The Skeletal System: The Appendicular Skeleton

Flashcards covering the key vocabulary and definitions related to the appendicular skeleton, including the pectoral girdle, upper limb, pelvic girdle, and lower limb. Also covers the development of the skeletal system.

Appendicular Skeleton

The bones of the appendicular skeleton are primarily involved in body movements and include those of the upper and lower limbs (including the girdles that attach them to the axial skeleton).

Pectoral (Shoulder) Girdle

Consists of a clavicle and a scapula.

Clavicle

Also known as the collarbone, is S-shaped, with the medial (sternal) end articulating with the manubrium of the sternum and the lateral (acromial) end articulating with the acromion of the scapula.

Scapula

A flat bone located in the superior part of the posterior thorax between the second and seventh ribs; its glenoid cavity is the attachment point for the humerus.

Humerus

The arm bone that articulates with the scapula proximally (its rounded head fits into the glenoid cavity) and with the radius and ulna distally (the trochlea articulates with the ulna and the capitulum with the radius).

Ulna and Radius

The two bones of the forearm. The olecranon and coronoid process at the proximal end of the ulna form the trochlear notch which wraps around the trochlea of the humerus making up the elbow joint. The radius is located on the lateral (thumb) side of the forearm and articulation of its head with the capitulum of the humerus and with the ulna allow the forearm to rotate.

Carpal Bones

8 small bones connected to each other by ligaments and they are arranged in two rows of four bones each. The proximal row (scaphoid, lunate, triquetrum, pisiform) articulates with the distal radius and ulna. The distal row (trapezium, trapezoid, capitate, hamate) articulates with the metacarpals.

Metacarpals

Five bones that make up the palm and back of the hand; numbered I through V (or 1–5) starting with the thumb; bases articulate with the distal carpals while their heads articulate with the proximal phalanges.

Phalanges

The bones of the digits; 14 total; the thumb contains 2 (proximal and distal) while the other 4 fingers contain 3 each (proximal, middle and distal).

Pelvic Girdle

Made up of two hip bones (os coxa, coxal bones) that articulate with the sacrum posteriorly; Each hip bone is actually made up of three individual bones: ilium, ischium, pubis; The two bones articulate anteriorly at the pubic symphysis.

Acetabulum

Composed of parts of all three of the bones that make up the hip bone, the head of the femur articulates with the acetabulum of the hip bone as a ball and socket joint.

False (greater) Pelvis

The area of the bony pelvis superior to the pelvic brim.

True (lesser) Pelvis

The area of the bony pelvis inferior to the pelvic brim.

Femur

The longest, heaviest, and strongest bone in the body; the proximal end (head) inserts into the acetabulum of the hip bone and the distal end articulates with the tibia and patella.

Patella

A triangular bone that develops in the quadriceps tendon and its posterior surface articulates with the femur.

Tibia and Fibula

The bones that consists of the lower leg; The tibia’s proximal end articulates with the femur, the tibia’s distal end articulates with the talus bone of the ankle, and the tibial tuberosity on the anterior surface is the point of attachment for the patellar ligament.

Tarsus

Contains 7 tarsal bones: the talus, calcaneus, navicular, 3 cuneiforms and the cuboid.

Metatarsus

Made up of 5 metatarsal bones, numbered I through V (1–5) starting with the big toe; they make up the sole and dorsal surface of the foot. The proximal ends articulate with the 3 cuneiform bones and the cuboid, and the distal ends articulate with the proximal phalanges.

Arches of the Foot

The foot has two arches (the longitudinal and transverse arches) that are supported by ligaments and tendons. The purpose of the arches is to allow the foot to support the weight of the body, provide leverage while walking, and distribute the body’s weight over the foot.

Mesoderm

Most skeletal tissue arises from this middle primary germ layer in embryos.

Ectoderm

Skull arises from this outer layer.

Cartilaginous Neurocranium

Skull bones develop in 2 ways. This hyaline cartilage undergoes endochondral ossification.

Membranous Neurocranium

Skull bones develop in 2 ways. This undergoes intramembranous ossification.

Viscerocranium

The bones of the face form from this.

Limb Girdles and Limbs Development

The skeleton of the limb girdles and limbs is derived from mesoderm; between week 4 and week 8 after fertilization, there is an extensive amount of growth and development in the formation of the upper and lower limbs.