FORENSIC ANATOMY OF SKELETON OF LIMBS

BONES OF THE UPPER LIMB

Humerus

• The humerus, the largest

bone in the upper limb.

• Articulates with the

scapula at the

glenohumeral joint and

the radius and ulna at the

elbow joint.

• It is composed of proximal

end, body (shaft )& distal

end.

• The proximal end of the humerus has a head,

surgical and anatomical necks, and greater and

lesser tubercles.

• Head- less than ½ sphere is directed medially,

upward &posteriorly and articulates with the

glenoid cavity of the scapula.

• The anatomical neck- a groove separates head

from the greater and lesser tubercles

• surgical neck- It is the narrow part distal to the

head and tubercles (common site of fracture).

• The junction of the head and neck with the shaft of the

humerus is indicated by the greater and lesser tubercles,

which provide attachment and leverage to some

scapulohumeral muscles.

• The intertubercular (bicipital) groove separates the tubercles

and provides passage for tendon of the long head of the

biceps muscle

• The shaft: upper ½ of the shaft is cylindrical while the lower

½ is like a prism.

• It has two prominent features:

the deltoid tuberosity for attachment of the deltoid

muscle.

the oblique radial groove groove for radial nerve

• The inferior end formed from

(from medial lateral)

medial epicondyle,

trochlea, capitulum&

lateral epicondyle.

• With 2 fossae anteriorly

(coronoid & radial)

one fossa posteriorly

(olecranon).

BONES OF FOREARM

Ulna

• The ulna is the stabilizing bone of the

forearm.

• It is the medial and longer of the two

forearm bones.

• Its proximal end - articulation with the

humerus.

• The ulna has two prominent

projections: the olecranon, which

projects proximally from its posterior

aspect (forming the point of the elbow)

• The coronoid process projects

anteriorly.

• Inferior to the coronoid process is the

tuberosity of the ulna attachment of

tendon of the brachialis muscle

• The shaft of the ulna is thick and cylindrical

proximally.

• It tapers, diminishing in diameter, as it continues

distally.

• At the narrow distal end of the ulna is a small but

abrupt enlargement, the disc-like head of the ulna

with a small, conical ulnar styloid process.

Radius

• The radius is the lateral and shorter of the

two forearm bone.

• It consist of thin narrow upper end ,body &

thick expanded lower end .

The upper end consist of :

• The head- it is disc like

with 2 articular surfaces :

• the upper surface

articulate with the

capitulum of the Humerus

.

• Lateral surface with the

radial notch of the ulna

• The neck - constricted

part below the head .

• The radial tuberosity -

below the medial part of

the neck .

• The shaft of the radius, in contrast to that of the

ulna, gradually enlarges as it passes distally.

• The distal end of the radius is essentially four sided

when sectioned transversely.

• Its medial aspect forms a concavity, the ulnar notch

which accommodates the head of the ulna.

• Its lateral aspect becomes increasingly ridge-like,

terminating distally in the radial styloid process.

BONES OF HAND

•The skeleton of the hand

is subdivided into three

segments-

•The carpus or wrist

bones

•The metacarpus or

bones of the palm

•The phalanges or bones

of the digits

THE CARPUS

• The carpal bones- eight in number

• They are arranged in two rows.

• Proximal row, from the radial ulnar

scaphoid, lunate, Triquetrum, and pisiform.

• Distal row, radial ulnar

Trapezium, trapezoid, capitate, and hamate.

SCAPHOID

• A boat-shaped bone

• Has a prominent scaphoid tubercle

• It is the largest bone in the proximal row of

carpals.

• articulates with five bones: the radius

proximally, trapezium and trapezoid distally,

and capitate and lunate medially.

LUNATE

• A moon-shaped bone between the scaphoid

and the triquetral bones.

• It is broader anteriorly than posteriorly.

• articulates with five bones: the radius

proximally, capitate and hamate distally,

Scaphoid laterally, and triquetral medially.

TRIQUETRUM

• A pyramidal bone on the medial side of the

carpus;

• Articulates with three bones: the lunate laterally,

the pisiform in front, the hamate distally; and

with the triangular articular disk which

separates it from the lower end of the ulna

Pisiform:

• A small, pea-shaped bone

• It lies on the palmar surface of the triquetrum.

Trapezium:

• A four-sided bone on the lateral side of the carpus.

• It articulates with the 1st and 2nd metacarpals,

scaphoid, and trapezoid bones.

Trapezoid:

• A wedge-shaped bone

• It resembles the trapezium.

• It articulates with the 2nd metacarpal, trapezium,

capitate, and scaphoid bones.

Capitate:

• A head-shaped bone with a rounded extremity

• The largest bone in the carpus.

• It articulates primarily with the 3rd metacarpal

distally and with the trapezoid, scaphoid, lunate,

and hamate.

Hamate:

• A wedge-shaped bone on the medial side of the hand.

• It articulates with the 4th and 5th metacarpal,

capitate, and triquetral bones.

• It has a distinctive hooked process, the hook of the

hamate, that extends anteriorly.

METACARPUS

• The metacarpus forms the skeleton of the palm

of the hand between the carpus and the

phalanges.

• It is composed of five metacarpal bones

(metacarpals).

• Each metacarpal consists of a base, shaft, and

head.

• The proximal bases of the metacarpals

articulate with the carpal bones, and the distal

heads of the metacarpals articulate with the

proximal phalanges and form the knuckles.

• The 1st metacarpal (of the

thumb) is the thickest and

shortest of these bones.

• The 3rd metacarpal is

distinguished by a styloid

process on the lateral side of

its base

PHALANGES

• Each phalanx has a base proximally, a shaft (body), and a

head distally.

• The proximal phalanges are the largest, the middle ones are

intermediate in size, and the distal ones are the smallest.

• The shafts of the phalanges taper distally.

• Each digit has three phalanges except for the first (the

thumb), which has only two

• The terminal phalanges are flattened and expanded at their

distal ends, which underlie the nail beds.

• The phalanges are convex on their dorsal and flat on their

volar surfaces.

BONES OF LOWER LIMBThe femur

• The femur, or thigh bone is

the longest and heaviest

bone in the body.

• Its length varies from one

fourth to one third of that of

the body

• The femur is well covered

with muscles, so that only its

superior and inferior ends

are palpable.

• It is formed of upper end ,

shaft (body) & lower end.

THE UPPER END

• It consists of the head , the neck ,the greater

trochanter & the lesser trochanter .

• The round head of the femur makes up two thirds of

a sphere that is covered with articular cartilage,

except for a medially placed depression or pit, the

fovea for the ligament of the head.

• In early life, the ligament gives passage to an artery

supplying the epiphysis of the head

THE NECK

• It is trapezoidal,

• Its narrow end supporting the head and its

broader base is continuous with the shaft.

• Its average diameter is three quarters that of

the femoral head.

• The proximal femur is “bent” (L-shaped) so that

the long axis of the head and neck projects

superomedially at an angle to that of the

obliquely oriented shaft.

• The angle of inclination-helps to maintain

bipedal walking.

• Where the neck joins the femoral shaft are two large,

blunt elevations called trochanters.

• Lesser trochanter –

abrupt, conical and rounded

extends medially from the posteromedial part of the

junction of the neck and shaft.

• The greater trochanter –

large

laterally placed bony mass that projects superiorly

and posteriorly where the neck joins the femoral

shaft.

Shaft

• It is cylindrical in shape

• flattened posteriorly & downward.

• It is very slightly curved (convex) anteriorly.

• linea aspera -Along the middle of the shaft

posteriorly there is rough ridge

• The lateral lip of linea aspera superiorly join the

gluteal tuberosity which extends upward to the base

of greater trochanter.

• The medial lip of linea aspera passes above to form

the spiral line & ends in the intertrochanteric line.

The lower end of femur

• consist of two condyles.

• The medial and lateral femoral condyles

• The two condyles are on the same horizontal level when

the bone is in its anatomical position

• isolated femur is placed upright with both condyles

contacting the floor or tabletopthe femoral shaft will

assume the same oblique position it occupies in the

living body (about 9° from vertical in males and slightly

greater in females).

• The femoral condyles articulate with menisci (crescentic

plates of cartilage) and tibial condyles to form the knee

joint.

The Patella

• The patella is a flat & the largest sesamoid bone located in

the tendon of quadriceps femoris

• It is triangular in shape

• A base (upper border )

• An apex (rounded lower tip )

• 2 borders (medial & lateral)

• 2 surfaces (ant. & post.)

• The lower 1/3 of the posterior surface is rough

• The upper 2/3 is smooth. articular surface as it articulates

with the patellar surface of the femur.

THE BONES OF THE LEG

•The tibia and fibula are

the bones of the leg.

•The shafts of the tibia

and fibula are connected

by a dense interosseous

membrane

TIBIA

• Located on the antero-medial side of the leg.

• The proximal end widens to form medial and

lateral condyles

• Tibial plateau -This plateau consists of two smooth

articular surfaces.

• The medial one slightly concave and the lateral

one slightly convex.

• It articulate with the large condyles of the femur.

• The articular surfaces are separated by an

intercondylar eminence formed by two

intercondylar tubercles.

• The shaft of the tibia is vertical within the leg

• It is triangular in cross-section, having three surfaces and

borders: medial, lateral/interosseous, and posterior.

• The anterior border of the tibia is the most prominent border.

• It and the adjacent medial surface are subcutaneous “shin”.

• Their periosteal covering and overlying skin are vulnerable to

bruising.

• At the superior end of the anterior border, a broad, oblong

tibial tuberosity - distal attachment for the patellar ligament.

• On the posterior surface of the proximal part of the tibial

shaft is a rough diagonal ridge, called the soleal line, which

runs inferomedially to the medial border

• The distal end of the tibia is smaller than the

proximal end, flaring only medially.

• The medial expansion extends inferior to the

rest of the shaft as the medial malleolus.

• The inferior surface of the shaft and the

lateral surface of the medial malleolus

articulate with the talus and are covered with

articular cartilage.

• Helps in weight bearing.

FIBULA

• The slender fibula lies

posterolateral to the tibia

• It is firmly attached to Tibia

by the Tibio-fibular

syndesmosis.

• The fibula has no function in

weight-bearing.

• It serves mainly for muscle

attachment.

• The proximal end of the fibula consists of an

enlarged head superior to a small neck.

• The head has a pointed apex.

• The head of the fibula articulates with the fibular

facet on the posterolateral, inferior aspect of the

lateral tibial condyle.

• The shaft of the fibula is twisted

• It is marked by the sites of muscular

attachments.

• It is also important for the stability of the

ankle joint.

• It is triangular in cross-section

• It has three borders anterior, interosseous,

and posterior.

• Three surfaces medial, posterior, and

lateral.

• The distal end enlarges

• It is prolonged laterally and inferiorly as the

lateral malleolus.

• The lateral malleolus is more prominent and

posterior than the medial malleolus and

extends approximately 1 cm more distally.

BONES OF FOOT

• The bones of the foot include The Tarsus,

Metatarsus, and Phalanges.

7 tarsal bones,

5 metatarsal bones

14 phalanges

THE TARSUS

• Consists of seven bones

• talus, calcaneus, cuboid, navicular, and

three cuneiforms.

• Only one bone, the talus, articulates with

the leg bones.

THE CALCANEUS• It is the largest and strongest bone in the foot.

• When standing, the calcaneus transmits the majority of the

body's weight from the talus to the ground.

• The anterior two thirds of the calcaneus's superior surface

articulates with the talus and its anterior surface

articulates with the cuboid.

• The posterior part of the calcaneus has a massive, weight-

bearing prominence, the calcaneal tuberosity, which has

medial, lateral, and anterior tubercles.

• Only the medial tubercle contacts the ground during

standing.

Talus

• The talus has a body, neck, and head.

• The superior surface, or trochlea of the talus, is gripped by the two

malleoli.

• It receives the weight of the body from the tibia. The talus

transmits that weight in turn, dividing it between the calcaneus,

on which the body of talus rests, and the forefoot, via an

osseoligamentous “hammock”.

• Most of its surface is covered with articular cartilage.

• The talar body bears the trochlea superiorly and narrows into a

posterior process that features a groove

• This groove is for the tendon of the flexor hallucis longus, flanked

by a prominent lateral tubercle and a less prominent medial

tubercle.

The Navicular

• It is a flattened, boat-shaped bone.

• It is located between the head of the talus

posteriorly and the three cuneiforms anteriorly.

• The medial surface of the navicular projects

inferiorly to form the navicular tuberosity.

• It is an important site for tendon attachment

• It forms a longitudinal arch of the foot, which must

be supported centrally.

• If this tuberosity is too prominent, it may press

against the medial part of the shoe and cause foot

pain.

The Cuboid

• Cuboid is approximately cubical in shape.

• It is the most lateral bone in the distal row of the

tarsus.

• It lies between the calcaneus and the lateral 2

metatarsals.

Cuneiform bones

• The three cuneiform bones are the medial (1st),

intermediate (2nd), and lateral (3rd).

• The medial cuneiform is the largest bone.

• The intermediate cuneiform is the smallest.

• Each cuneiform articulates with the navicular

posteriorly and the base of its appropriate

metatarsal anteriorly.

• The lateral cuneiform articulates with the cuboid.

Metatarsus

• Consists of five metatarsals that are numbered from the

medial side of the foot.

• The 1st metatarsal is shorter and stouter than the

others.

• The 2nd metatarsal is the longest.

• Each metatarsal has a base proximally, a shaft, and a

head distally.

• The base of each metatarsal is the larger, proximal end.

• The bases of the metatarsals articulate with the

cuneiform and cuboid bones, and the heads articulate

with the proximal phalanges.

Phalanges

• The 14 phalanges are as follows-

the 1st digit (great toe) has 2 phalanges (proximal

and distal).

the other four digits have 3 phalanges each:

proximal, middle, and distal.

• Each phalanx has a base (proximally), a shaft, and a

head (distally).

• The phalanges of the 1st digit are short, broad, and

strong.

• The middle and distal phalanges of the 5th digit may

be fused in elderly people

MEDICO-LEGAL IMPORTANCE OF BONES OF LIMBS.

• Identification- age, sex, race, stature, and

specific identification factors

• Time since death

• Trauma analysis

AGE

• the appearance and union of epiphyses and

other ossification centers,

• Remodeling,

• Bone Loss,

• Arthritic Changes,

• Shifts in chemical composition

OSSIFICATION CENTER APPEARANCE AND EPIPHYSEAL

UNION

• appearance and

union of

ossification centres

are used to

estimate age

during

development and

growth from the

immature to adult

stage.

BONE REMODELING-

• Kerley histological technique

• Circular fields located adjacent to the periosteal

edge of the bone on its anterior, posterior, medial,

and lateral surfaces are measured.

• the numbers of primary osteons, secondary osteons,

and osteon fragments must be counted

• with increasing age, the percentage of

circumferential lamellar bone and the number of

primary osteons decrease while the number of

secondary osteons and osteon fragments increases

RADIOLOGICAL METHOD (BONE LOSS)

• Bone density observed on

radiographs to assess bone loss

with age and disease.

• height of the apex of the

medullary cavity, structure of

trabecular bone, cavity

formation in the major

tubercles, and the thinning of

the cortex are observed.

• Arthritic Changes

• General changes associated with arthritis provide an

additional source of age information from bones

• Generalized changes provide clues to advancing age,

but pathological conditions can produce such evidence

prematurely or with varied expressions in different

anatomical areas.

• Chemical Changes

• Racemization is a chemical reaction whereby the L-

forms of amino acids change to D-forms, and this

change correlates highly with the age of the protein. D-

L ratio increases with the age.

SEXThere are two methodological approaches to

sexing in adults:

• Morphological- focus on shape, the bony

configurations that are macroscopically

visible.

• Metric – based on bone dimensions

Morphological differences between

male (left) and female (right)

humerus:

(a) trochlear constriction: less

pinched in males, more pinched in

females;

(b) trochlear symmetry: assymetrical

in males, symmetrical in females;

(c) olecranon fossa shape: triangular

in males, oval in females;

(d) angle of medial epicondyle:

horizontal in males, angled in females

• Femur

• the vertical diameter of head is greater than

45 mm in the male and less than 41 mm in

the female,

• angle that the shaft makes with the

vertical- 76deg in females and 80 deg in

males

• collodiaphyseal angle- < 40 deg in males and

>50 deg in females

STATURE

• The most common method used- linear regression.

• With this technique, the known statures of adults in a given

population are plotted against the lengths of skeletal elements

and the best lines are fitted to the scatter plots

• Various regression formulae for calculating height have been

compiled, based on a number of different populations and sex.

• Karl pearson’s formula: a constant factor is to be added to the

product of the length of the bone with the multiplying factor

• femur- (Males) 81.306 +1.880 x length of femur,

(F)72.884+1.945 x length

• Tibia – (M)78.664 + 2.376 x length, (F) 74.774 +2.352 X length

• Humerus – 70.641+2.891 x length, (F)71.745+ 2.754 x length

• Trotter and Gleser formula- Different formulae were

calculated for the three major race types (white, negro

and mongoloid) and extensievely used.

• As such, these formulae cannot be satisfactorily used

on all populations and people from different regions

bear different morphology.

• Some of different formulae available for different

parts of india are

• Pan’s formula- Bihar Bengal and Orissa

• Nat’s formula – UP

• Siddiqui and Shah’s formula- Punjab

STATURE FROM FRAGMENT OF LONG BONES

• The most common approach is to use a

fragment of a long bone to estimate its

total length and then to employ this in

an existing formula.

• Alternatively, the length of the

fragment can be used directly to

estimate stature.

• They defined a number of landmarks

establishing few segments in the bones

like 4 in femur, five in the tibia, and

four in the humerus. Each segment is

defined as the distance between two

consecutively numbered points

RACE

• with respect to ancestry, postcranial

differences are largely nonexistent

• However Differences in the anterior

curvature of the diaphysis of femur can be

assessed for race determination.

PERSONAL IDENTITY

• Discrete abnormalities such as healing

fractures, metal prostheses, bone disease or

congenital defects. Some artefacts, such as

drill holes or wire can be used in

identification.

TIME SINCE DEATH

Based on physical appearance

• If soft tissues are still attached : 2weeks to 2

months

• No soft tissue but greasy : 1-3months

• Completely dry but foul smell : 3months to 1 year

• After 1yr unpreserved bones get destroyed

• Physical tests: silvery-blue fluorescence in

ultraviolet light

• From 3 to 80 years, greatly depending upon the

environmental conditions, the outer zone and

the zone around the marrow cavity

progressively lose fluorescence

• After a century or more, the residual

fluorescence contracts to a narrowing central

sandwich

• By second century fluorescence completely

vanishes

• Chemical tests: diminishing of amino acids

• Radio nucleotide method: radiocarbon (C-14)

analysis (this method is, however, insufficient for a

PMI of less than 100 years)

• strontium-90 and plutonium is used for shorter

PMI.

CAUSE OF DEATH

• It can be made out if there are fractures or

marks of deep cuts in bones, or marks of

burns or evidence of firearm injuries or any

disease. Metallic poisons can be found in

bones long after death.

NATURE OF INJURY• identification of the skeletal defects and establishment of

the timing of injury into ante-mortem peri-mortem and

postmortem

• Antemortem injury- signs of healing like grooves around

the fracture, active bone remodeling, callus formation,

and edge resorption are seen

• Perimortem injury- no evidence of healing on the bone.

characterized by a “green bone response” where the

collagen fibres in living bone allow some bending or

bowing to take place

• Postmortem injury- Transverse fractures and right-

angled edges