Appendicular Skeleton

ANP1106A

Pectoral girdle

• 2 pairs of bones: clavicles & scapulae almost a complete circle around upper trunk

  • bones are light & very movable- because scapulae only attached laterally- not attached to the axial skeleton

  • socket of shoulder joint (glenoid cavity) is shallow & poorly reinforced

  • attachment points of muscles that move upper limbs

Clavicles

• collarbones

• mildly S-shaped sternal end articulates with the sternum (curvature ensures outward fracture, away from subclavian artery)

• Flattened acromial end articulates laterally with scapula

• sternal end articulates with manubrium

• insertion points for muscles, also a brace to push arms laterally

Scapulae

• shoulder blades

• thin, triangular, irregular bones

• dorsally, between ribs 2 & 7

• Each has 3 borders:

  • superior

  • medial

  • lateral - near armpit, ends superiorly in glenoid cavity fossa (shoulder joint)

• Several large fossae, named according to location

  • spine

  • acromion

    • lateral projection that articulates with acromial end of clavicle

    • number of muscles attach here as well

  • coracoid process

    • For biceps muscle

Upper Limb

30 bones form skeletal framework of each upper limb

• Arm

  • Humerus

• Forearm

  • Radius and ulna

• Hand

  • 8 carpal bones in the wrist

  • 5 metacarpal bones in the palm

  • 14 phalanges in the fingers

Upper Limb

• Humerus

• Forearm

• Ulna

• Radius

Humerus

• longest, largest bone of upper limb and the only bone of the arm articulates with scapula, radius & ulna

  • Head - inserts into the glenoid cavity

  • Anatomical neck vs surgical neck

    • surgical neck (black semicircle) is below the greater and lesser tubercle and it more commonly fractured

  • Greater & lesser tubercle separated by the intertubercular sulcus (groove)

  • Deltoid tuberosity

  • Fossae: olecranon (elbow bone), coronoid and radial

• Two condyles:

  • Trochlea articulates with the ulna

  • Capitulum articulate with the radius

• Two epicondyles

  • point of attachment for muscles to allow movement of fingers

    • Medial and lateral

      • Note: the ulnar nerve behind medial epicondyle (nerve that gets irritated when you hit the ‘funny bone’)

Forearm

• parallel long bones: radius & ulna

• Articulates with

  • Humerus (proximal) & wrist bones (distal)

  • with each other at superior & inferior radio-ulnar joints

• What is the interosseous membrane

  • white structure, a fibrous sheath of CT that spans length of the bones. It holds them together, limiting their movement

Ulna (elbow joint)

• slightly longer than radius

• olecranon & coronoid processes

  • locking of olecranon prevents elbow hyperextension

• radial notch on coronoid process

• Styloid process: ligaments to the wrist

Radius(Wrist joint)

• head at proximal end

• distal end at the wider end

• distal end has medial ulnar notch & lateral styloid process

Articulation at the elbow

Hand

• 27 bones

  • includes bones of carpus, metacarpus and phalanges

• Carpus (wrist)

  • 8 carpal bones in two rows

  • Proximal row:

    • scaphoid, lunate, triquetrum, pisiform (“So Long To Pittsburgh” )

• Distal Row

  • trapezium, trapezoid, capitate, hamate

    • (“Time To Call Home” )

• Only scaphoid, lunate and triquetrum form the wrist join

  • (“Sally Left The Party To Take Cathy Home)

Carpus

• wrist

  • 8 carpal bones in two rows

  • Proximal row:

    • scaphoid, lunate, triquetrum, pisiform (“So Long To Pittsburgh” )

• Distal Row

  • trapezium, trapezoid, capitate, hamate

    • (“Time To Call Home” )

• Only scaphoid, lunate and triquetrum form the wrist join

  • (“Sally Left The Party To Take Cathy Home)

Metacarpals

• 5 long bones - distal ends are knuckles

• numbered I - V from thumb to little finger

• Bases articulate with carpals, and heads articulate with proximal phalanges

Phalanges (fingers)

• numbered I-V from thumb to little finger

• Miniature long bones - phalanges

• Digits II to V has 3 bones: proximal, middle & distal phalanx

• Digit I (pollex) has 2 bones

Pelvic girdle

• Two hip bones (each also called coxal bone or os coxae); form a complete circle

• left & right coxal bones unite with each other anteriorly & with sacrum posteriorly

• attach the lower limbs, transmits weight of upper body to lower limbs; support pelvic organs

• Each os coxa consists of 3 bones that fuse at puberty: ilium, ischium, pubis

• Acetabulum is area where all 3 bones join »» forms socket of hip joint

Pelvic girdle: ilium

• large flaring bone that forms most of os coxa

• iliac crest (superior border); iliac spines (attachment of muscles)

• Greater sciatic notch

• Auricular surface: connects to sacrum to make sacral ilium

• anteriorly, the body of the ilium joins the ischium and the pubis

Ischium

• postero-inferior part of hip bone

• thicker superior body joining ilium and thinner, inferior ramus (joins the pubis)

• ramus= bar of bone

What is Ischial tuberosity?

• supports your weight while sitting and is supported by ischial tuberosity

Pubis

• anterior part of ox cosa

• Consists of the body and superior and inferior pubic rami

• 2 pubic bones unite at pubis symphysis

Pelvic structure and childbearing

• Female pelvis tends to be wider, shallower, lighter, and rounder than male’s

  • Adapted for childbearing

• Pelvic brim

  • the bony rim (pelvic inlet) that separates the upper "false pelvis" (part of the abdomen) from the lower "true pelvis" (the actual pelvic cavity)

    • True pelvis: inferior to pelvic brim; defines birth canal

• Pelvic outlet: inferior margin of true pelvis

Comparison of male and female pelvis

Lower limb

• Carries entire weight of erect body

• Subjected to exceptional forces during jumping or running

• Three segments of lower limb

  • Thigh

  • Leg

  • Foot

Thigh

• Femur is the largest, strongest and longest bone in the body making up about ¼ of a person’s height.

  • Articulates proximally with acetabulum of hip and distally with tibia and patella

  • Fovea capitis

  • Head and neck

    • neck (angles laterally to shaft; weak → fractures)

• Greater and lesser trochanters: site for muscle attachment

• Linea aspera: roughened ridge on surface of femoral shaft; site for muscle attachment

• Distally

  • Lateral & medial condyles (attachment site for joint)

    • articulate with tibia

  • Lateral & medial epicondyles

    • Sites of muscle attachment

• Patellar surface (between condyles)

  • patella site in between it

Lower limb: leg

• 2 parallel bones: tibia & fibula connected by interosseus membrane and proximal & distal tibiofibular joints (rigid)

• fibula not contributor to knee join

Tibia

• next largest & strongest bone

• receives weight from femur & transfers it to foot

• medial bone of the leg

• medial & lateral condyles

• tibial tuberosity (patellar ligament): insertion point for tendons of quadricep muscles

• Medial malleolus

Fibula

• not weight bearing/no articulation with femur

• head

• lateral bone of leg

• Lateral malleolus

Lower limb: foot

• total of 26 bones: tarsus (ankle bone), metatarsus & phalanges

Tarsus

• 7 tarsal bones

  • cuboid, navicular, medial, intermediate, and lateral cuneiform, talus and calcaneus

  • largest is the calcaneus (heel bone) and second largest is the talus (part of ankle joint).

    • talus connects to tibia, which is weight of upper body is transferred

  • these two primarily carry the weight of the body

Metatarsus

• 5 miniature long bones numbered I-V from the hallux to the little toe

• hallux: has only proximal and distal end

• Phalanx~single, phalanges~ plural

  • naming a bone: position AND what toe or finger it is

• in numbering of phalanges of upper limb, number from pinky to pollex (medial to lateral)

Phalanges of lower limb

• 14 bones of toes

• Digit I (hallux) has two

• Digits II to V have 3 bones - proximal, middle & distal phalanx

Arches of the foot

• Maintained by interlocking foot bones, ligaments, and tendons

• Allow foot to bear weight

• Three arches

• flat foot= collapse of medial and longitudinal arche, walking = overpronation=foot rolls inward too much

• arches too high cause stress on lateral structures

• plantar fasciitis: band of tissue runs along

3 arches of the foot

• Lateral longitudinal: low curve that elevates lateral part of foot

• Medial longitudinal: arch curves upward

• Transverse: runs obliquely from one side of foot to other