Bones of the limbs

Question 1

Label the bones of the hand and wrist on notability

Answer 1

Revision–>Anatomy–>bones of the hand and wrist

Question 2

Label the bones of the foot and ankle on notability

Answer 2

Revision–>Anatomy–>bones of the foot and ankle

Question 3

Describe the structure of long bones.

How are long bones adapted to their functions? Give examples of long bones

Answer 3

Diaphysis or shaft forms the long axis of the bone, and the wider ends are called epiphyses. Periosteum, made of compact bone, covers entire outer surface of bone. Endosteum, made of spongey bone, makes up internal surface.
New osteoblasts migrate to the parts of the periosteum experiencing the most strain to improve resistance to compressive and tensile forces in that direction
They enable reaching movements, and are important in locomotion as they act as levers.
Humerus, femur, ulna, radius, tibia, fibula, metacarpals, metatarsals, phalanges

Question 4

Describe the structure of short bones.

How are short bones adapted to their functions? Give examples of short bones

Answer 4

Many shapes and sizes, but specifically lack the diaphysis/epiphyses structure. Periosteum and endosteum still present.
Useful more for smaller and finer movements on account of their shortness
Carpals and tarsals

Question 5

Describe the structure of flat bones.

How are flat bones adapted to their functions? Give examples of flat bones

Answer 5

Periosteum|Endosteum|Periosteum sandwich shape, and obviously have a flatter appearance
Important sites of attachment for many muscle groups and bones due to their large surface area
Scapula, sternum

Question 6

What group of bones do sesamoid bones fit into? Describe their structure and specialised functions. Give examples.

Answer 6

A subset of short bones.
Form within tendons, and vary in size and number within a population
Can alter the direction of pull of a tendon, or they can reduce friction and modify pressure in tendons, to prevent abrasion and tearing, providing a smooth surface for the tendon to slide over
Patella

Question 7

Describe the clavicle, giving details of the course and location of the bone and its attachment sites

Answer 7

Clavicle runs from the sternum/sternoclavicular joint to the /acromion acromioclavicular joint, horizontally across the superior thorax on the anterior surface. It is convex for 2/3 of its length away from the sternum and then concave for the final 1/3 towards the acromion process of the scapula.

The clavicle also attaches to the scapula via the coracoclavicular ligaments to the coracoid process- the ligament runs from the trapezoid line (trapezoid ligament) and conoid tubercle (conoid ligament) located inferiorly on the clavicle at the acromial end.

Question 8

Describe the ilium, giving details of the course and location of the bone and its attachment sites

Answer 8

The ilium is a large flaring bone that forms the superior region of the hip bone. The flaring, superior portion is known as the ala, and the superior margin is called the iliac crest.

The iliac crest [from medial to lateral] sweeps from the sharp posterior superior iliac spine, posterior to the sacrum, up, horizontally and anteriorly to end at the blunt anterior superior iliac spine (easily palpable). Inferior to both of these spines are the inferior posterior and inferior anterior iliac spines.

Inferior to the inferior posterior iliac spine is a deep indentation forming the greater sciatic notch, through which the sciatic nerve passes.

The anterior surface of the ala is concave. Medially and posterior to the fossa is a roughened surface called the auricular surface which articulates with the sacrum to form the sacroiliac joint. The posterior surface of the ala has articulations with the gluteal muscles, and is crossed by three ridges: the posterior, the anterior and the inferior gluteal lines

The body of the ilium articulates posteriorly with the ischium and anteriorly with the pubis.

Question 9

Label the pelvic girdle on notability

Answer 9

Revision–>Anatomy–>Pelvic girdle

Question 10

Label the pectoral girdle on notability

Answer 10

Revision–>Anatomy–>Pectoral girdle

Question 11

Describe the scapula, giving details of the course and location of the bone and its attachment sites

Answer 11

The scapula is a thin, triangular flat bone located posterior to ribs 2-7. It has a short, sharp superior border, a long medial border that runs parallel to the vertebral column and the lateral border runs obliquely to abut the axilla superiorly in the glenoid fossa. The glenoid fossa is a shallow cavity that points laterally and is found between the lateral border, the superior border, the anterior and the posterior surface- it articulates with the head of the humerus.

The anterior surface is slightly concave, and this concavity forms the subscapular fossa. The coracoid process protrudes anteriorly from the lateral part of the superior border and it bends laterally (it is an important site of attachment for the short head of biceps and coracobrachialis). Medial to the coracoid process is an indentation of the superior surface called the suprascapular notch, through which passes the suprascapular nerve.

The posterior surface has a prominent spine which runs at a slight angle superior to horizontal, and ends laterally in a flat projection called the acromion process. Superior to the spine is the supraspinous fossa and inferior to the spine is the infraspinous fossa

Question 12

Briefly outline the components of the pelvic girdle

Answer 12

Consists of the paired hip bones and the sacrum. The paired hip bones are the ilium, ischium and pubis, which fuse in adulthood to form the coxal/pelvic/hip bone. At their Y-shaped junction is a deep cavity called the acetabulum, which receives the head of the femur.

Question 13

Describe the ischium, giving details of the course and location of the bone and its attachment sites

Answer 13

Forms the posteroinferior region of the hip bone. It is arc shaped, with its superior body articulating anteriorly with the pubis and superiorly with the ilium, and its thinner inferior ramus articulating only with the pubis. Located posteriorly and protruding medially is the ischial spine which is an important attachment site for the sacrospinous ligament. Immediately inferior to this, and formed by the spine, is the lesser sciatic notch, through which pass perineal nerves and vessels.
The inferior border of the ischial body is the ischial tuberosity, a site of attachment for the hamstring muscles, as well as the sacrotuberous ligament which helps to hold the pelvis together.

Question 14

Describe the pubis, giving details of the course and location of the bone and its attachment sites

Answer 14

Forms the anterior region of the hip bone, lying close to the coronal plane. It is V shaped, with the peak of the V forming the pubic body, located medially (just lateral to the pubic symphysis). The anterior surface of the pubic body forms the pubic crest, and at is superolateral is the pubic tubercle, an attachment site for the inguinal ligament.
Both pubic rami extend laterally, the inferior pubic ramus joining the ischial ramus and the superior pubic ramus joining the bodies of the ilium (superiorly) and ischium (posteriorly).
The obturator foramen is formed between the pubic rami and the ischial ramus, covered up almost entirely by the obturator membrane
Pubic bodies are joined by fibrocartilaginous discs to form pubic symphysis and the angle formed inferior to this by the inferior pubic and ischial rami is called the subpubic angle or the pubic arch

Question 15

Describe the bone of the arm

Answer 15

Only one - humerus

A long bone, whose head articulates with the glenoid fossa of the pectoral girdle. The humeral head points posteromedially and is covered in hyaline cartilage. At the base of the humeral head is the anatomical neck. The other neck of the humerus is the surgical neck, so called because fractures frequently occur there. The surgical neck is inferior to the two tubercles of the humerus, spanning the circumference of the most proximal portion of the shaft.

Between the two necks are the two tubercles. The greater tubercle is lateral to the humeral head, and the lesser tubercle is medial to the greater tubercle and inferior to the anatomical neck. They are the site of insertion for the rotator cuff muscles. Between the two tubercle is the intertubercular sulcus or groove. The long head of biceps passes through this groove to insert on the rim of the glenoid fossa.

Halfway down the humeral shaft, on the lateral side, is a v-shaped roughened area called the deltoid tuberosity, and this is the insertion point of the deltoid tendon. Posterior to this is a ridge running obliquely down the posterior surface of the humeral shaft called the radial groove. The radial nerve courses along this groove.

At the distal end of the humerus are two condyles. The medial condyle is called the trochlea, and it has an hourglass-on-its-side shape which articulates with the trochlea notch of the ulna. The lateral condyle is called the capitulum and it is hemispherical, articulating with the head of the radius. Beside the two condyles are the medial and lateral epicondyles respectively, and these are at the distal end of the medial and lateral supracondylar ridges that fan outwards.

On the posterior surface, proximal to the trochlea, is the olecranon fossa. On the corresponding anterior surface, proximal to the trochlea is the coronoid fossa. Lateral to this is the radial fossa. These fossae are present to receive the ulna and radius respectively during movement of the forearm.

Question 16

Describe the bone of the thigh

Answer 16

One bone - femur

Largest and strongest bone in the body. Courses medially from the hip joint to the knee joint to place the knee joint closer to the body’s centre of gravity.

The head of the femur is ball shaped, and in the centre of this ball on the superior surface is a small cavity called the fovea capitis, which is the attachment site of the ligament of the head of the femur which also attaches to the acetabulum.

The neck of the femur is much wider than the head of the femur, and it points inferiorly and laterally to join the shaft. This is the weakest point of the femur.

Between the neck and the shaft are the two trochanters. The greater trochanter is laterally placed and the lesser trochanter is posteromedially positioned (important muscle attachment sites). Joining these two structures anteriorly is the intertrochanteric line and posteriorly the intertrochanteric crest.

Running down the posterior shaft, beginning inferior to the greater trochanter and ending at the middle of the shaft is a ridge known as the gluteal tuberosity. This merges into the linea aspera at the halfway point of the posterior shaft (both are important muscle attachment sites). The linea aspera splits in the distal posterior shaft to form the medial supracondylar line medially and the lateral supracondylar line laterally. These run down distally to their respective epicondyles.

The distal femur broadens to form two condyles, the lateral and medial condyles. Their epicondyles lie superior to them, and are important muscle attachment sites. Moving proximally along the medial supracondylar line from the medial epicondyle is a bum called the adductor tubercle.

Two regions separate the condyles- anteriorly, the patellar surface (articulating with the patella) and posteriorly the intercondylar fossa.

Question 17

Describe the bones of the forearm

Answer 17

Ulna:

A long bone, monkey wrench shaped

Proximal end has two prominent projections. The more proximal and posterior is the olecranon process, and the more distal and anterior is the coronoid process. These form a fossa called the trochlea fossa between them, which articulates with the trochlea of the humerus. During elbow flexion, the coronoid process is received by the coronoid fossa of the humerus, and when the elbow is flexed, the olecranon locks into the olecranon fossa of the humerus.

Lateral to the coronoid process is the radial notch, which receives medial portion of the radial head.

The distal end of the ulna is much narrower, and lateral articulates with the ulnar notch of the radius, forming the distal radioulnar joint. Posteromedial to this is the ulnar styloid process, onto which ligaments of the wrist attach.

Radius:

The radius is almost opposite to the ulna, in that its most proximal end is very narrower, and its most distal end is very wide. The superior surface of the radial head is concave, and articulates with the capitulum of the humerus. Via the medial portion of the radial head it articulates with the radial notch, forming the proximal radioulnar joint.

Just distal to the base of the radial head, the radial neck, on the proximal anteromedial shaft is the radial tuberosity (site of insertion of the biceps brachii muscle).

Distally, the medially located ulnar notch articulates with the head of the ulna, and the laterally located radial styloid process

When the hand is pronated, the radius crosses over the ulna. The two forearm bones are connected by a flat ligament called the interosseous membrane

Question 18

Describe the bones of the leg

Answer 18

Two parallel bones, the fibula and the tibia. Their articulations with each other (tibiofibular joints) allow almost no movement.

Tibia:

The more massive and medial of the two bones, it is the only one to contribute to the knee joint, and stabilises the medial side of the ankle joint.

At the proximal end, it has two condyles, the medial and the lateral, with curved articular surfaces which articulate with the condyles of the femur. The two condyles have eminences at their adjacent edges, forming the intercondylar eminence. The superior tibiofibular joint occurs between the head of the fibula and an articular facet on the inferolateral surface of the lateral condyle.

Just inferior to the condyles, in the centre of the long bone, on the anterior surface is the tibial tuberosity, to which the patellar ligament attaches.

The distal tibia articulates with the talus of the foot on its medial malleolar facet. Medial to this articulating surface is an inferior projection called the medial malleolus, which forms the medial ankle. The inferior tibiofibular joint occurs at the fibular notch on the lateral side of the distal tibia.

Fibula:

Thin long bone, no articulation with the femur. Its most superior articulation is between the medial head of the fibular and the lateral condyle of the tibia.

The distal end of the fibular is the lateral malleolus, which articulates with the lateral malleolar facet of the talus, with its most inferolateral projection forming the lateral ankle.

Question 19

Carpal bones medial to lateral, proximal row then distal row

Answer 19

scaphoid, lunate, triquetrium, pisiform

trapezium, trapezoid, capitate, hamate

Question 20

Tarsal bones medial to lateral, proximal row then distal row

Answer 20

navicular (distal of talus), talus, calcaneus

medial, intermediate and lateral cuneiforms, cuboid

Question 21

What bones do the metacarpels articulate with?

Answer 21

I = trapezium, II, proximal phalanx I, two sesamoid bones proximal to the IP joint
II = trapezoid, I, III, proximal phalanx II
III = capitate, II, IV, proximal phalanx III
IV = hamate, III, V, proximal phalanx IV
V = hamate, IV, proximal phalanx V

Question 22

1. What surface articulates with the tibia on the talus? 2. What surface of the calcaneus articulates with the talus?
2. What part of the calcaneus touches the ground?
3. What bones does the Achilles’ tendon attach to?

Answer 22

1. Trochlea of talus
2. Sustentaculum tali (shelflike projection articulating with inferior surface of talus)
3. Calcaneal tuberosity
4. Posterior face of calcaneus

Question 23

Which structure forms the ball of the foot?

Answer 23

The distal head of metatarsal I

Question 24

What is significant about the size, and thus function, of the phalanges of the toes compared to those of the fingers?

Answer 24

They are small, and thus less nimble and adapted to perform finer movements.
The foot thus reflects its weight bearing function in having thicker and longer metacarpals, and larger tarsus bones.

Question 25

What are the arches of the foot called, and where are they located?

How are these arches formed?

Outline their functions

Answer 25

Medial longitudinal arch, lateral longitudinal arch and transverse arch

MLA formed by capitulum articulating with more superior talus, which descends down to the navicular- arch is raised off the ground.

LLA formed by calcaneus rising to cuboid, and cuboid falling to metatarsals IV and V

TA runs obliquely across foot between the two pillars formed by the MLA and LLA

The half dome formed ensures that 50% of body weight is distributed to heels and metatarsal heads. It also allows a certain amount of bending when weight is applied, and can then spring back to reform the half dome when it is taken away.