumb which has only proximal & distal

Pelvic Girdle

• Attaches lower limbs, transmits weight of upper body to lower limbs, supports visceral organs of pelvis
• Forms a complete circle
• Left & right hip bones (coxal bones) unite anteriorly & with sacrum at back
• Each os coxa consists of 3 bones that fuse at puberty: ilium, ischium, pubis
  • Acetabulum is the area where all 3 bones join and forms the socket of the hip joint

Ilium

• Large flaring bone that forms most of the os coxa
• Note: iliac crest, iliac spines, pelvic brim

Ischium

• Postero-inferior part of the hip bone
• Note: ischial tuberosity

Pubis

• Anterior part of the ox cosa
• 2 pubic bones unite at pubis symphysis
• Note: pubic crest, obturator foramen

Lower Limb

• Thigh, leg & foot

Thigh

• Femur: largest, longest and strongest bone
  • Major parts: head, fovia capitis, neck, linea aspera, lat & med condyles, lat & med epicondyles, patellar surface
  • Greater & lesser trochanters: attachment for muscles

Patella

• Sesamoid bone, embedded in the tendon of the quadriceps muscles

Leg

• 2 parallel bones: tibia & fibula
• Interosseus membrane + proximal & distal tibiofibular joints (rigid)
• Fibula does not contribute to the knee joint
• Tibia: transfers weight from the femur to the foot, next largest & strongest bone
  • Note: med & lat condyles, anterior border, tibial tuberosity
• Fibula: note head & lateral malleolus

Foot

• 26 bones: tarsus (ankle bone), metatarsus & phalanges

Tarsus

• 7 tarsal bones: largest is the calcaneus (heel bone), second largest is the talus (part of the ankle joint)

Metatarsus

• 5 miniature long bones numbered 1-5 (medial great toe = +1)

Phalanges (foot)

• Big toe (hallux) has two & remaining toes have 3 each - proximal, middle & distal

Explore the intricate anatomy of the vertebral column, including its structure, supporting elements, and functions. Learn about the vertebrae, ligaments, and intervertebral discs that play crucial roles in maintaining stability and flexibility. This quiz will test your knowledge on the various components of the spine.