Transcript Anatomy of the Shoulder

Myology 2
(HS 201)
Lecture 1
Anatomical Review
and
Anatomy of the
Shoulder
1
Anatomical Position
Position In which the body is
standing upright, the feet parallel,
the arms hanging by the sides,
and the palms and face directed
forward.
2
PLANES OF THE ANATOMICAL
POSITION
A. Median (Mid-Sagittal): divides the body into symmetrical
right and left halves.
B. Sagittal: any plane parallel to the median plane
C. Coronal: any vertical plane perpendicular to the median
plane. It divides the body into anterior and posterior parts.
D. Transverse: divides the body into superior and inferior parts
E. Oblique: any plane on an angle
3
Movement of Body Parts
• Flexion: movement in a sagittal plane which takes a part of the
body forward from the anatomical position, causing a decrease in
the angle of a joint.
• Extension: movement in a sagittal plane which takes a part of
the body backward from the anatomical position causing an
increase in the angle of a joint.
• Abduction: a movement in the frontal plane which takes a part
of the body away from the median plane.
** For the fingers and toes the reference points used is
the axis of the hand (middle finger) or foot (second toe).
• Adduction: a movement in the frontal plane which takes a part
of the body toward the median plane.
4
Movement of Body Parts
• Horizontal Abduction: movement in a transverse plane
with the arm or leg beginning 90 degrees from the trunk,
taking the arm or leg away from the midline.
• Horizontal Adduction: movement in a transverse plane
with the arm or leg beginning 90 degrees from the trunk,
taking the arm or leg toward the midline.
• Lateral (External) rotation: movement of an extremity
in a transverse plane which takes a body part outward.
• Medial (Internal) rotation: movement of an extremity in
a transverse plane which takes a part of the body inward.
5
Movement of Body Parts
• Circumduction: combo of flexion-extension and
abduction-adduction in succession
• Supination: of the forearm, the palm faces forward
• Pronation: of the forearm, the palm faces backward
• Inversion: of the foot, soles facing inward
• Eversion: of the foot, soles facing outward
• Plantarflexion: of the foot, toes pointing down
• Dorsiflexion: of the foot, toes point upward
6
Movement of Body Parts
• Lateral flexion: applies to the head, neck or trunk. Have
movement in the frontal plane away from the median plane.
• Rotation: applies to the head, neck or trunk. Movement in a
transverse plane where the body part turns either to the left or
right.
• Protraction: drawing a structure forward
• Retraction: drawing a structure backward
7
Other Anatomical Reference Terms
a.
b.
c.
d.
e.
Medial: closer to the median plane
Lateral: further from the median plane
Anterior: facing or located to the front
Posterior: facing toward or located at the back
Superior: facing toward or located at the top (closer to the
head)
f. Inferior: facing toward or located at the bottom (further from
the head)
g. Proximal: closer to the trunk or some major joint
h. Distal: further from the trunk or some major joint
i. Superficial: near the outside surface of the body, particular
bone, or organ.
j. Deep: inside the body, particular bone, or organ
8
NAMING OF MUSCLES
1. Direction of muscle fibers:
a. Rectus: fibers run parallel to the midline (rectus
abdominis)
b. Transverse: fibers run perpendicular to the midline
(transverse abdominis)
c. Oblique: fibers run diagonally to the midline (external
oblique)
2. Location:
a. named for a nearby bone: (frontalis) frontal bone
b. position relative to a bone: (tibialis anterior) tibia
c. section of a muscle having more than one part (anterior
deltoid)
9
NAMING OF MUSCLES (cont)
3. Size:
a. large muscle (gluteus maximus)
b. small muscle (gluteus minimus)
c. long muscle (extensor digitorum longus)
d. short muscle (peroneus brevis)
4. Number of origins:
a. two origins: biceps femoris
b. three origins: triceps brachii
c. four origins: pronator quadratus
10
NAMING OF MUSCLES (cont)
5. Shape:
a. triangular: deltoid
b. trapezoid: trapezius
c. saw-toothed: serratus
d. rhomboid or diamond shaped: rhomboids
6. Origin and Insertion:
a. sternum, clavicle, and mastoid process: SCM
11
NAMING OF MUSCLES (cont)
7. Action:
a. decreases an angle of a joint: flexor digitorum
b. increases an angle of a joint: extensor carpi ulnaris
c. moves bone away from midline: abductor pollicis brevis
d. moves bone closer to midline: adductor longus
e. upward movement: levator scapulae
f. downward movement: depressor labii
g. turns palm up or anteriorly: supinator
h. turns palm down or posteriorly: pronator
i. decreases size of an opening: external anal sphincter
j. makes a body part more rigid: tensor fascia latae
k. moves a bone around its longitudinal axis: rotator
12
MUSCLE TERMINOLOGY
1. Belly: main portion of muscle which contains contractile fibers
2. Tendon: connective tissues which attaches muscle to the bone
(they resist pulling)
3. Aponeurosis: tendon that fans out and attaches to a broad area.
4. Insertion: movable end of a muscle attached to a bone that is
being moved
5. Origin: fixed end of a muscle which does not move
6. Fascia: connective tissue that holds fibers of muscles in place
(also hold organs)
13
Bone Surface Markings
• Depressions and openings:
• Processes for tendon and
ligament attachment:
– Fissure: narrow opening between
–
–
–
–
adjacent parts of bones for nerves
and vessels
Foramen: hole, opening
Fossa: shallow depression
Sulcus: groove
Meatus: tubelike passageway
• Processes that form joints
– Condyle: large rounded
prominence
– Facet: smooth flat surface
– Head: rounded articular
projection
– Crest: prominent border or ridge
– Epicondyle: prominence above a
condyle
– Linea: line, less prominent than a
crest
– Trochanter: large projection of
bone found only on the femur
– Tubercle: small rounded process
– Tuberosity: large, rounded, usually
roughened process
14
MUSCLE ACTIONS
1. Agonist: main muscle that moves a joint
2. Antagonist: opposes action of the agonist, moves the
muscle back to place, there is balance between the agonist
and antagonist
3. Synergist: muscles acting in a coordinated fashion to
provide a movement.
Examples: levator scapulae and trapezius cause
elevation of scapula, gastrocnemius, soleus, and
plantaris cause us to step on toes
4. Fixator: muscle used to stabilize bones. Holds bone in
place so other muscles can act.
5. Neutralizer: Two muscles that cancel each other
out in one action but work synergistically to perform another
action.
15
Anatomy of the Shoulder
16
Shoulder Girdle
– Shoulder girdle consists of the scapula and the
clavicle
– Function of the shoulder girdle is to attach the
upper extremity to the trunk
– The scapula and clavicle are united at the
acromioclavicular joint (a gliding joint)
17
Scapula
• Triangular bone, located on posterior thorax between levels of 2nd
and 7th ribs
• Anatomy:
– Scapular spine: sharp ridge of bone, running diagonally across
the posterior surface of the scapula.
– Body: main triangular portion of the scapula
– Acromion: flattened lateral end of the scapular spine (high
point of the shoulder).
• Acromion process articulates with the lateral end of the
clavicle
– Glenoid cavity (fossa): depression on the lateral end of the
scapula for articulation with the head of the humerus
– Medial (vertebral) border: thin edge of the scapular body near
vertebral column
– Lateral (axillary) border: thicker edge of scapular body on the
lateral side
18
Scapula
• Anatomy (cont):
– Inferior angle: angle formed by the joining of the medial and
lateral borders
– Superior border: superior edge of scapula
– Superior angle: angle formed by the joining of the superior
border and medial border.
– Scapular notch: indentation in superior border for
suprascapular nerves
– Coracoid process: hooked projection of bone from the anterior
surface of the scapula. Functions as a point of muscle
attachment.
– 3 fossae:
• Supraspinous fossa: fossa above the scapular spine
• Infraspinous fossa: fossa below scapular spine
• Subscapular fossa: fossa on the anterior surface of the
scapula
19
Anatomical Review: Scapula
20
Clavicle
• Long slender S-shaped bone known as the collarbone
– Medial 1/3 of clavicle is convex anteriorly, Lateral 1/3 is concave
– Junction of the two curves is weakest point and subject to
fractures.
• Anatomy:
– Sternal end: medial rounded end of clavicle.
• Articulates with sternum forming the sternoclavicular joint.
– Acromial end: broad, flat, lateral end of clavicle
• Articulates with acromion process of scapula forming the
acromioclavicular joint (A-C joint).
– Conoid tubercle: on inferior lateral end of clavicle for
ligamentous attachment
– Costal tuberosity: on inferior medial end of clavicle also for
ligamentous attachment.
21
Anatomical Review: Clavicle
22
Proximal Humerus
• Anatomy:
– Head: rounded surface articulating with glenoid fossa
– Anatomical neck: groove distal to the head of the humerus
– Greater tubercle: lateral projection distal to the neck
– Lesser tubercle: anterior projection of bone
– Intertubercular sulcus (Bicipital groove): groove between the
greater and lesser tubercle. Receives the long head of the
biceps muscle.
– Surgical neck: constricted portion distal to the two tubercles
• Named so because a common site of humeral fracture
– Shaft: diaphysis of the arm bone
– Deltoid tuberosity: roughened V-shaped area of bone on the
lateral portion of the shaft
23
Anatomical Review: Proximal Humerus
24
Articular Anatomy of the Shoulder
1. Sternoclavicular Joint: gliding joint where head of clavicle fits
into notch on sternum.
2. Acromioclavicular Joint: gliding joint where clavicle articulates
with acromion process of scapula. Shoulder separation occurs at the
AC joint
3. Glenohumeral joint: ball and socket joint between glenoid fossa
of scapula and head of the humerus. Shoulder dislocation takes
place at the glenohumeral joint.
4. Scapulothoracic joint: where anterior scapula articulates with
the ribs
25
Soft Tissue Anatomy of the Shoulder
1. Rotator Cuff: attachment of rotator cuff muscles around the
shoulder joint capsule. It is thick and strong.
2. Biceps Tendon: attaches biceps muscle to scapula
3. Bursa: fluid filled sacs which lubricates tendons as they move
across each other:
a. subscapular bursa
b. subdeltoid bursa
c. subacromial bursa
d. subcoracoid bursa
26
Soft Tissue Anatomy of the Shoulder (Cont)
Ligaments:
1. Coracohumeral ligament:
is a strong, broad ligament
that strengthens the superior
part of the articular capsule.
Extends from the coracoid
process of the scapula to the
greater tubercle of the
humerus.
2. Acromioclavicular ligament:
lateral clavicle to superior
surface of acromion
3. Coracoacromial ligament: a
scapular ligament. From
coracoid to acromion; strengthens
superior articular capsule
27
Soft Tissue Anatomy of the Shoulder (Cont)
Ligaments (cont):
4. Coracoclavicular ligament: strong
ligament divided into two
ligaments (conoid and trapezoid)
They anchor the lateral part of the
clavicle to the coracoid process.
a. Conoid: passes from the
coracoid process to the
clavicle. Resists forward
movement of the scapula
without corresponding
movements of the clavicle.
b. Trapezoid: resists
backward movement of the
scapula.
•
28
Soft Tissue Anatomy of the Shoulder (Cont)
Ligaments (cont):
5. Costoclavicular ligament:
from first costal cartilage to
medial clavicle. Limits
elevation of the clavicle.
6. Sternoclavicular ligament:
from sternum to clavicle.
Reinforces articular capsule
of sternoclavicular joint.
7. Interclavicular ligament:
extends across jugular notch.
Stabilizes the sternoclavicular
joint.
29
Soft Tissue Anatomy of the Shoulder (Cont)
8. Articular capsule: is a thin,
loose sac that completely
envelopes the shoulder joint.
It extends from the glenoid
cavity to the anatomical neck
of the humerus. The inferior
part of the capsule is its
weakest area.
9. Glenoid Labrum: a rim of
fibrocartilage around the edge
of the glenoid cavity. It
functions to deepen and
enlarge the glenoid cavity
30