appendicular skeleton

Appendicular skeleton:

The bones of the appendicular skeleton are contained in the pectoral girdle, the pelvis girdle, the upper and lower extremities

The pectoral girdle, or shoulder girdle attaches the bones of the upper extremities to the axial skeleton. Each of the two pectoral girdles is made up of a clavicle and a scapula. The clavicle is the anterior and more delicate of the two, and articulated with the sternum. The posterior scapula is free, held in place by muscles, articulates with the clavicle and humerus

The clavicles, or collarbones, are long, slender bones. They are S-shaped, located superiorly to the first rib. The medial end is called the sternal extremity. It is rounded and articulates with the sternum. The broader, flatter end is the acromonial extremity, which articulated with the acromion of the scapulae. The joint there formed is the acromonioclavicular joint. The conoid tubercle is on the inferior aspect of the bone, towards the lateral end, and serves as an attachment for ligaments. Also on the inferior surface is the costal tubercle, towards the medial end, with the same purpose
The scapulae, or shoulder blades, are flat, roughly triangular bones between the second and seventh ribs. A sharp ridge, the spine, run diagonally across the dorsal aspect of the body, which is the main section of the bone. Laterally, the bone forms the acromion that articulates with the clavicle. Inferior to the acromion is the glenoid cavity. This cavity articulates with the head of the humerus. The thin, medial edge is the medial, or vertebral, border. The outer is thicker, the lateral, or axillary, border. The superior is the superior border, which joins to the vertebral border at the superior angle. The scapular notch is a prominent indentation along the superior border. The lateral end of the superior border is a projection named the coracoid process to which muscles attached. Both above and below the spine are the supraspinous and the infraspinous fossae. Both serve as surfaces of attachment for shoulder muscles. On the ventral aspect of the scapulae are slightly hollowed sections named the subscapular fossae

The upper extremities are made up of sixty bones. They consist of two each humerus, radius, ulna, carpals, metacarpals, and phalanges

The humerus, or arm bone, is both the longest and largest or the upper extremities. The proximal end consists of a head which articulates with the glenoid cavity or fossa of the scapula. It also has an anatomical neck, which is an oblique groove just inferior to the head. The greater tubercle is a lateral projection distal to the neck. The lesser tubercle is the anterior process. Between the tubercles runs an intertubercular sulcus, or bicipital groove. The surgical neck is a constricted portion just distal to the tubercles, the name coming from it's liability to fracture. The body is roughly cylindrical at the proximal end, becoming more triangular as it descends. Along the middle portion of the shaft is a roughened V-shaped area called the deltoid tuberosity, that attachment point for the deltoid muscle. At the distal end is an almost 'double-joint'. the capitulum is the part of the knob that articulates with the radius, and the trochlea with the ulna. The coronoid fossa is the anterior depression that receive the ulna when the arm is flexed. When the arm is fully extended, the olecranon fossa recedes the olecranon of the ulna. The medial epicondyle and lateral epicondyle are the rough projections of either side of the distal end of the humerus
The radius and ulna make up the forearm, the radius being the thumb-side bone. The proximal end of the ulna is the olecranon (process). The coronoid process is an anterior projection. The trochlear, or semilunar, notch is a curved area between the olecranon and the coronoid process. the radial notch is a depression located inferiorly to the trochlear notch, which receives the head of the radius. The distal end of the ulna consists of a head separated from the wrist by a fibrocartilage disc, and a posterior styloid process
The radius has, at the proximal end, a disc-shaped head that articulates with the radial notch (ulna) and the capitulum (humerus). It also has a raised, roughened area called the radial tuberosity, attachment for the biceps. The distal end, like the ulna, has a styloid process on the lateral side. On the medial side is located an ulnar notch for articulation with the ulna
The carpus, or wrist, is made up of eight small short bones: the hamate, triquetral, pisiform, lunate, scaphoid, trapezium, trapezoid and capitate; counterclockwise from the pinky finger. The hand bones are the carpals, numbered I, II, III, IV and V from the thumb. The phalanges are made up of proximal, middle, and distal bones, except the thumb, which has no middle

The pelvic girdle consists of two coxal bones joined to the sacrum at the sacroiliac joint. These are, in turn, made up of three bones fused together. The superior ilium, the inferior and anterior pubis, and the inferior and posterior ischium. The three fuse at the socket of the femur, called the acetabulum. The ilium is the largest of the bones. It's superior crest is the iliac crest, ending anteriorly in the anterior superior iliac spine, and posteriorly in the posterior superior iliac spine. Inferior to the posterior superior iliac spine is the greater sciatic notch. The internal surface of the ilium seen from the medial side is the iliac fossa. Posterior to this is the auricular surface. The ischium contains the prominent ischial spine, appearing as the point on the end of the curve of the greater sciatic notch. From this point, another, smaller curve is seen, the lesser sciatic notch. Seen anteriorly, there are tow foramina inferior to the pelvic inlet, the obturator foramina. The pubis is made up of a superior and inferior ramus, and a body that helps make up the symphysis pubis. The symphysis pubis is the fibrocartilage joint between the two os coxae

The lower extremities are composed of sixty bones, being the two femurs, patellas, tibias, fibulas, tarsals, metatarsals, and phalanges

The femur is the longest and heaviest bone in the human body. The head articulates with the acetabulum, then narrows into the neck. Inferior to that are the greater and lesser trochanters, the greater being the lateral of the two. The body of the femur has on it a rough, vertical ridge, the linea aspera. The distal end expands to include the medial and lateral condyles and epicondyles. There is a depressed area between the two condyles called the intercondylar fossa, on the posterior aspect. On the anterior, between the condyles, is the patellar surface
The patella, or kneecap, is a small, triangular bone. The broader, superior end is the base, the other is the apex. The posterior aspect contains two articular facets, for the medial and lateral condyles of the femur
The medial bone of the lower leg is the tibia. It is larger, and is the only one of the two that articulates with the femur. The proximal and has on it lateral and medial condyles for this purpose. They are slightly concave, separated by the intercondylar eminance. The tibial tuberosity on the anterior aspect is the point of attachment for patellar ligaments. The medial surface of the distal end forms the medial malleolus, which articulates with the talus. The fibular notch is the point of articulation with the fibula. The fibula is smaller, and it's distal end makes up the lateral malleolus
The tarsus is the collective name for the tarsals: cuboid, navicular, first (medial), second (intermedial), and third (lateral) cuniforms, talus, and the massive calcaneus
The metatarsus is numbers I to V from the great toe, as are the phalanges The bones of the foot make up two arches: the longitudinal arch (which is two parts, medial and lateral), and the transverse arch

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