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Skeletomuscular
System
Chapters 7 – 9: Part 1
Muscles, Bones, and
Ligaments of the Arm
Muscle Attachment
Does NOT move when
muscle contracts
Classification of Muscle Group Actions
• Agonist (Prime Mover)
▫ Muscle most responsible for
movement
• Antagonist
▫ Opposes prime mover
▫ Provides precision and control during
prime mover contraction
▫ Relaxes when prime mover contracts
• Synergist
▫ Aides prime mover
▫ Contracts at same time as prime mover
What is a Ligament?
• Short band of tough, flexible,
fibrous connective tissue that
connects two bones or cartilages or
holds together a joint
▫ Ligaments are similar to tendons as
they are all made of connective
tissue.
• The study of ligaments is known
as desmology (Greek, desmos =
"bond“)
• Ligaments have a slow healing
process and if severe enough, need
corrective surgery
Ligaments of the Elbow
• Medial (Ulnar) Collateral
Ligament (UCL): thick
triangular band at the medial
aspect of the elbow uniting
the distal aspect of
the humerus to the proximal
aspect of the ulna
• Lateral (Radial) Collateral
Ligament (RCL): Y-shaped
ligament complex; attaches
distal aspect of humerus to
proximal aspect of radius.
Shoulder Joints
• Acromioclavicular
(AC): clavicle and
scapula
• Glenohumeral:
humerus and scapula
Acromioclavicular Ligaments
• Acromioclavicular
ligament: attaches the
clavicle to the acromion
of the scapula
• Coracoacromial
ligament: which runs
from the coracoid process
to the acromion
• Coracoclavicular
ligament: serves to
connect the clavicle with
the coracoid process of
the scapula
Glenohumeral Joint
• Ball-and socket joint that is formed
between the humerus and scapula.
• Labrum: piece of cartilage that lies
directly between the the humerus
head and the glenoid.
▫ Provides a smooth surface that allows
for the humerus head to rotate with
minimal friction, thus cushioning both
the humerus and the scapula
▫ Shaped like a ring, with the outer part
of the labrum being much thicker than
the center of the ring.
Muscles of the Glenohumeral Joint
• The main muscles that are
used in conjunction with
the glenohumeral joint are
the group of muscles
known as the rotator cuff.
▫ Rotator cuff muscles:
supraspinatus,
subscapularis,
infraspinatus, and teres
minor.
Ligaments of the Shoulder
• In addition to the
labrum and the rotator
cuff muscles, there are
four ligaments that
help with the
glenohumeral joint
▫ Coracohumeral
ligament (between the
coracoid process and
the humerus) and the
three glenohumeral
ligaments
Limb muscles
Muscles of the limb function in: Movement, grasping, balance
• Deltoid: muscle forming the rounded contour of the shoulder;
moves upper arm
• Pectoralis major: thick, fan-shaped muscle, situated at the chest
(anterior) of the human body; moves upper arm
• Biceps brachii: two-headed muscle that lies on the upper arm
between the shoulder and the elbow; flexes arm
• Brachialis: muscle in the upper arm that flexes the elbow joint
• Brachioradialis: muscle of the forearm that flexes the forearm at
the elbow; capable of both pronation and supination
• Palmaris longus: muscle which starts up near the elbow and
runs across the middle of the forearm; flexes hand
• Flexor carpi ulnaris: muscle of the human forearm that acts to
flex and adduct the hand
• Flexor carpi radialis: muscle of the human forearm that acts to
flex and abduct the hand
Color Key
•Purple: Muscles that move the
upper arm
•Orange: Muscles that move the
forearm
•Brown: Muscles that flex the
hand
Anterior
superficial
muscles of
the shoulder
and arm
Posterior Arm Muscles
• Triceps brachii: muscle (3 heads) on the back of the upper
arm; moves forearm
• Anconeus: small triangular elbow muscle connecting the
medial side of the ulna to the lateral side of the humerus;
extends forearm
• Extensor carpi radialis longus: found on the lateral side of
the humerus, and attaching to the base of metacarpal 2
(pointer finger)
• Extensor carpi radialis brevis: found on the lateral side of
the humerus, running alongside the radius; extends/abduct
the wrist
• Extensor digitorum: extends the medial four digits
(phalanges) of the hand
• Extensor digiti minimi: muscle of the forearm that extends
phalanx 5 (pinky finger!)
• Extensor carpi ulnaris: extend and adduct at the wrist
Color Key
•Orange: Muscles that move the
forearm
•Brown: Muscles that extend
the hand
Flexor Carpi Ulnaris
Posterior
superficial
muscles of
the arm
Anconeus
14
Extensor digiti
minimi
Musculoskeletal
System
Chapters 7 – 9: Part 2
Muscles, Joints, and
Ligaments of the Leg
Ligaments of the Ankle
• Deltoid Ligament: medial part of
the ankle joint; attaches the medial
malleolus to multiple tarsal bones
• Anterior talofibular ligament:
connects the talus bone to the
anterior fibula; weakest and most
commonly injured ligament
• Posterior talofibular ligament:
connects fibula to tubercle on the
posterior surface of the talus
• Calcaneofibular ligament:
connects the talus and calcaneus
• Plantar Fascia: connects your heel
bone to your toes; supports the arch
of your foot.
Ligaments of the Knee
Anterior Cruciate Ligament (ACL)
• The ACL is one of the four
stabilizing ligaments located in
the knee.
▫ Crosses the knee joint in a
diagonal direction and
prevents the forward
movement of the tibia (shin
bone).
• Torn ACL is a common skeletal
injury in people who play sports
or in anyone who applies a
twisting force to the knee.
Posterior Cruciate Ligament (PCL)
• PCL works in conjunction with
the ACL to provide stability by
preventing the tibia to move
backward.
• A torn PCL may be the result
from falling with your knee
bent.
▫ If the shinbone hits the
ground before the knee, a
PCL tear is likely.
Medial Collateral Ligament
▫ MCL resists force from the
outer surface of the knee.
 It joins the femur (thigh
bone) and tibia to prevent
the inner portion of the joint
from widening when
stressed.
Lateral Collateral Ligament
▫ The lateral collateral
ligament (LCL) works with
the MCL for stabilization of
the skeletal system.
 Runs along the outside of the
knee, connecting the
thighbone to the fibula (calf
bone).
Knee Muscles/Connections
• Patellar ligament: connects to two different
bones, the patella and the tibia.
• Quadriceps tendon: attaches patella to the
quadriceps muscles
• Meniscus: lateral and medial
▫ Two vital functions:
 Transfer the load from the upper leg to the lower leg
 Stabilize the knee during flexion, extension and during
circular movements.
▫ The menisci move during the backward flexion and
the forward extension of the knee in order to
balance the change of the articular surfaces.
anterior
cruciate
ligament
medial meniscus
posterior
cruciate
ligament
patella
patellar
ligament
lateral
meniscus
quadriceps
tendon
Knee
Joint
fibular (lateral)
collateral
ligament
tibial (medial)
collateral
ligament
Anterior
(with tendon & ligament removed)
Posterior
Anterior Upper Leg Muscles
• Quadriceps: 4-headed muscle made up of the vastus
lateralis, vastus intermedius, vastus medialis, and rectus
femoris; moves lower leg
• Sartorius: assists in flexing, weak abduction and lateral
rotation of the hip, and flexion of knee
• Gracilis: originates at the ischiopubic ramus and
extends down to the tibia; responsible for hip adduction
and assists knee flexion
• Adductor Longus: main function is to adduct the thigh
Upper Leg
(Anterior)
quadriceps
rectus femoris
vastus intermedius
(under rectus femoris)
vastus medials
vastus lateralis
Upper Leg
(Anterior)
sartorius
quadriceps tendon
patellar ligament
Posterior Upper Leg
• Gluteus Maximus: located in the buttocks and is
regarded as one of the strongest muscles in the human
body; responsible for movement of the hip and thigh
• Illotibial band: works to extend, abduct, and laterally
rotate the hip; knee stabilization
• Biceps femoris: Both heads of the biceps
femoris perform knee flexion. Since the long head
originates in the pelvis it is also involved in hip
extension; hamstrings
• Semimembranosus: enabling the leg to flex and rotate,
and serving as a thigh extensor; hamstrings
• Semitendinosis: long, superficial muscle in the back of
the thigh; hamstrings
gluteus medius
hamstring group
biceps femoris
gluteus maximus
iliotibial band
semitendinosus
semimembranosus
Upper Leg
(Posterior)
Muscles of the Lower Leg
• Gastrocnemius: Along with the soleus muscle, it
forms half of the calf muscle; function in plantar
flexion of the foot and flexing the leg at the knee joint
• Soleus: plantar flexion of the foot; powerful muscle
vital in walking, running, and dancing
• Achilles tendon: largest and strongest tendon in the
human body; connects the calcaneus to the muscles at
the back of the calf
• Extensor digitorum: wing-shaped muscle works to
extend the foot at the ankle, along with phalanx 2-5
• Tibialis anterior: dorsiflexion and inversion of the
ankle
• Fibularis longus: also known as the peroneus
longus; muscle inside the outer area of the human leg,
which everts (bends in an outward direction) and
flexes the ankle.
adductor longus
gracilis
gastrocnemius
sartorius
Medial Leg
Muscles
soleus
calcaneal (Achilles)
tendon
Lower
Lateral Leg
tibialis anterior
extensor digitorum
fibularis
(peroneus)
longus
retinaculum
Head and Neck Muscles
There are 4 basic functions
of head and neck muscles:
o swallowing and
chewing (mastication)
o making facial
expressions
o moving your neck
o supporting your head
Muscles of the Head and Neck
Connects frontalis and occipitalis
Strains vs. Sprains
• A strain is when you "pull" a muscle and a
sprain is when you damage a ligament.
• Classification of Strains and Sprains:
▫ First degree: a few fibers of the ligament/
muscle are torn and loss of function is mild
▫ Second degree: roughly half of the fibers of
the ligament/ muscle are torn loss of
function is moderate to severe
▫ Third degree: all or most of the fibers of the
ligament/muscle are torn and loss of
function is severe
• RICE:
▫
▫
▫
▫
Rest
Ice
Compression
Elevation