9. Skeletal System: Bone Markings, Axial, and Appendicular Skeleton

Comprehensive vocabulary flashcards covering anatomical terminology, bone markings, cranial and facial structures, the vertebral column, thoracic cage, and appendicular anatomy based on lecture notes.

Bone markings

Surface features that characterize each bone in the body, categorized into depressions, openings, and projections.

Depressions

Clefts located where a bone meets another structure that allow blood vessels and nerves to travel along the bone and allow two bones to articulate.

Openings

Holes in the bone that indicate where blood vessels or nerves travel through the bone.

Projections

Bony extensions of various shapes and sizes that serve as attachment points for muscles, tendons, and ligaments.

Facet

A smooth, nearly flat articular depression; exemplified by the articular facet on a rib for articulation with a transverse process.

Fossa

A shallow, basin-like bone depression (plural: fossae); exemplified by the olecranon fossa on the distal portion of the humerus.

Fovea

A small pit or depression bone marking; exemplified by the fovea capitis on the head of the femur.

Groove (or sulcus)

A furrow or elongated depression along a bone; exemplified by the costal groove of a rib.

Canal (or meatus)

A passageway or tunnel through a bone; exemplified by the external acoustic meatus of the temporal bone.

Fissure

A narrow, slit-like opening through a bone; exemplified by the superior orbital fissure of the sphenoid bone.

Foramen

A round or oval opening through a bone (plural: foramina); exemplified by the supraorbital foramen of the frontal bone.

Condyle

A rounded articular projection on a bone; exemplified by the mandibular condyle of the mandible.

Crest

A prominent, narrow ridge of bone; exemplified by the iliac crest of the ilium.

Epicondyle

A raised area on or above a condyle; exemplified by the medial epicondyle of the humerus.

Protuberance

A bony outgrowth or protruding prominence; exemplified by the external occipital protuberance of the occipital bone.

Trochanter

A very large, blunt, irregularly shaped process found only on the femur; exemplified by the greater trochanter.

Line

A narrow ridge of bone that is less prominent than a crest; exemplified by the linea aspera of the femur.

Axial skeleton

The skeletal division forming the long axis of the body, including the skull, vertebral column, and rib cage, functioning in protection, support, and carrying other body parts.

Appendicular skeleton

The skeletal division consisting of the upper and lower limbs and girdles (shoulder and hip), primarily involved in locomotion.

Sutures

Interlocking, immovable joints with saw-toothed or serrated appearances that unite all bones of the adult skull except the freely movable mandible.

Cranial vault

The rounded superior, lateral, and posterior portions of the skull that enclose the brain.

Cranial base

The interior floor of the skull divided into three contoured depressions called fossae.

Foramen magnus

The large opening in the base of the cranium through which the spinal cord exits.

Anterior cranial fossa

Depression formed by the frontal bone, ethmoid bone, and sphenoid bone that supports the frontal lobe of the cerebrum.

Middle cranial fossa

Depression formed by the sphenoid bone and temporal bone that supports the temporal lobe of the cerebrum and the pituitary gland.

Posterior cranial fossa

Depression formed by the temporal bone and occipital bone that supports the cerebellum and part of the brainstem.

Coronal suture

Suture that extends laterally across the superior surface along the coronal plane, articulating the frontal bone with the parietal bones.

Lambdoid suture

Suture that arcs across the posterior skull surface resembling the Greek letter lambda ($\lambda$), articulating the parietal bones with the occipital bone.

Sagittal suture

Suture extending along the midsagittal plane between the coronal and lambdoid sutures, articulating the paired parietal bones.

Squamous suture

Suture located on each lateral side of the skull articulating the temporal bone with the parietal bone.

Facial skeleton

The framework of $14$ bones (single: mandible, vomer; paired: nasal, lacrimal, zygomatic, palantine, maxilla, inferior nasal concha) that forms facial features, secures teeth, anchors muscles, and houses special sense organs.

Cranial cavity

The largest cavity of the skull that surrounds and encloses the brain.

Orbital cavities

Skull cavities that contain the eyeballs, muscles, nerves, blood vessels, and lacrimal tear glands; formed by the frontal, sphenoid, ethmoid, zygomatic, palantine, maxilla, and lacrimal bones.

Nasal cavity

Cavity forming the first part of the respiratory tract, containing sensory neurons for smell and air passages, and divided along the midline by the nasal septum (vomer and ethmoid bone).

Oral cavity

Cavity formed by the maxilla and mandible containing the teeth, tongue, salivary glands, and passages for both food and air.

Paranasal sinuses

Four pairs of air-filled, mucus-lined cavities (frontal, ethmoid, sphenoidal, and maxillary) that warm and humidify air, lighten the skull, and enhance vocal resonance.

Hyoid bone

A U-shaped bone in the anterior neck that does not articulate directly with any other bone; has greater and lesser horns and serves as an attachment site for muscles of swallowing and speech.

Vertebral arch

Posterior composite structure of a vertebra composed of two pedicles and two laminae, which together with the body encloses the vertebral foramen.

Anulus fibrosis

The outer ring of an intervertebral disc composed of collagen fibers and fibrocartilage that limits the expansion of the inner nucleus pulposus.

Nucleus pulposus

The elastic, compressible inner gelatinous core of an intervertebral disc.

Cervical vertebrae

Seven vertebrae ($C_1-C_7$) characterized by small oval bodies ($C_1$ lacks a body; $C_2$ has the dens), triangular vertebral foramina, transverse foramina, and mostly fork-shaped spinous processes.

Thoracic vertebrae

Twelve vertebrae ($T_1-T_{12}$) characterized by heart-shaped bodies with costal facets, circular vertebral foramina, facets for ribs on long transverse processes, and long spinous processes pointing inferiorly.

Lumbar vertebrae

Five vertebrae ($L_1-L_5$) characterized by large kidney-shaped bodies, flattened triangular vertebral foramina, short transverse processes without facets or foramina, and thick, posteriorly pointing spinous processes.

Sacrum

Triangular bone formed by $5$ fused sacral vertebrae ($S_1-S_5$) whose superior articular processes articulate with the hip bone, featuring foramina for blood vessels and spinal nerves.

Coccyx

The tailbone, formed by $4$ fused coccygeal vertebrae ($\text{Co}_1-\text{Co}_4$) that typically fuse around age $25$ and serves as an attachment site for several ligaments.

Manubrium

The superior bone of the sternum that articulates with the clavicles and rib pair $1$.

Xiphoid process

The inferior portion of the sternum that starts as hyaline cartilage, ossifies by age $40$, and serves as an attachment point for abdominal muscles.

True ribs

Rib pairs $1$ through $7$ that attach directly to the sternum via their own individual costal cartilages.

False ribs

Rib pairs $8$ through $12$; ribs $8-10$ attach indirectly to the sternum by connecting to the cartilage of rib $7$, while ribs $11-12$ are floating ribs.

Floating ribs

Rib pairs $11$ and $12$, which do not have an anterior attachment to the sternum.

Clavicle

The S-shaped collarbone of the pectoral girdle that acts as a brace holding the arm and scapula laterally away from the body; features a sternal end and an acromial end.

Scapula

The triangular posterior shoulder blade featuring a dorsal spine ending at the acromion, a glenoid cavity, and three fossae (subscapular, supraspinous, and infraspinous).

Glenoid cavity

The shallow lateral fossa of the scapula that articulates with the head of the humerus to form the shoulder joint.

Capitulum

The lateral, rounded articular knob on the distal humerus that articulates with the head of the radius.

Trochlea

The medial, pulley-shaped articular surface on the distal humerus that articulates with the trochlear notch of the ulna.

Deltoid tuberosity

A roughened, V-shaped area on the lateral shaft of the humerus serving as the insertion point for the deltoid muscle.

Ulna

The medial bone of the forearm, slightly longer than the radius, featuring the olecranon, trochlear notch, radial notch, and styloid process.

Carpal bones

Eight wrist bones per limb arranged in two rows: proximal (scaphoid, lunate, triquetrum, pisiform) and distal (trapezium, trapezoid, capitate, hamate).

Metacarpal bones

Five long bones forming the palm of the hand, numbered $I$ (thumb/pollux) to $V$ (pinky) from lateral to medial, whose distal heads form the knuckles.

Pelvic girdle

A pair of os coxae (hip bones) that attach the lower limbs to the axial skeleton; each formed by the childhood fusion (ages $13-15$) of the ilium, ischium, and pubis.

Ischial tuberosities

Roughened, thickened projections on the posteroinferior aspect of the ischium that bear the weight of the body when sitting.

Obturator foramen

The large opening formed by the rami of the pubis and ischium through which blood vessels and nerves pass into the thigh.

Acetabulum

The deep, cup-shaped socket formed at the junction of the ilium, ischium, and pubis that articulates with the head of the femur.

Pubic arch

The angle formed by the inferior pubic rami below the pubic symphysis; acute (less than $90^\circ$) in males and obtuse (greater than $90^\circ$) in females.

Femur

The largest, strongest, and longest bone in the body (approximately $\frac{1}{4}$ of total body height), extending from the hip to the knee.

Patella

Sesamoid bone (kneecap) enclosed within the quadriceps femoris tendon that protects the knee joint and improves the leverage of the thigh muscle.

Tibia

The larger, medial, weight-bearing bone of the lower leg whose distal end forms the medial malleolus.

Fibula

The slender, lateral bone of the lower leg that articulates with the tibia and talus, whose distal end forms the lateral malleolus.

Talus

The tarsal bone that articulates superiorly with the tibia and fibula to transmit weight to the foot and form the ankle joint.

Calcaneus

The heel bone located inferior to the talus that carries weight to the ground and serves as the attachment site for the Achilles tendon.

Hallux

The great toe (digit $I$), which contains only two phalanges (proximal and distal) unlike digits $II-V$ which each contain three.

Medial longitudinal arch

The highest arch of the foot extending from the heel to the ball of the great toe, preventing the medial foot from touching the ground and giving footprints their characteristic shape.

Lateral longitudinal arch

The lower longitudinal arch of the foot extending from the heel to the little toe, contributing to weight redistribution.

Transverse arch

The foot arch running perpendicular to the longitudinal arches, formed by the distal row of tarsal bones and the bases of the metatarsals.