studied_ Week 2 lecture Chapter 7 Student Copy.pptx

Human Anatomy and Physiology BIOL3306 Fall 2024

Week 2: The Skeletal System

  • Professor: Nour Nissan, Carleton University.

Structure of the Skeleton and Skeletal Cartilages

Overview of the Skeleton

  • The skeleton consists of approximately 206 bones and associated skeletal cartilages.

Key Components:

  • Skull:

    • Most complex structure; contains 22 bones.

      • Cranial Bones: encase the brain (8 bones).

      • Facial Bones: form the framework for the face (14 bones).

  • Vertebral Column:

    • Includes 24 vertebrae (cervical, thoracic, lumbar);

      • Top 7 vertebrae encase the spinal cord.

      • Inferior bones (sacrum and coccyx) are fused vertebrae.

  • Thoracic (Rib) Cage:

    • Comprises 12 pairs of ribs and the sternum, protecting thoracic cavity structures (lungs and heart).

Additional Groups:

  • Pectoral Girdle: composed of the clavicle and scapula, supporting the upper limb.

  • Upper Limb: includes the humerus, radius, ulna, carpals, metacarpals, and phalanges.

  • Pelvic Girdle: made up of the pelvic bones and sacrum, supporting the lower limb.

    • Composed of three bones: ilium, ischium, and pubis.

Structural Divisions of the Skeleton

  • Axial Skeleton:

    • Forms the longitudinal axis of the body; designed for protection (skull, vertebral column, thoracic cage).

  • Appendicular Skeleton:

    • Structured for motion; includes bones of the girdles and upper and lower limbs.

Overview of Skull Structure

Skull Composition

  • All skull bones are united in adults by immovable joints known as sutures (exception: mandible).

  • Cranial Bones:

    • Single Bones: Frontal, Occipital, Ethmoid, Sphenoid.

    • Paired Bones: Temporal, Parietal.

  • Facial Bones:

    • Single Bones: Mandible, Vomer.

    • Paired Bones: Maxilla, Zygomatic, Nasal, Lacrimal, Palatine, Inferior Nasal Concha.

Skull Visualization

  • Basic structure of the skull includes anterolateral views of various cranial and facial bones.

  • Cavities of the Skull:

    • Orbit: houses the eyeball and associated structures (formed by 7 bones).

    • Paranasal Sinuses: found within certain bones; help lighten the skull and enhance voice resonance.

    • Oral Cavity: contains teeth, tongue, and salivary glands.

Hyoid Bone

  • A small, C-shaped bone in the superior neck; serves as an attachment point for muscles involved in swallowing and speech.

Overview of the Vertebral Column

General Structure

  • Average of 33 vertebrae.

    • 7 Cervical: located in the neck.

    • 12 Thoracic: articulate with ribs.

    • 5 Lumbar: located in the lower back.

    • 5 fused Sacral: articulate with pelvic bones.

    • 3-5 fused Coccygeal: located at the most inferior end.

Spinal Curvatures

  • Primary: Thoracic and sacral curvatures present at birth.

  • Secondary: Cervical (develops when infant raises head) and lumbar (develops with walking).

Abnormal Spinal Curvatures

  • Kyphosis: exaggerated thoracic curvature, resembles a humpback.

  • Scoliosis: lateral curvatures that may appear C- or S-shaped; may be congenital or idiopathic.

Structure of Vertebrae

Comparison of Vertebrae Types

  • Cervical Vertebrae: Small and oval; most have foramina in transverse processes.

  • Thoracic Vertebrae: Heart-shaped body with costal facets; larger than cervical.

  • Lumbar Vertebrae: Largest and heaviest; kidney-shaped body, thick spinous processes.

Sacrum and Coccyx

  • Sacrum: Forms the posterior wall of the pelvic cavity; fuses by ages 20-25.

  • Coccyx: generally composed of 4 fused vertebrae; fuses around age 25.

Thoracic Cage

Ribs Composition

  • Includes 12 pairs of ribs with costal cartilages.

  • Intercostal Spaces: spaces between ribs, vital for respiratory movement.

Classification of Ribs

  • True Ribs (1-7): attach directly to the sternum.

  • False Ribs (8-12): do not attach directly to the sternum.

    • Costal Margin: formed by costal cartilages of ribs 8-10 that attach to rib 7.

    • Floating Ribs (11-12): do not attach to the sternum at all.

Sternum

  • Central bone of the chest where ribs attach; critical in Cardiopulmonary Resuscitation (CPR).

The Pectoral Girdle

Components

  • Comprises the clavicle and scapula.

    • Clavicle: S-shaped bone acting as a brace for upper limb.

    • Scapula: sits on the rib cage, injuries to the AC joint may lead to a separated shoulder.

Bones of the Upper Limb

Humerus

  • Only bone of the arm (brachium); considered a long bone.

Forearm

  • Composed of radius (lateral) and ulna (medial).

    • Proximal radius articulates with the capitulum at the elbow joint.

Wrist

Fractures

  • Commonly occur due to falls; often involve the distal radius.

  • Colles Fracture: a specific distal radius fracture.

Bones of the Hand

  • Comprises metacarpals (5 total) and phalanges (14 total).

Pelvic Girdle and Pelvis

Overview

  • Composed of two pelvic bones and the sacrum, forming the pelvic inlet with the pelvic brim.

Pelvic Bone Composition

  • Each pelvic bone includes ilium, ischium, and pubis.

Gender Differences

  • Female pelvis is wider, shallower, and lighter than the male pelvis.

Bones of the Thigh and Leg

Thigh

  • Femur: longest and strongest bone in the body; connects to the patella (kneecap).

Leg

  • Comprised of tibia (medial) and fibula (lateral), held together by interosseous membrane.