BIOL1411 Chapter 8: The Appendicular Skeleton

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What is the appendicular skeleton system composed of?

The appendicular skeleton system is composed of the upper and lower limbs, and the girdles (pectoral and pelvic) that attach the limbs to the axial skeleton.

Pectoral girdle consists of:
-scapula (spine, infraspinous fossa, supraspinous fossa, subscapular fossa, glenoid cavity which is attached to the head of the humerus, acromion which is attached to the clavicle, coracoid process)
-clavicle (acromial end which is attached to acromion of the scapula, sternal end which is attached to the sternum)

Shoulder girdle consists of:
-

Upper limb consists of:
-arm (humerus, radius which is lateral and smaller, ulna which is proximal and bigger, interosseous membrane which connects radius and ulna)
-humerus: (PROXIMAL: head, greater tubercle, lesser tubercle, intertubercular groove, radial groove, deltoid tuberosity; DISTAL: trochlea, capitulum, coronoid fossa, olecranon fossa, medial epicondyle, lateral epicondyle, radial fossa)
-radius: (head, tubercle, styloid process, ulnar notch)
-ulna (coronoid process, olecranon, radial notch, trochlear notch, styloid process, head)

-wrist: 8 bones
(scaphoid which is attached to radius, lunate which is attached to scaphoid and ulna, triquetral, pisiform back of triquetal, capitate, hamate, trapezium, trapezoid)

-hand: metacarpals, proximal phalanges, middle phalanges, distal phalanges

-carpal tunnel: flexor retinaculum, carpal bones, flexor tendons, median nerve

Pelvic girdle (or hip girdle) consists of:
-ilium (iliac crest, iliac fossa, anterior inferior iliac spine, anterior superior iliac spine, posterior inferior iliac spine, posterior superior iliac spine, auricular surface, greater sciatic notch)
-ischium (lesser sciatic notch, ischial tuberosity, ischial spine, lunate surface of acetabulum, pubic arch, obturator foramen/ischial surface)
-pubis (pubic arch, pubic crest, pubic tubercle, obturator crrest, obturator foramen/pubis surface)
pubic symphysis

Lower limb consists of:
-femur (head which is attached to the pelvis, neck, greater trochanter, less trochanter, lateral condyle, lateral epicondyle, medial condyle, medial epicondyle, gluteal tuberosity, linea aspera)
-tibia/more outer part of lower leg (medial condyle, lateral condyle, tibial tuberosity, anterior border, medial malleolus)
-fibula (head, lateral mallelus)

Tarcus (the foot) consists of: (calcaneus which is the ankle area, talus which is attached to fibula and tibia, cuboid, navicular, lateral cuneiform, intermediate cuneiform, medial cuneiform, metatarsal, proximal/middle/distal phalanx)

Foot arches: longitudinal arches, tranverse arch (shock-absorbing structure)

Joints are between the bones

Joints w/ no movement (made of fiber)
-synarthroses: bones joined by skull sutures, with fibrous joints
1.) gomphoses: located in the teeth, mandible, and maxilla
2.) synchrondoses: located in the first ribs and sternum

Joints w/ slight movement (made of fiber & cartilage)
-syndesmoses: slight movement (located in the tibia, fibula, tibia, tibiofibular ligament)
-symphyses: slight movement (located in the hip bones, pubic symphysis, vertebrae, intervertebral disc)

Joints w/ full movement (have hyaline cartilage & capsule w/ synovial fluid)
-synovial joint (6 types): elbow ligaments, articulating bones, articular capsule
**only synovial joint has capsule
1.) gliding joints: vertebrae, carpal, tarsal
2.) hinge joint: elbow, finger (flexion, extension, but no hyperextension; SINGLE AXIS)
3.) pivot joint: 1st and 2nd vertebrae (atlas and axis)
4.) condyloid joint: radius, carpal bones (flexion, extension, circumduction)
5.) saddle joint: trapezium, first metacarpal (thumb)
6.) ball and socket joints: freely moving joint that can rotate on any axis (hip, shoulder)

Ligaments reinforce synovial joints and limit movement, to prevent injury.
-The knee, a major synovial joint, is stabilized by several ligaments.

-anterior cruciate ligament
-posterior cruciate ligament
-medial/lateral collateral ligament
-(medial/lateral meniscus)
-patellar ligaments

As we age, our cartilage degenerates (osteoarthritis)

PECTORAL GIRDLE
Clavicle: slender S-shaped collar bone
-articulates medially with the manubrium of the sternum AND with the acromion of the scapula
-major landmarks: sternal end, acromial end

Scapula: major site for muscle attachments, and connects upper limb to the axial skeleton
-major landmarks: spine, acromion (attachment for clavicle), glenoid cavity (attachment for head of humerus), coracoid process (looks like hook; muscle attachment), medial and lateral borders, superior and inferior angles, supraspinous/infraspinous/subscapular fossa

UPPER LIMB
-consists of 1x arm bone, 2x forearm bones, 8x wrist bones, 5x palm of hand bones, 14x finger bones
(1x arm) Humerus: longest and largest bone in upper limb
-articulates proximally w/ glenoid cavity AND distally w/ radius and ulna at elbow joint
-major landmarks divided into two regions:
1.) proximal end: head, anatomical neck, greater tubercle (posterior), lesser tubercle (anterior), surgical neck, deltoid tuberosity
2.) distal end: capitulum (lateral), trochlea (medial), radial fossa, coronoid fossa, olecranon fossa (posterior; connects to radius), medial epicondyle, lateral epicondyle

(2x forearm) Ulna: bigger and medial lower forearm
-articulates proximally at elbow w/ humerus AND distally with three of the carpals
-connected by interosseous membrane (w/ radius)
-major landmarks: olecranon, trochlear notch (lateral; attachment to humerus), coronoid process, radial notch (attachment to radius), ulnar tuberosity, head, styloid process
Radius: smaller and lateral lower forearm
-major landmarks: head, neck, radial tuberosity, ulnar notch, styloid process

(8x wrist) 5x metacarpal/palm bones and 3x phalanges/finger bones
Carpals: palm of hand
-major landmarks: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate
(mnemonic for carpal bones: “Stop letting those people touch the cadaver’s hand)

PELVIC GIRDLE: composed of 2x coxal bones (hip bones) formed by fusion of three bones (ilium, ischium, pubis), forms the pelvis
-supports the vertebral column, protects the lower abdominal and pelvic viscera, attaches the lower limbs to the axial skeleton

Coxal bone: hip bone in pelvic girdle
-articulates w/ each other anteriorly at pubic symphysis AND w/ sacrum of vertebrae posteriorly
-major landmarks: acetabulum (formed by all 3 bones; articulates w/ femur head), obturator foramen (formed by ischium and pubis, opening for nerves and blood vessels), pelvic brim (formed by all 3 bones and sacrum, defining pelvic cavity)

Ilium: largest and major site of muscle attachment
-major landmarks: iliac crest, greater sciatic notch, auricular surface, arcuate line, spines (anterior, posterior, superior, inferior)

Ischium: inferior, posterior part of hip bone
-major landmarks: body, ramus, ischial spine, lesser sciatic notch, ischial tuberosity, obturator foramen (posterior half)

Pubis: anterior, inferior part of hip bone
-pubic arch: formed by right and left pubis bones at pubic symphysis
-major landmarks: body, superior ramus, inferior ramus, pubic crest, pubic tubercle, obturator foramen (anterior half)

Pelvic brim: oval ridge that runs from sacral promontory, to the arcuate lines, to the superior region of the pubic symphysis
-False pelvis: superior to pelvic brim, part of abdomen
-True pelvis: inferior to pelvic brim, superior pelvic inlet and inferior pelvic outlet, pelvic axis defines the route of the birth canal

Male and Female Pelves
Males: larger, heavier, narrower, smaller pubic arch (less than 90 degrees), heart-shaped pelvic brim
Females: wide, shallow, more space in true pelvis, accommodate pregnancy and childbirth, larger pubic arch (greater than 90 degrees), oval shaped pelvic brim

LOWER LIMB
-consists of 1x thigh bone, 1x kneecap bone, 2x leg bones, 7x ankle bones, 5x foot bones, 14x toe bones
(1x thigh bone) Femur: longest and heaviest bone in the body
-articulates proximally w/ acetabulum AND distally w/ tibia and patella at knee joint
-major landmarks: body (shaft), head, neck, greater trochanter, less trochanter, fovea capitis, gluteal tuberosity, linea aspera, medial and lateral condyles, and medial and lateral epicondyles

(1x kneecap bone) Patella: sesamoid bone located anterior to the knee joint
-enclosed superiorly within the tendon of the quadriceps
-attached inferiorly to tibia by patellar ligament
-two posterior articulating surfaces w/ femur

(2x leg bones) Tibia: larger and medial leg bone, shin bone
-the only leg bone that articulates proximally w/ femur & patella
-also articulates distally w/ talus of ankle
-major landmarks: medial condyle, lateral condyle, tibial tuberosity, anterior border, medial malleolus, fibular notch
Fibula: smaller and lateral leg bone
-major landmarks: head, lateral malleolus

(7x ankle bones) Tarsus: two bones
-includes talus; most superior and only one that articulates w/ tibia and fibula
-includes calcaneus: largest and strongest; heel bone
-navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, cuboid
Metatarsals: five intermediate foot bones
-five sesamoid bones, 1st starting at thumb
Phalanges: proximal, middle, distal

Phalange: