7.1 - Bones of the limbs Flashcards
anatomic planes and positions
what does the axial skeleton consist of
bones of the head - cranium / skull
neck - hyoid bone / cervical vertebrae
trunk - rubs / sternum / vertebrae / sacrum
what does the appendicular skeleton consist of
bones of the limbs = including those forming the pectoral (shoulder) and pelvic girdles
bones in appendicular skeleton
what is the skeleton composed of
cartilage and bones
what is cartilage
resilient, semirigid form of connective tissue that forms parts of the skeleton where more flexibility is required
what is ossification
process by which cartilage turns into bone
what is primary ossification
process of bone formation that occurs in the diaphysis (shaft/ middle) of a long bone, starting during embryonic development.
when does primary ossification occur
Occurs at the primary ossification center, usually in the middle of the cartilage model of a long bone (hyaline cartilage)
process of primary ossification
Cartilage model of bone is replaced by bone tissue.
Chondrocytes in the cartilage hypertrophy and die, and the surrounding matrix calcifies.
Osteoblasts invade and lay down bone matrix.
Perichondrium becomes the periosteum, and the first bone tissue is formed.
Blood vessels invade the region, bringing in osteoblasts and osteoclasts.
What is secondary ossification and where does it occur?
process of bone formation that occurs in the epiphyses (ends) of a long bone, generally after birth.
Occurs at the secondary ossification centers in the epiphyses.
process of secondary ossification
Hypertrophic chondrocytes in the epiphyses begin to calcify, followed by osteoblast invasion.
Epiphyseal cartilage remains in the form of articular cartilage (on the joint surface) and the epiphyseal plate (growth plate).
Spongy bone forms in the epiphysis, while the shaft continues to elongate
What are the diaphysis and epiphyses in long bones
diaphysis = central shaft
epiphyses = expanded ends
what is the growth plate
is a cartilage layer located between the epiphysis (end of the bone) and the diaphysis (shaft of the bone)
types of bone
compact / cortical
spongy / trabecular
compact / cortical bone
Dense form of bone found in bone shafts and external surfaces of bone
Haversian canal = compact nature of the bone requires channels for blood
vessels to reach the bone cells to provide nutrition = seen microscopically
Spongy/ trabecular bone
Lightweight + porous + elastic structure
Found in the ends of long bones, short bones and in bodies of vertebrae
Red bone marrow may be found -> contains stem cells that can give rise to
WBCs (erythrocytes and leucocytes) and platelets -> via haematopoiesis
function of compact bone
provides strength for weight bearing / resistance to bending and torsion
minimal deformability in daily activities = low strain tolerance + limited flexibility
function of spongy bone
acts like shock absorber in regions with excessive compressive forces
undergoes deformation even under normal activities
types of bone in the appendicular skeleton
long
flat
short
irregular
sesamoid
flat bones - function + location
long bone - function + location
short bone - function and location
irregular bones - function + location
sesamoid bone - function + location
How are long bones (e.g., femur, humerus) adapted for strength and force transmission?
The shaft provides leverage for muscles to act on, facilitating movement.
Spongy bone at the ends absorbs shock and distributes forces across joints
How are flat bones (e.g., skull, ribs) adapted for strength and force transmission?
Strength and resilience against impact forces, like a shield.
The spongy bone (diploë) helps to distribute force and reduce weight while maintaining strength.
The structure is optimized for energy absorption during trauma (e.g., skull during a fall).
How are short bones (e.g., carpals, tarsals) adapted for strength and force transmission?
Provide stability and allow for a wide range of motion.
Facilitate complex movements by offering a high degree of flexibility without sacrificing strength.
Absorb shock and distribute force within joints to reduce wear and tear.
Adapted for force transmission between bones in joints, especially where flexibility and mobility are needed.
know these
how are bone impressions formed
appear wherever tendons / ligaments / fascia’s / muscles are attached
large muscle attachments form elevations on the bone - ridges / crests / tubercles = serve as support for movement
bones of the upper limb
shoulder girdle - clavicle + scapula
arm - humerus
forearm - ulna (medial) + radius (lateral)
hand - carpal / metacarpal / phalanges
bones of the lower limb
pelvic girdle - pubis / ischium / illium / acetabulum
thigh - femur
leg - tibia (medial) + fibula (lateral)
foot - tarsals / metatarsals / phalenges
weight transmission of upper limb
bones of shoulder girdle
clavicle and scapula (shoulder blade)
Each clavicle articulates with the scapula laterally at the acromioclavicular joint
Each clavicle articulates with the manubrium (of the sternum) medially at the
sternoclavicular joint
Glenoid fossa articulates with the head of the humerus at the glenohumeral joint
key structures of the scapula
Glenoid fossa: Socket that forms the shoulder joint with the humerus.
Acromion: The bony process on the scapula that forms the highest point of the shoulder.
Coracoid process: A hook-like structure for muscle attachment.
Spine of scapula: A prominent ridge that divides the back of the scapula.
bones of the arm
between radius and ulna - interosseus membrane
bones of the hand
thumb = only has 2
ulna and radius disclaimer
head of radius is proximal but head of ulna is distal
bones of the pelvic girdle
Pubis
Ischium
Ilium
Acetabulum
bones of the thigh
femur
bones of the leg
bones of foot
calcaneus
talus
How do the shoulder girdle (clavicle, scapula) compare to the pelvic girdle (pubis, ischium, ilium)?
glenoid fossa (shoulder) - shallow BUT acetabulum (pelvis) is more deep
The shoulder girdle is more flexible and mobile (allows arm movement) but less stable, whereas the pelvic girdle is more stable and robust for weight-bearing and supports locomotion.
The pelvic girdle is closed and provides strength for walking, while the shoulder girdle is open to provide more range of motion in the arm.
How does the humerus compare with the femur?
humerous - short neck
femur = long neck
trochanter = on femur not humerous
fossa = on humerous not femur
The femur is much larger and more robust, designed for weight-bearing in the lower limb, whereas the humerus is relatively lighter and adapted for arm movement.
The femur has larger trochanters for more muscle attachment, while the humerus has greater tuberosities
How do the ulna and radius compare to the tibia and fibula?
The ulna and radius allow for forearm rotation (pronation/supination), while the tibia and fibula are involved in weight-bearing and stability = cant do that
The radius and fibula are smaller than their corresponding partner bones (ulna and tibia), and the tibia is the primary weight-bearing bone in the lower leg, whereas the ulna and radius share load-bearing in the forearm.
How do the bones of the hand compare to the bones of the foot?
metatarsal bones = stronger + higher cortical density then metacarpal
thumb + big toe = sesamoid bones
metacarpal = longer - more skilfull movements
Hand bones are more flexible and adapted for grip, dexterity, and fine motor skills, while the foot bones are designed for weight-bearing, shock absorption, and balance during standing, walking, and running.
The foot has a sturdier structure, with tarsals that provide support and stability, whereas the carpals in the hand allow for mobility and flexibility
function of the coracoid and spine on the scapula
coracoid = Provides attachment for muscles (e.g., pectoralis minor, biceps brachii)
spine = Provides attachment for the trapezius and deltoid muscles.
What are the important landmarks on the humerus?
lesser tuberosity
greater tuberosity
epicondyles / condolyes
what are greater and lesser tuberosity on the humerous
lesser =Attachment for the subscapularis muscle (part of the rotator cuff).
greater =Attachment for the supraspinatus, infraspinatus, and teres minor muscles (rotator cuff muscles).
what are condyles and epicondyles
The condyle is the smooth surface area at the end of a bone that forms part of a joint.
The epicondyle is a rounded protuberance at the end of a bone, serving as a place of attachment for ligaments, tendons, and muscles.
function of epicondyles - humerus
Function: Sites for attachment of the forearm muscles.
Medial Epicondyle: Attachment for flexor muscles of the forearm.
Lateral Epicondyle: Attachment for extensor muscles of the forearm.
Located at the distal end of the humerus, near the elbow.
function of condyles - humerus
Capitulum (Lateral Condyle):
Located at the distal end of the humerus.
Articulates with the radius to form the elbow joint.
Trochlea (Medial Condyle):
Located at the distal end of the humerus.
Articulates with the ulna to form the elbow joint.
function of epicondyles - femur
Medial Epicondyle:
Located on the medial side of the distal femur, just above the medial condyle.
Attachment site for the medial collateral ligament (MCL) of the knee.
Lateral Epicondyle:
Located on the lateral side of the distal femur, just above the lateral condyle.
Attachment site for the lateral collateral ligament (LCL) of the knee.
function of condyles - femur
Medial Condyle:
Located at the distal end of the femur.
Articulates with the tibia to form the knee joint.
Larger and more prominent than the lateral condyle.
Lateral Condyle:
Located at the distal end of the femur.
Articulates with the tibia to form the knee joint.
Smaller than the medial condyle.
What are the important landmarks on the femur?
greater and lesser trochanters
linea aspera
epicondyles
What is the greater trochanter of the femur, and what is its function?
Located on the lateral side of the proximal femur, at the junction of the femur’s neck and shaft.
Provides attachment points for muscles like the gluteus medius and gluteus minimus (important for hip abduction and stabilization).
What is the lesser trochanter of the femur, and what is its function?
Located on the medial side of the femur, just below the neck of the femur.
Attachment for the iliopsoas muscle (primary hip flexor).
What is the linea aspera of the femur, and what is its function?
A prominent ridge running along the posterior surface of the femur shaft.
Serves as an attachment site for muscles such as the adductors / hamstrings / vastus muscles
What are the major palpable bony landmarks around the shoulder, elbow, and wrist?
Clavicle
Acromion:
Coracoid Process:
Greater Tuberosity of Humerus
Olecranon Process:
Medial Epicondyle of the Humerus
Lateral Epicondyle of the Humerus
Styloid Process of Radius
Styloid Process of Ulna
Scaphoid
Pisiform
what is the metaphysis
A metaphysis is the region linking the epiphysis and the central diaphysis/shaft of the bone,such as the femoral neck, and tends to be the last part to ossify during development as the ossification centres link together
What are the key functions of bone in the human body?
- Support the body and prevent it crumpling under its own weight
- Provide a surface onto which muscles can be attached and hence transfer force for movement
- Protect soft tissues within, such as in the vertebral column
- Act as a calcium store so there isn’t too much in the blood
- Haematopoiesis – synthesise erythrocytes within the bone marrow
What are the main components of bone
Collagen & Hydroxyapatite
collagen - structure + function
superhelical protein made of Gly-X-Y triplet repeats.
Provides flexibility and elasticity to bone, allowing it to withstand stress without breaking easily.
Hydroxyapatite - structure + function
Crystalline form of calcium phosphate and calcium carbonate.
Gives bone its rigidity and hardness, making it strong and able to bear weight
Hydroxyapatite crystals are interspersed within collagen fibers, enhancing bone strength and rigidity.
