Connective Tissue and Skeletal System: Lab Study Guide

Connective Tissue

Overview of Connective Tissue

Connective tissue is one of the four primary tissue types in the human body. It provides structural and metabolic support for other tissues and organs. Key features include the presence of collagen and elastin fibers and an extracellular matrix that surrounds the cells.

• Collagen fibers: Strong, flexible protein fibers that provide tensile strength.

• Elastin fibers: Stretchy fibers that allow tissues to return to their original shape after stretching.

• Extracellular matrix: Non-cellular material composed of ground substance and fibers.

Connective Tissue Proper

• Loose Connective Tissue

  • Areolar connective tissue: Contains fibroblast cells; found under epithelia, surrounds blood vessels and organs. Function: Cushions organs, provides support but permits independent movement.

  • Adipose tissue: Contains adipocyte cells; found under skin, around kidneys, and in the abdomen. Function: Stores energy, insulates, and cushions organs.

• Dense (Fibrous) Connective Tissue

  • Regular dense connective tissue: Contains fibroblast cells; collagen fibers are aligned in parallel. Location: Tendons and ligaments. Function: Attaches muscles to bones or bones to bones; withstands great tensile stress in one direction.

  • Irregular dense connective tissue: Contains fibroblast cells; collagen fibers are arranged irregularly. Location: Dermis of the skin, joint capsules. Function: Provides strength to resist forces from many directions.

Cartilage

• General features: Contains chondrocyte cells within lacunae; avascular; firm, flexible matrix.

• Types of Cartilage:

  • Hyaline cartilage: Most common; found in nose, trachea, ends of long bones. Function: Provides support and flexibility; reduces friction between bony surfaces.

  • Fibrocartilage: Contains thick collagen fibers; found in intervertebral discs, pubic symphysis, menisci. Function: Resists compression and absorbs shock.

  • Elastic cartilage: Contains elastic fibers; found in external ear, epiglottis. Function: Maintains shape while allowing flexibility.

Additional info: Bone and blood are also connective tissues, but are covered in later objectives.

Skeletal System: Terms, Histology, and Microanatomy

Divisions of the Skeleton

• Axial skeleton: Consists of the skull, vertebral column, and thoracic cage (ribs and sternum).

• Appendicular skeleton: Includes the limbs and girdles (pectoral and pelvic girdles).

Bone Structure and Microanatomy

• Compact bone: Dense, solid bone forming the outer layer of bones; contains osteons.

• Spongy bone: Porous bone found at the ends of long bones and inside flat bones; contains trabeculae.

• Marrow cavity: Central cavity in long bones containing bone marrow (red or yellow).

• Foramen: Opening or hole in a bone for passage of nerves and blood vessels.

• Diaphysis: Shaft of a long bone.

• Epiphyses (proximal/distal): Ends of a long bone.

• Periosteum: Dense connective tissue membrane covering the outer surface of bone.

• Endosteum: Thin membrane lining the internal surfaces of bone.

• Osteon (Haversian system): Structural unit of compact bone.

• Central (Haversian) canal: Channel in the center of each osteon containing blood vessels and nerves.

• Perforating (Volkmann’s) canal: Canals that run perpendicular to central canals, connecting them.

• Lamellae: Concentric rings of bone matrix in an osteon.

• Lacunae: Small spaces housing osteocytes.

• Osteocyte: Mature bone cell residing in a lacuna.

• Trabecula: Lattice-like network of spongy bone.

Bones of the Skull

Major Bones

• Frontal bone

• Parietal bones

• Temporal bones

• Occipital bone

• Maxillae (maxillary bones)

• Zygomatic bones

• Sphenoid bone

• Ethmoid bone

• Lacrimal bones

• Nasal bones

• Palatine bones

• Vomer

• Mandible

Major Skull Sutures

• Coronal suture: Between frontal and parietal bones.

• Sagittal suture: Between the two parietal bones.

• Squamous sutures: Between parietal and temporal bones.

• Lambdoid suture: Between parietal and occipital bones.

Key Skull Features

• Mastoid process (temporal bone)

• Occipital condyles (occipital bone)

• Styloid process (temporal bone)

• Foramen magnum (occipital bone)

• External auditory meatus (temporal bone)

• Mandibular fossa (temporal bone)

• Cribriform plate (ethmoid bone)

• Crista galli (ethmoid bone)

• Sella turcica (sphenoid bone)

• Optic canal (sphenoid bone)

• Hard palate (maxilla and palatine bones)

• Coronoid process (mandible)

• Zygomatic arch (zygomatic and temporal bones)

• Mandibular condyle (mandible)

• Hyoid bone: Not part of the skull; supports the tongue.

Vertebral Column and Bony Thorax

General Vertebral Features

• Body: Main weight-bearing portion.

• Vertebral canal: Passage for the spinal cord.

• Intervertebral discs: Pads of fibrocartilage between vertebrae.

• Transverse processes: Lateral projections for muscle attachment.

• Spinous process: Posterior projection for muscle/ligament attachment.

Types of Vertebrae

• Cervical vertebrae: 7 vertebrae in the neck; have transverse foramina.

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

• Axis (C2): Has the odontoid process (dens); allows rotation of the head.

• Thoracic vertebrae: 12 vertebrae; articulate with ribs.

• Lumbar vertebrae: 5 vertebrae; largest, support lower back.

• Sacrum: 5 fused vertebrae; forms posterior pelvis.

• Coccyx: 3-5 fused vertebrae; tailbone.

Bony Thorax

• Ribs: 12 pairs; true ribs (1-7), false ribs (8-12), floating ribs (11-12).

• Sternum: Consists of manubrium, body, and xiphoid process.

• Costal cartilages: Connect ribs to sternum.

Pectoral Girdle and Upper Limb

• Clavicle

• Scapula: Features include spine, acromion, coracoid process, glenoid cavity.

• Humerus: Features include head, greater and lesser tubercles, coronoid and olecranon fossae, trochlea, capitulum.

• Ulna: Features include olecranon process, trochlear notch, coronoid process, radial notch, styloid process.

• Radius: Features include head, radial tuberosity, styloid process.

• Hand: Carpals (wrist bones), metacarpals (palm), phalanges (fingers).

Pelvic Girdle and Lower Limb

• Pelvic Bones (os coxae): Ilium, ischium, pubis; features include acetabulum, pubic symphysis, pubic arch, ischial tuberosity, obturator foramen, iliac crest, greater sciatic notch.

• Femur: Head, neck, greater and lesser trochanters, lateral/medial condyles.

• Patella: Kneecap.

• Tibia: Lateral/medial condyles, tibial tuberosity, anterior crest, medial malleolus.

• Fibula: Head, lateral malleolus.

• Foot: Tarsals (including calcaneus and talus), metatarsals, phalanges.

Example Table: Types of Connective Tissue

Type	Main Cell Type	Location	Function
Areolar	Fibroblast	Under epithelia, around organs	Support, elasticity
Adipose	Adipocyte	Subcutaneous, around kidneys	Energy storage, insulation
Dense Regular	Fibroblast	Tendons, ligaments	Strong attachment
Dense Irregular	Fibroblast	Dermis, joint capsules	Strength in multiple directions
Hyaline Cartilage	Chondrocyte	Ends of long bones, nose	Support, reduces friction
Fibrocartilage	Chondrocyte	Intervertebral discs	Shock absorption
Elastic Cartilage	Chondrocyte	External ear	Flexibility

Additional info: For exam preparation, focus on being able to identify the location and function of each tissue type, as well as the anatomical features of bones and their markings.