1. Appendicular Skeleton
HESC310
6/9/2018
Appendicular Skeleton
Slides by Vince Austin;
figures from Marieb & Hoehn 7th and 8th eds.;
modifications and some slides by W. Rose
Portions copyright Pearson Education
Axial Skeleton

2. Appendicular Skeleton
Limb bones and their girdles
Pectoral girdles attach upper limbs to trunk
Pelvic girdle secures lower limbs

3. Pectoral Girdles (Shoulder Girdles)
Consist of anterior clavicles and posterior scapulae
Attach upper limbs to axial skeleton in a manner that allows for maximum movement
Provide attachment points for muscles that move upper limbs

4. Pectoral Girdles (Shoulder Girdles)
Figure 7.22a

5. Clavicles (Collarbones)
Slender, doubly curved long bones lying across the superior thorax
The acromial (lateral) end articulates with the scapula, and the sternal (medial) end articulates with the sternum
Provide attachment points for numerous muscles, and act as braces to hold the scapulae and arms out laterally away from the body

6. Clavicles (Collarbones)
Figure 7.22b, c

7. Scapulae (Shoulder Blades)
Triangular, flat bones lying on the dorsal surface of the rib cage, between the second and seventh ribs
Scapulae have three borders and three angles
Major markings include the suprascapular notch, the supraspinous and infraspinous fossae, the spine, the acromion, and the coracoid process

8. Scapulae (Shoulder Blades)
Figure 7.22d

9. Scapulae (Shoulder Blades)
Figure 7.22e

10. Scapulae (Shoulder Blades)
Figure 7.22f

11. The Upper Limb
The upper limb consists of the arm (brachium), forearm (antebrachium), and hand (manus)
Thirty-two bones form the skeletal framework of each upper limb

12. Arm
The humerus is the sole bone of the arm
It articulates with the scapula at the shoulder, and the radius and ulna at the elbow

13. Arm
Major markings
Proximal humerus includes the head, anatomical and surgical necks, greater and lesser tubercles, and the intertubercular groove
Distal humerus includes the capitulum, trochlea, medial and lateral epicondyles, and the coronoid and olecranon fossae
Medial portion includes the radial groove and the deltoid process

14. Humerus of the Arm
Figure 7.23

15. Forearm
The bones of the forearm are the radius and ulna
They articulate proximally with the humerus and distally with the wrist bones
They also articulate with each other proximally and distally at small radioulnar joints
Interosseous membrane connects the two bones along their entire length

16. Bones of the Forearm
Figure 7.24

17. Ulna
The ulna lies medially in the forearm and is slightly longer than the radius
Forms the major portion of the elbow joint with the humerus
Its major markings include the olecranon, coronoid process, trochlear notch, radial notch, and the styloid process

18. Radius
The radius lies opposite (lateral to) the ulna and is thin at its proximal end, widened distally
The superior surface of the head articulates with the capitulum of the humerus
Medially, the head articulates with the radial notch of the ulna
Major markings include the radial tuberosity, ulnar notch, and styloid process

19. Radius and Ulna
Figure 7.24

20. Hand
Skeleton of the hand contains wrist bones (carpals), bones of the palm (metacarpals), and bones of the fingers (phalanges)
Figure 7.26a

21. Consists of eight bones
Carpus (Wrist)
Consists of eight bones
Scaphoid, lunate, triquetral, and pisiform proximally
Trapezium, trapezoid, capitate, and hamate distally

22. Metacarpus (Palm)
Five numbered (1-5) metacarpal bones radiate from the wrist to form the palm
Their bases articulate with the carpals proximally, and with each other medially and laterally
Heads articulate with the phalanges

23. Phalanges (Fingers)
Each hand contains 14 miniature long bones called phalanges
Fingers (digits) are numbered 1-5, beginning with the thumb (pollex)
Each finger (except the thumb) has three phalanges – distal, middle, and proximal
The thumb has no middle phalanx

24. Hip formed by 2 coxal bones (coxae, hip bones, innominate bones)
Pelvic Girdle (Hip)
Hip formed by 2 coxal bones (coxae, hip bones, innominate bones)
Bony pelvis = 2 coxal bones + sacrum + coccyx
Attaches lower limbs to the axial skeleton with the strongest ligaments of the body
Transmits weight of the upper body to the lower limbs
Supports the visceral organs of the pelvis

25. Figure 7.29 Pelvis Two coxal (hip) bones (which together form pelvic girdle), sacrum, and coccyx
Base of sacrum
Iliac crest
Sacroiliac
joint
Iliac fossa
Anterior
superior
iliac spine
Coxal
bone
(hip bone)
llium
Sacrum
Pubic
bone
Pelvic brim
Coccyx
Acetabulum
Ischium
Pubic symphysis
Pubic arch

26. Ilium
The ilium is a large flaring bone that forms the superior region of the coxal bone
It consists of a body and a superior winglike portion called the ala
The broad posterolateral surface is called the gluteal surface

27. Ilium Articulates with the sacrum via sacroiliac joint
Major markings include:
iliac crest
four spines (on each side): ASIS, PSIS, AIIS, PIIS
ala
iliac fossa
pelvic brim
acetabulum (with ischium & pubis)

28. Figure 7.30a Bony pelvis: lateral view, right coxal bone
Ilium
Ala
Iliac crest
Posterior
superior
iIiac spine
Anterior
superior
iliac spine
Ischial body
Acetabulum
Pubic body
Pubis
Ischium
Inferior ramus
of pubis
Ischial tuberosity
Obturator foramen
Ischial ramus

29. Figure 7.30b Bony pelvis: medial view, right coxal bone
Ilium
Iliac fossa
Iliac crest
Posterior
superior
iliac spine
Anterior
superior
iliac spine
Auricular
surface
Body of ilium
Superior ramus
of pubis
Obturator
foramen
Articular surface
of pubis (at pubic
symphysis)
Ischium
Inferior ramus
of pubis
Ischial ramus

30. Forms posteroinferior part of coxal (hip) bone
Ischium
Forms posteroinferior part of coxal (hip) bone
Thick body articulates with ilium, thinner ramus articulates with pubis
Major markings include:
ischial spine
ischial tuberosity (sometimes called the sit bone or sitz bone)

31. Pubis Pubic bone forms anterior portion of coxal bone
Articulates with ischium and ilium
Major markings include:
superior and inferior rami
pubic symphysis (really a joint)
pubic arch (formed by inf. rami + symphysis)
obturator foramen (along with ilium)
acetabulum (along with ilium and ischium)

32. Comparison of Male and Female Pelvic Structure
Characteristic
Female
Male
Bone thickness
Lighter, thinner, and smoother
Heavier, thicker, and more prominent markings
Pubic arch angle
80˚–90˚
50˚–60˚
Acetabula
Small; farther apart
Large; closer together
Sacrum
Wider, shorter; sacral curvature is accentuated
Narrow, longer; sacral promontory more ventral
Coccyx
More movable; straighter
Less movable; curves ventrally

33. Comparison of Male and Female Pelves
Table 7.4.2

34. The Lower Limb
The three segments of the lower limb are the thigh, leg, and foot
They carry the weight of the erect body, and are subjected to exceptional forces when one jumps or runs

35. Femur
The sole bone of the thigh is the femur, the largest and strongest bone in the body
It articulates proximally with the hip and distally with the tibia and fibula
Major markings include the head, fovea capitis, greater and lesser trochanters, gluteal tuberosity, lateral and medial condyles and epicondyles, linea aspera, patellar surface, and the intercondylar notch

36. Femur
Figure 7.28b

37. Leg
The tibia and fibula form the skeleton of the leg
They are connected to each other by the interosseous membrane
They articulate with the femur proximally and with the ankle bones distally
They also articulate with each other via the immovable tibiofibular joints

38. Tibia
Receives the weight of the body from the femur and transmits it to the foot
Major markings include medial and lateral condyles, intercondylar eminence, the tibial tuberosity, anterior crest, medial malleolus, and fibular notch

39. Tibia and Fibula
Figure 7.29

40. Fibula Long bone parallel to and lateral to tibia
Much thinner than tibia
Bears less weight than tibia, but not nothing*
Major markings
Head
At top
Touches underside of head of tibia
Lateral malleolus
At bottom
Forms the bump on lateral side of ankle
* Takebe et al 1984: Fibula bears 6.4% with STJN, more when dorsiflexed or everted. Goh et al 1992 found fibula bears 7.1% of total force in fibula plus tibia. Wang et al 1996 found fibula bears 15% of load, % was > when load was >, and % was > in dorsiflexion.

41. Foot
The skeleton of the foot includes the tarsus, metatarsus, and the phalanges (toes)
The foot supports body weight and acts as a lever to propel the body forward in walking and running
Figure 7.31a

42. Tarsus
Composed of seven bones that form the posterior half of the foot
Body weight is carried primarily on the talus and calcaneus
Talus articulates with the tibia and fibula superiorly, and the calcaneus inferiorly
Other tarsus bones include the cuboid and navicular, and the medial, intermediate, and lateral cuneiforms

43. Tarsus
Figure 7.31b, c

44. Calcaneus
Forms the heel of the foot
Carries the talus on its superior surface
Point of attachment for the calcaneal (Achilles) tendon of the calf muscles

45. Metatarsus and Phalanges
Metatarsals
Five (1-5) long bones that articulate with the proximal phalanges
The enlarged head of metatarsal 1 forms the “ball of the foot”
Phalanges
The 14 bones of the toes
Each digit has three phalanges except the hallux, which has no middle phalanx

46. Metatarsus and Phalanges
Figure 7.31a

47. Arches allow the foot to hold up weight The arches are:
Arches of the Foot
The foot has three arches maintained by interlocking foot bones and strong ligaments
Arches allow the foot to hold up weight
The arches are:
Lateral longitudinal – cuboid is keystone of this arch
Medial longitudinal – talus is keystone of this arch
Transverse – runs obliquely from one side of the foot to the other

48. Arches of the Foot
Figure 7.32

49. Developmental Aspects: Fetal Skull
Infant skull has more bones than the adult skull
At birth, fetal skull bones are incomplete and connected by fontanels
Fontanels
Unossified remnants of fibrous membranes between fetal skull bones
The four fontanels are anterior, posterior, mastoid, and sphenoid

50. Developmental Aspects: Fetal Skull
Skull bones such as the mandible and maxilla are unfused
Figure 7.33

51. Developmental Aspects: Growth Rates
At birth, the cranium is huge relative to the face
Mandible and maxilla are foreshortened but lengthen with age
The arms and legs grow at a faster rate than the head and trunk, leading to adult proportions
Figure 7.34

52. Developmental Aspects: Spinal Curvature
Only thoracic and sacral curvatures are present at birth
The primary curvatures are convex posteriorly, causing the infant spine to arch like a four-legged animal
Secondary curvatures – cervical and lumbar – are convex anteriorly and are associated with the child’s development

53. Developmental Aspects: Old Age
Intervertebral discs become thin, less hydrated, and less elastic
Risk of disc herniation increases
Loss of stature by several centimeters is common after age 55
Costal cartilages ossify causing the thorax to become rigid
All bones lose mass