Appendicular Skeleton

Pectoral girdle

Supports and anchors the forelimbs, providing muscle attachment and facilitating locomotion.

Pelvic girdle

Supports and anchors the hindlimbs, providing muscle attachment and facilitating locomotion.

Dermal bones supporting fins in Actinopterygii

Clavicle, cleithrum, post-cleithrum.

Structure of the bony fish pectoral girdle

Includes dermal bones (clavicle, cleithrum, post-cleithrum) and scapulocoracoid; attaches dorsally to the skull.

Chondrichthyes fin supports

Pectoral: coracoid bar; Pelvic: pubioischiac bar, fused across the midline.

Bones of the shoulder in tetrapods

Scapula, procoracoid, coracoid (procoracoid is lost in mammals, replaced by manubrium).

Frog pectoral girdle structure

Includes suprascapula, scapula, clavicle (replaces procoracoid), coracoid, and a multi-part sternum.

Crocodilian pectoral girdle differences

Enlarged scapula, coracoid, and interclavicle; lizards typically lack the interclavicle.

Pectoral girdle bones in turtles

Scapula, coracoid, acromion process (procoracoid), interclavicle (entoplastron), clavicles (epiplastron).

Bird pectoral girdle structure

Includes scapula, coracoid, and furcula (fused clavicle and interclavicle) providing strong support for flight muscles.

Mammalian pectoral girdle prominence

Scapula; allows a wide range of limb movement; clavicle is reduced or absent.

Frog pelvic girdle structure

Composed of ilium, ischium, and pubis, supporting hindlimbs and connecting to the vertebral column.

Innominate bone in birds

Fused ilium, ischium, and pubis forming a strong pelvic structure.

Turtle pelvic girdle parts

Ilium, ischium, pubis, and epipubis.

Sacroiliac joint importance

Joint between the sacrum and ilium, transferring weight from the spine to the pelvis and hindlimbs.

Digit

A finger or toe.

Phalanx

A bone segment of a digit.

Polyphalangy

Having more than three phalanges per digit.

Polydactyly

Having more than five digits per limb.

Digit numbering in vertebrates

Digits are numbered I–V from medial (thumb/big toe) to lateral; radius aligns with digit I.

Fused forelimb bones in frogs

Radioulna.

Fused hindlimb bones in frogs

Tibiofibula.

Tarsal bones in frogs

Astragalus (medial) and calcaneum (lateral).

Bird forelimb adaptations for flight

Lightweight, fused bones: carpometacarpus, reduced digits, alula aids in maneuvering.

Carpal bones in birds

Radial and ulnar bones.

Metacarpal bones in birds

Major and minor, fused into carpometacarpus.

Alula in birds

Small digit at the carpus (digit I) aiding in airflow control and maneuverability during flight.

Olecranon in mammals

Proximal extension of ulna, forming the elbow.

Calcaneus in mammals

Heel bone, serving as an attachment for the gastrocnemius via the calcaneal tendon.

Horse forelimb common names

Carpus = 'knee', Metacarpal III = cannon bone, Metacarpals II & IV = splint bones, Phalanges: P1 (long pastern), P2 (short pastern), P3 (coffin bone).

Horse hindlimb structure

Same structure as forelimb; Digit III bears weight.

Bird hindlimb bones

Femur, patella, tibiotarsus (fused tibia + tarsals), tarsometatarsus (fused metatarsals), phalanges.

Hallux in birds

Digit I, often reversed for perching; varies by species.

Bird toe arrangements

Anisodactyl (3 forward, 1 back), zygodactyl (2 forward, 2 back), heterodactyl (2 forward, 2 back), syndactyl (fused toes), pamprodactyl (all toes forward).

Plantigrade stance

Entire foot on ground, seen in humans and bears.

Digitigrade stance

Toes bear weight, seen in dogs and cats.

Unguligrade stance

Tips of toes bear weight, seen in horses and deer.

Carpometacarpus function in birds

Fused structure of metacarpals, providing rigidity and surface for feather attachment in flight.

Tarsometatarsus function in birds

Fused metatarsals in the hindlimb, supporting walking and perching.

Function of the furcula in birds

Acts as a spring during flight; formed by fused clavicles and interclavicle.

Acetabulum in vertebrates

Hip socket formed by ilium, ischium, and pubis; femur articulates with it.