Humerus bone anatomy pptx Upperlimb 12345

Anatomy of Humerus bone

1. Humerus
Dr. Sami

2. The humerusis a long bone of the upper arm. It is one of the longestbones in
the body, which makes it more prone to fracturesupon impact. The word
“humerus” comes from the Latinwordfor upper arm.

3. Where is the humeruslocated?
The humerusbone is located in the upper arm, between the shoulder joint
and the elbow joint. The shoulder joint, also known as the glenohumeral
joint, is a ball and socket joint. The ballis the humeralhead, and the socket
is the glenoid fossaof the scapula. The joint is supported by ligaments, and
surrounded by the four rotator cuff muscles and their tendons: the
supraspinatus, infraspinatus, teresminor, and subscapularis. These muscles
originate on the scapula and insert on the humeral head.

4. Anatomical Position:

5. Parts of Humerus:
Proximal End: This is the upper part of your humerusclosest to your shoulder.
Body or shaft: This is the long, middle portion of your humerus.
Distal End: This is the lower area of your humerusthat’s closest to your
elbow.

6. Proximal Part:
Head:.
The head is nearly hemisphericalin form.
It is directed upward, medialward, and a little backward.
It articulates with the glenoid cavity of the scapula to form
the glenohumeraljoint (shoulder joint). The head form
about one third of the sphere and is much greater than
glenoid cavity.

7. Anatomical Neck:
The line separatingthe headfrom rest of the upper end is
called the anatomical neck.
The anatomical neck is a slight narrowing below the
articular surface of the head.
The anatomical neck is obliquely directed, forming an
obtuse angle with the body.
(More than 90 & less than 18)
It is best marked in the lower half of its circumference; in
the upper half it is represented by a narrow groove
separating the head from the tubercles.

8. Surgical neck:
The surgical neck of the humerusis a bony constriction at
the proximal end of shaft of humerus.
It is situated distal to the greater tubercle and lesser
tubercle, and proximal to the deltoid tuberosity.
The surgical neck is a narrow area distal to the tubercles
that is a common site of fracture.It makes contactwith the
axillary nerve and the posterior humeral circumflex artery.
Damage to the axillary nerve affects function of the teres
minor and deltoid muscles,resulting in loss of abduction of
arm (from 15-90 degrees), weak flexion, extension, and
rotationof shoulder as well as loss of sensation of the skin
over a small part of the lateral shoulder.

9. Greater tubercle:
The greater tubercle (greater tuberosity)is a large, posteriorlyplaced
projection that is placedlaterally.
It provides attachmentpoints for the supraspinatus, infraspinatus, and teres
minormuscles, three of the four muscles of the rotator cuff (except
subscapularis on lesser tubercle), a muscle group that stabilizesthe shoulder
joint. (SIT)
The upper surface of the greater tubercle is rounded, and marked by three flat
impressions:
the highest ("superior facet") gives insertion to the supraspinatusmuscle.
the middle ("middlefacet") gives insertion to the infraspinatusmuscle.
the lowest ("inferiorfacet"), and the body of the bone for about 2.5 cm, gives
insertion to the teresminormuscle.
The lateral surface of the greater tubercle is convex, rough, and continuous
with the lateral surface of the body of the humerus. It can be described as
having a cranial and a caudal

11. Between the greater tubercle and the lesser tubercle is the bicipital groove
(intertubercularsulcus).

12. Lesser Tubercle :
The lesser tubercle of the humerus, although smaller, is moreprominentthan
the greatertubercle: it is situated in front, and is directedmediallyand
anteriorly.
The projectionof the lesser tubercle is anteriorfromthe junctionthat is
found between the anatomical neck and the shaftof the humerusand easily
identified due to the intertubercularsulcus(Bicipitalgroove).
The crestof the lesser tubercle forms the medial lip of the bicipital groove
and is the sitefor insertionof teresmajor and latissimus dorsimuscles.
Above and in front it presents an impressionfor the insertionof the tendon of
the subscapularis muscle.

14. Bicipital groove
The bicipital groove separatesthe greater tubercle
from the lesser tubercle. It is usually around 8 cm
long and 1 cm wide in adults. It lodges the long tendon
of the biceps brachiimuscle between the tendon of the
pectoralis major muscle on the lateral lip and the
tendon of the teresmajor muscle on the medial lip. It
also transmitsa branch of the anterior humeral
circumflex artery to the shoulder joint.
The insertion of the latissimus dorsimuscle is found
along the floor of the bicipital groove. The teresmajor
muscle inserts on the medial lip of the groove.
It runs obliquely downward, and ends near the junction
of the upper with the middle third of the bone. It is the
lateral wall of the axilla.

17. Distal humerus
The distalor lower extremity of the humerusis flattenedfrom before backward,
and curved slightly forward; it ends below in a broad, articular surface, which is
divided into twopartsby a slight ridge. Projecting on either side are the lateral
and medial epicondyles.

19. Articular surface
The articular surface extends a little lower than the epicondyles, and is
curvedslightlyforward; its medial extremity occupies a lower level than the
lateral.
The lateral portion of this surface consists of a smooth, roundedeminence,
named the capitulumlittle headof the humerus; it articulateswith the cup-
shapeddepressionon the head of the radius, and is limitedto the frontand
lowerpartof the bone.
The trochlea (pulley) is a pulleyshapedsurface. It articulateswith the
trochlear notch of the ulna. The medial edge of the trochlea projects down 6
mm more than the lateral edge. This results in the formation of carrying
angle .

21. Fossae:
Above the front part of the trochlea is a small depression, the coronoid
fossa, which receivesthe coronoidprocessof the ulnaduring flexionof the
forearm.

22. Above the back part of the trochlea is a deep triangular depression, the
olecranon fossa, in which the summitof the olecranonis receivedin
extensionof the forearm.

23. Above the front part of the capitulumis a slightdepression, the radial fossa,
which receivesthe anteriorborderof the head of the radius, when the
forearmis flexed.

24. Epicondyles
The epicondyles are continuous above with the supracondylar ridges.
The lateral epicondyle of the humerusis a large, tuberculatedeminence,
curveda little forward, and givingattachmentto the radialcollateral
ligamentof the elbow joint, and to a tendoncommon to the origin of the
supinatorand some of the extensormuscles.
Specifically, these extensor muscles include the anconeusmuscle, the
supinator, extensorcarpiradialisbrevis, extensordigitorum, extensordigiti
minimi, and extensorcarpiulnaris. ( SAD hubecause of EX so DUR raho)

26. The medial epicondyle of the humerusis an epicondyle of the humerusbone
of the upper arm in humans. It is largerand moreprominentthan the lateral
epicondyleand is directed slightly more posteriorly in the anatomical
position.
The medialepicondyleis locatedon the distalendof the humerus.
Additionally, the medial epicondyle isinferior to the medial supracondylar
ridge. It is also proximalto the olecranonfossa.
The medial epicondyle gives attachmentto the ulnar collateral ligament of
elbow joint, to the pronator teres, and to a common tendon of origin (the
common flexor tendon) of some of the flexormusclesof the forearm: the
flexor carpi radialis, the flexor carpi ulnaris, the flexor digitorum
superficialis, and the palmaris longus. ( PLUS R )
The medial epicondyle protects the ulnar nerve, which runs in a groove on
the back of this epicondyle. The ulnar nerve is vulnerable because it passes
close to the surface along the back of the bone. Strikingthe medial
epicondyle causes a tingling sensation in the ulnar nerve. This response is
known as striking the "funny bone".

29. The Medial supracondylar crest forms the sharp medial border of the distal
humeruscontinuing superiorly from the medial epicondyle. The Lateral
Supracondylar crest forms the sharp lateral borderof the distal humerus
continuing superiorly from the lateral epicondyle.

30. Shaft or Body:
Borders:
Its three borders are:
Anterior: the anterior border runs from the front of the greater tubercle
above to the coronoid fossa below, separatingthe antero-medialfrom the
antero-lateral surface. Its upper part is a prominent ridge, the crest of the
greater tubercle; it serves for the insertionof the tendonof the pectoralis
major muscle.About its centerit forms the anteriorboundaryof the deltoid
tuberosity, on which the deltoid muscle attaches; below, it is smoothand
rounded, affording attachmentto the brachialis muscle.

34. Lateral: the lateral border runs from the back part of the greater tubercle to
the lateral epicondyle, and separates the anterolateral from the posterior
surface. Its upper half is rounded and indistinctly marked, serving for the
attachment of the lower part of the insertion of the teresminor muscle, and
below this giving origin to the lateral head of the triceps brachiimuscle; its
centeris traversed by a broad but shallow oblique depression, the spiral
groove (musculospiralgroove). The radial nerve runs in the spiral groove. Its
lower part forms a prominent, rough margin, a little curved from backward,
forwardthe lateral supracondylarridge, which presents an anteriorlipfor the
origin of the brachioradialismuscleabove, and extensorcarpiradialislongus
muscle above, a posteriorlipfor the tricepsbrachiimuscle, and an
intermediate ridge for the attachment of the lateral intermuscular septum.

39. Medial:
the medial border extends from the lesser tubercle to the medial epicondyle.
Its upperthirdconsists of a prominentridge, the crestof the lessertubercle,
which gives insertion to the tendon of the teresmajor muscle. About its
centeris a slight impressionfor the insertion of the coracobrachialis muscle,
and just belowthis is the entrance of the nutrient canal, directed downward;
sometimes there is a second nutrient canal at the commencement of the
radial sulcus. The inferiorthirdof this border is raised into a slight ridge, the
medial supracondylar ridge, which became very prominentbelow; it presents
an anterior lip for the originsof the brachialis muscle and the pronator teres
muscle, a posteriorlip for the medial head of the triceps brachiimuscle, and
an intermediateridgefor the attachment of the medial intermuscular
septum.

41. The body or shaftof the humerusis triangularto cylindricalin cut section and
is compressed anteroposterior. It has 3surfaces, namely:
Anterolateral surface:
the area between the lateral border of the humerusto the linedrawnas a
continuation of the crest of the greater tubercle.
The antero-lateral surface is directed lateralwardabove, where it is smooth,
rounded, and covered by the deltoid muscle;forward and lateralwardbelow,
where it is slightly concave from above downward, and gives origin to part of
the Brachialis.
About the middle of this surface is a rough, rectangularelevation, the deltoid
tuberosityfor the insertion of the deltoidmuscle; belowthis is the radial
sulcus, directed obliquely from behind, forward, and downward, and
transmitting the radial nerve and profundaartery.

43. Anteromedial surface:
the area between the medial border of the humerusto the line drawn as a
continuation of the crest of the greater tubercle. The antero-medial surface,
less extensive than the antero-lateral, is directed medialwardabove, forward
and medialwardbelow; its upper part is narrow, and forms the floor of the
intertuberculargroovewhich gives insertion to the tendon of the latissimus
dorsimuscle; its middle part is slightly rough for the attachmentof some of
the fibersof the tendon of insertion of the coracobrachialis muscle; its lower
part is smooth, concave from above downward, and gives origin to the
brachialis muscle.

46. Posterior surface:
the area between the medial and lateral borders. The posterior surface
appears somewhat twisted, so that its upper part is directed a little
medialward, its lower part backward and a little lateralward. Nearly the
whole of this surface is covered by the lateral and medial heads of the Triceps
brachii, the former arising above, the latter below the radial sulcus.

48. The Deltoid tuberosity is a roughened surface on the lateral surface of the
shaft of the Humerusand acts as the site of insertion of deltoideusmuscle.
The posterorsuperiorpart of the shaft has a crest, beginning just below the
surgical neck of the humerusand extends till the superior tip of the deltoid
tuberosity. This is where the lateral head of triceps brachiiis attached.

50. The radial sulcus, also known as the spiral groove is found on the posterior
surface of the shaft and is a shallow oblique groove through which the radial
nerve passes along with deep vessels. This is located posteroinferiorto the
deltoid tuberosity. The inferior boundary of the spiral groove is continuous
distally with the lateral border of the shaft.

52. The nutrient foramenof the humerusis located in the anteromedial surface
of the humerus. The nutrient arteries enter the humerusthrough this
foramen.