This document describes the scapula, brachium (humerus), and associated muscles. It includes: 1. Descriptions of bone markings on the scapula like the coracoid process and acromion process, as well as the glenoid cavity. 2. Descriptions of bone markings on the humerus including the greater and lesser tubercles, trochlea, and epicondyles. 3. Details about muscle attachments to these bones like the supraspinatus originating on the supraglenoid tubercle. 4. Information about the blood supply including arteries like the suprascapular artery, and veins following the arterial drainage patterns.

1. SCAPULAR REGION &
BRACHIUM.
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2. OBJECTIVES.
1. To describe the scapula and the
humerus.
2. To describe the muscle
attachments to the scapula and
their action at the shoulder
joint
3. To describe the muscle
attachments to the humerus

3. Objectives contd
4. To describe the blood supply to the
scapula and brachium and
understand the clinical relevance of
their anastomoses.
5. To describe the nerve supply to the
muscles of the scapula and brachium.
6. Review the lymphatic drainage of the
scapula and brachial regions

5. The
Scapula
The scapula body forms
a broad triangle with
many surface markings
- sites of attachment for
muscles, tendons, and
ligament
3 sides of the scapular
triangle are called
borders: Superior;
Medial (vertebral); and
Lateral (axillary)
- muscles that position
the scapula attach along
these edges
Corners or angles:
Superior; Inferior; and
Lateral
- lateral angle, or scapula
head forms a broad process
that supports the glenoid
cavity (fossa)

6. Scapula
Bone
Markings
Coracoid (‘crow’s beak’) –
smaller process projects
anteriorly and slightly laterally
- origin for short head of
biceps brachii muscle
-insertion for Pectoralis minor
Acromion – larger process
projects anteriorly
- insertion for part of the
trapezius muscle
-origin for part of Deltoid muscle
- articulates with the clavicle
at the acromioclavicular joint
- both processes are attached
to ligaments and tendons
associated with the shoulder joint
Surface markings represent
attachment sites for muscles
that position the shoulder and
arm
- supraglenoid and
infraglenoid tubercle: biceps
brachii
- supraspinous and
infraspinous fossa: supra,
infraspinatus

7. Fig 7.5a-e The Scapula
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

8. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

9. Fig 7.5c,f The Scapula
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

10. Posterior view

11. Ligaments of Shoulder Girdle
(clavicle, humerus, scapula)
• Glenohumeral Ligaments- they are 3 and only
seen within the joint cavity (superior, middle
and inferior)
• Coracohumeral- from coracoid process to
greater tuberosity
• Coracoacromial
• Transverse humeral ligament
Coracoclavicular:
Trapezoid and Conoid portions

13. ARTERIES AND
VEINS.
Posterior scapular
region.
•3 major arteries:
Suprascapular
,posterior circumflex
humeral, and
circumflex scapular
arteries.
•Suprascapular
artery;-Originates in
the base of the neck,
-A branch of the
thyrocervical trunk,
which is a major
branch of the
Subclavian artery
•It may also originate
directly from 3rd part of
subclavian artery.

14. POSTERIOR SCAPULAR
REGION
• Suprascapular artery
enters the region superior to
suprascapular foramen, nerve
passes through the foramen.
• Supplies supraspinatus and
infraspinatus muscles & to
numerous structures along its
course.
Posterior circumflex humeral
artery; Originates from 3rd
part of axillary artery in the
axilla, enters the region
through the quadrangular
space with the axillary nerve.
• Supplies related muscles
and the glenohumeral
joint.
Circumflex scapular
artery;-A branch of the
subscapular artery that
originates from 3rd part of
axillary artery in the axilla
• Leaves the axilla through
the triangular space,
anastomoses with other
arteries in the posterior
scapular region.
Veins follow the arteries and
connect with vessels in the
neck , back, arm and axilla.

15. Areas of the brachial plexus
Answer / Feedback
1. Superior
2. Middle
3. Inferior
4. Lateral
5. Posterior
6. Medial
7. Musculocutaneous nerve (C5, 6, 7)
8. Axillary nerve (C5, 6)
9. Radial nerve (C5, 6, 7, 8, T1
10. Median nerve (C5, 6, 7, 8, T1)
11. Ulnar nerve (C7, 8, T1)

16. The Brachium
(Humerus)
• Head
articulates
with the
glenoid
cavity
• Shaft – body
• Anatomical
neck
• Surgical neck

17. Humerus Bone Markings
• Greater tubercle – Insertion sites for muscles
supraspinatus and infraspinatus, teres minor
• Lesser tubercle – subscapularis muscle
- intertubercular sulcus (groove) – a biceps tendon
• Deltoid tuberosity – deltoid muscle
• Trochlea (‘pulley’) – articulates with the ulna
• Coronoid and olecranon fossa – accept
projections from the ulna
• Capitulum – articulates with the head of the
radius
• Medial and lateral epicondyles – ulnar nerve
crosses the medial epicondyles

18. Figure 7.6b,c The Humerus

19. Fig 7.6d

20. Humerus & Scapula
Bone markings.

21. Muscles of the anterior compartment of the
arm
Muscle Origin Insertion Innervation Function
Coracobrachi
alis
Apex of
coracoid
process
Linear
roughening
on mid-shaft
of humerus
on medial
side
Musculocutan
eous nerve
[C5,C6,C7]
Flexor of the
arm at the
gleno-
humeral joint
Biceps brachii Long head-
supraglenoid
tubercle of
scapula; short
head-apex of
coracoid
process
Radial
tuberosity
Musculocutan
eous nerve
[C5,C6]
Powerful
flexor of the
forearm at
the elbow
joint and
supinator of
the forearm;
accessory
flexor of the
arm at the
glenohumeral
joint
Brachialis Anterior Tuberosity of (small Powerful

22. Muscle of the posterior compartment of the arm
Muscle Origin Insertion Innervatio
n
Function
Triceps
brachii
Long head-
infraglenoi
d tubercle
of scapula;
medial
head-
posterior
surface of
humerus;
lateral
head-
posterior
surface of
humerus
Olecranon Radial
nerve
[C6,C7,C8]
Extension
of the
forearm at
the elbow
joint. Long
head can
also extend
and adduct
the arm at
the
shoulder
joint
---

23. Brachial artery and its branches.

24. NERVES.
Anteriorly. Posteriorly.

25. LYMPH DRAINAGE
• It is of considerable
clinical importance
because of the
frequent
development of
cancer of the gland
and the
dissemination of the
malignant cells along
the lymph vessels.

26. Six groups
• Anterior (pectoral)- drains lateral part of breast
and anterolateral abd wall above the umbilicus
• Posterior (subscapular)-receives superficial
vessels from the back down as far as the level of
the iliac crest, axillary tail of the breast
• Lateral group (humeral)- drains the upper limb
except the lateral side
• Central group- receives lymph from above 3 gps
• Infraclavicular (deltopectoral)- drains lateral side
of hand, forearm and arm
• Apical- receives efferent vessels form all the
above
Axillary lymph nodes

27. CLINICAL APPLICATIONS.
Fractures of the scapula.
• Are usually the result of
severe trauma e.g. run-
over accident victims,
occupants of automobiles
involved in crashes.
• Are usually associated
with fractured ribs.
• Most require little
treatment because
muscles on the anterior
and posterior surfaces
adequately splint the
fragments.
Dropped Shoulder
• Occurs with paralysis of the
trapezius.
Winged Scapula.
• Is caused by paralysis of the
Serratus anterior due to
damage to the Long thoracic
nerve.
• Medial border, and particularly
the inferior angle, of the
scapula to elevate away from
the thoracic wall on pushing
forward with the arm.
Furthermore, normal elevation
at the arm is no longer
possible.

28. Fractures of the Proximal End of the Humerus.
Humeral Head Fractures.
• Can occur during the
process of anterior &
posterior dislocations of
the shoulder joint.
• The fibrocartilaginous
glenoid labrum of the
scapula produces the
fracture.
• The labrum can
become jammed in the
defect, making
reduction of the
shoulder joint difficult.
Greater Tuberosity
Fractures.
• Causes;-Direct trauma
-displacement by the glenoid
labrum during dislocation of
the shoulder joint.
-avulsion by violent
contractions of the
supraspinatus muscle.
• Bone fragment will have the
attachments of
supraspinatus, teres minor
and infraspinatus muscles
(part of rotator cuff).

29. Greater Tuberosity
Fractures associated
with a shoulder
dislocation.
• Severe tearing of the cuff
with the fracture results in
the tuberosity remaining
displaced posteriorly after
the shoulder joint has been
reduced.
• Rx; open reduction of the
fracture to attach the
rotator cuff back in place.
Lesser Tuberosity
Fractures.
• Occasionally accompany
posterior dislocation of the
shoulder joint.
• Subscapularis tendon
inserts in the fragment.
Surgical Neck Fractures.
• Causes;- Direct blow on
the lateral aspect of the
shoulder.
-Indirectly by falling on the
outstretched hand.
Fractures of the Shaft of
the Humerus.
• Are common.
• Fracture line proximal to
the deltoid insertion, the
proximal fragment is
adducted by the pectoralis
major, latissimus dorsi,
and teres major muscles;
the distal fragment is
pulled proximally by the
deltoid, biceps, and
triceps.

30. Fractures of the Shaft of the
Humerus.
• When fracture is distal to the
deltoid insertion, the
proximal fragment is
abducted by the deltoid, and
the distal fragment is pulled
proximally by the biceps and
triceps.
• Radial nerve can be
damaged where it lies in the
spiral groove on the posterior
surface of the humerus under
cover of the triceps muscle.
Fractures of the Distal End
of the Humerus.
• Supracondylar fractures are
common in children.
• Occur when the child falls on
the outstretched hand with
the elbow partially flexed.
• Injuries to the medial,
radial and ulna nerves are
common, although
function usually quickly
returns after reduction of
the fracture.
• Damage to or pressure on
the brachial artery can
occur at the time of the
fracture or from swelling
of the surrounding
tissues; circulation to the
forearm may be
interfered with leading to
Volkmann’s ischaemic
contracture.

31. Fractures of the Distal
End of the Humerus.
• Medial epicondyle can be
avulsed by the medial
collateral ligament of the
elbow joint if the forearm
is forcibly abducted. The
ulna nerve can be injured
at the time of the fracture,
or become involved later
in the callus as the
fracture heals, or can
undergo irritation on the
irregular bony surface
after the bone fragments
are reunited.

32. • Anterior-inferior dislocations
& posterior dislocations of
the shoulder joint.
HISTOLOGY.
Bones:
Gross structures; Can be divided
into several regions.
• Epiphysis; In long bones, is the
region between the growth plate
or growth plate scar and the
expanded end of bone, covered
by articular cartilage.
• In adults it consists of abundant
trabecular bone and a thin shell
of cortical bone.
Cortical bone is composed of
haversian systems (osteons). Each
osteon has a central haversian
canal and peripheral concentric
layers of lamellae.
• Metaphysis; Is the junctional
region between the growth plate
and the diaphysis. It contains
abundant trabecular bone, but the
cortical bone thins here relative to
the diaphysis.

33. • Diaphysis; Is the shaft of long
bones and is located in the
region between metaphyses,
composed mainly of compact
cortical bone.
The medullary canal contains
marrow and a small amount of
trabecular bone.
• Physis; (epiphyseal plate,
growth plate) Is the region that
separates the epiphysis from
the metaphysis. It is the zone of
endochondral ossification in an
actively growing bone or the
epiphyseal scar in a fully grown
bone.
Skeletal Muscle:
• Consists of very long tubular cells
called muscle fibres.Average
length of skeletal muscle cells in
humans is about 3 cm. Their
diameters vary from 10 to 100
µm.
• Skeletal muscle fibres contain
many peripherally placed nuclei.
Up to several hundred rather
small nuclei with 1 or 2 nucleoli
are located just beneath the
plasma membrane
• Skeletal muscle fibres show
characteristic cross-striations. It is
therefore also called striated
muscle.

34. SKELETAL MUSCLE.
Longitudinal skeletal muscle is non-branching and
identified by peripheral nuclei.large white vertical
lines are knife marks from sectioning (artifact). Bar
= 250 Microns
At higher magnification, the striations become
visible. I-bands (isotropic) are light while A-
bands (anisotropic) are dark. Bar = 30 Microns
In cross section, skeletal
muscle is identified by
peripheral nuclei and large
amounts of cytoplasm. Bar
= 50 Microns

35. Peripheral Nerves
• One nerve fibre consists of
an axon and its nerve
sheath of Schwann cells.
• An individual Schwann cell
may surround the axon for
several hundred
micrometers, and it may, in
the case of unmyelinated
nerve fibers, surround up to
30 separate axons.
• The axons are housed within
infoldings of the Schwann
cell cytoplasm and cell
membrane, the mesaxon .
• The myelin sheath formed by
the Schwann cell insulates
the axon, improves its
ability to conduct and, thus,
provides the basis for the fast
saltatory transmission of
impulses.
• Each Schwann cell forms a
myelin segment, in which the
cell nucleus is located
approximately in the middle of
the segment.
• The node of Ranvier is the
place along the course of the
axon where two myelin
segments meet.

36. THANK YOU.