Anatomy Ch. 8

appendicular skeleton
limb bones and their girdles that are attached to the axial skeleton

basic parts of the appendicular skeleton
1) the pectoral girdle, 2) the upper limb, 3) the pelvic girdle, 4) the lower limb

pectoral girdle or shoulder girdle
– consists of a clavicle and a scapula; – it attaches the upper limbs to the trunk; – do not encircle the body completely; – provides attachment for muscles that move the upper limb – girdle is very light and upper limbs are mobile – shoulder joint glenoid cavity socket is shallow – good for flexibility but bad for stability

clavicles
– slender, S-shaped bones that extend horizontally across the superior thorax on the anterior surface; – sternal end attaches with the manubrium and acromial end attaches with the scapula – holds the scapulae and arms laterally – transmits forces from upper limbs to bony thorax (axial skelet)

scapulae
– thin triangular flat bones that lie on the dorsal surface of the rib cage (ribs 2-7) – have 3 borders: superior (shortest and sharpest), medial (parallels the vertebral column), and lateral (abuts the armpit) – have 3 angles: superior (where the superior and medial borders meet), inferior (the junction of the medial and lateral borders; moves as the arm is raised and lowered), lateral (where the glenoid cavity lies)

the upper limb
– 30 bones form the skeleton of the upper limb, grouped into bones of the arm (between shoulder and elbow; humerus), forearm (radius and ulna), and hand (carpus, metacarpus, and phalanges)

humerus
– the only bone of the arm – longest and strongest bone of the upper limb – articulates with the scapula at the shoulder – articulates with the radius (trochlea) and ulna (capitulum) – provides sites for muscle attachment

forearm
– formed from the radius and ulna – proximal ends articulate with the humerus – distal ends articulate with carpals – In anatomical position, radius is lateral and the ulna is medial – the interosseous membrane interconnects radius and ulna

Ulna
– main bone responsible for forming the elbow joint w/ humerus – hinge joint allows forearm to bend on arm – distal end is separated from carpals by fibrocartilage – plays little or no role in hand movement

radius
– articulates with the hand & wrist; also w/capitulum of humerus – medially, head of radius articulates w/the radial notch of ulna – contributes heavily to the wrist joint – distal radius articulates with the carpal bones – when the radius moves, the hand moves with it

hand
– includes the following bones: carpus (wrist), metacarpals (palm), phalanges (fingers)

carpus
– forms the true wrist (the proximal region of the hand) – gliding movements occur between carpals – composed of 8 marble sized bones

carpal bones
– “Sally Left The Party To Take Carmen Home” – Proximal Row from lateral to medial: Scaphoid, Lunate, Triquetral, Pisiform – Distal Row lateral to medial: Trapezium, Trapezoid, Capitate, Hamate

metacarpus
– numbered 1-5 that radiate distally from the wrist starting with the pollex (thumb) – metacarpals form the palm – articulates proximally with the carpals and distally with the phalanges

phalanges
– numbered 1-5 beginning with the pollex – except for the thumb, each finger has 3 phalanges: proximal, middle, and distal

pelvic girdle
– consists of the paired hip bones (coxal bone); each hip bone unites with its partner anteriorly and with the sacrum posteriorly – attaches lower limbs to the spine – supports visceral organs – attaches to the axial skeleton by strong ligaments – acetabulum is a deep cut (like a cup) that holds the head of the femur – lower limbs have less freedom than upper limbs, but more stable than arm

bony pelvis
– a deep basin-like structure – formed by coxal bones (hip bones) , sacrum (last section of the 5 fused vertebrae), and coccyx (tailbone) – divided into two parts: the false (greater) pelvis, which is bounded by alae of the iliac bones and the true (lesser) pelvis, which lies inferior to the pelvic brim that forms a bowl containing the pelvic organs

coxal bones
– consists of 3 separate bones in childhood: ilium, ishium, and pubis

ilium
– the large, flaring bone that forms the superior region of the hip bone – consists of an inferior body and a superior winglike ala (thickened superior margin of the ala is the iliac crest) – site for attachment for many muscles, thickest at the tubercle of the iliac crest – articulates with the axial skeleton by the sacrum forming the sacroiliac joint

ischium
– forms the posteroinferior region of the hip bone – anteriorly joins the the pubis – the inferior surface of the ischial body is the ischial tuberosity, which are the strongest parts of the hip bones that bears your weight when you sit

pubis
– most anteroinferior bone of the pelvic girdle – lies horizontally in anatomical position and the bladder rests upon it – the pubic bones are joined by fibrocartilage at the midline

the lower limb
– carries the entire weight of the erect body – bones of lower limb are thicker and stronger than upper limbs – divided into 3 sections: thigh (femur), leg (tibia & fibula), and foot (tarsus, metatarsals, & phalanges)

thigh or femur
– articulates with the acetabulum by the fovea capitis and tibia – the region of the lower limb between the hip and the knee – the femur is the single bone of the thigh, which is the longest and strongest bone of the body

patella
– triangular sesmoid bone – embedded in the tendon that secures the quadriceps muscles – protects the knees anteriorly – improves leverage of the thigh muscles across the knee

leg
– refers to the region of the lower limb between the knee and ankle – composed of the tibia and fibula

tibia
more massive medial bone of the leg that receives the weight of the body from the femur – does NOT have a “HEAD” – forms the knee and ankle joint

fibula
– stick-like lateral bone of the leg – does NOT connect to the PATELLA – stabilizes the ankle joint

the foot
– composed of tarsus, metatarsals, and the phalanges – important functions: 1) supports body weight, 2) acts as a lever to propel body forward when walking – segmentation makes foot pliable and adapted to uneven ground

tarsus
– makes up the posterior half of the foot – the weight of the body is carried by two largest, most posterior tarsal bones: talus (ankle) and calcaneus (largest tarsal bone; heel) – contains 7 bones called tarsals: talus, calcaneus, navicular (medial and boat-like), cuboid (lateral and cubet-shaped), lateral cuniform (wedge-shaped in middle), intermediate cuneiform (inside middle), and the medial cuneiform (most medial)

metatarsus
– consists of 5 small bones called metatarsals – numbered 1-5 beginning with the hallux (big toe) – first metatarsal supports body weight

phalanges of the foot
– 14 phalanges of the toe same as fingers, with the hallux having only two phalanges

arches of the foot
– has three arches: the medial (highest and talus is keystone) and lateral (lowest and cuboid is keystone) longitudinal arches and the transverse (runs obliquely from one side of the foot to the other) arch – arches are maintained by interlocking shapes of tarsals, ligaments, and tendons

disorders of the appendicular skeleton
– hip dyspasia: congenital disclocation of the hip that is a common birth defect which affect females more than males – clubfoot: soles of the feet turn medially and the toes point inferiorly

upper-lower (UL) body ratio
– at birth, the UL ratio is 1.7 to 1 – by age 10, the UL ratio is about 1 to 1

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The pectoral girdle connects to the axial skeleton where the __________. clavicle articulates with the sternum Which of the following is most commonly fractured in a fall? clavicle WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY FOR …

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