Skeletal Muscle Flashcards
Functions of skeletal muscle
- Produce movement
- Maintain posture and balance
- Support soft tissue
- Guard entrances and exits
- Maintain body temperature
Structure of skeletal muscle
- Contain muscle cells are called “muscle fibre” and supported by connective tissue, blood vessels and nerves.
- Different from typical cells as they are long (up to 60cm) and multinucleated (nuclei at periphery)
- Consists of repeated units of myofilament such as thick filaments of myosin and thin filaments of actin. Both filaments interact to produce muscle contraction.
What determines the location and shape of muscle?
- Depends on the muscle function.
E.g thick muscle across joints to produce movement such as biceps
Flat sheet muscle protect support soft tissue such as abdominal organs
Circular muscle are guard openings such as mouth
How many muscle makes up the axial muscle?
Made up of 60% skeletal muscle
What are the functions for head, neck and face?
Swallowing, facial expression and chewing
Functions of muscle for Facial Expressions
A. Thin sheet of muscle beneath the skin and underlying tissue
B. Attached to fascia hence, move only skin
C. Surrounds the lips, eyes, mouth and ears
List the muscle of facial expression
- Frontalis: raise the eyebrow and wrinkles on forehead
- Orbicularis oculi: surrounds and close the eyes
- Orbicularis oris: compresses the lips, surrounds the mouth
- Risorius: draw the angle of mouth laterally
- Buccinator: compresses the lip and cheeks against the teeth
- Zygomaticus: draw the lips upward and outward like smiling
Muscle of Mastoid Process
- Temporalis: elevate mandible or closes mouth
2, Masseter: elevate mandible or closes mouth - Pterygloids: move mandible from side to side
What are the two muscles of neck
- Platysma
2. Sternocleidomastoid
Describe Platysma
- Thin sheet of superficial fascia of neck
- Originated from deep fascia of neck
- Covers the mandible and skin of cheek
- Action includes; tense or tightness of neck and depresses mandible
Describe sternocleidomastoid
- Originated from the clavicle and sternum
- Prominent muscle of both side of neck
- Covers the temporal of mastoid processes
- Action includes; flex the neck on both sides and turning face from opposite side
List the components of structure that is covered by the muscle of trunk
- Vertebrae column
- Thorax
- Abdominal wall
Describe vertebrae column
- Made up of several layers of muscle arranged in longitudinally
- Responsible for flexion and extension of head, neck and trunk
- Muscle involved is “erector spinae muscle”
Describe “Aponeurosis”
Thin strong sheet of fibrous tissue
2 Muscles under Thoracic Region
- Intercostal Muscle
2. Diaphragm
Describe intercostal muscle
- Made up of 3 layers of muscle between ribs
A. External: Elevate Ribs (inhale)
B. Internal: Depress Ribs (exhale)
C. Transverse Thoracis: Depress Ribs
Important for respiration
Describe Diaphragm
- Large dome shape that separates the thoracic from abdominal cavity.
- Consist of 3 openings such as aorta, inferior vena cava and oesophagus
- Actions include :
A. Aid in respiration
B. Assist in abdominal muscle of labour, defecation and micturition
4.supplied by nerves known as phrenic nerve
What is the purpose of abdominal wall?
Protect the abdominal organs
List the two muscles under abdominal wall
- Lateral
2. Medial Muscle
List the muscle under the lateral muscle
- External Oblique Muscle:
A. Broad Thin Muscle
B. Runs downward medially
C. Forms the lower border of muscle known as “Inguinal Ligament” - Internal Oblique Muscle
A. Runs upward medially
B. Beneath the external oblique muscle but superficial to transverse abdominis muscle - Transverse Abdominis Muscle
A. Runs horizontally
B. Lies deep into internal oblique muscle
Describe the medial muscle
- Consist of rectal muscle
- Thick muscle on either side of midline
- Fibre runs vertically
- Covered by rectal sheath
Lists the two segments of medial muscle
- Linea alba : form medial edge
2. Linea semilunaris: forms lateral edge
Action of medial muscle
- Protect and support abdominal organ
- Flex and rotate trunk
- Help in vomiting, micturition, defecation and parturition
What is abdominal hernia
Protrusion part of abdomen contents beyond the abdominal wall due to ageing and abdominal surgery
