Lecture 9
Selected Joints &
Muscular System I:
Architecture
9-1
Shoulder Joint
Fig. 9.15
Ligaments of the Shoulder Joint
• Glenohumeral (3)
• Transverse humeral
• Coracohumeral
• Coracoacromial
• Coracoclavicular
Muscles of Shoulder Joint
• Rotator cuff (4 muscles)
9-2
Knee Joint
• Menisci: Fibrocartilage articular disks
• Cruciate ligaments: Anterior cruciate ligament and
posterior cruciate ligament
• Collateral ligaments: Fibular and tibial
Fig. 9.19
9-3
Knee Injuries and Disorders
• Football injuries
– Damage to
collateral ligaments
due to blow
– Torn menisci
– Torn cruciate
ligaments
Figure from Clinical View on page 278
9-4
Properties of Muscle
• Contractility
– Ability of a muscle to shorten with force
• Excitability
– Capacity of muscle to respond to a stimulus
• Extensibility
– Muscle can be stretched to its normal resting length and
beyond to a limited degree
• Elasticity
– Ability of muscle to recoil to original resting length
after stretched
9-5
General Principles of Muscles
• Tendons: Attach muscles to bones
– Aponeurosis: A very broad tendon
• Muscles
– Origin or head: Muscle end attached to more stationary of two
bones
– Insertion: Muscle end attached to bone with greatest
movement
– Belly: Largest portion of the muscle between origin and
insertion
– Synergists: Muscles that work together to cause a movement
• Prime mover: Plays major role in accomplishing movement
– Agonist: Muscle causing an action when contracts
– Antagonist: A muscle working in opposition to agonist
– Fixators: Stabilize joint/s crossed by the prime mover
9-6
Muscle Shapes
Table 10.5
9-7
Muscle Shapes
Table 10.5
9-8
Nomenclature
Fig. 10.14
9-9
Nomenclature
Fig. 10.14
• Example - extensor carpi radialis longus
9-10
Review Question
The muscle name transversus thoracis is
derived from a combination of its
(a) Size and function
(b) Orientation and location
(c) Relative length and location
(d) Shape and orientation
(e) Function and shape
9-11
Points to Remember
• Skeletal muscles have many shapes and in
each instance contraction of the muscle
tissue causes body movements through their
attachments to the skeleton or beneath the
skin.
• Understanding the meaning of the parts of a
muscle name helps one to learn the muscle.
9-12
Questions?
9-13