Chapter 11: Axial Musculature
Introduction
• The skeletal muscles of the body can be subdivided into:
– Axial musculature
▪ Muscles that position the head and vertebral column
▪ Muscles that move the rib cage
– Appendicular musculature
▪ Muscles that stabilize or move the appendicular skeleton
• The muscles are innervated by nerves
The Four Groups of Axial Muscles
• The axial muscles can be placed into four groups based on location or function
– Muscles of the head and neck
– Muscles of the vertebral column
– Muscles of the rib cage and lateral walls of the abdominal and pelvic cavities
– Muscles of the pelvic floor
Muscles of the Head and Neck
• Several groups of muscles of the head and neck are:
– Muscles of facial expression
– Extra-ocular muscles
– Muscles of mastication
– Muscles of the tongue
– Muscles of the pharynx
– Anterior muscles of the neck
• Muscles of Facial Expression
– Facial expression muscles are divided into five groups
▪ Mouth/eyes/scalp/nose/neck
▪ All are innervated by CN VII
– Orbicularis oris
– Buccinator
– Temporoparietalis
– Occipitofrontalis
– Platysma
• Extra-ocular Muscles
– Extrinsic eye muscles (muscles that control eye movement)
▪ Medial and lateral rectus muscles
▪ Superior and inferior rectus muscles
▪ Superior and inferior oblique muscles
▪ Inferior rectus/medial rectus/superior rectus/Inferior oblique: innervated by CN III
▪ Lateral rectus: innervated by CN VI
▪ Superior oblique: innervated by CN IV
– Eye movements
▪ Lateral rectus: rotates the eye laterally
▪ Medial rectus: rotates the eye medially
▪ Superior rectus: rotates the eye upward
▪ Inferior rectus: rotates the eye downward
▪ Superior oblique: rotates the eye downward and laterally
▪ Inferior oblique: rotates the eye upward and laterally
• Muscles of Mastication
– Masseter
– Temporalis
– Pterygoids
– All are innervated by CN V
• Muscles of the Tongue
– Genioglossus
– Hyoglossus
– Palatoglossus
– Styloglossus
– Genioglossus/Hyoglossus/ Styloglossus: innervated by CN XII
– Palatoglossus: innervated by CN X
• Muscles of the Pharynx
– Pharyngeal constrictors: Superior/Middle/Inferior constrictors
– Laryngeal elevators: Palatopharyngeus/ Salpingopharyngeus/ Stylopharyngeus
– Palatal muscles: Tensor veli palatini/ levator veli palatini
– Constrictors are innervated by CN X
– Elevators are innervated by CN IX and CN X
– Palatals are innervated by CN V and CN X
• Anterior Muscles of the Neck
– Digastric: Anterior belly (CN V)/ Posterior belly (CN VII)
– Mylohyoid: CN V
– Geniohyoid: CN XII
– Stylohyoid: CN VII
– Sternocleidomastoid: CN XI
– Omohyoid: Cervical nerve C 1–C 3
– Sternothyroid: Cervical nerve C 1–C 3
– Sternohyoid: Cervical nerve C 1–C 3
– Thyrohyoid: CN XII
Muscles of the Vertebral Column
• The muscles of the back form three distinct layers
– Superficial layer (extrinsic back muscles): move the neck
– Intermediate layer (extrinsic back muscles): move the vertebral column
– Deep layer (intrinsic back muscles): interconnect the vertebrae
• The Superficial Layer of the Intrinsic Back Muscles
– Splenius capitis
– Splenius cervicis
– Both are innervated by cervical nerves
• The Intermediate Layer of the Intrinsic Back Muscles
– Erector spinae (group of three muscles)
▪ Spinalis (most medial of the three)
▪ Longissimus
▪ Iliocostalis (most lateral of the three)
• The Deep Layers of the Intrinsic Back Muscles
– Transversospinales (a group of five muscles)
▪ Semispinalis
▪ Multifidus
▪ Rotatores
▪ Interspinales
▪ Intertransversarii
• Spinal Flexors
– Longus capitis
– Longus colli
▪ The above two muscles rotate or flex the neck
– Quadratus lumborum
▪ Flexes the vertebral column laterally
Oblique and Rectus Muscles
• These muscles can be grouped in this manner:
– Cervical muscles
▪ Scalene muscles
– Thoracic muscles
▪ Intercostals/transversus muscles/serratus
– Abdominal muscles
▪ Oblique/Transversus abdominis
• Cervical muscles
– Scalene muscles
▪ Anterior
▪ Middle
▪ Posterior
– All scalenes will elevate the ribs (inhalation)
• Thoracic muscles
– Intercostal muscles
▪ External intercostal: elevates the ribs
▪ Internal intercostal: depresses the ribs
– Transversus thoracis: depresses the ribs
– Serratus posterior muscles
▪ Superior: elevates the ribs
▪ Inferior: depresses the ribs
• Abdominal muscles
– External oblique
▪ Compresses the abdomen/depresses ribs/laterally flexes the torso
– Internal oblique
▪ Compresses the abdomen/depresses ribs/laterally flexes the torso
• Rectus muscles
– Cervical region
▪ Geniohyoid/Omohyoid
▪ Sternohyoid/Sternothyroid
– Thoracic region
▪ Diaphragm
– contracts and expands thoracic cavity
– Abdominal region
▪ Rectus abdominis
– Depresses ribs/flexes vertebral column
– Consists of linea alba and tendinous inscriptions
• The Diaphragm
– Major breathing muscle
– When it contracts, the diaphragm lowers to increase the volume of the thoracic cavity
▪ Inspiration
– When it relaxes, the diaphragm rises to lower the volume of the thoracic cavity
▪ Expiration
Muscles of the Perineal Region and the Pelvic Diaphragm
• The perineal region (pelvic floor)
– Divided into two triangles
▪ Urogenital triangle (anterior triangle)
▪ Anal triangle (posterior triangle)
– Pelvic diaphragm: forms the foundation
– The two triangles are separated by:
▪ Superficial transverse perineal muscle
• Muscles of the urogenital triangle
– Superficial urogenital triangle muscles
▪ Superficial transverse perineal
▪ Ischiocavernosus
▪ Bulbospongiosus
– Deep urogenital triangle muscles
▪ Deep transverse perineal
▪ External urethral sphincter
• Muscles of the anal triangle
– Coccygeus
– Levator ani
▪ Iliococcygeus
▪ Pubococcygeus
– External anal sphincter
Chapter 11: Appendicular Muscles
Appendicular muscles are responsible for:
▪ Stabilizing the pectoral and pelvic girdles
▪ Moving the upper and lower limbs
▪ Absorbing shocks and jolts as you walk, run, or jump
▪ Aiding in strengthening the joint area
• Two major groups of appendicular muscles
– The muscles of the pectoral girdle and upper limbs
– The muscles of the pelvic girdle and lower limbs
Factors Affecting Appendicular Muscle Function
• Action lines of the shoulder joint
– Direction of pull
– Flexion and extension at the shoulder joint
– Adduction and abduction at the shoulder joint
– Medial and lateral rotation at the shoulder joint
• Spurt and shunt muscles
– Flexors and extensors
– Spurt
▪ Muscle that inserts close to the joint
– Shunt
▪ Muscle that inserts far away from the joint
• Action lines at the hip joint
– Flexion and extension
– Abduction and adduction
– Medial rotation and lateral rotation
Muscles of the Pectoral Girdle and Upper Limbs
• Muscles associated with the pectoral girdle and upper limbs can be divided into four groups
– Muscles that position the pectoral girdle
– Muscles that move the arm
– Muscles that move the forearm and hand
– Muscles that move the hand and fingers
• Muscles That Position the Pectoral Girdle
– These muscles also coordinate with the muscles that move the arm
▪ Trapezius: Rotates scapula and extend the neck
▪ Rhomboid: Adducts the scapula
▪ Levator scapulae: Elevates the scapula
▪ Pectoralis minor: Protracts the shoulder
▪ Serratus anterior: Protracts the scapula
▪ Subclavius: Protracts the scapula
Muscles of the Pectoral Girdle and Upper
Limbs (3 of 10)
• Muscles That Move the Arm
– Deltoid: Abducts the arm
– Supraspinatus: Abduction
at the shoulder
– Infraspinatus: Lateral
rotation at the shoulder
– Subscapularis: Medial
rotation at the shoulder
– Teres major: Extension and
medial rotation at shoulder
– Teres minor: Lateral
rotation and adduction at
shoulder
9
Muscles of the Pectoral Girdle and Upper
Limbs (4 of 10)
• Muscles That Move the Arm
– Coracobrachialis: Adduction
and flexion at shoulder
– Pectoralis major: Adducts,
flexes, and medially rotates
the arm
– Latissimus dorsi: Extension,
adduction, medial rotation at
shoulder
• Rotator cuff: consists of the
following muscles: supraspinatus,
infraspinatus, subscapularis, and
teres minor
Muscles of the Pectoral Girdle and Upper
Limbs (5 of 10)
• Muscles That Move the Forearm and
Hand
– Triceps brachii: Extension at
the elbow
– Biceps brachii: Flexion at the
elbow and supinates the forearm
– Brachialis: Flexion at the elbow
– Brachioradialis: Flexion at the
elbow
– Anconeus: Extension at the
elbow
– Pronator teres: Pronates the
forearm
– Supinator: Supinates the
forearm
11
Muscles of the Pectoral Girdle and Upper
Limbs (6 of 10)
• Muscles That Move the Forearm
and Hand
– Flexor carpi ulnaris: Flexion
and adduction at wrist
– Flexor carpi radialis:
Flexion and abduction at
wrist
– Palmaris longus: Flexion at
wrist
Muscles of the Pectoral Girdle and Upper
Limbs (7 of 10)
• Muscles That Move the
Forearm and Hand
– Extensor carpi ulnaris:
Extension and adduction
at wrist
– Extensor carpi radialis:
Extension and abduction
at wrist
▪ Extensor carpi
radialis longus
▪ Extensor carpi
radialis brevis
– Pronator quadratus:
Pronates forearm and
hand
13
Muscles of the Pectoral Girdle and Upper
Limbs (8 of 10)
• Muscles That Move the Hand and Fingers
– Extrinsic Muscles of the Hand
▪ These muscles are found mostly in
the forearm
– Abductor pollicis longus
– Extensor digitorum
– Extensor pollicis brevis
– Extensor indicis
– Extensor digiti minimi
– Flexor digitorum superficialis
– Flexor digitorum profundus
– Flexor pollicis longus
Extensor retinaculum
(not a muscle)
Flexor retinaculum (not
a muscle)
Muscles of the Pectoral Girdle and Upper
Limbs (9 of 10)
• Muscles That Move the Hand and Fingers
– Extrinsic Muscles of the Hand
▪ Tendons of the muscles listed on
the previous slide pass through
synovial tendon sheaths,
located within the wrist area
15
Muscles of the Pectoral Girdle and Upper
Limbs (10 of 10)
• Muscles That Move the Hand and Fingers
– Intrinsic Muscles of the Hand
▪ These muscles are found mostly
in the palm or the dorsum of the
hand
– Adductor pollicis
– Opponens pollicis
– Palmaris brevis
– Abductor digiti minimi
– Abductor pollicis brevis
– Flexor pollicis brevis
– Flexor digiti minimi brevis
– Opponens digiti minimi
– Lumbrical
– Dorsal interossei
– Palmar interossei
Compartments and Sectional Anatomy of
the Arm and Forearm (1 of 2)
• The deep fascia extends between the bones and the superficial fascia and
separates the soft tissues of the limb into separate compartments
– Lateral intermuscular septum
– Medial intermuscular septum
– Both septa create compartments within the upper arm
Compartment Muscles Blood Vessels Nerves doublecross
Anterior
compartment
Biceps brachii
Brachialis
Coracobrachialis
Brachial artery
Inferior ulnar collateral artery
Superior ulnar collateral
artery
Brachial veins
Median nerve
Musculocutaneous
nerve
Ulnar nerve
Posterior
compartment
Triceps brachii Deep brachial artery Radial nerve
17
Compartments and Sectional Anatomy of
the Arm and Forearm (2 of 2)
• The forearm
– Divided into four compartments
Compartment Muscles Blood Vessels Nerves
Anterior
compartment
Superficial
Flexor carpi radialis
Flexor carpi ulnaris
Flexor digitorum superficialis
Palmaris longus
Pronator teres
Radial artery
Ulnar artery
Anterior interosseous artery
Anterior ulnar recurrent artery
Posterior ulnar recurrent artery
Median nerve
Ulnar nerve
Anterior interosseous nerve
Ulnar nerve
Median nerve
Deep Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus
Blank
Lateral
compartment
Brachioradialis
Extensor carpi radialis brevis
Extensor carpi radialis longus
Radial artery Radial nerve
Posterior
compartment
Abductor pollicis longus
Anconeus
Extensor carpi ulnaris
Extensor digitorum
Extensor digiti minimi
Extensor indicis
Extensor pollicis brevis
Extensor pollicis longus
Supinator
Posterior interosseous artery
Posterior ulnar recurrent artery
Posterior interosseous
nerve
Muscles of the Pelvic Girdle and Lower
Limb (1 of 16)
• The muscles of the lower limbs are larger
and more powerful than those of the upper
limbs
• These muscles can be divided into three
groups
– Muscles that move the thigh
– Muscles that move the leg
– Muscles that move the foot and toes
19
Muscles of the Pelvic Girdle and Lower
Limb (2 of 16)
• Muscles That Move the Thigh
– Originate on the pelvis; many are
large and powerful
– Four groups
▪ Gluteal group
▪ Lateral rotator group
▪ Adductor group
▪ Iliopsoas group
Muscles of the Pelvic Girdle and Lower
Limb (3 of 16)
• Muscles That Move the Thigh
– The gluteal muscles
▪ Gluteus maximus
– Extension and lateral
rotation at the hip
– Inserts within the tensor
fasciae latae via the
iliotibial tract to the tibia
▪ Gluteus medius
– Abduction and medial
rotation at the hip
▪ Gluteus minimus
– Abduction and medial
rotation at the hip
▪ Tensor fasciae latae
– Extension of the knee
and lateral rotation of the
leg
21
Muscles of the Pelvic Girdle and Lower
Limb (4 of 16)
• Muscles That Move the Thigh
– The lateral rotator group
▪ Obturator muscles
– Lateral rotation and
abduction of hip
▪ Piriformis
– Lateral rotation and
abduction of hip
▪ Gemelli muscles
– Lateral rotation and
abduction of hip
▪ Quadratus femoris
– Lateral rotation of hip
Muscles of the Pelvic Girdle and Lower
Limb (5 of 16)
• Muscles That Move the Thigh
– The adductor group
▪ Adductor brevis
– Adduction and flexion at the hip
▪ Adductor longus
– Adduction and medial rotation at the
hip
▪ Adductor magnus
– Adduction at the hip
▪ Pectineus
– Flexion and adduction at the hip
▪ Gracilis
– Flexion and medial rotation at the
knee
– Adduction and medial rotation at the
hip
23
Muscles of the Pelvic Girdle and Lower
Limb (6 of 16)
• Muscles That Move the Thigh
– The iliopsoas group
▪ Iliacus
– Flexion at the hip
▪ Psoas major
– Flexion at the hip
Muscles of the Pelvic Girdle and Lower
Limb (7 of 16)
• Muscles That Move the Leg
– Extensors of the knee
(collectively called the
quadriceps femoris). The first
three in this list are the vastus
muscles
▪ Vastus intermedius
– Extends the leg
▪ Vastus lateralis
– Extends the leg
▪ Vastus medialis
– Extends the leg
▪ Rectus femoris
– Extends the leg
– Flexion at the hip
25
Muscles of the Pelvic Girdle and Lower
Limb (8 of 16)
• Muscles That Move the Leg
– Flexors of the knee (collectively
called the hamstrings)
▪ Biceps femoris
– Flexes the leg
– Extension at the hip
▪ Semimembranosus
– Flexes the leg
▪ Semitendinosus
– Flexes the leg
Muscles of the Pelvic Girdle and Lower
Limb (9 of 16)
• Muscles That Move the Leg
– Flexors of the knee
▪ Sartorius
– Allows crossing of the
lower leg
– Flexes, abducts, and
laterally rotates the hip
– Not a part of the
quadriceps
▪ Popliteus
– Medially rotates the hip
– Not a part of the
hamstrings
27
Muscles of the Pelvic Girdle and Lower
Limb (10 of 16)
• Muscles That Move the Foot and
Toes
– Extrinsic Muscles of the Foot
▪ Muscles that originate on the
distal end of the femur or on
the tibia or fibula but yet move
the foot and toes
– Intrinsic muscles of the foot
▪ Muscles that originate on
some aspect of the foot but yet
move the toes
Muscles of the Pelvic Girdle and Lower
Limb (11 of 16)
• Muscles That Move the Foot and
Toes
– Extrinsic Muscles of the Foot
▪ Tibialis anterior: Dorsiflexion
and inversion of the foot
▪ Gastrocnemius: Plantar flexion
▪ Fibularis brevis: Plantar flexion
and eversion of the foot
▪ Fibularis longus: Plantar
flexion and eversion of the foot
▪ Plantaris: Plantar flexion
▪ Soleus: Plantar flexion
▪ Tibialis posterior: Plantar
flexion and inversion of the foot
29
Muscles of the Pelvic Girdle and Lower
Limb (12 of 16)
• Muscles That Move the Foot and
Toes
– Extrinsic Muscles of the Foot
▪ The gastrocnemius and
soleus insert onto the
calcaneal tendon, which
inserts onto the calcaneus
(calcaneal bone)
▪ The superior extensor
retinaculum and inferior
extensor retinaculum
stabilize the tendons in the
tarsal area
Muscles of the Pelvic Girdle and Lower
Limb (13 of 16)
•Muscles That Move the
Foot and Toes
– Extrinsic Muscles of
the Foot
▪ Flexor digitorum
longus: flexion of toes
2–5
▪ Flexor hallucis
longus: flexion of the
hallux
▪ Extensor digitorum
longus: extension of
toes 2–5
▪ Extensor hallucis
longus: extension of
the hallux
31
Muscles of the Pelvic Girdle and Lower
Limb (14 of 16)
• Muscles That Move the Foot and Toes
– Intrinsic Muscles of the Foot
▪ Abductor hallucis: abduction of the
hallux
▪ Flexor digitorum brevis: flexion of
toes 2–5
▪ Abductor digiti minimi: abduction
of the little toe
▪ Lumbricals: extension of toes 2–5
▪ Flexor hallucis brevis: flexion of
the hallux
▪ Flexor digiti minimi brevis: flexion
of the little toe
▪ Plantar aponeurosis is superficial fascia tissue of the plantar surface of the foot
– Intrinsic Muscles of the Foot
▪ Quadratus plantae: flexion of toes 2–5
▪ Adductor hallucis: adducts the hallux
▪ Plantar interossei: adduction of toes 3–5
Muscles That Move the Foot and Toes
Intrinsic Muscles of the Foot
▪ Extensor digitorum brevis
– Extension of the toes of digits 1–4
▪ Dorsal interossei
– Abduction of toes 3 and 4
– Extension of toes 2 through 4
Compartments and Sectional Anatomy of the Thigh and Leg
– Medial and lateral intermuscular septa
– Thigh is divided into compartments:
▪ Anterior
▪ Posterior
▪ Medial
– Lower leg is divided into compartments:
▪ Anterior
▪ Lateral
▪ Superficial posterior
▪ Deep posterior