Skeletal System Study Guide

Comprehensive flashcards for reviewing bone classification, structure, growth, functions, regional skeletal anatomy, and joint dynamics based on the BIOS 163 study guide.

What are long bones, and what is an example of one?

Long bones are elongated with expanded ends found in the arms and legs, such as the femur.

What are short bones, and where are they located?

Short bones are almost cube-like (equal in length and width), found in the wrist and ankle.

What are sesamoid bones?

Small, nodular bones that develop within tendons, such as the patella.

What are flat bones, and what are some examples?

Flat bones are plate-like with broad surfaces, such as ribs, scapulae, and flattened skull bones.

What are irregular bones, and what are some examples?

Irregular bones have varied shapes that often connect to other bones, such as vertebrae and facial bones.

What are epiphyses?

The expanded ends of long bones that form joints with adjacent bones.

What covers the ends of long bones at joints?

Articular cartilage (hyaline cartilage).

What is the diaphysis, and what type of bone tissue forms its outer layer?

The diaphysis is the central tubular shaft of a long bone, made of tightly packed compact bone.

What is the function of the epiphyseal plate (disc)?

It is an area of cartilage where bone grows in length.

What is the periosteum?

A tough layer of dense, vascular connective tissue covering the bone surface, continuous with ligaments and tendons.

What is contained within the diaphysis of a long bone?

A hollow medullary cavity lined with endosteum and filled with bone marrow.

What do bony processes or grooves on a bone indicate?

Places of attachment for tendons and ligaments.

Where are osteocytes located within compact bone?

Mature bone cells (osteocytes) sit in spaces called lacunae arranged in concentric rings around central (Haversian) canals.

What are canaliculi?

Tiny canals passing nutrients and gases/wastes back and forth through the bone matrix.

What components make up the extracellular matrix of bone tissue?

Collagen protein fibers (providing flexibility and strength) and inorganic calcium phosphate salts (providing hardness).

What is an osteon?

A cylindrical structural unit of compact bone made of osteocytes and intercellular material cemented together.

In what direction do central (Haversian) canals extend through bone?

Longitudinally (lengthwise through the bone tissue).

What are perforating (Volkmann's) canals?

Transverse canals that interconnect central canals to share blood supply.

Where is compact bone tissue found in a long bone?

In the diaphysis, making up the outer walls of bone shafts.

What are trabeculae?

Branching bony plates that form spongy bone.

Where is spongy bone located, and what is its purpose?

In the epiphyses of long bones and inside bone structures to reduce skeletal weight.

From what precursor tissue do intramembranous flat bones of the skull develop?

Sheet-like layers of undifferentiated connective tissue.

What is the role of osteoblasts in bone formation?

They are bone-forming cells that deposit bony matrix around themselves.

How do osteoblasts transform into osteocytes?

Once osteoblasts deposit bone matrix completely around themselves, they become enclosed in small compartments called lacunae and are then called osteocytes.

What forms the periosteum during intramembranous ossification?

Cells of the membranous connective tissue lying outside the developing bone.

How do endochondral bones initially develop before being replaced by bone?

As hyaline cartilage models shaped like future bones.

What occurs at the primary ossification center during endochondral ossification?

Cartilage tissue in the diaphysis is invaded by blood vessels and osteoblasts that first form spongy bone.

Where do secondary ossification centers appear in endochondral bone development?

In the epiphyses.

What is the epiphyseal plate?

A band of hyaline cartilage forming a growth plate between the primary and secondary ossification centers.

What roles do osteoclasts and osteoblasts play during bone remodeling?

Osteoclasts break down calcified cartilage matrix, and osteoblasts deposit new bone in its place.

How do bones increase in length versus thickness?

Epiphyseal plates are responsible for increasing bone length, while subperiosteal deposition via intramembranous ossification increases thickness.

How is the medullary cavity formed in the diaphysis?

By the erosion of inner bone by osteoclasts.

What happens to the epiphyseal plate at adulthood?

Cartilage cells stop dividing and the plate undergoes complete ossification, fusing into an epiphyseal line.

How does the skeletal system provide support?

It provides a structural framework that gives shape to the head, face, thorax, and limbs while supporting body weight.

How does the skeleton provide protection?

It shields delicate internal organs such as the brain, spinal cord, heart, and lungs.

How does the skeletal system assist in movement?

Bones act with muscles as levers to facilitate body movements via bony processes.

What is hematopoiesis and where does it occur?

Blood cell production occurring in red bone marrow to produce red blood cells, white blood cells, and platelets.

Which inorganic minerals are stored in bone tissue?

Calcium, phosphate salts, magnesium, sodium, and potassium.

Which primary tissue types are contained within a bone organ?

Bone tissue, cartilage, dense connective tissue, blood, and nervous tissue.

What structures constitute the axial skeleton?

The skull, hyoid bone, vertebral column (vertebrae and intervertebral disks), and thorax (ribs and sternum).

What structures constitute the appendicular skeleton?

The pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

What is the external acoustic meatus?

A tubelike passageway in the temporal bone leading to the ear opening.

Which bones form the prominence of the cheeks?

Zygomatic bones.

Which two bone structures form the nasal septum?

Perpendicular plate of the ethmoid and vomer.

Which bone structures form the hard palate?

Palatine processes of maxillae and horizontal plates of palatine bones.

Which two processes unite to form the zygomatic arch?

Temporal process of the zygomatic bone and zygomatic process of the temporal bone.

Which upper and lower jaw bones contain the teeth?

Maxillae (upper jaw) and mandible (lower jaw).

What are the nasal conchae?

Fragile, scroll-shaped bones in the nasal cavity that support mucous membranes and increase surface area.

What are fontanels?

Soft spots of unossified fibrous membrane in the infantile skull that allow cranial deformation during birth and brain expansion.

What pads separate adjacent vertebrae in the vertebral column?

Intervertebral disks.

What is the body (centrum) of a vertebra?

The thick, drum-shaped anterior portion of the vertebra that supports head and trunk weight.

What are the transverse processes of a vertebra?

Lateral projections that provide attachment sites for muscles and ligaments and articulate with ribs.

What is the spinous process of a vertebra?

A posterior/dorsal bony projection.

What are the names of the top two cervical vertebrae?

Atlas (C1) and Axis (C2).

How can cervical vertebrae be distinguished from other vertebrae?

By the presence of transverse foramina and bifid spinous processes.

What features distinguish thoracic vertebrae from other vertebrae?

Costal facets for rib articulation and long, pointed spinous processes.

How many lumbar vertebrae are in the human body?

5.

What is unique about sacral vertebrae?

They are fused into a single triangular bone called the sacrum.

What is the anatomical name for the tail bone?

Coccyx.

Which bones compose the thoracic cage?

Ribs, thoracic vertebrae, sternum, and costal cartilages.

How many pairs of true ribs are there, and how do they attach to the sternum?

7 pairs; they attach directly to the sternum via costal cartilage.

How many pairs of false ribs are present in the human thoracic cage?

5 pairs (which include 2 pairs of floating ribs that do not attach directly to the sternum).

What are the three distinct regions of the sternum?

Manubrium, body, and xiphoid process.

What shape characterizes the clavicle?

An elongated S-shape.

What structure divides the posterior surface of the scapula?

Spine.

What is the function of the acromion process of the scapula?

It articulates with the clavicle and forms the tip/summit of the shoulder.

What is the function of the coracoid process of the scapula?

It provides attachment sites for upper limb and chest muscles.

What is the glenoid cavity?

A shallow socket on the scapula that articulates with the head of the humerus.

Where is the head of the humerus located and what is its function?

Located at the proximal end; it articulates with the glenoid cavity of the scapula to form the shoulder joint.

Where does the distal end of the humerus articulate with the radius and ulna?

It articulates with the radius at the capitulum and with the ulna at the trochlea.

What are the two depressions (fossae) on the distal humerus?

Coronoid fossa and olecranon fossa.

What are the two knoblike processes located near the head of the humerus?

Greater and lesser tubercles.

On which side of the forearm is the radius located?

Lateral (thumb) side.

What is the purpose of the flattened head of the radius?

It articulates with the capitulum of the humerus and radial notch of the ulna to allow rotation (pronation/supination).

What are two key bony landmarks on the radius?

Radial tuberosity and styloid process.

What wrench-like notch on the ulna articulates with the humerus?

Trochlear notch.

What two processes of the ulna form the boundaries of the trochlear notch in the elbow joint?

Olecranon process and coronoid process.

What is unusual about the location of the head of the ulna?

It is located at the distal end near the wrist.

How many carpal bones make up the wrist?

8 carpal bones.

What are the bones of the hand (palm) and fingers called?

Metacarpals (palm bones) and phalanges (finger bones).

How many phalanges are in each finger versus the thumb?

3 in each finger; 2 in the thumb.

What is the ilium, and where does it articulate?

The largest, most superior portion of the coxal bone (a flared broad bone featuring the iliac crest); it joins the sacrum at the sacroiliac joint.

What is the ischium?

The posterior L-shaped portion of the coxal bone that supports body weight during sitting.

What is the pubis, and where does it articulate anteriorly?

The anterior portion of the coxal bone; it articulates at the pubic symphysis with fibrocartilage between the bones.

What is the obturator foramen?

A large opening in each coxal bone framed by the pubis and ischium.

What is the femur?

The thighbone, extending from hip to knee; it is the longest and strongest bone in the human body.

What are the proximal and distal articulations of the femur?

Its head articulates proximally with the acetabulum; its medial and lateral condyles articulate distally with the tibia.

What are key distinguishing features of the femur?

Fovea capitis, neck, and greater and lesser trochanters.

What is the patella?

The kneecap; a sesamoid bone located in the quadriceps tendon.

What is the tibia, and what bones does it articulate with?

The shinbone (medial weight-bearing lower leg bone); it articulates proximally with the femur and distally with the talus.

What is the function of the tibial tuberosity?

It is a prominent anterior process on the tibia that serves as the attachment point for the patellar ligament.

What is the medial malleolus?

An inner ankle prominence located at the distal end of the tibia.

What is the fibula?

A slender bone lying lateral on the lower leg that does not bear body weight.

What structure forms the outer ankle prominence?

Lateral malleolus (on the fibula).

How many tarsal bones make up the ankle?

7 tarsal bones.

Which tarsal bone articulates directly with the tibia and fibula?

Talus.

What is the calcaneus?

The heel bone that supports body weight and attaches to the Achilles tendon.

What bones form the instep and arch of the foot?

5 metatarsal bones.

How many phalanges does each toe contain?

3 phalanges in each toe, with the exception of the great toe, which has 2 (lacking a middle phalanx).

What is a suture joint?

An immovable fibrous joint located between flat bones of the skull.