CH 4-8 FLASHCARDS

Axial skeleton

The portion of the skeleton that includes the skull, vertebral column (including sacrum and coccyx), rib cage with sternum, and the hyoid bone.

Appendicular skeleton

The bones of the limbs; begins with the clavicle and includes the shoulder girdle, arms, legs, and pelvis (os coxae).

Clavicle

An appendicular bone that forms the sternoclavicular joint with the sternum, linking the upper limb to the axial skeleton.

Sternoclavicular joint

The joint between the sternum (axial skeleton) and the clavicle (appendicular skeleton).

Os coxae

Hip bones; part of the pelvis that joins the sacrum at the sacroiliac joint.

Sacroiliac joint

Joint between the sacrum and the ilium, connecting the axial and appendicular skeleton.

Hyoid bone

A horseshoe-shaped bone in front of the larynx; unique in that it does not form a joint with another bone; muscles/ligaments attach to it; fracture can indicate strangulation.

Cranium

The part of the skull that houses the brain; contains eight cranial bones.

Cranial bones

The eight bones of the cranium: frontal, two parietals, two temporals, occipital, sphenoid, and ethmoid.

Frontal bone

A cranial bone that forms the forehead and contributes to the orbital cavities.

Parietal bone

Paired cranial bones forming the sides and roof of the cranium (two in total).

Temporal bone

Paired cranial bones located near the ears, containing structures of the ear.

Occipital bone

Cranial bone at the back of the skull; articulates with the atlas via the occipital condyles.

Sphenoid bone

A central cranial bone that articulates with all the cranial bones; lies at the base of the skull and helps form the orbit; contains the sella turcica region for the pituitary gland.

Ethmoid bone

Cranial bone between the nose and the orbits; contributes to the nasal cavity and the medial walls of the orbits.

Maxillae

Upper jaw bones; contain alveolar sockets for teeth; form the anterior two-thirds of the hard palate; fuse at the midline.

Palatine bones

Two bones forming the posterior part of the hard palate; contribute to the nasal cavity and the orbit.

Zygomatic bones

Cheek bones; form part of the orbit.

Nasal bones

Two small bones forming the bridge of the nose.

Lacrimal bones

Small bones forming part of the medial wall of each orbit; contain the nasolacrimal canal for tears.

Inferior nasal conchae

Paired bones with a hook shape; form the inferior turbinates in the nasal cavity to help humidify and filter air.

Vomer

A small triangular bone forming part of the nasal septum.

Mandible

Lower jaw bone; the only movable bone of the skull via the temporomandibular joint; contains teeth sockets (alveoli).

Temporomandibular joint (TMJ)

The joint between the mandible and the temporal bone; the only movable joint in the skull; functions like a hinge.

Alveolar sockets

Sockets in the maxillae and mandible that hold teeth.

Hard palate

The bony palate formed by the anterior maxillae (two-thirds) and the posterior palatine bones (one-third); fusion is necessary during development.

Intervertebral disc

Fibrocartilage between vertebral bodies that provides cushioning and houses the nucleus pulposus in the center.

Nucleus pulposus

The gel-like center of an intervertebral disc that provides cushioning within the disc.

Intervertebral foramen

Openings between adjacent vertebrae through which spinal nerves exit the spinal column.

Cervical vertebrae

Seven vertebrae in the neck region.

Thoracic vertebrae

Twelve vertebrae in the mid-back that articulate with the ribs.

Lumbar vertebrae

Five vertebrae in the lower back.

Sacrum

A fused set of five vertebrae forming part of the pelvis and connecting to the ilium at the sacroiliac joint.

Coccyx

Tailbone; typically four fused vertebrae.

Atlas (C1)

First cervical vertebra; no vertebral body; has two flat surfaces (condyles) that articulate with the occipital bone; supports the skull.

Axis (C2)

Second cervical vertebra; contains the dens (odontoid process) that pivots with the atlas to enable rotation.

Occipital condyles

The joints on the occipital bone that articulate with the atlas, forming the atlanto-occipital joint.

Scoliosis

Lateral (sideways) curvature of the spine; severe thoracic scoliosis can impair lung expansion and gait.

Kyphosis

Exaggerated thoracic curvature (hunchback); commonly associated with osteoporosis and vertebral collapse.

Lordosis

Exaggerated lumbar curvature (swayback).

Sacroiliac joint

Joint between the sacrum and ilium that links the axial and appendicular skeleton.

Ribs: true ribs

Ribs 1–7 that connect to the sternum via their own hyaline cartilage.

Ribs: false ribs

Ribs 8–12 whose cartilage connects to the cartilage of the rib above rather than directly to the sternum.

Ribs: floating ribs

Ribs 11–12 that do not attach to the sternum or to cartilage of another rib.

Frontal sinus

A paranasal sinus within the frontal bone that contributes to resonance and reduces skull weight.

Maxillary sinus

A paranasal sinus within the maxilla; one of the common sites of sinus infections.

Ethmoid sinus

Paranasal sinus located within the ethmoid area; contributes to nasal cavity air spaces.

Sphenoid sinus

Paranasal sinus within the sphenoid bone; part of the complex sinus system behind the orbits.

Paranasal sinuses

Air-filled spaces in the frontal, maxillary, ethmoid, and sphenoid bones; lightens the skull, aids resonance, and helps drain mucus.

Orbit bones

The orbital socket is formed by multiple bones: frontal, sphenoid, zygomatic, maxilla, lacrimal, ethmoid, and palatine.

Phalanges (hand)

The finger bones; there are 14 in total, with each finger having proximal, middle, and distal phalanges; the thumb has only proximal and distal phalanges.

Phalanx (singular)

A single finger bone; the plural is phalanges.

Proximal phalanx

The phalanx closest to the hand; forms a joint with the corresponding metacarpal.

Middle phalanx

The middle finger bone between proximal and distal phalanges; present in all fingers except the thumb.

Distal phalanx

The phalanx at the fingertip; forms a joint with the middle phalanx.

Phalange numbering (1–5)

Digits are numbered 1 through 5 from the thumb side; the proximal phalanx of finger 4 is the ring finger’s proximal bone.

Thumb phalanges

The thumb has two phalanges: proximal and distal.

Metacarpals

Five long bones in the hand between the phalanges and the carpals; numbered 1–5 from the thumb side.

Carpal bones

Eight wrist bones arranged in two rows of four; includes scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate.

Scaphoid

One of the proximal row carpal bones; articulates with the radius.

Lunate

Proximal row carpal bone that articulates with the radius.

Triquetrum

Proximal row carpal bone; part of the eight carpal bones.

Pisiform

Wrist carpal bone in the proximal row; pea-shaped accessory bone.

Trapezium

Distal row carpal bone; articulates with the first metacarpal (thumb).

Trapezoid

Distal row carpal bone; articulates with the second metacarpal.

Capitate

Largest carpal bone in the distal row; articulates with the third metacarpal.

Hamate

Distal row carpal bone with a hook-like projection; articulates with the fourth and fifth metacarpals.

Radius

Forearm bone on the thumb side; larger distal end; forms the major wrist joint with the carpals.

Ulna

Forearm bone on the little finger side; forms the major elbow joint with the humerus.

Elbow joint

Hinge joint between the humerus and ulna.

Humerus

Upper arm bone; proximal end forms a joint with the scapula; distal end forms a joint with the radius/ulna.

Glenoid cavity

Shallow socket on the scapula that receives the head of the humerus to form the shoulder joint.

Scapula

Shoulder blade; connects to the clavicle and forms the shoulder joint with the humerus; capable of movement over the rib cage.

Clavicle

Collarbone; connects the scapula to the sternum; the key link between the appendicular and axial skeleton.

Sternum

Breastbone; central chest bone connected to the clavicles; part of the axial skeleton.

Os coxae

Hip bone; composed of three parts: ilium, ischium, and pubis.

Ilium

Uppermost part of the os coxae; contributes to the acetabulum and sacroiliac joint.

Ischium

Posterior part of the os coxae; contributes to the acetabulum and supports sitting.

Pubis

Anterior part of the os coxae; forms part of the acetabulum.

Acetabulum

Hip socket formed by the ilium, ischium, and pubis; where the head of the femur articulates.

Sacroiliac joint

Joint between the sacrum and the ilium; part of the pelvic girdle.

Pubic angle

Angle at the anterior pelvis formed by the two pubic bones;

Pelvis

Bony basin formed by two os coaxae and the sacrum (and coccyx); supports trunk and birth canal.

Acetabulum (repeat)

Hip socket formed by the ilium, ischium, and pubis; point of articulation for the femur.

Os coxae (repeat)

Hip bone consisting of ilium, ischium, and pubis; forms the hip socket with the femur.

Ilium, Ischium, Pubis

Three bones that comprise each os coxae; together form the hip socket, acetabulum.

Sacrum

Triangular bone at the base of the spine; forms the SI joint with the ilium.

Coccyx

Small tailbone at the bottom of the vertebral column; part of the pelvis.

Tarsal bones

Seven ankle bones; include talus, calcaneus, navicular, cuboid, and three cuneiforms (medial, intermediate, lateral).

Talus

The ankle bone; articulates with the tibia and fibula to form the ankle joint.

Calcaneus

Heel bone.

Navicular

Tarsal bone anterior to the talus.

Cuboid

Tarsal bone on the lateral side of the foot.

Cuneiforms

Three tarsal bones (medial, intermediate, lateral) located anterior to the navicular.

Metatarsals

Five bones of the foot between the tarsals and the toes; numbered 1–5 from the big toe side.

Phalanges (toes)

Toe bones; 14 in total; each toe has proximal, middle, distal phalanges except the big toe, which has only proximal and distal.

Colles' fracture

Distal radius fracture typically from falling on an outstretched hand; common in skateboard/bike accidents.

Ankle joint spaces

Two important spaces: talotibial (between talus and tibia) and talofibular (between talus and fibula) used in realignment after injury.

Ossification (osteogenesis)

The process of bone formation, occurring in embryonic development, fracture repair, and lifelong remodeling; includes endochondral and intramembranous pathways.

Endochondral ossification

Bone forms by replacing a hyaline cartilage model; primary ossification center develops in the diaphysis, followed by secondary centers in the epiphyses.