Chapter 8: The Appendicular Skeleton

pelvic girdle

attach to the lower limbs and must withstand the stresses involved in weight bearing and mobility consists of the two hip bones

the patella

-a large sesamoid bone that forms within the tendon of the quadriceps femoris, a group of muscles that extend (straighten) the knee. -the patella has a rough convex anterior surface and a broad base -the patellar ligament connects the apex of the patella to the tibia -ossification begins at 2-3, ends at puberty - normally, the patella glides across the patellar surface of the femur. direction of movement is superior-inferior

the tarsal bones

-ankle or tarsus consists of 7 seven tarsal bones -the large talus transmits the weight of the body from the tibia towards the toes -the calcenous or heel bone, is the largest of the tarsal bones. -calcaneal/Achilles tendon is attached to the posterior end of the calcenous -the cuboid articulates with the anterior surface of the calcenus. -the navicular is anterior to the talus, on the medial side of the ankle-it articulates with the talus and with three cuneiform bones-medial, intermediate, and lateral. -proximally the cuneiform bones articulate with the navicular

the pelvis

-consists of the two hip bones, the sacrum, and the coccyx -the pelvis may be divided into the true(lesser) pelvis and false(greater) pelvis. the true pelvis encloses the pelvic cavity. the bony edge of the true pelvis is called the pelvic brim or linea terminalis. the enclosed space is the pelvic inlets -the false pelvis consists of the expanded, bladlike portions of each ilium superior to the pelvic brim -the pelvic outlet is the opening bounded by the coccyx, the ischial tuberosities, and the inferior border of the pubic symphsis. -in females the pelvis is generally smoother and lighter and has less prominent markings.

the appendicular skeleton

-includes the bones of the limbs and the supporting bone(pectoral and pelvic) girdles that connect them to the trunk -lets you manipulate objects and move from place to place -dominated by long bones that support the limbs

the femur

-longest and heaviest bone in the body -articulates with the hip bone at the hip joint and with the tibia at the knee joint -the rounded epiphyses, or femoral head articulates with the pelvis at the acetabulum -a ligament attaches the acetabulum to the femur at the fovea capitis, a small pit in the center of the femoral head. the neck of the femur joins the shaft at an angle of about 125 degrees

the clavicles

-originate at the superior lateral border of the manubrium of the sternum, lateral to the jugular notch. -from the pyramidal shaped sternal end, each clavicle curves laterally and posteriorly for about half its length -the flat acromial end of the clavicle is broader than the sternal end -the smooth, superior surface of the clavicle lies just beneath the skin. The acromial end has a rough inferior surface that has prominent lines and tubercles. These surface markings are attachment sites for muscles and ligaments of the shoulder. -clavicle is small and fragile. fortunately, clavicle fractures heal rapidly with simple clavicle strap

the tibia

-shinbone, the large medial bone of the leg - the intercondylar eminence is a ridge that separates the condyles. -the anterior surface of the tibia near the condyles has a prominent rough tibial tuberosity. this tuberosity marks the attachment of the patellar ligament -as it nears the ankle joint the tibia broadens, and the medial border ends in the medial malleolus, a large process familiar to you as the medial bump at the ankle. the inferior surface of the tibia articulates with the proximal bone of the ankle. the medial malleolus supports this joint medially

the humerus

-the arm, or brachium, contains only one bone, the humerus, which extends from the scalpula to the elbow. at the proximal end of the humerus, the round head articulates with the scalpula -the prominent greater tubercle is a rounded projection on the lateral surface of the epiphysis, near the margin of the humeral head. -the lesser tubercle is a smaller projection that lies on the anterior, medial surface of the epiphyses, separated from the greater tubercle by the intertubercular groove.a large tendon runs along the groove. both tubercles are important sites for muscle attachment -the anatomical neck lies between tubercles and the articular surface of the head.the narrower distal surgical neck corresponds to the metaphysis of growing bone

the carpal bones

-the carpus, or wrist contains 8 carpal bones. these bones form 2 rows, one with 4 proximal carpal bones and the other with 4 distal carpal bones -the proximal carpal bones are the scaphoid, lunate, triquetrum, and pisiform - the scaphoid is the proximal carpal bone on the lateral border of the wrist. It is the carpal closest to the styloid process of the radius -the lunate lies medial to the scaphoid. like the scaphoid, it articulates with the radius -the triquetrum is medial to the lunate. it articulates with the disc that separates the ulnar head from the wrist -pisiform sits anterior to the triquetrum Distal carpal bones are the trapezium, trapezoid, capitate, and hamate -the trapezium is the lateral bone of the distal row. Its proximal surface articulates with the scaphoid -trapezoid lies medial to the trapezium. it also has proximal articulation with the scaphoid -the capitate is the largest carpal bone. It sits between the trapezoid and the hamate -the hamate is the medial distal carpal bone

humerus pt 2

-the deltoid tuberosity is a large, rough elevation on the lateral surface. - on the posterior surface, the deltoid tuberosity ends at the radial groove. -near the distal articulation with the bones of the foreaem, the shaft expands to either side at the medial and lateral epicondyles. -the ulnar nerve crosses the posterior surface of the medial epicondyle. -at the condyle, the humerus articulates with the radius and the ulna, the bones of the forearm. -condyle is divided into two articular regions: the trochlea and the capitulum -the trochlea is the spool shaped medial portion of the condyle.it extends from the base of the coronoid fossa on the anterior to the olecranon fossa on the posterior surface. rounded capitulum forms the lateral surface of the condyle. -a shallow radial fossa superior to the capitulum accommodates a portion of the radial head as the foramen approaches the humerus.

the femur 2

-the greater and lesser trochanters are large, rough projections that originate at the junction of the neck and shaft.these trochanters develop where large tendons attach to the femur -the linea aspera is a rough ridge that runs along the center of the posterior surface of the femur, marking the attachment site of powerful hip muscles as it approaches the knee joint, the linea aspera divides into a pair of ridges that continue to the medial and lateral epicondyles. these smoothly rounded projections form superior to the medial and lateral condyles, which are a part of the knee joint. the two condyles are separated by a deep intercondylar fossa.

hip bones 2

-the ilium provides an extensive area for the attachment of muscles, tendons and ligaments - the pubic ramus and ischial ramus encircle the obturator. this space is closed by a sheet of collagen fibers whose inner and outer surfaces provide a firm base for the attachment of muscles of the hip -the broadest part of the ilium extends between the arcuate line, which is continuous with the pectineal line, and the iliac crest. these prominent ridges mark the attachments of ligaments and muscles. -the area between the arcuate line and iliac crest forms a shallow depression known as the iliac fossa-the concave surface of the iliac fossa helps support the abdominal organs and provides additional area for muscle attachment -pubic symphsis- two pelvic bones attached to a median pad of fibrocartilage

the radius

-the radius is the lateral bone of the forearm(further away from the midline). - the disc shaped radial head articulates with the capitulum of the humerus. - a narrow neck extends from the radial head to the radial tuberosity.-this tuberosity marks the attachment site of the biceps brachii muscle -the ulnar notch on the medial surface of the radius marks the site of articulation with the head of the ulna. -the styloid process on the lateral surface of the radius helps stabilize this joint

the ulna

-the ulna and radius are parallel bones that support the forearm or antebarchium. In the anatomical position the ulna lies medial(ulna is closer to the midline of the body than the radius) to the radius - the olecranon, the proximal end of the ulna is point of the elbow - on the anterior surface of the proximal epiphysis, the trochlear notch of the ulna articulates with the trochlea of the humerus at the elbow joint. -the olecranon forms the superior lip of the trochlear notch. - the coronoid process forms its inferior lip - during extension, the olecranon swings into the olecranon fossa on the posterior surface on the humerus -during flexion, the coronoid process projects into the coronoid fossa on the anterior humeral surface -lateral to the coronoid process, a smooth radial notch accommodates the head of the radius at the proximal radioulnar joint -the interosseous membrane, a fibrous sheet, connects the lateral margin of the ulna to the radius. -near the wrist, the shaft of the ulna narrows before ending at a disc shaped ulnar head. The posterior, lateral surface of the ulnar head has a short styloid process.

pectoral/shoulder girdle

-where each arm articulates with the trunk at a pectoral girdle. consists of 2 S shaped clavicles and 2 broad flat scalpulae -skeletal muscles support and position the scalpulae, which have no direct bony or ligamentous connections with to the thoracic cage. as a result the shoulders are extremely mobile, but not very strong -the surfaces of thee scalpulae and clavicles are extremely important as sites for muscle attachment. -bony ridges and projections mark the attachment sites of major muscles. other bone markings, such as sulci or foramina, indicate the positions of nerves that control the muscles or the passage of blood vessels that nourish the muscles and bones.

metatarsal bones and phalanges

5 long bones that form the distal portion of the foot identified by roman numerals I-V, medial to lateral metatarsal bones I-III articulate with the three cuneiform bones and metatarsal bones IV-V articulate with the cuboid phalanges or toe bones are same as fingers hallux/big toe has 2 phalanges, the rest have three, proximal, middle, distal

hip fracture

actually involves femur-not hip bone two types of hip fractures are femoral neck fractures and intertrochanteric fractures in a femoral neck fracture the femoral head is separated from the femur(and its blood supply). in the intertrochanteric there is no disconnection to the blood supply, therefore such fractures may be repaired with a metal plate and screws

hip bones

also called coxal or pelvic bones each hip bone is formed by the fusion of three bones: ilium, ischium, and a pubis. the ilia have a sturdy articulation with the auricular surfaces of the sacrum-attaching the pelvic girdle to the axial skeleton -the medial surfaces of the hip bones are connected by a pad of fibrocartilage at a joint called the pubic symphysis -on the lateral surface of each hip bone is an acetabulum, a concave socket that articulates with the head of the femur. -the anterior and inferior portion of the ridge is incomplete, leaving a gap called the acetbular notch -the smooth, cup-shaped articular surface of the acetabulum is the lunate surface -the ilium, ischium, and pubis meet inside the acetabulum

runners knee

also known as patellaofemoral stress syndrome develops from improper tracking of the patella across the patellar surface patella is forced outside its normal track, so that it shifts laterally running on hard or slanted surfaces and inadequate arch support are often responsible misalignment puts pressure on the knee, resulting in swelling and tenderness after exercise

The largest carpal bone in the hand is the

capitate

Which bone provides the only fixed support for the pectoral girdle

clavicle

lower limb

consists of femur(thigh) patella(kneecap) tibia and fibula(leg) and the tarsal bones, metatarsal bones and phalanges of the foot anatomical terminology uses thigh and leg lower limbs transfer the body weight to the ground

the metacarpal bones and phalanges

five metacarpal bones articulate with the distal carpal bones and support the hand. Roman numerals I-V identify the metacarpal bones, beginning with the lateral metacarpal bone which articulates with the trapezium. for example, metacarpal I articulates with the proximal bone of the thumb. each hand has 14 finger bones or phalanges the first finger is known as the pollex/thumb-has two phalanges -each of the other fingers has 3 phalanges- proximal,middle and distal

potts fracture

forceful movement of the foot outward and backward that can dislocate the ankle, breaking both the lateral malleolus of the fibula and the medial malleolus of the tibia

stress fractures

hairline fractures that develop in bones subjected to repeated shocks or impacts stress fractures of the foot usually involve one of the metatarsal bones caused by either improper placement of the foot while running or by poor arch support

the fibula

head of fibula articulates with the tibia the medial border of the thin shaft is bound to the tibia by the interosseous membrane, which extends to the lateral margin of the tibia.this membrane helps stabilize the position of the two bones and provides additional surface area for muscle attachment doesn't transfer weight, but important site for the attachment of muscles that move the foot and toes -fibular process-lateral malleolus gives lateral stability to the ankle.

carpal tunnel syndrome

inflammation of the connective tissues between the flexor and retinaculum and the carpal bones can compress the tendons and adjacent median nerve. the result is pain, weakness and reduced wrist mobility

The primary function of the pectoral girdle is to

position the shoulder joint and provide a base for arm movement

What structural characteristics of the pectoral girdle allow for a great deal of movement?

relatively weak joint

the scalpulae

the anterior surface of the body of each scalpula forms a broad triangle. the three sides of the triangle are the superior border, the medial border(vertebral border), and the lateral border(axillary border). corners of the triangle are called superior, inferior, and lateral angle the lateral angle or head of the scalpula, forms a broad process that supports the cup-shaped glenoid cavity.-where scalpula articulates with the humerus -the depression in the anterior surface is called the subscalpular fossa. -smaller anterior projection is the coracoid process -the acromion is the larger, posterior process. -the acromion is continuous with the scalpular spine, a ridge that crosses the posterior surface of the scalpular body before ending at the medial border -the area superior to this spine is the supraspinous fossa and the region inferior is the infraspinous fossa

congenital talipes equinovarus

the arches of the foot are usually present at birth. sometimes, however, they fail to develop properly. In congenital talipes equinovarus abnormal muscle development distorts growing bones and joints. One or more feet may be involved.condition can be mild moderate or severe. in most cases tibia, ankle, and foot and affected. longitudinal arch is exaggerated and the feet are turned medially and inverted. 1 in 1000 births. twice as common in boys than girls. casts help. less than half the cases require surgery

The sacrum and the coccyx are curved in

the male pelvis

skeletal variation

we can estimate a persons muscular development and muscle mass from the various ridges and from the appearance of various ridges and from the general bone mass. sex and age can be determined can also provide clues about the individuals nutritional state, handedness and occupation changes begin at 3 minths and continue through life

arches of the foot

weight transfer occurs along the longitudinal arch of the foot. Ligaments and tendons maintain this arch by tying the calcenous to the distal portions of the metatarsal bones -the elasticity of the talar portion of the longitudinal arch absorbs the shocks from sudden changes in weight loading -the transverse arch describes the degree of curvature change from medial to the lateral borders of the foot -during flexion at the ankle all ur body weight rests on the calcaneus -during extension at the ankle, the talus and calcaneus transfer your weight to the metatarsal bones and phalanges through the more anterior tarsal bones